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Codeine and acetaminophen in combination have proven to be an effective analgesic treatment for moderate-to-severe and postoperative pain in humans. Studies have demonstrated that codeine and acetaminophen, when administered as sole agents, are well tolerated by horses. In the current study, we hypothesized that administration of the combination of codeine and acetaminophen would result in a significant thermal antinociceptive effect compared with administration of either alone. Six horses were administered oral doses of codeine (1.2 mg/kg), acetaminophen (20 mg/kg), and codeine plus acetaminophen (1.2 mg/kg codeine and 6-6.4 mg/kg acetaminophen) in a three-way balanced crossover design. Plasma samples were collected, concentrations of drug and metabolites determined via liquid chromatography-mass spectrometry, and pharmacokinetic analyses were performed. Pharmacodynamic outcomes, including effect on thermal thresholds, were assessed. Codeine C max and AUC were significantly different between the codeine and combination group. There was considerable inter-individual variation in the pharmacokinetic parameters for codeine, acetaminophen, and their metabolites in horses. All treatments were well tolerated with minimal significant adverse effects. An increase in the thermal threshold was noted at 1.5 and 2 h, from 15 min through 6 h and 0.5, 1, 1.5, and 3 h in the codeine, acetaminophen, and combination groups, respectively., (© 2023 John Wiley & Sons Ltd.)

Background: Clodronate is a potent antiresorptive agent labelled for use in horses over 4 years of age, for the treatment of navicular syndrome. Concerns regarding the extra-label use of clodronate in equine athletes, such as racehorses, have been raised as inhibition of osteoclast activity by clodronate has been postulated to interfere with normal bone healing, which is imperative to the repair of microfractures. The paucity of data describing the long-term pharmacokinetics of clodronate and effects on biomarkers of bone resorption necessitates further study., Objectives: (1) To determine clodronate concentrations in blood and urine over a 6-month period in horses undergoing treadmill exercise and (2) to assess the effects of clodronate on protein biomarkers of bone remodelling in this same group of horses., Study Design: Randomised controlled experimental study., Methods: Seven exercised Thoroughbred horses received a single im administration of 1.8 mg/kg clodronate and four horses received an equivalent volume of saline. Blood and urine samples were collected prior to, during and for 182 days post drug administration for drug concentration determination using liquid chromatography-tandem mass spectrometry, and determination of protein biomarker (CTX-1 and TRAcP5B) concentrations., Results: Clodronate was detectable in blood for 14-175 days and for up to 175 days in urine. For some horses, concentrations were nondetectable at one time point but detectable at a subsequent time point. The terminal serum half-life ranged from 1.80 to 283.9 days. CTX-1 concentrations were significantly higher, relative to baseline, in both treated and control groups while concentrations of TRAcP5B were significantly lower in the treated group., Main Limitations: Relatively small number of horses studied., Conclusions: Based on assessment of protein biomarkers, clodronate appears to influence osteoclasts at label doses. Furthermore, results of this study support racing regulations that preclude horses administered bisphosphonates for medical reasons, from racing for a prolonged period of time., (© 2022 EVJ Ltd.)

Background: Gastrointestinal disease has been associated with shedding of Salmonella with previous studies demonstrating that horses with colic have a higher risk of acquiring and shedding Salmonella organisms., Objectives: The purpose of this study was to determine the prevalence of and risk factors associated with Salmonella shedding in a colic population at a referral clinic., Study Design: Retrospective case-control study., Methods: For each colic case that was positive for Salmonella (n = 56), two colic cases (n = 112) that tested negative for Salmonella, were enrolled as controls. Associations between variables and Salmonella shedding were identified using logistic regression. Univariate and multivariable models were developed pertaining to (1) presenting clinicopathological data and (2) clinical variables that developed during hospitalisation., Results: Of the equids presenting with colic, 1585/1917 had a sample submitted for Salmonella testing. Of these, 56 were positive for Salmonella yielding a prevalence of 3.5%. Equids shedding Salmonella were more likely to present in July (odds ratio [OR] = 7.2; 95% confidence interval [CI] = 1.63-32.13; p = 0.009) and present with a history of fever (OR = 53.5; 95% CI = 2.57-1113.03; p = 0.01), increased lactate (OR = 1.6; 95% CI = 1.14-2.29; p = 0.007) and/or neutropenia (OR = 0.79; 95% CI = 0.65-0.97; p = 0.02). Hospitalised equids shedding Salmonella were more likely to be febrile (OR = 4.8; 95% CI = 1.47-15.8; p = 0.01) and 10 times more likely to develop reflux (OR = 10.1; 95% CI = 1.67-61.43; p = 0.01) compared to colic controls., Main Limitations: Retrospective nature of the study and bias inherent to the retrieval of data from medical records cannot be discounted. Classifying Salmonella status based on a single sample may have resulted in misclassification bias., Conclusions: The prevalence of Salmonella shedding in this colic population was low compared to earlier reports. Certain predictors such as the development of a fever or reflux in hospitalised colic cases were associated with Salmonella shedding and may help the clinician to promptly identify horses likely to shed; thus, helping institute effective use of barrier nursing precautions., (© 2022 EVJ Ltd.)

Objective: The goal of this study was to determine plasma, urine, and synovial fluid concentrations and describe the effects on biomarkers of cartilage toxicity following intra-articular dexmedetomidine administration to horses., Animals: 12 research horses., Procedures: Horses received a single intra-articular administration of 1 μg/kg or 5 μg/kg dexmedetomidine or saline. Plasma, urine, and synovial fluid were collected prior to and up to 48 hours postadministration, and concentrations were determined. The effects on CS846 and C2C were determined in synovial fluid at 0, 12, and 24 hours postadministration using immunoassays., Results: Plasma concentrations of dexmedetomidine fell below the limit of quantification (LOQ) (0.005 ng/mL) by 2.5 and 8 hours postadministration of 1 and 5 μg/kg, respectively. Synovial fluid concentrations were above the LOQ (0.1 ng/mL) of the assay at 24 hours in both dose groups. Drug was not detected in urine samples at any time postdrug administration. CS846 concentrations were significantly decreased relative to baseline at 12 hours postadministration in the saline group and significantly increased in the 5-μg/kg-dose group at 24 hours. Concentrations of C2C were significantly decreased at 12 and 24 hours postadministration in the saline treatment group. There were no significant differences in CS846 or C2C concentrations between dose groups at any time., Clinical Relevance: Systemic concentrations of dexmedetomidine remained low, compared to synovial fluid concentrations. CS846, a marker of articular cartilage synthesis, increased in a dose-dependent fashion. Based on these findings, further dose titration and investigation of analgesic and adverse effects are warranted.

Background: Cervical osteoarthritis (OA) has been documented as a potential source of pain and poor performance in sport horses., Objectives: To assess the prevalence of cervical OA in a population of Warmblood jumpers and its correlation with age, level of performance, neck pain and mobility., Study Design: Descriptive observational study., Methods: Warmblood jumpers free of lameness or neurological disorders were selected. Cervical pain and range of motion of the neck were subjectively assessed. Left to right lateral views were taken at C3-C4, C4-C5, C5-C6 and C6-C7. The presence of OA at the cervical articular process joints (APJs) was evaluated and graded as absent, mild or moderate to severe by three board-certified radiologists. The agreement between radiologists and the potential associations between OA grades with age and other variables were statistically assessed (P < .05)., Results: One hundred and four horses were included [median age = 10 years (range 6-18 years)]. Agreement between radiologists varied from fair to substantial (Kappa-weighted 0.37-0.61). The C6-C7 APJ was most commonly affected by OA with only 32.7% of APJ considered free of radiographic abnormalities at this location versus 60.5% at C5-C6, 81.7% at C4-C5 and 84.6% at C3-C4. Horses competing in higher level classes (peak of performance) had significantly higher OA grades at C6-C7 (P = .013). There was no association between age, age when started jumping, neck pain and neck range of motion with the presence of OA on radiographs., Main Limitations: Open enrolment and lack of orthogonal views., Conclusions: This study showed that, although there is a range of interpretation of radiographic findings of the APJ, OA of the caudal cervical region is not rare in performing sound Warmblood jumpers. This suggests that OA in the caudal cervical region may be of low clinical significance., (© 2020 EVJ Ltd.)

Flunixin meglumine is a highly efficacious nonsteroidal anti-inflammatory drug commonly used in equine medicine and especially in performance horses. Recently, a new transdermal flunixin meglumine product has been approved for use in cattle. Although not currently approved for use in the horse, the convenience of this product may prove appealing for use in horses, warranting study. Six horses were administered a single transdermal dose of 500 mg and blood and urine samples collected for up to 96 h post-administration. Serum for determination of thromboxane concentrations and whole blood samples was collected at various time and challenged with lipopolysaccharide, calcium ionophore, or methanol to induce ex vivo synthesis of eicosanoids. Concentrations of flunixin, 5-OH flunixin, and eicosanoids were measured using LC-MS/MS and non-compartmental pharmacokinetic analysis performed on concentration data. Serum concentrations of flunixin and 5-OH flunixin were above the limit of quantitation at 96 h post-administration in both serum and urine. The mean (range) for C max , T max and the terminal half-life were 515.6 (369.7-714.0) ng/ml, 8.67 (8.0 12.0) h, and 22.4 (18.3-42.5) h, respectively. Following transdermal administration, based on effects on eicosanoid synthesis, flunixin meglumine inhibited cyclooxygenase 1 and 2 and 15-lipooxygenase activity, with anti-inflammatory effects lasting for 24-72 h., (© 2021 John Wiley & Sons Ltd.)

Background: Chronic progressive lymphoedema (CPL) is a disabling condition affecting various draft horse breeds, including Friesian horses., Hypothesis: The high incidence of CPL in Friesian horses suggests a genetic component and a predisposing phenotype., Animals: For the genomic study, 26 affected and 19 control horses were evaluated. Body measurements were taken from 28 affected and nine control Friesian horses., Methods and Materials: Axiom® Equine Genotyping Array with a total of 307,474 single nucleotide polymorphism (SNPs) was used for the case/control genome-wide association study (GWAS). Height, weight and leg measurements (seven different body measurements) were obtained and compared between groups., Results: No significant associations were identified with the GWAS. There were significant differences (P < 0.05) in gaskin length measurements between CPL-affected horses and controls., Conclusion: The current study suggests that the potential genetic contribution to CPL in Friesian horses is complex and may include other SNP-associated factors. Significantly increased gaskin length of affected horses suggests a phenotype prone to developing CPL., (© 2019 ESVD and ACVD.)

Background: Antimicrobial treatment protocols for foals with sepsis that do not improve clinically often are adjusted based on bacteriological and antimicrobial susceptibility testing results from samples collected at hospital admission., Objectives: To evaluate whether hospitalization for ≥48 hours affects bacteriological and antimicrobial susceptibility testing results., Animals: Two-hundred sixty-seven foals <30 days of age admitted to a neonatal intensive care unit and diagnosed with sepsis., Methods: Medical records were reviewed retrospectively to identify foals with sepsis and positive bacteriological cultures. Results from samples collected at hospital admission were compared to those collected ≥48 hours after admission. Logistic regression for clustered data and exact logistic regression were used for statistical analysis., Results: Three-hundred fifty-three unique bacterial isolates were obtained from 231 foals at hospital admission and 92 unique bacterial isolates were obtained from 57 foals after ≥48 hours of hospitalization. Relative isolation frequency after ≥48 hours of hospitalization increased for Acinetobacter spp., 0.6% versus 3.3% (odds ratio [OR], 7.63; 95% confidence interval [CI], 1.28-45.45); Enterococcus spp., 4.8% versus 19.6% (OR, 5.37; 95% CI, 2.64-10.90); Klebsiella spp., 5.1% versus 10.9% (OR, 2.27; 95% CI, 1.05-4.89); Pseudomonas spp., 3.0% versus 7.6% (OR, 3.49; 95% CI, 3.49-240.50); and Serratia spp., 3.0% versus 5.4% (OR, 20.23; 95% CI, 2.20-186.14). Bacteria isolated after ≥48 hours of hospitalization were less susceptible to all tested antimicrobial drugs, except for imipenem., Conclusions and Clinical Importance: Decreased antimicrobial susceptibility of bacteria isolated after ≥48 hours of hospitalization provides a rationale for repeated bacteriological culture and susceptibility testing in hospitalized foals with sepsis., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

OBJECTIVE To assess incidence of incisional infection in horses following management with 1 of 3 protective dressings after exploratory celiotomy for treatment of acute signs of abdominal pain (ie, colic) and determine the risk of complications associated with each wound management approach. DESIGN Prospective, randomized, controlled study. ANIMALS 85 horses. PROCEDURES Horses were assigned to 3 groups. After standardized abdominal closure, a sterile cotton towel (group 1) or polyhexamethylene biguanide-impregnated dressing (group 2) was secured over the incision site with 4 or 5 cruciate sutures of nonabsorbable monofilament, or sterile gauze was placed over the site and secured with an iodine-impregnated adhesive drape (group 3). Demographic and clinicopathologic data, intraoperative and postoperative variables, and development of complications were recorded and compared among groups by statistical methods. Follow-up information was collected 30 and 90 days after surgery. Incidence and odds of incisional complications were calculated. RESULTS 75 horses completed the study. Group 3 typically had dressing displacement necessitating removal during anesthetic recovery; dressings were in place for a mean of 44 and 31 hours for groups 1 and 2, respectively. Purulent or persistent serosanguinous incisional discharge (ie, infection) was detected in 11 of 75 (15%) horses (2/24, 0/26, and 9/25 from groups 1, 2, and 3, respectively). Odds of incisional complications were significantly greater for group 3 than for groups 1 or 2. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that risk of infection after celiotomy for treatment of colic is lower for incisions covered with sterile towels or polyhexamethylene biguanide-impregnated dressings secured with sutures than for incisions covered with gauze secured with iodine-impregnated adhesive drapes.

Phenylbutazone (PBZ) is a potent mon-steroidal anti-inflammatory drug used commonly in performance horses. The objectives of the current study were to describe blood and urine concentrations and the pharmacokinetics of PBZ and its metabolites following intravenous (IV) and oral administration and to describe the duration of pharmacodynamic effect. To that end, 17 horses received an IV administration and 18 horses an oral administration of 2 g of PBZ. Blood and urine samples were collected prior to and for up to 96 hours post drug administration. Whole blood samples were collected at various time points and challenged with lipopolysaccharide or calcium ionophore to induce ex vivo synthesis of eicosanoids. Concentrations of PBZ and eicosanoids were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and non-compartmental pharmacokinetic analysis performed on concentration data from IV and oral administration. Serum concentrations of PBZ and its metabolites were below the limit of quantitation at 96 hours post administration. The volume of distribution at steady state, systemic clearance, and terminal half-life was 0.194 ± 0.019 L/kg, 23.9 ± 4.48 mL/h/kg, and 10.9 ± 5.32 hours, respectively. The terminal half-life following oral administration was 13.4 ± 3.01 (paste) and 15.1 ± 3.96 hours (tablets). Stimulation of PBZ treated whole blood with lipopolysaccharide and calcium ionophore resulted in an inhibition of TXB 2 , PGE 2 , LTB 4 and 15-HETE production for a prolonged period of time post drug administration. The results of this study suggest that PBZ has a prolonged anti-inflammatory following IV or oral administration of 2 g to horses., (© 2018 John Wiley & Sons, Ltd.)

The study objectives were to provide cumulative antimicrobial susceptibility data at the patient level and to evaluate the effect of initial antimicrobial treatment on survival in foals with sepsis. Foals below 30days of age with a diagnosis of sepsis, confirmed by isolation of bacteria from normally sterile sites on the day of hospital admission, were included. Susceptibility testing was performed using the broth microdilution procedure. In total, 213 foals and 306 bacterial isolates were included. The likelihood of survival for foals from which all bacteria were susceptible to the initial antimicrobial treatment was 65.4% (n=106/162; 95% confidence interval (CI) 57.6% to 72.7%) versus 41.7% (n=10/24; 95% CI 22.1% to 63.4%) if one or more isolates were resistant (relative risk 1.57, 95% CI 0.96 to 3.06). Based on this study, amikacin combined with ampicillin remains an appropriate antimicrobial drug combination for initial treatment of foals with sepsis., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Neuroglycopenia refers to a shortage of glucose in the brain resulting in neuronal dysfunction and death if left untreated. Presumed neuroglycopenia has not been described in horses., Objective: To report neurological signs in horses with presumed neuroglycopenia as the result of severe hypoglycemia., Animals: Ninety horses (hours to 28 years of age) diagnosed with hypoglycemia (blood glucose concentration < 75 mg/dL [< 4.2 mmol/L])., Methods: Retrospective study. Electronic medical records were searched. Signalment, history, complaint, clinical signs, laboratory findings including CSF analysis, electroencephalogram, clinical or definitive diagnosis, and outcome were recorded. Kruskal-Wallis analysis of variance and logistic regression were used to investigate association between blood glucose concentration and data extracted. Statistical significance was set at P < 0.05., Results: Thirty-eight and 52 horses had mild (50-74 mg/dL [2.8-4.1 mmol/L]), and severe hypoglycemia (< 50 mg/dL [< 2.8 mmol/L]), respectively. Most common causes of hypoglycemia included liver and gastrointestinal (40%) disease, sepsis (33%), neoplasia (7%), and insulin-induced (4%). Most common neurologic deficits included obtundation (100%), seizures (42%), and disorientation (22%). CSF-glucose was severely low (mean 2.5 mg/dL [0.1 mmol/L], median 0 mg/dL). Paroxysmal discharges in support of seizures were identified in the occipital (visual) and parietal (closest to temporal-auditory) cortical regions upon EEG examination (8/8 horses)., Conclusions and Clinical Importance: Neuroglycopenia is presumed to occur in horses as the result of severe hypoglycemia. Subclinical seizures, and intermittent blindness and deafness of cortical origin can occur. Severe altered state of consciousness and seizures can be observed at a blood glucose cut-off value of < 42 mg/dL (< 2.3 mmol/L)., (Copyright © 2018 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: Due to the high prevalence of EIPH in racehorses and its potential impact on the horse's health, furosemide administration is permitted up to 4-h prior to post time in most North American racing jurisdictions. Anecdotal reports suggest that administration of furosemide 24-h prior to strenuous exercise may be equally effective in decreasing the severity of EIPH., Objectives: To 1) compare the efficacy of furosemide in reducing the presence and severity of EIPH when administered 4- or 24-h prior to strenuous exercise 2) characterise electrolyte and blood parameters following administration of furosemide at 4- and 24-h prior to exercise., Study Design: 3-way crossover., Methods: Fifteen Thoroughbred racehorses received 5 mL of 0.9% NaCl or 250 mg of furosemide either 4- or 24-h prior to a 5-furlong simulated race. Blood samples were collected prior to and post-run for determination of furosemide, lactate, haemoglobin and electrolyte concentrations. One-hour post-race, an endoscopic exam and bronchoalveolar lavage (BAL) were performed. Horses were assigned an EIPH score based on predetermined criteria and the number of red blood cells in BAL fluid was determined., Results: Endoscopic EIPH scores were lower in the 4-h vs. the 24-h (P = 0.03) furosemide groups. RBC counts in BAL fluid were lower in the 4-h furosemide vs. saline treatment groups (P = 0.01) but no difference was noted between the saline and 24-h furosemide groups (P = 0.3), nor between the 4- and 24-h groups (P = 0.5)., Main Limitations: Small sample size and large range of running times for the 5-furlong work., Conclusions: While none of the treatments prevented EIPH, endoscopic scores and RBC counts in BAL fluid support the efficacy of furosemide in reducing the severity of EIPH. Endoscopic scores were lower in the 4-h furosemide group compared with 24-h administration. Red blood cell counts were lower in the 4-h furosemide group compared with saline treatment., (© 2017 EVJ Ltd.)

Background: Temporohyoid osteoarthropathy (THO) is a cause of neurological disease in horses that is characterised by facial and vestibulocochlear nerve deficits. Studies reporting and comparing survival following medical or surgical treatment of THO are lacking., Objectives: To compare survival and prognosis in horses with THO treated medically or surgically, and to report surgical complications., Study Design: Retrospective study., Methods: The medical records of horses diagnosed with THO were retrieved, and data on signalment, clinical signs and duration, corneal ulceration and bilateral occurrence were recorded. Neurological severity was graded according to clinical signs. Preoperative radiographic and endoscopic images were graded according to the severity of changes. Factors potentially affecting survival and treatment were compared using Cox proportional hazards regression., Results: A total of 77 horses were identified as having THO during the period 1990-2014. Of these, 25 horses underwent ceratohyoid ostectomy (CHO) and eight underwent partial stylohyoid ostectomy (PSHO). Thirteen of 20, one of 25 and one of eight horses treated by medical therapy, CHO and PSHO, respectively, died or were subjected to euthanasia as a consequence of THO. Compared with CHO, medical therapy was significantly associated with nonsurvival, but there were no significant differences in survival between horses undergoing PSHO and medical therapy. The duration of clinical signs, and neurological, radiographic and endoscopic grades were not associated with survival of THO. However, the age of the horse was significantly associated with poorer survival. Survival time was significantly shorter in the medical therapy group compared with the two surgical groups combined, but did not differ significantly between the two surgical groups. No significant difference between groups was seen in the incidence of surgical complications (33.3% in the PSHO and 22.2% in the CHO group)., Main Limitations: This was a nonrandomised study of treatment effects on survival and included a low number of cases., Conclusions: The survival prognosis in horses with THO is good to excellent in those submitted to surgical intervention, and fair in those treated with medical therapy alone., (© 2017 EVJ Ltd.)

Few studies have evaluated the effects of age and illness on serum triglyceride concentrations in neonatal foals. The objectives of this study were to evaluate triglyceride concentrations in neonatal foals and their dams through serial measurement immediately postpartum and at 1-2 days and 10-12 days of age, as well as to measure them in sick foals. Serially measured serum triglycerides in seven healthy foals varied with age. Median (range) triglyceride concentrations were 28mg/dL (12-50mg/dL), 89mg/dL (51-264mg/dL), and 60mg/dL (28-135mg/dL) immediately postpartum, at 1-2 days of age, and 10-12 days of age, respectively (P<0.001). Triglyceride concentrations varied hourly by up to 117mg/dL in individual foals. The dams had lower triglycerides (median, 20mg/dL; range, 12-49mg/dL) than the foals, once foals were >24h old. Sick foals <24h old had lower triglycerides than sick foals aged 1-7 days (median, 41mg/dL [range, 16-116]; median, 110mg/dL [range, 24-379mg/dL]; P<0.001). Age and triglyceride concentration showed a non-linear association independent of foal health status (P=0.01). Sick foals with positive bacterial cultures had higher triglycerides than those with negative cultures (median, 111mg/dL [range, 10-379mg/dL] and median 53mg/dL [range, 17-271mg/dL], respectively; P=0.033). Nonsurvivors had higher triglycerides than survivors (median, 116mg/dL [range, 41-379mg/dL] and median, 55mg/dL [range, 10-311mg/dL], respectively; P=0.04). In conclusion, triglycerides were highest in healthy neonatal foals aged 1-2 days, and in nonsurviving sick foals and those with positive bacterial cultures. Age was associated with triglyceride concentration regardless of health status., (Copyright © 2017. Published by Elsevier Ltd.)

Background: There are several reports of incisor tooth resorption and hypercementosis in horses but, to date, studies have been limited in case numbers and to advanced lesions. Tooth resorption in other species is a radiographic diagnosis of types of resorption that are often identified before clinical signs. Our goal was to evaluate radiographically incisor tooth resorption in a large population of horses, utilising interpretation criteria from canine and human dentistry., Objective: To document and classify incisor tooth resorption and hypercementosis., Study Design: Retrospective descriptive case series., Methods: Horses presented for routine dental care >5 years old were included only if owners were unaware of incisor pathology. Radiographs (three views) were obtained of the incisor teeth and incisor teeth resorption was classified according to the radiographic criteria described for man and dogs. Hypercementosis and its location were recorded., Results: Tooth resorption was detected in 149 of 169 (88.2%) horses and 951 of 1952 (48.7%) of incisor teeth. The classification system used was applicable in 926 (97.2%) of 951 affected teeth. Hypercementosis was detected in 34 (20.1%) horses and 148 (7.6%) teeth. As horses increased in age, resorption and hypercementosis was more frequent; no significant differences were found among sex or breed categories. All horses with hypercementosis had resorption, but only 23.4% of horses with resorption had hypercementosis. Advanced (stage ≥3) resorption was detected in 159 (8.1%) teeth and 54 (32.0%) horses in an otherwise clinically healthy population., Main Limitations: Certain horses' anatomy precluded isolation of the mandibular third incisor teeth from the canine teeth due to superimposition., Conclusions: Incisor tooth resorption, in particular external replacement resorption and external inflammatory resorption, is common in horses. Hypercementosis is consistently associated with resorption, but the inverse association is inconsistent., (© 2016 EVJ Ltd.)

Objective: To determine if preoperative and intraoperative physiologic variables, and surgical factors correlate with survival to anesthetic recovery or hospital discharge, repeat celiotomy, and postoperative nasogastric intubation (NGT) in horses undergoing exploratory celiotomy for small intestinal (SI) strangulating lesions., Study Design: Retrospective case series., Animals: Horses that had surgical correction of SI strangulating lesions (n = 258)., Methods: Medical records (January 2000-December 2014) of horses that had surgical correction of SI strangulating lesions were reviewed. Data collection included signalment, preoperative physical examination variables, hematologic values, presence of gastric reflux, peritoneal fluid analysis, intraoperative physiologic variables, intraoperative findings/treatments, and arterial blood gas values. Risk factors for survival to anesthetic recovery and hospital discharge were determined using exact logistic regression., Results: Survival to anesthetic recovery was 76% and survival to discharge after anesthetic recovery was 79%. The difference between abdominal and peripheral lactate concentrations and intraoperative tachycardia were associated with not surviving to anesthetic recovery or hospital discharge. Intraoperative hypotension, hypocapnia, and low intraoperative packed cell volume (PCV) were negative predictors of survival to anesthetic recovery. Low intraoperative PCV was also associated with NGT postoperatively. Performing resection-anastomosis and jejunocecostomy were associated with repeat celiotomy and with not surviving to hospital discharge., Conclusion: Several hematological and cardiorespiratory variables show good correlation with short-term survival in horses undergoing surgery for SI strangulating lesions. These variables are easily measured and could be useful for prognosticating survival in horses presenting with SI strangulating lesions., (© 2017 The American College of Veterinary Surgeons.)

Objective: To compare signalment, presentation, treatment, and outcome in horses diagnosed with corneal degeneration (CD) or calcific band keratopathy (CBK) at a referral hospital., Animals Studied: Sixty-nine horses (87 eyes) diagnosed with either CD or CBK., Procedures: Medical records of horses diagnosed with CD or CBK at the University of California-Davis Veterinary Medical Teaching Hospital (UCD-VMTH) between 2000 and 2013 were reviewed. Signalment, concurrent ophthalmic diagnoses, previous therapies, diagnostic tests, systemic diagnoses, treatment, follow-up, and outcomes were compared between horses diagnosed with CD or CBK. Age, breed, and gender were compared between the CD/CBK and UCD-VMTH populations., Results: Thirty-three horses (42 eyes) and 36 horses (45 eyes) were diagnosed with CD and CBK, respectively. Horses with CD or CBK were significantly older (P < 0.001) than the UCD-VMTH population with a median age of 16 or 18 years, respectively. Appaloosas were significantly overrepresented in the CD/CBK population (33%) in comparison with the UCD-VMTH population (1.8%, P < 0.001). Equine recurrent uveitis was concurrently diagnosed in 67% and 84% of horses with CD or CBK, respectively. Pituitary pars intermedia dysfunction (PPID) was diagnosed significantly less often in horses with CD vs. CBK (P = 0.03). Chemical chelation with ethylenediaminetetraacetic acid was performed significantly less frequently in horses diagnosed with CD (7.1%) vs. CBK (31.1% of eyes) (P = 0.012)., Conclusions: Despite some differences, equine CD and CBK are relatively similar conditions and may represent a continuum of disease severity. Horses with PPID should be monitored closely for corneal disease including CBK., (© 2016 American College of Veterinary Ophthalmologists.)

Reasons for Performing Study: The ante mortem diagnosis of equine multinodular pulmonary fibrosis (EMPF) relies on histopathological results and polymerase chain reaction (PCR)-positive equine herpesvirus (EHV)-5 testing of lung tissue. Polymerase chain reaction detection of EHV-5 in bronchoalveolar lavage fluid (BALF) is commonly used to support a diagnosis of EMPF. However, the diagnostic power of EHV-5 testing on BALF and other biological samples such as blood and nasal secretions has yet to be shown to support a diagnosis of EMPF., Objectives: To determine the frequency of detection and the viral loads of EHV-5 by quantitative PCR (qPCR) in blood, nasal secretions and BALF from horses confirmed with EMPF, healthy horses and horses with non-EMPF pulmonary diseases., Study Design: Prospective study., Methods: The study population consisted of 70 adult horses divided into 4 groups based on a combination of clinical findings, cytology of BALF, imaging studies of the thoracic cavity and histopathology of pulmonary tissue: control group (n = 14), EMPF group (n = 11); inflammatory airway disease group (n = 32); and non-EMPF interstitial lung disease group (n = 13). For each horse, whole blood, nasal secretions and BALF were available for EHV-5 qPCR testing. Sensitivities, specificities and their respective 95% confidence intervals were calculated for viral loads from blood, nasal secretions and BALF. In addition, these measures were calculated for combined use of blood and nasal secretions., Results: The detection of EHV-5 in BALF was strongly associated with EMPF (sensitivity 91%, specificity 98.3%). Detection of EHV-5 in blood was, independent of the viral loads, strongly associated with EMPF with a sensitivity of 91% and specificity of 83.1%. The detection of EHV-5 in nasal secretions displayed the highest sensitivity (72.7%) and specificity (83.1%) at a level of >245,890 glycoprotein B target genes/million cells to support a diagnosis of EMPF. Dually positive blood and nasal secretions at any viral loads in support of EMPF yielded a sensitivity and specificity of 90% and 89.8%, respectively., Conclusions: Although histopathological confirmation (lung biopsy) is considered the gold standard for EMPF diagnosis, results of qPCR testing of BALF or a combination of whole blood and nasal secretions should be regarded as clinically useful in support of this diagnosis. The latter testing may be relevant when dealing with horses in respiratory distress, for which invasive procedures such as BALF collection or lung biopsies may be detrimental to their health., (© 2015 EVJ Ltd.)

Background: Immune-mediated myositis (IMM) is a cause of rhabdomyolysis, stiffness, and muscle atrophy predominantly affecting Quarter horses. Limited information is available with regard to outcome, prognostic indicators, and associations with concurrent diseases., Hypothesis/objectives: To report outcomes and associations between outcome and clinical and laboratory parameters, and presence of concurrent illness., Animals: Sixty-eight horses; 52 Quarter horses and related breeds and 16 other breeds., Methods: Retrospective cohort study (1991-2014). Medical records of horses with histological diagnosis of IMM were reviewed. Data recovery included signalment, laboratory variables, therapy, and outcome. Logistic regression was used to quantify the association between potential prognostic factors and survival to discharge., Results: Quarter horses were younger (mean < 4 years, range 3 months-21 years) than other breeds (mean < 10 years, range 1-23 years). Pathogens causing concurrent or recent infection included S. equi equi, S. equi zooepidemicus, C. pseudotuberculosis, Anaplasma phagocytophilum, herpes virus-1, and influenza. The most common clinical signs consisted of rapidly progressive diffuse symmetrical muscle atrophy (80%), stiff gait (74%), and fever (44%). All horses that received medical therapy immediately upon admission survived to discharge (survival proportion = 87%). Leucocytosis was a common finding (60%). Horses with concurrent fever and other illness had a poor prognosis for hospital discharge., Conclusions and Clinical Importance: Horses with IMM can have a favorable outcome. Horses with concurrent fever and another illness had decreased probability of survival to discharge., (Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

OBJECTIVE To investigate the impact of age and inferred prior vaccination history on the persistence of vaccine-induced antibody against rabies in horses. DESIGN Serologic response evaluation. ANIMALS 48 horses with an undocumented vaccination history. PROCEDURES Horses were vaccinated against rabies once. Blood samples were collected prior to vaccination, 3 to 7 weeks after vaccination, and at 6-month intervals for 2 to 3 years. Serum rabies virus-neutralizing antibody (RVNA) values were measured. An RVNA value of ≥ 0.5 U/mL was used to define a predicted protective immune response on the basis of World Health Organization recommendations for humans. Values were compared between horses < 20 and ≥ 20 years of age and between horses inferred to have been previously vaccinated and those inferred to be immunologically naïve. RESULTS A protective RVNA value (≥ 0.5 U/mL) was maintained for 2 to 3 years in horses inferred to have been previously vaccinated on the basis of prevaccination RVNA values. No significant difference was evident in response to rabies vaccination or duration of protective RVNA values between horses < 20 and ≥ 20 years of age. Seven horses were poor responders to vaccination. Significant differences were identified between horses inferred to have been previously vaccinated and horses inferred to be naïve prior to the study. CONCLUSIONS AND CLINICAL RELEVANCE A rabies vaccination interval > 1 year may be appropriate for previously vaccinated horses but not for horses vaccinated only once. Additional research is required to confirm this finding and characterize the optimal primary dose series for rabies vaccination.

Background: Klebsiella spp. are implicated as a common cause of bacterial pneumonia in horses, but few reports describe clinical presentation and disease progression., Hypothesis/objectives: To describe the signalment, clinicopathologic data, radiographic and ultrasonographic findings, antimicrobial susceptibility, outcome, and pathologic lesions associated with Klebsiella spp. pneumonia in horses., Animals: Forty-six horses from which Klebsiella spp. was isolated from the lower respiratory tract., Methods: Retrospective study. Medical records from 1993 to 2013 at the William R. Pritchard Veterinary Medical Teaching Hospital, University of California, Davis were reviewed. Exact logistic regression was performed to determine if any variables were associated with survival to hospital discharge., Results: Survival in horses <1 year old was 73%. Overall survival in adults was 63%. For adults in which Klebsiella pneumoniae was the primary isolate, survival was 52%. Mechanical ventilation preceded development of pneumonia in 11 horses. Complications occurred in 25/46 horses, with thrombophlebitis and laminitis occurring most frequently. Multi-drug resistance was found in 47% of bacterial isolates. Variables that significantly impacted survival included hemorrhagic nasal discharge, laminitis, and thoracic radiographs with a sharp demarcation between marked caudal pulmonary alveolar infiltration and more normal-appearing caudodorsal lung., Conclusions and Clinical Importance: Klebsiella spp. should be considered as a differential diagnosis for horses presenting with hemorrhagic pneumonia and for horses developing pneumonia after mechanical ventilation. Multi-drug resistance is common. Prognosis for survival generally is fair, but is guarded for adult horses in which K. pneumoniae is isolated as the primary organism., (Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Thirty-three foals from a farm with a high exposure rate to Sarcocystis neurona were assigned to either an untreated or a diclazuril-treated group. Treated foals received daily 0.5 mg/kg of diclazuril pellets from 1 to 12 months of age. Monthly blood was tested for IgG against S. neurona using the indirect fluorescent antibody test. Following ingestion of colostral antibodies to S. neurona, there was a steady and continuous decline in seroprevalence to S. neurona until foals from both groups reached weaning age. Thereafter, the untreated foal group showed a significant increase in monthly seroprevalence compared to the diclazuril-treated foal group. The difference in temporal seroprevalence could be explained by the successful reduction of S. neurona infection in foals receiving a daily low-dose diclazuril., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Objectives: To determine the role of equine herpesvirus (EHV) in idiopathic keratoconjunctivitis in horses and to determine whether sample collection method affects detection of EHV DNA by quantitative polymerase chain reaction (qPCR)., Animals Studied: Twelve horses with idiopathic keratoconjunctivitis and six horses without signs of ophthalmic disease., Procedures: Conjunctival swabs, corneal scrapings, and conjunctival biopsies were collected from 18 horses: 12 clinical cases with idiopathic keratoconjunctivitis and six euthanized controls. In horses with both eyes involved, the samples were taken from the eye judged to be more severely affected. Samples were tested with qPCR for EHV-1, EHV-2, EHV-4, and EHV-5 DNA. Quantity of EHV DNA and viral replicative activity were compared between the two populations and among the different sampling techniques; relative sensitivities of the sampling techniques were determined., Results: Prevalence of EHV DNA as assessed by qPCR did not differ significantly between control horses and those with idiopathic keratoconjunctivitis. Sampling by conjunctival swab was more likely to yield viral DNA as assessed by qPCR than was conjunctival biopsy. EHV-1 and EHV-4 DNA were not detected in either normal or IKC-affected horses; EHV-2 DNA was detected in two of 12 affected horses but not in normal horses. EHV-5 DNA was commonly found in ophthalmically normal horses and horses with idiopathic keratoconjunctivitis., Conclusions: Because EHV-5 DNA was commonly found in control horses and in horses with idiopathic keratoconjunctivitis, qPCR was not useful for the etiological diagnosis of equine keratoconjunctivitis. Conjunctival swabs were significantly better at obtaining viral DNA samples than conjunctival biopsy in horses in which EHV-5 DNA was found., (© 2015 American College of Veterinary Ophthalmologists.)

Background: Few studies report the minimum inhibitory concentrations for antimicrobials against equine Corynebacterium pseudotuberculosis isolates., Hypothesis/objectives: To evaluate trends in the in vitro activities of 20 antimicrobials against equine Corynebacterium pseudotuberculosis isolates from 1996 to 2012 and to determine if a relationship exists between the minimum inhibitory concentration (MIC) and location of the abscess., Animals: Corynebacterium pseudotuberculosis isolates from 196 horses with naturally occurring disease., Methods: Retrospective and cross-sectional design. Medical records were reviewed to obtain clinical and MIC data. Minimum inhibitory concentrations were determined by the microdilution technique. The MIC results over 3 periods were compared (1996-2001, 2002-2006, 2007-2012)., Results: The MIC90 values for clinically relevant antimicrobials were as follows: chloramphenicol ≤ 4 μg/mL, enrofloxacin ≤ 0.25 μg/mL, gentamicin ≤ 1 μg/mL, penicillin =0.25 μg/mL, rifampin ≤ 1 μg/mL, tetracycline ≤ 2 μg/mL, trimethoprim-sulfamethoxazole (TMS) ≤ 0.5 μg/mL, ceftiofur =2 μg/mL, and doxycycline ≤ 2 μg/mL. There were no significant changes in MIC results over the study period. There was no relationship between MIC patterns and abscess location., Conclusions and Clinical Importance: The MIC50 and MIC90 values of antimicrobials evaluated in this study for equine isolates of C. pseudotuberculosis did not vary over time. Abscess location was not associated with different MIC patterns in cultured isolates. Several commonly used antimicrobials are active in vitro against C. pseudotuberculosis in vitro., (Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of American College of Veterinary Internal Medicine.)

Background: Recent surveillance studies for equine respiratory viruses have shown that equine influenza virus (EIV) continues to be a prevalent respiratory virus of equids throughout the United States and Europe., Objectives: To gain a better understanding of the prevalence and epidemiology of EIV shed by horses, mules and donkeys in the United States from March 2010 to November 2013., Animals: 2,605 equids., Methods: Nasal secretions from index cases with acute onset of respiratory disease were tested by qPCR for EIV. Multilevel logistic regression was used to model the association between EIV status and prevalence factors. Furthermore, observations from EIV-positive study horses were compared to previous data from March 2008 to February 2010., Results: A total of 230 (9.7%) index cases tested qPCR positive for EIV. A higher-than-expected proportion of EIV qPCR-positive horses occurred in the 1-5, 6-10, and 11-15 age groups when compared to the <1 year of age group. Fever, nasal discharge and coughing were positively associated with EIV-positive horses. EIV qPCR-positive study cases were significantly older and more often vaccinated against EIV compared to EIV qPCR-positive animals from the 2008-2010 study period., Conclusions and Clinical Importance: This study provides valuable and contemporary information on the frequency of EIV detected by qPCR in the United States. The results also underscore that older and previously vaccinated horses were susceptible to EIV., (Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of American College of Veterinary Internal Medicine.)

Reasons for Performing Study: There are currently few data available on the prognosis and outcome of recumbent horses., Objectives: To investigate the outcome of hospitalised horses that had been recumbent in the field or hospital and factors affecting their survival within the first 3 days of hospitalisation and survival after 3 days to hospital discharge., Study Design: Retrospective analysis of clinical records., Methods: Records of 148 horses admitted to the William R. Pritchard Veterinary Medical Teaching Hospital, University of California Davis from January 1995 to December 2010 with a history of recumbency or horses that became recumbent while hospitalised were evaluated. Exact logistic regression was used to assess the association between clinical parameters and survival within the first 3 days of hospitalisation and survival to hospital discharge after 3 days., Results: There were 109 nonsurvivors and 39 survivors. Multivariate analysis showed variables associated with an increased odds of death within the first 3 days of hospitalisation included duration of clinical signs prior to presentation, with horses showing clinical signs for over 24 h having increased odds of death (P = 0.043, odds ratio [OR] 4.16, 95% confidence interval [95% CI] 1.04-16.59), the presence of band neutrophils (P = 0.02, OR 7.94, 95% CI 1.39-45.46), the horse not using the sling (P = 0.031, OR 4.22, 95% confidence interval 1.14-15.68) and horses that were unable to stand after treatment (P<0.0001, OR 231.15, 95% CI 22.82-2341.33). Increasing cost was associated with lower odds of death (P = 0.017, OR 0.96, for each additional $100 billed, 95% CI 0.93-0.99)., Conclusions: This study demonstrates that the duration of clinical signs, response to treatment and the ability of horses to use a sling are associated with survival to hospital discharge for recumbent horses., (© 2013 EVJ Ltd.)

Equine infection with Corynebacterium pseudotuberculosis can manifest in several forms, including external or internal abscesses. The objective of this study was to phenotype clinical isolates of C. pseudotuberculosis and to investigate the relationship between lesion location and extent of lesions in the animals from which they were collected. One hundred and seventy-one C. pseudotuberculosis biovar equi isolates were collected from horses presenting to the University of California Veterinary Medical Teaching Hospital and two other sources in the period between September 1996 and December 2011. Bacterial isolates were grouped on the bases of biochemical characteristics and growth on brain heart infusion agar. Six phenotypes were identified: (1) large colonies that metabolized sucrose (n = 81); (2) large sucrose-negative colonies (n = 47); (3) medium sucrose-positive (n = 20); (4) medium sucrose-negative (n = 11); (5) small sucrose-positive (n = 7), and (6) small sucrose-negative (n = 5). Medical records corresponding to each isolate were accessed from the University's administrative computer system or from the submitting source in order to determine the anatomical site from which the isolate was collected (n = 171), as well as the extent of lesions (n = 164) in the patient. The relationship between phenotype, lesion location and extent of lesions was then investigated statistically. No significant relationship between strain and lesion location or extent of lesions was found. This suggests that phenotypic differences during in vitro culture does not account for external versus internal disease in horses. Further work to characterize strains genotypically and to identify determinants for bacterial virulence should be performed. Importantly, host and environmental factors should also be further investigated., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Reasons for Performing Study: Vasopressin dysregulation occurs in critically ill human patients and in neonatal foals. Limited data about serial plasma vasopressin dynamics exist in sick neonatal foals., Objectives: To evaluate serial plasma arginine vasopressin (AVP) concentrations in sick neonatal foals., Study Design: Prospective, longitudinal clinical study., Methods: Plasma samples were collected from 7 healthy and 26 sick foals before and after initial fluid resuscitation and 12, 24, 36, 48 and 96 h after presentation. Foals with a modified sepsis score ≥ 11 were considered septic., Results: Admission AVP was increased in septic foals compared to healthy and to sick, nonseptic foals. There were no significant differences between groups on subsequent days. Nonsurvivors had higher AVP concentrations than survivors., Conclusions: Plasma AVP concentrations are higher in septic foals on admission than in healthy and sick nonseptic foals. Higher early plasma AVP concentrations are associated with increased mortality., (© 2013 EVJ Ltd.)

Reasons for Performing Study: Sepsis is an important cause of death in foals. Knowledge of which pathogens are likely to be involved is important for selection of antimicrobial drugs for initial treatment., Objectives: To identify temporal trends in prevalence of bacteria isolated from foals with sepsis between 1979 and 2010., Study Design: Retrospective review of medical records., Methods: All foals ≤30 days of age presented to the Veterinary Medical Teaching Hospital (VMTH) at the University of California, Davis between 1979 and 2010, with a diagnosis of sepsis confirmed by culture of bacteria from blood or internal organs (antemortem or at necropsy), were included in the study. Conventional microbiological methods were used to identify isolated organisms. The Cochran-Armitage trend test was used for statistical analysis., Results: The percentage of Gram-positive isolates increased significantly over the years. The percentage Enterobacteriacea, and Klebsiella spp. in particular, decreased over time. Enterococcus spp. isolates were cultured more often in recent years., Conclusions: Whereas Gram-negative bacteria, particularly Enterobacteriaceae, remain the most common isolates from neonatal foals with sepsis, the prevalence of Gram-positive bacteria is increasing. This trend underlines the importance of including antimicrobial drugs active against both Gram-positive and Gram-negative bacteria in treatment protocols while awaiting the results of bacteriological culture and susceptibility tests. The increased prevalence of Enterococcus spp. is of concern because antimicrobial susceptibility patterns for enterococci are unpredictable and enterococci can also act as donors of antimicrobial resistance genes to other bacteria., (© 2013 EVJ Ltd.)

Reasons for Performing the Study: Monitoring the development of antimicrobial resistance is important for the rational selection of appropriate antimicrobial drugs to initiate treatment of foals with sepsis., Objectives: To identify temporal trends in antimicrobial susceptibility patterns of bacteria isolated from foals with sepsis., Study Design: Retrospective review of medical records., Methods: Foals aged <30 days with a diagnosis of sepsis, confirmed by culture of bacteria, were included. Susceptibility data, expressed as minimum inhibitory concentrations (MICs) (MIC50 , MIC90 , MIC range) and percent of isolates that were susceptible to a particular antimicrobial drug, were compared for bacteria isolated from foals during 3 different time periods: 1979-1990, 1991-1997 and 1998-2010. The Cochran-Armitage trend test and the Jonckheere-Terpstra test were used for statistical analysis., Results: A total of 1091 bacterial isolates were cultured from 588 foals. Enterobacteriaceae, Actinobacillus spp. and β-haemolytic Streptococcus spp. showed a decrease in percent of isolates susceptible to gentamicin over time. Enterobacteriaceae, Actinobacillus spp. and β-haemolytic Streptococcus spp. showed an increase in MIC values for amikacin. Enterobacteriaceae showed a decrease in percent of isolates susceptible to ceftiofur. Enterococcus spp. and Pseudomonas spp. showed increased MIC values to ceftiofur. Enterobacteriaceae showed increased MIC values to ceftizoxime. Enterococcus spp. became more resistant to imipenem and showed increased MIC values to ticarcillin/clavulanic acid. In contrast, several trends in increased susceptibility were also seen., Conclusions: Based on these in vitro results, the combination of amikacin and ampicillin remains an appropriate choice for initiating treatment of sepsis in foals while awaiting culture and susceptibility test results, although increasing development of resistance to amikacin was demonstrated. The decrease in in vitro activity of ceftiofur against Enterobacteriaceae is of concern. Similarly, the development of resistance of Enterococcus spp. to imipenem is an important finding that warrants monitoring in the future. Judicious use of antimicrobials is therefore crucial., (© 2013 EVJ Ltd.)

Objective: To determine clinical, laboratory analysis, and necropsy findings for equids with oleander toxicosis and to identify factors associated with outcome., Design: Retrospective case series., Animals: 30 equids., Procedures: Medical records of equids with detectable concentrations of oleandrin in serum, plasma, urine, or gastrointestinal fluid samples and equids that had not received cardiac glycoside drugs but had detectable concentrations of digoxin in serum were identified via a medical records database search. Descriptive statistics were calculated for medical history, physical examination, laboratory analysis, and necropsy variables. Logistic regression analysis was used to identify physical examination and laboratory analysis factors significantly associated with outcome., Results: 3 of 30 (10.0%) equids died before or immediately after arrival at the hospital. Of the other 27 equids, 23 (85.2%) had gastrointestinal tract abnormalities, azotemia was detected for 19 (70.4%), and a cardiac arrhythmia was ausculted for 18 (66.7%). Mortality rate for all equids was 50.0%; mortality rate for hospitalized equids was 44.4%. The most common cause of death was cardiac dysfunction. Odds of survival to discharge from the hospital were lower for equids with cardiac arrhythmias versus those without arrhythmias and decreased with increasing Hct and serum glucose concentrations. Odds of survival increased with increasing serum chloride concentration and duration of hospitalization., Conclusions and Clinical Relevance: Equids with oleander toxicosis frequently had simultaneous gastrointestinal tract, cardiac, and renal problems. Oleander intoxication should be a differential diagnosis for equids with colic in geographic areas where oleander is found, especially when azotemia or cardiac arrhythmias are detected concurrently.

Pregnancy losses include early embryonic death (EED) and later (postimplantation) abortion. Abortions, particularly Equid herpesvirus (EHV-1) abortion epizootics, cause severe economic and production losses. The long-term effects of EHV-1 and other abortions on subsequent reproductive performance in broodmare populations, however, remain undefined. This study described the relationships of EED and abortion with the following reproductive outcomes in Thoroughbred systems: breeding efficiency, month of last breeding, subsequent pregnancy and live foal rates. A prospective cohort study in broodmare populations following EHV-1 epizootics on two South African farms was used to develop predictive models of the relative influences and interactions of reproductive variables associated with EHV-1 and other abortion causes on reproductive performance. EED predicted all the reproductive outcomes. Abortion predicted increased effort and month of breeding to establish pregnancy, but not becoming pregnant or foaling. Increasing age predicted decreased reproductive efficiency, and pregnancy and foaling probabilities. Mare reproductive status predicted breeding efficiency and the last month of breeding, but not establishing pregnancy. The last month of breeding predicted efficiency, pregnancy and foaling. Interestingly, breeding in the first month of the season was associated with an improved probability of pregnancy among barren mares.

Objective: To determine if preoperative physical examination and blood work values, intraoperative physiologic variables, and intraoperative treatments can be correlated with survival to anesthetic recovery and short-term survival to hospital discharge in horses that undergo exploratory celiotomy for large colon volvulus (LCV) with and without colon resection., Study Design: Retrospective case series., Animals: Horses (n = 156) undergoing exploratory celiotomy for correction of LCV ≥ 360(ο) ., Methods: Medical records (January 2000-December 2009) of horses that had surgical correction of LCV ≥ 360(ο) were reviewed. Data collection included signalment, preoperative physical examination variables and hematologic values as well as intraoperative physiologic variables, intraoperative treatments, and arterial blood gas values. Risk factors for survival to anesthetic recovery and hospital discharge were determined using exact logistic regression., Results: High preoperative heart rate and packed cell volume were associated with not surviving to anesthetic recovery or hospital discharge. A low intraoperative total serum protein concentration was associated with not surviving to anesthetic recovery or to hospital discharge. Intraoperative tachycardia and hypercapnia were associated with not surviving to hospital discharge. Intraoperative hypotension was a negative predictor of survival to anesthetic recovery. There was no increase in death for horses in which a resection and anastomosis was performed compared with those having manual correction., Conclusions: Several hematologic and cardiorespiratory variables that are easily measured preoperatively and intraoperatively show good correlation with postanesthetic survival in horses undergoing surgical correction of LCV. These measurements might be useful for prognosticating survival in horses admitted for correction of LCV ≥ 360(ο) ., (© Copyright 2012 by The American College of Veterinary Surgeons.)

Objective: To (1) determine if histologic scores of pelvic flexure biopsies can predict short-term survival in horses with large colon volvulus (LCV) and (2) identify clinical variables predictive of short-term survival., Study Design: Case series., Animals: Horses (n = 28) with LCV (≥ 360°)., Methods: Medical records (January 2000-February 2008) of 28 horses were reviewed and clinical data recorded. Pelvic flexure biopsies were reviewed by 2 board-certified veterinary pathologists, unaware of clinical history and outcome, using 2 scoring systems. Exact logistic regression analysis was used to determine the relationship between histopathology scores (tissue viability), clinical data, and short-term survival (hospital discharge)., Results: Twenty-four horses (86%) survived to hospital discharge. Using a similar cutoff, neither scoring system was capable of predicting short-term survival. One scoring system failed to correctly predict clinical outcome in 5/25 horses (20%) and the other failed in 6/28 horses (22.4%). Heart rate (at admission and 24 hours after surgery) and packed cell volume 24 hours after surgery were significantly associated with short-term survival., Conclusion: Histopathologic evaluation of pelvic flexure biopsies did not accurately predict short-term survival in a significant proportion of horses with LCV in this study., (© Copyright 2012 by The American College of Veterinary Surgeons.)

Equine proliferative enteropathy caused by Lawsonia intracellularis is an emerging disease with as yet unaddressed preventative measures. The hypothesis of this study was that vaccination will prevent clinical and sub-clinical disease. Weanling Thoroughbreds (n=202) from Central Kentucky were randomly assigned into two groups (vaccinated and non-vaccinated). Vaccinated foals received 30 mL of an avirulent, live L. intracellularis vaccine intra-rectally twice, 30 days apart. Foals were monitored for clinical disease, total solids and average weight gain until yearling age. There was an overall decreased disease incidence on the farms involved in the study that did not differ significantly between the groups. This decreased disease prevalence in the study population may be associated with the ongoing vaccine trial on these farms, as disease prevalence in Central Kentucky did not change in 2009 compared to 2008., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Reasons for Performing Study: No previous study compares computed tomography (CT), contrast-enhanced computed tomography (CECT) and standing low-field magnetic resonance imaging (LFMRI) to detect lesions in horses with lameness localised to the foot. This study will help clinicians understand the limitations of these techniques., Objectives: To determine if CT, CECT and LFMRI would identify lesions within the distal limb and document discrepancies with lesion distribution and lesion classification., Methods: Lesions in specific structures identified on CT and MR images of feet (31 limbs) from the same horse were reviewed and compared. Distributions of lesions were compared using a Chi-squared test and techniques analysed using the paired marginal homogeneity test for concordance., Results: Lesions of the deep digital flexor tendon (DDFT) were most common and CT/CECT identified more lesions than LFMRI. Deep digital flexor tendon lesions seen on LFMRI only were frequently distal to the proximal extent of the distal sesamoid and DDFT lesions seen on CT/CECT only were frequently proximal to the distal sesamoid. Lesions identified on LFMRI only were core (23.3%) or splits (43.3%), whereas lesions identified only on CT were abrasions (29.8%), core (15.8%), enlargement (15.8%) or mineralisation (12.3%). Contrast-enhanced CT improved lesion identification at the DDFT insertion compared to CT and resulted in distal sesamoidean impar ligament and collateral sesamoidean ligament vascular enhancement in 75% of cases. Low-field MRI and CT/CECT failed to identify soft tissue mineralisation and bone oedema, respectively., Conclusions and Potential Relevance: Multiple lesions are detected with CT, CECT and LFMRI but there is variability in lesion detection and classification. LFMRI centred only on the podotrochlear apparatus may fail to identify lesions of the pastern or soft tissue mineralisation. Computed tomography may fail to identify DDFT lesions distal to the proximal border of the distal sesamoid., (© 2011 EVJ Ltd.)

This retrospective study reports on the clinical presentation of equine atopic skin disease and evaluates response to treatment with allergen-specific immunotherapy (ASIT) based on intradermal testing and/or serum testing. Computerized medical records from January 1991 to December 2008 yielded 54 horses included in the study. Presenting clinical signs (CS) included urticaria (n=28), pruritus (n=8) or both (n=18). Forty-one of 54 horses received ASIT, and response to ASIT (n=32) was evaluated via telephone survey. Eighty-four per cent (n=27) of owners reported that ASIT reduced their horse's CS; 59% (n=19) were able to manage CS by ASIT alone. Three horses (9%) were managed with ASIT in combination with doxepin and discontinued use of corticosteroids. There was no statistical significance between type of test performed and reported success of ASIT (χ(2) analysis, P=0.53). Ninety-three per cent (n=30) of owners reported use of antipruritic medications prior to starting ASIT; 57% (n=17) of these owners reported discontinuing those medications due to success of ASIT. Adverse effects were limited to swelling at the injection site, seen in 16% (n=5). Seventy-five per cent (n=24) of owners elected to discontinue ASIT after 6 months to 8 years (mean 2.2 years): 15 due to resolution of CS, six due to persistent CS, two because the horse was sold, and one due to cost. Ten owners reported no recurrence of CS after discontinuing ASIT; five had recurrence within a median of 2 years of discontinuing ASIT (range 1-12 years). Allergen-specific immunotherapy is a safe and effective way to manage equine atopic skin disease., (© 2011 The Authors. Veterinary Dermatology © 2011 ESVD and ACVD.)

Reasons for Performing Study: To date, few reports exist comparing magnetic resonance imaging (MRI) and computed tomography (CT) for imaging of the equine distal limb, yet clinicians are required to decide which modality to use regularly., Objectives: To report and compare anatomic visualisation scores obtained for CT, contrast enhanced CT (CECT) and standing low-field MRI (LFMRI) in the equine foot., Hypothesis: Anatomic visualisation score discrepancies would exist between CT, CECT and LFMRI., Methods: Images of 22 lame horses (31 limbs) undergoing both CT and LFMRI of the foot were reviewed. When available, CECT images were reviewed. The deep digital flexor tendon (DDFT) was categorised into proximal to distal levels (A-D), structures were assigned visualisation scores (Grades 0-3) and technique comparisons were made using the paired marginal homogeneity test., Results: Computed tomography and LFMRI had similar visibility scores for the navicular bone, middle phalanx, DDFT-B, collateral ligaments of the distal interphalangeal joint and collateral sesamoidean ligament of the navicular bone. The proximal and distal phalanx had lower visibility scores with LFMRI. The distal DDFT (C-D), distal sesamoidean impar ligament and synovial structures had higher scores with LFMRI. Contrast enhanced CT lowered DDFT and collateral sesamoidean ligament scores and raised distal interphalangeal synovium CT visualisation scores., Conclusions and Potential Relevance: Visualisation scores differ depending on imaging technique and anatomic structure of interest. This information increases our understanding of the limitations of CT, CECT and LFMRI to visualise anatomy in clinical cases., (© 2011 EVJ Ltd.)

Background: Serial measurement of lactate concentration is utilized for therapeutic and prognostic purposes in human critical care. The prognostic value of serial lactate measurement in equine acute colitis warrants investigation., Hypothesis: Serial lactate concentrations are predictive of outcome in horses with colitis., Animals: A total of 101 horses with colitis., Methods: Retrospective study. Plasma L-lactate concentrations were measured at admission and at 4-8 and 24 hours after admission. Associations between admission, early (4-8 hours) and late (24 hours) lactate concentrations, and survival status were determined. The percent reduction in lactate concentration between admission and the early time point, and between admission and the late time point, was calculated. Using a cutoff value, associations between percent reduction in lactate and survival status and associations between percent reduction in lactate and clinical and clinicopathologic data were determined., Results: There was no association between admission plasma lactate concentration and survival status (P = .26). The 4-8 and 24 hour after admission lactate concentrations were associated with survival status (P = .023, .013, respectively). Lactate cutoffs of ≤2.3 and ≤1.5 mmol/L had the maximum sensitivity and specificity for predicting survival at the 4-8 and 24 hour time points, respectively. When lactate reduction ≥30% at 4-8 hours and ≥50% at 24 hours after admission were used as the cutoffs, the percent reduction of lactate concentration was significantly associated with survival (P = .012 and .019, respectively)., Conclusion and Clinical Importance: The prognostic ability of serial measurement of blood lactate concentration warrants prospective study as a measure of therapeutic response in horses with colitis., (Copyright © 2011 by the American College of Veterinary Internal Medicine.)

Objective: To determine whether high liver enzyme activities were negatively associated with outcome in sick neonatal foals as compared with foals that did not have high liver enzyme activities., Design: Retrospective case-control study., Animals: 147 foals < 30 days old with high γ-glutamyltransferase activity, high sorbitol dehydrogenase activity, or both (case foals) and 263 foals < 30 days old with γ-glutamyltransferase and sorbitol dehydrogenase activities within reference limits (control foals)., Procedures: Medical records were reviewed for information on signalment, physical examination findings, and results of hematologic and serum biochemical analyses performed at the time of admission to a veterinary medical teaching hospital., Results: Case foals were significantly more likely to die or be euthanized, compared with control foals (odds ratio, 2.22; 95% confidence interval, 1.28 to 3.85). Case foals were significantly more likely than control foals to have sepsis, and septic foals were significantly less likely to survive than were nonseptic foals. For case foals, other factors associated with a greater likelihood of nonsurvival were higher anion gap and higher logarithm of aspartate aminotransferase activity. When sepsis status was controlled for, the presence of high liver enzyme activities was not significantly associated with outcome., Conclusions and Clinical Relevance: Results suggested that high liver enzyme activities were common in sick neonatal foals, especially foals with sepsis. Foals with high liver enzyme activities were more likely to be septic, and septic foals were less likely to survive than were foals without sepsis. However, high liver enzyme activities alone were not a useful negative prognostic indicator.

The prevalence and epidemiology of important viral (equine influenza virus [EIV], equine herpesvirus type 1 [EHV-1] and EHV-4) and bacterial (Streptococcus equi subspecies equi) respiratory pathogens shed by horses presented to equine veterinarians with upper respiratory tract signs and/or acute febrile neurological disease were studied. Veterinarians from throughout the USA were enrolled in a surveillance programme and were asked to collect blood and nasal secretions from equine cases with acute infectious upper respiratory tract disease and/or acute onset of neurological disease. A questionnaire was used to collect information pertaining to each case and its clinical signs. Samples were tested by real-time PCR for the presence of EHV-1, EHV-4, EIV and S equi subspecies equi. A total of 761 horses, mules and donkeys were enrolled in the surveillance programme over a 24-month study period. In total, 201 (26.4 per cent) index cases tested PCR-positive for one or more of the four pathogens. The highest detection rate was for EHV-4 (82 cases), followed by EIV (60 cases), S equi subspecies equi (49 cases) and EHV-1 (23 cases). There were 15 horses with double infections and one horse with a triple infection. The detection rate by PCR for the different pathogens varied with season and with the age, breed, sex and use of the animal.

The purpose of this study was to compare the clinical, microbiological, radiological, haematological and cytological features of foals with pneumonia caused by Rhodococcus equi infection and with other bacteria, in order to provide markers for early diagnosis and treatment. A retrospective study of 113 cases of bacterial pneumonia was undertaken. Although there was considerable overlap in the affected populations, foals with R. equi pneumonia were significantly younger and had higher respiratory rates. Radiological evidence of thoracic abscessation had a sensitivity of 71% and a specificity of 85% for the diagnosis of R. equi pneumonia. Foals positive for R. equi also had higher peripheral white cell counts and fibrinogen concentrations than animals not infected with this pathogen. Respiratory rate, fibrinogen concentration and the log of the neutrophil count were retained in the final multivariate analysis. Using microbiological culture as the 'gold standard', identification of Gram-positive coccobacilli in tracheal aspirates was highly specific (91%), but poorly sensitive (35%) for R. equi infection. White cell counts >20,000cells/μL (86% specificity), fibrinogen concentrations >700mg/dL (92% specificity), radiological evidence of thoracic abscessation (85% specificity), and the presence of Gram-positive coccobacilli in tracheal aspirates (91% specificity) in pneumonic foals are highly suggestive of R. equi infection and justify early targeted antimicrobial intervention while awaiting culture results., (2009 Elsevier Ltd. All rights reserved.)

Cutaneous vasculitis was identified by histopathological findings in 72 equines. The most frequent clinical findings were crusts/scales and oedema of the legs with the most common underlying disease being photo-aggravated dermatitis. Common laboratory findings were anaemia, neutrophilia, hyperglycaemia and hyperglobulinaemia. Histopathological patterns were most commonly cell-poor and lymphocytic/histiocytic. While statistically supported treatment recommendations could not be made due to the large numbers of confounding factors, trimethoprim-sulfa antibiotics, corticosteroids, and/or resolution or control of the underlying disease process were the most common treatment modalities.

Objective: To compare clinical, microbiologic, and clinicopathologic findings among horses infected with Clostridium difficile that had toxin A in their feces, horses with evidence of C difficile infection that were negative for toxin A in their feces, and horses with diarrhea that were negative for C difficile infection., Design: Cross-sectional study., Animals: 292 horses and foals with diarrhea., Procedures: Feces were submitted for microbial culture and tested for the C difficile antigen glutamate dehydrogenase and for toxin A with a commercial ELISA., Results: Horses with toxin A in their feces had higher band neutrophil count, rectal temperature, hospitalization time prior to the onset of diarrhea, and total hospitalization time than did horses without evidence of C difficile infection, and 32 of the 33 (97%) horses with toxin A in their feces had received antimicrobials prior to the onset of diarrhea. Horses with toxin A in their feces had a significantly higher mortality rate than did horses negative for toxin A in their feces. Sensitivity and specificity of the ELISA for detection of C difficile antigen were 93% and 88%, when assay results were compared with results of microbial culture following direct plating, and 66% and 93%, when assay results were compared with results of microbial culture following broth enrichment., Conclusions and Clinical Relevance: Results provided some evidence that horses positive for toxin A had more severe clinical disease than did horses with evidence of C difficile infection that were negative for toxin A and horses with diarrhea without evidence of C difficile infection.

Background: Facial and vestibulocochlear nerve dysfunction occurs commonly in horses with temporohyoid osteoarthropathy (THO); however, auditory dysfunction has not been thoroughly assessed., Objective: To determine if auditory abnormalities occur in horses with THO., Animals: Eleven diseased and 8 control horses., Methods: This is a prospective study in which brainstem auditory-evoked responses (BAER) were recorded in 11 horses diagnosed with THO through neurologic, endoscopic, radiographic, or computed tomographic examinations. BAER findings were compared with those recorded from 8 adult control horses., Results: All horses with THO were found to have BAER abnormalities that included complete unilateral BAER loss (82%, n=9/11), partial unilateral BAER loss (18%, n=2/11) on the most affected side, and contralateral partial BAER loss (46%, n=5/11). Nine horses had bilateral THO based on diagnostic imaging findings; of these, 5 (56%) horses also had bilateral BAER abnormalities. The complete absence of BAER in affected horses was most consistent with peripheral sensorineural hearing loss. There was a significant association between complete BAER loss and neurologic and diagnostic abnormalities., Conclusions and Clinical Importance: Auditory abnormalities such as complete or partial BAER loss are common in horses with THO. The BAER test is an objective diagnostic tool that can aid along with other diagnostic modalities in the assessment, management, and follow-up of horses with THO. Furthermore, BAER studies may help to elucidate the pathophysiology of THO in horses.

Objective: To describe ultrasonographic landmarks for use in collection of CSF from the lumbosacral region in equids., Design: Prospective study., Animals: 37 equids (27 with neurologic disease and 10 with nonneurologic disease)., Procedures: Standing equids (n = 17) were sedated with detomidine hydrochloride (0.006 to 0.01 mg/kg [0.003 to 0.005 mg/lb], IV) followed by butorphanol tartrate (0.01 mg/kg, IV) and restrained with a nose twitch for collection of CSF. The CSF was collected from 20 laterally recumbent equids (10 sedated and 10 immediately after euthanasia). Anatomic landmarks were identified ultrasonographically. Height at the dorsal point of the shoulders, body weight, depth of the spinal needle, number of attempts to collect CSF, and cytologic evaluation of CSF were recorded., Results: Lumbosacral puncture cranial to the cranial border of the most superficial location of both tuber sacrale along the midline was consistently successful for CSF collection (35/37 equids). Two horses had anatomic abnormalities that precluded CSF collection. Mean number of attempts to collect CSF per animal was 1.1. Height and body weight were strongly correlated with needle depth for CSF collection. Pelvic and sacral displacement was observed in several laterally recumbent animals, which resulted in discrepancies of the midline between the cranial and caudal aspects of the vertebral column. In most equids, the spinal needle was aligned on the midline of the caudal aspect of the vertebral column., Conclusions and Clinical Relevance: Ultrasonography was a useful aid for collection of CSF from the lumbosacral space and decreased the risk of repeated trauma and contamination in equids.

Twenty horses with pemphigus foliaceus were seen over a period of 15 years in a veterinary medical teaching hospital. Breeds seen were seven quarterhorses, five thoroughbreds, three cross-bred horses, two Arabians and one of each of the following: standardbred, Tennessee walker and warmblood. There was no breed, age or sex predisposition. Nine were mares, ten were geldings and one was a stallion. Ages ranged from 2.5 months to 25 years, with a mean of 8.6 years. Sixteen (80%) of the pemphigus foliaceus horses first exhibited signs between September and February. There was a statistically significant more common occurrence of pemphigus foliaceus during those months. Signs in the four other horses were first noted in March, May or June. Three of those horses were < 13 months of age. Oedema (14/20) and crusts (13/20) were the most common lesions. Pain was present in 9/20 horses, pruritus in 7/20 and pyrexia in 7/20. Follow-up was available for 13 horses. Five of these horses were euthanased. In three horses the reason for euthanasia was laminitis secondary to treatment. Four horses remained lesion-free after medication was discontinued. Two horses required maintenance medication and are doing well at the time of writing.

Computed tomography (CT) of the caudal fossa of 10 canine and nine equine cadaver heads was performed with conventional slice widths of 5 and 10 mm, respectively, and with thin collimations of 1 and 2 mm, respectively. Reformatting of thinly collimated slices was done by addition of thinly collimated slices to section thicknesses of 5 and 10 mm, respectively. Seventy-six pairs of conventional and reformatted images of identical anatomic locations were evaluated for magnitude of skull-base-related artifacts and image noise. A film-based subjective evaluation of artifact and noise was performed by four radiologists on a five-point score system. There was a statistically significant reduction of artifacts of canine and equine heads by 33% and 50%, respectively, on reformatted images compared with conventional ones but no difference in image noise. On objective artifact assessment based on the magnitude of standard deviation of attenuation values in the interpetrosal region, there was a statistically significant reduction of artifacts of canine and equine heads by 23% and 39%, respectively, on reformatted images. Thick-section reformatting significantly improves image quality of CT scans of the caudal fossa in dogs and horses.