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BackgroundThere is limited information on the incidence of clinical signs, concurrent illness and treatment options for atrial fibrillation (AF) in New World Camelids (NWC).ObjectiveDescribe clinical signs and outcome of AF in NWC.AnimalsEight New World Camelids admitted with AF.MethodsA retrospective observational study of camelids diagnosed with AF based on characteristic findings on electrocardiogram (ECG).ResultsAll animals had an irregularly irregular heart rhythm detected on physical examination and 4 cases had obtunded mentation on admission. Three camelids were diagnosed with AF secondary to oleander intoxication, 3 animals had underlying cardiovascular disease, 1 was diagnosed with lone AF and 1 had AF diagnosed on examination for a urethral obstruction. Five of eight animals survived to discharge and nonsurvivors consisted of animals which died or were euthanized as a result of cardiovascular disease (2/8) or extra-cardiac disease unrelated to the AF (1/8).Conclusions and clinical importanceAtrial fibrillation occurs in NWC in association with cardiovascular disease, extra-cardiac disease or as lone AF. Amiodarone and transthoracic cardioversion were attempted in one llama with lone AF, but were unsuccessful. Atrial fibrillation was recorded in 0.1% of admissions.

BackgroundKlebsiella spp. are implicated as a common cause of bacterial pneumonia in horses, but few reports describe clinical presentation and disease progression.Hypothesis/objectivesTo describe the signalment, clinicopathologic data, radiographic and ultrasonographic findings, antimicrobial susceptibility, outcome, and pathologic lesions associated with Klebsiella spp. pneumonia in horses.AnimalsForty-six horses from which Klebsiella spp. was isolated from the lower respiratory tract.MethodsRetrospective 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.ResultsSurvival in horses

BackgroundEquine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (NAD/EDM) is a neurodegenerative disorder affecting genetically predisposed foals maintained on α-tocopherol (α-TP)-deficient diet.ObjectiveIntramuscular α-TP and selenium (Se) administration at 4 days of age would have no significant effect on serum or cerebrospinal fluid (CSF) α-TP in healthy foals. Serum and CSF α-TP, but not Se, would be significantly decreased in NAD/EDM-affected foals during first year of life.AnimalsFourteen Quarter horse foals; 10 healthy foals supplemented with 0.02 mL/kg injectable α-TP and Se (n = 5) or saline (n = 5) at 4 days of age and 4 unsupplemented NAD/EDM-affected foals.MethodsComplete neurologic examinations were performed, blood and CSF were collected before (4 days of age) and after supplementation at 10, 30, 60, 120, 180, 240, and 360 days of age. Additional blood collections occurred at 90, 150, 210, and 300 days. At 540 days, NAD/EDM-affected foals and 1 unsupplemented healthy foal were euthanized and necropsies performed.ResultsSignificant decreases in blood, CSF α-TP and Se found in the first year of life in all foals, with most significant changes in serum α-TP from 4-150 days. Dam α-TP and Se significantly influenced blood concentrations in foals. Injection of α-TP and Se did not significantly increase CSF Se, blood or CSF α-TP in healthy foals. NAD/EDM-affected foals had significantly lower CSF α-TP through 120 days.Conclusions and clinical importanceInjection of α-TP and Se at 4 days of age does not significantly increase blood or CSF α-TP. Despite all 14 foals remaining deficient in α-TP, only the 4 genetically predisposed foals developed NAD/EDM.

Background: Diagnosis of colitis has been shown to impact morbidity and mortality in hospitalised horses. There are no studies to date that describe the incidence of infectious colitis after exploratory laparotomy., Objectives: To investigate risk factors associated with the development of colitis and infectious colitis post-exploratory laparotomy., Study Design: Retrospective case-control., Methods: Medical records of equids admitted from 2011 to 2020 were reviewed. The primary outcome was a diagnosis of colitis following exploratory laparotomy. Bivariable associations between colitis and risk factors were assessed using the 2-sample t-test and Fisher's exact test. All risk factors were subjected to a backward elimination variable reduction algorithm within a logistic regression framework (p-value set to 0.05). Odds ratios and 95% confidence intervals were computed for the final model., Results: A total of 504 equids were included in the study. Forty-two patients (8.3%) were diagnosed with postoperative colitis. Five patients were diagnosed with Salmonella spp. and two with Clostridioides difficile. The odds of postoperative colitis were higher among patients that had pelvic flexure enterotomy (OR = 3.7, 95% CI = 1.7-7.9, p = 0.001), postoperative leukopenia or leukocytosis (OR = 21.2, 95% CI = 9.7-46.7, p < 0.001), or plasma lactate 2.0-4.0 mmol/L (OR = 3.0, 95% CI = 1.3-6.7, p < 0.008). Patients diagnosed with colitis had a longer median length of hospitalisation (9 days; range 2-21) compared with patients without colitis (7 days; range 2-25). Patients with colitis had a survival to discharge rate similar to patients without colitis (95% compared to 93%)., Main Limitations: Risk factors for infectious colitis could not be determined due to variation in testing protocols in this retrospective study and the low number of positive cases., Conclusions: Colitis as a postoperative complication does not negatively impact survival to discharge but is associated with longer hospitalisation. Pelvic flexure enterotomy, postoperative leukopenia or leukocytosis, and increased plasma lactate were identified as significant risk factors associated with colitis., (© 2023 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.)

Equine protozoal myeloencephalitis (EPM) is a debilitating neurologic disease affecting horses across the Americas. Gaps in understanding the inflammatory immune response in EPM-affected horses create difficulties with diagnosis and treatment, subsequently negatively impacting the prognosis of affected horses. The purpose of the current study was to evaluate circulating levels of the inflammatory immune marker soluble CD14 (sCD14), in horses with EPM (n = 7) and determine if they differed from healthy neurologically normal horses (n = 6). Paired sera and cerebrospinal fluid (CSF) samples were analyzed for sCD14. Inclusion criteria for EPM horses consisted of the presence of neurologic signs consistent with EPM, Sarcocystis neurona surface antigens 2, 4/3 (SnSAG 2, 4/3) ELISA serum: CSF antibody ratio ≤ 100, and a postmortem diagnosis of EPM. Control horses were neurologically normal, healthy horses with SnSAG 2, 4/3 ELISA serum: CSF antibody ratios of > 100. Serum anti-Sarcocystis neurona antibodies indicate that healthy control horses were exposed to S. neurona but resistant to developing clinical EPM. EPM cases had significantly greater concentrations of sCD14 in CSF samples compared to control horses and increased serum sCD14 concentrations. A positive correlation between sCD14 serum and CSF concentrations was observed in EPM-affected horses but not healthy horses. Soluble CD14 is an inflammatory marker, and the study results suggest it is elevated in EPM patients. When performed in conjunction with clinical evaluation and standard antibody testing, there may be potential for sCD14 to be utilized as a correlate for EPM., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: Information concerning clinical presentation, conditions associated with immune-mediated haemolytic anaemia (IMHA) and thrombocytopenia (IMTP) and outcome in equids is lacking. Previous case reports suggest that immune-mediated disease and neoplasia are associated., Objectives: Characterise the clinical presentation, clinicopathologic data, underlying conditions, treatment and outcome of IMHA and IMTP cases in equids. We hypothesise that IMHA with concurrent thrombocytopenia occurs more often than IMHA or IMTP alone, and that neoplasia is commonly associated with these immune diseases and cases frequently have a poor prognosis., Study Design: Retrospective case-control study., Methods: Medical records were reviewed from 1997 to 2016. Twenty-five equids were diagnosed with IMHA, IMTP or IMHA with thrombocytopenia by Coombs test or flow cytometry. Controls were equids presented for nonimmune-mediated disease immediately prior to and after study animals. Fisher's exact test was used to compare between groups for categorical variables (P < .05). Results reported as odds ratios (OR) and 95% confidence intervals (CI). Unpaired t test and Mann-Whitney test were used to compare between groups for continuous variables (P < .05)., Results: Neoplasia incidence was significantly higher in the study population (28%) versus controls (8%) (P = .04). Equids with primary disease were more likely to survive to discharge than equids with secondary disease (8/9 vs 7/16; P = .03; OR = 13.3; 95% CI: 1.3-134.7). Survivors had a significantly lower blood urea nitrogen (BUN) than those that died or were subjected to euthanasia (survivors, 6.1 ± 2.5 mmol/L vs nonsurvivors, 9.9 ± 3.1 mmol/L P = .003). The odds of short-term mortality were higher in horses presenting with increased BUN (OR = 19.5; 95% CI, 1.8-214.1; P = .009)., Main Limitations: Retrospective nature of the study, small case numbers and limited long-term follow-up., Conclusions: Primary IMHA/IMTP cases have a reasonable prognosis and warrant treatment. Secondary cases have a poor prognosis, and are frequently associated with cancer. BUN may have utility as a prognostic indicator for IMHA/IMTP cases., (© 2020 EVJ Ltd.)

To the authors' knowledge, there have been no studies evaluating the pharmacokinetics of chloramphenicol administered orally to horses at the currently recommended dose of 50 mg/kg PO q6 h for multiple days. The published antimicrobial susceptibility breakpoint is 8.0 ug/mL; it is unknown if this concentration is achievable at the recommended dose rate in horses. The aim of this prospective multi-dose pharmacokinetic study was to perform pharmacokinetic analysis of chloramphenicol after multiple doses. The authors hypothesize that the antimicrobial susceptibility breakpoint will not be reached. Seven healthy adult horses were administered 50 mg/kg chloramphenicol base tablets PO q6 h for 4 days. Blood was collected via venipuncture daily at 4 and 6 h after administration for the first 15 doses. After the 16th dose, an IV catheter was aseptically placed in the right jugular vein and blood was collected at regular intervals for pharmacokinetic analysis. Maximum chloramphenicol concentration was variable between horses (2.1-42.7 μg/mL). The highest average chloramphenicol concentration was just below the susceptibility breakpoint at 7.7 ug/mL while the lowest was well below the breakpoint at 1.5 ug/mL. On average, the time above 8.0 μg/mL was 75 min, considerably less than the recommended 50% of the dosing interval. When chloramphenicol is administered at a dose of 50 mg/kg PO q6 h in horses, the highest reliably achievable steady state concentration for at least half of the dosing interval is 2.0 μg/mL. The established susceptibility breakpoint of 8.0 ug/mL is not achievable in adult horses, and should be re-evaluated., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Chloramphenicol is commonly used in horses; however, there are no studies evaluating the pharmacokinetics of veterinary canine-approved tablets. Studies using different formulations and earlier analytical techniques led to concerns over low bioavailability in horses. Safety concerns about human health have led many veterinarians to prescribe compounded formulations that are already in suspension or paste form. The objective of this study was to evaluate the pharmacokinetics of approved chloramphenicol tablets in horses, along with compounded preparations. The hypothesis was that chloramphenicol has low absorption and a short half-life in horses leading to low serum concentrations and that compounded preparations have lower relative bioavailability. Seven horses were administered chloramphenicol tablets (50 mg/kg orally). In a crossover design, they were administered two compounded preparations to compare all three formulations at the same dose (50 mg/kg). C max was 5.25 ± 4.07 μg/ml at 4.89 hr, 4.96 ± 3.31 μg/ml at 4.14 hr, and 3.84 ± 2.96 μg/ml at 4.39 hr for the tablets, paste, and suspension, respectively. Elimination half-life was 2.65 ± 0.75, 3.47 ± 1.47, and 4.36 ± 4.54 hr for tablets, paste, and suspension, respectively. The AUC 0→∞ was 17.93 ± 7.69, 16.25 ± 1.85, and 14.00 ± 5.47 hr*μg/ml for the tablets, compounded paste, and compounded suspension, respectively. Relative bioavailability of compounded suspension and paste was 78.1% and 90.6%. C max after administration of all formulations did not reach the recommended MIC target of 8 μg/ml set by the Clinical Laboratory Standards Institute (CLSI) for most bacteria. Multidose studies are warranted, but the low serum concentrations suggest that bacteria with MIC values lower than CLSI recommendations should be targeted in adult horses., (© 2019 John Wiley & Sons Ltd.)

Temporohyoid osteoarthropathy is a well-recognized cause of equine neurologic disease. Temporal bone fractures associated with temporohyoid osteoarthropathy have been recognized with CT, however, little information is available regarding these fractures. The aims of this retrospective analytical study were to assess the prevalence of these fractures and to describe the specific configurations and associated imaging and clinical features. Fracture of the temporal bone was identified with CT in 16 of 39 included horses. All fractures were unilateral, minimally displaced and extended through the temporal bone in a rostrodorsal to caudoventral orientation. Two fracture configurations were identified: in nine cases, the fracture extended the full width of the petrous pyramid into the cranial vault and in seven cases, the fracture only extended through the lateral part of the petrous temporal bone, not involving the cranial vault. Fusion of the temporohyoid joint was present in 13 of the 16 fracture cases. Quarter Horses were over-represented in the fractured population (14/16). All horses with fractures had ipsilateral neurologic deficits. Patient outcomes were not significantly different between temporohyoid osteoarthropathy horses with and without temporal bone fractures (P = 0.68). However, six of the nine patients with cranial vault involvement did not return to their previous use. Findings support previous studies indicating that temporal bones should be carefully assessed for concurrent fractures when temporohyoid osteoarthropathy is identified in CT images, especially when there is fusion of the temporohyoid joint. An improved awareness of specific fracture configurations will help with detection of these fractures., (© 2018 American College of Veterinary Radiology.)

Background: Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is a neurodegenerative disorder affecting genetically predisposed foals maintained on an α-tocopherol (α-TOH) deficient diet. Currently no antemortem diagnostic test for eNAD/EDM is available., Hypothesis: Because α-TOH deficiency is associated with increased lipid peroxidation, it was hypothesized that F 2 -isoprostanes (F 2 IsoP), F 4 -neuroprostanes (F 4 NP) and oxysterols derived from free radical oxidation would be increased in the cerebrospinal fluid (CSF) and neural tissue of eNAD/EDM affected horses and could serve as potential biomarkers for disease., Animals: Isoprostane Study A: 14 Quarter horse foals (10 healthy foals and 4 eNAD/EDM affected foals) at 1 and 6 months of age. Isoprostane Study B: 17 eNAD/EDM affected and 10 unaffected horses ≥ 1-4 years of age. Oxysterol study: eNAD/EDM affected (n = 14, serum; n = 11, CSF; n = 10, spinal cord [SC]) and unaffected horses 1-4 years of age (n = 12, serum; n = 10, CSF; n = 7, SC)., Procedures: Cerebrospinal fluid [F 2 IsoP] and [F 4 NP] were assessed using gas chromatography-negative ion chemical ionization mass spectrometry. Serum, CSF, and cervical SC [oxysterols] were quantified using high performance liquid chromatography mass spectrometry. Results were compared with respective α-TOH concentrations., Results: Spinal cord [7-ketocholesterol], [7-hydroxycholesterol], and [7-keto-27-hydrocholesterol] were higher in eNAD/EDM horses whereas [24-ketocholesterol] was lower. No significant difference was found in CSF [F 2 IsoP] and [F 4 NP], serum [oxysterols] and CSF [oxysterols] between eNAD/EDM affected and unaffected horses. No correlation was found between [F 2 IsoP], [F 4 NP], or [oxysterols] and respective [α-TOH]., Conclusions and Clinical Importance: In the SC, targeted markers of cholesterol oxidation were significantly increased in horses with eNAD/EDM., (© 2018 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

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.)

A 14-year-old Quarter Horse was examined for a draining tract of 8 months' duration on the right mandible that was non-responsive to antibiotic therapy and surgical therapy. Further investigation and subsequent treatment with sialoendoscopy and ultrasonography were performed to relieve an obstruction of plant awns in the mandibular salivary duct.

Reasons for Performing Study: Data associating quantitative viral load with severity, clinical signs and survival in equine herpesvirus-1 myeloencephalopathy (EHM) have not been reported., Objectives: To report the clinical signs, treatment, and temporal progression of viral loads in 7 horses with naturally occurring EHM and to examine the association of these factors with survival., Study Design: Retrospective case series., Methods: The population included 7 horses with EHM presented to the University of California, Davis William R. Pritchard Veterinary Medical Teaching Hospital from May to September 2011. Horses were graded using a neurological grading scale. Daily quantitative PCR was performed on nasal secretions and whole blood. Treatment, survival, outcome and histopathology were reported., Results: At presentation, one horse was neurological grade 5/5, 3 were grade 4/5 and 3 were grade 3/5. All were treated with anti-inflammatory drugs, valacyclovir and management in a sling if necessary. All were infected with equine herpesvirus-1 of DNA polymerase D752 genotype. Peak viral load in nasal secretions and blood of 5 survivors ranged from 6.9 × 10(3) to 2.81 × 10(5) (median 5.11 × 10(4) ) and from 143 to 4340 gB gene copies/million eukaryotic cells (median 3146), respectively. The 2 nonsurvivors presented with grade 3/5 neurological signs and progressed to encephalopathy. Peak viral load was higher in nonsurvivors, with levels in nasal secretions of 1.9 × 10(9) and 2.2 × 10(9) and in blood of 2.05 × 10(4) and 1.02 × 10(5) gB gene copies/million eukaryotic cells. Case fatality was 2/7., Conclusions: Nonsurvivors had viral loads 1000-fold higher in nasal secretions and 10-fold higher in blood than survivors. There was no relationship between severity of clinical signs at presentation and survival. Thus, encephalopathy and high viral load were negatively associated with survival in this population. Further research should be performed to determine whether high viral loads are associated with encephalopathy and poor prognosis. The Summary is available in Chinese - see Supporting information., (© 2014 EVJ Ltd.)