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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.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.Retrospective case-control study.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.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.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.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.背景: 胃肠道疾病与沙门氏菌散播有关；先前的研究表明，有腹痛的马匹有更高罹患和散播沙门氏菌的风险。 目的: 本研究的目的是确定由于腹痛进入转诊医院马匹中，沙门氏菌散播的流行率和相关的危险因素。 研究设计: 回顾性病例对照研究 方法: 对每一例沙门氏菌阳性的腹痛病例(n = 56)，选两例沙门氏菌阴性的腹痛病例(n = 112)作为对照。各种变量与沙门氏菌散播之间的联系使用逻辑回归确定。建立单变量和多变量模型研究以下联系:(1)临床病理数据，(2)住院期间产生的临床变量。 结果: 在1917匹发生腹痛的马匹的样本中，1585匹完成了沙门氏菌检测。其中56例沙门氏菌阳性，患病率为3.5%。马属动物散播沙门氏菌常出现在7月份(OR = 7.2; 95% CI = 1.63-32.13; p = 0.009)。常伴随发热史(OR = 53.5；95% CI = 2.57-1113.03；p = 0.01)，乳酸升高(OR = 1.6；95% CI = 1.14-2.29；p = 0.007)和/或中性粒细胞减少(OR = 0.79；95% CI = 0.65 -0.97；p = 0.02)。住院马匹散播沙门氏菌的更可能发热(OR = 4.8；95% CI = 1.47 -15.8；p = 0.01)，和阴性腹痛对照组相比，发生胃返流的可能性增加10倍(OR = 10.1；95% CI = 1.67 -61.43；p = 0.01)。 主要限制: 回顾性研究的性质和从医疗记录中检索数据的固有主观性局限。基于单一样本对沙门氏菌状态进行分类可能会导致分类偏差和不合理。 结论: 与早期报道相比，该设计中马匹的沙门氏菌散播流行率较低。某些预测因素，如发烧或返流在住院腹痛病例中与沙门氏菌散播相关，可以帮助临床医生及时识别可能散毒的马匹，从而帮助建立有效的屏障以及护理预防措施。.

OBJECTIVE To determine whether IV regional limb perfusion (IVRLP) performed in the cephalic vein with a wide rubber tourniquet (WRT) applied proximal and distal to the carpus results in a higher peak concentration (Cmax) of amikacin in the radiocarpal joint (RCJ), compared with the Cmax for IVRLP using a single WRT proximal to the carpus. Animals 7 healthy adult horses. Procedures Horses underwent IVRLP using standing sedation with 2 g of amikacin sulfate diluted to 60 mL by use of saline (0.9% NaCl) solution in the cephalic vein with 2 different tourniquet techniques; proximal WRT (P) and proximal and distal WRT (PD). Synovial fluid was collected from the RCJ at 5, 10, 15, 20, 25, and 30 minutes after IVRLP. Tourniquets were removed after the 30-minute sample was collected. Blood samples from the jugular vein were collected at 5, 10, 15, 20, 25, 29, and 31 minutes after IVRLP. Amikacin concentration was quantified by a fluorescence polarization immunoassay. Median peak concentration (Cmax) of amikacin and time to maximum drug concentration (Tmax) within the RCJ were determined. Results Median peak concentration in the RCJ was 1331.4 μg/mL with technique P and 683.1 μg/mL with technique PD. Median Tmax occurred at 30 minutes with technique P and 25 minutes with technique PD. No significant (Cmax, P = 0.18; Tmax, P = 0.6) difference in amikacin Cmax or Tmax between techniques was detected. Clinical Relevance Placement of 2 WRTs offers no advantage to a single proximal WRT when performing IVRLP to deliver maximal amikacin concentrations to the RCJ using IVRLP.

Clostridium perfringens and Clostridioides difficile cause significant morbidity and mortality in foals. Antemortem diagnosis of C. perfringens infection has been complicated by a paucity of tests available for toxin detection. Fecal PCR panels have assays for a variety of C. perfringens toxin gene sequences as well as for several other foal gastrointestinal pathogens. We evaluated results of a comprehensive fecal diarrhea PCR panel in 28 foals that had been presented to a referral hospital because of diarrhea. Sixteen (57%) foals were positive for C. perfringens and/or C. difficile toxin gene sequences on fecal PCR, including 3 foals positive for NetF toxin. These foals were younger ( p = 0.0029) and had higher hematocrits ( p = 0.0087), hemoglobin ( p = 0.0067), and red blood cell concentrations ( p = 0.028) than foals with diarrhea that tested negative for clostridial toxins. The foals had lower total protein concentrations ( p = 0.045) and were more likely to have band neutrophils on a CBC ( p = 0.013; OR: 16.2). All 3 foals with NetF toxin gene sequences detected in feces survived to discharge, indicating that diarrhea caused by NetF toxigenic C. perfringens isolates is not uniformly fatal.

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

The neurokinin-1 (NK-1) receptor antagonist, maropitant citrate, mitigates nausea and vomiting in dogs and cats. Nausea is poorly understood in horses, and clinical use of NK-1 receptor antagonists has not been reported. This study aimed to determine the pharmacokinetics and safety of maropitant after administration of multiple doses. We hypothesized that maropitant concentrations would be similar at steady state to those reported in dogs, with minimal adverse effects. Maropitant was administered at 4 mg/kg orally, once daily for 5 days in seven adult horses. Serial plasma maropitant concentrations were measured by liquid chromatography-mass spectrometry. Noncompartmental pharmacokinetic parameters were determined. The maximum, minimum, and average concentrations of maropitant achieved at steady state were 375.5 ± 200, 16.8 ± 7.7, and 73.5 ± 45.1 ng/ml, respectively. The terminal elimination half-life was 11.6 ± 1.4 hr, and the accumulation index was 1.3 ± 0.07. Heart rate decreased between Day 1 and Day 5 (p = .005), with three horses having heart rates of 20 beats per minute and atrioventricular block on Day 5. Pharmacokinetics of repeated maropitant administration suggests the drug could be considered for use in healthy horses. Further investigation on the clinical relevancy of its cardiac effects is warranted.

Equine familial isolated hypoparathyroidism (EFIH) and fragile foal syndrome (FFS) are both fatal recessive conditions reported in Thoroughbred foals. The causal variants for EFIH (RAPGEF5 c.2624CA; EquCab3.0. chr4: g.54108297GT) and FFS (PLOD1 c.2032GA; EquCab3.0, chr2: g.39927817) were recently reported. Prevalence assessment for these variants in a large cohort of samples is needed to provide evidence-based recommendations for genetic testing.To estimate the frequency of the EFIH and FFS variant alleles in the United States Thoroughbred population between 1988 and 2019, and determine whether these are recent mutations or are increasing in frequency due to current breeding practices.Population allele frequency study.Genomic DNA from hair and serum samples were genotyped for the EFIH and FFS. Allele frequencies between cohorts, based on year of birth (1988-2000, n = 728) and (2001-2019, n = 1059), as well as across the seven geographical regions of the United States were compared by Fisher's Exact tests.EFIH and FFS allele frequencies were not significantly different between the two time points studied (0.008 and 0.004, respectively, in the older cohorts and 0.008 and 0.009 in most recent years). No EFIH or FFS homozygotes were detected. A sample from 1992 was identified as a carrier for EFIH and one from 1993 a carrier for FFS. Non-significant changes in geographical distribution of carriers for both traits were observed.The earliest samples available for study were from foals born in 1988.The EFIH and FFS variants are present at low frequency in the United States Thoroughbred population but are not recent mutations. There is no evidence to support changes in allele frequency over time. However, given the closed studbook and breeding practices, continued monitoring of breed allele frequencies and genetic testing is recommended to avoid the mating of carriers and production of affected foals.

IntroductionLymphoma is the most common hemopoietic neoplasia in horses. Common clinicopathologic abnormalities in equine lymphoma include hyperglobulinemia, hypoalbuminemia, hyperfibrinogenemia, anemia, thrombocytopenia and lymphocytosis. Hypoglobulinemia has been reported in other species with lymphoma, however it has not been well-described in horses. The objectives of this study were to examine the prevalence of hypoglobulinemia in equine lymphoma, and to identify prognosis and clinicopathological abnormalities associated with serum globulin concentrations.MethodsNinety-six horses with lymphoma were investigated in this retrospective study. Patients were allocated into groups based on serum globulin concentration. Survival analysis was performed to determine risk factors associated with globulin concentration and outcome.ResultsNineteen horses were hypoglobulinemic (≤2.1 g/dL), 63/98 were normoglobulinemic (2.2–4.3 g/dL), and 16/98 were hyperglobulinemic (≥4.4 g/dL). Hyperglobulinemia was associated with a higher anion gap (P = 0.0005), lower bicarbonate (P = 0.006), sodium (P = 0.03) and chloride concentrations (P = 0.002), and higher total protein than hypoglobulinemic horses (P < 0.0001). For location, 37% of horses with mucocutaneous lymphoma were hypoglobulinemic, compared to none in the hyperglobulinemic group (P = 0.02). Survival times were significantly different between low, normal and high globulin groups (P = 0.0002, median [range] survival times: 333 [1–3792], 43 [1–4,001] and 4 [1–129] days, respectively). Significant risk factors for shortened time to death were hyperglobulinemia (HR 2.4, P = 0.02), T cell lymphoma (HR 3.5, P < 0.0001), and multicentric (HR 3.1, P = 0.0008) and mediastinal (HR 6.4, P = 0.006) forms of lymphoma. Lack of chemotherapy was associated with shortened survival time (HR 4.5, P < 0.0001). B cell lymphomas (P < 0.0001) and mucocutaneous lymphoma location (P < 0.0001) were associated with longer survival times.DiscussionSerum globulin concentrations are associated with location of lymphoma, clinicopathologic abnormalities, and survival times in equine lymphoma.

Elevated plasma adrenocorticotropic hormone (ACTH) is often used to diagnose pituitary pars intermedia dysfunction (PPID) in horses. The hormone naturally increases in the fall in horses, and donkeys have been found to have higher ACTH concentrations than horses. However, circannual variation of ACTH has not been assessed in donkeys. The objective of the study was to establish seasonal variation of basal plasma ACTH concentrations over the course of a year in clinically healthy, non-geriatric donkeys. It was hypothesized that donkey ACTH concentrations would be higher than those reported in horses without PPID in all seasons, and that, similarly to horses, ACTH concentrations would further increase in the fall months. Twenty-six healthy adult donkeys (10 standards, 16 miniatures), a median (range) of 6 (2–13) years of age, were included. Donkeys were housed at a single location. Serial plasma samples were obtained monthly for 12 months. Plasma ACTH concentrations were determined by immunoassay. Data are presented as median (range), with a P-value < 0.05 considered significant. ACTH concentrations were lowest in the winter and spring [12.8 (5.0–73.6) pg/ml and 12.5 (2.8–62.6) pg/ml, respectively], with an increase in the summer [53.2 (29.7–305.0) pg/ml], and peak in the fall [77.1 (12.4–319.0) pg/ml]. ACTH concentrations were highest in the month of September [122.0 (41.7–319.0) pg/ml]. Donkey ACTH concentrations were higher than equine reference ranges from May through November but showed similar circannual variation with dramatic increases in the fall months. Species-specific reference ranges are necessary for accurate interpretation of endocrinopathy screenings in donkeys.

OBJECTIVE To evaluate changes in electrolyte concentrations and hydration status that take place in endurance horses prior to the start of a competition and determine whether these changes would be associated with elimination. ANIMALS 19 horses entered in the 2016 Tevis Cup 100-Miles (160 km) One-Day Western States Trail Ride. PROCEDURES Heparinized blood samples were collected at 5 time points: prior to transport to the ride (T0), during check-in the day before the ride (T1), 1 to 2 hours before the start of the ride (T2), at the 15-km mark (T3), and at the 55-km mark (T4). Packed cell volume and plasma sodium, potassium, chloride, urea nitrogen, glucose, bicarbonate, and total protein concentrations were determined and compared across time points and between finishers and nonfinishers. RESULTS Signif icant differences were detected among plasma sodium, potassium, and urea nitrogen concentrations measured prior to the start of the ride (ie, T0, T1, and T2). For all variables except chloride and bicarbonate concentrations, significant differences were detected between values obtained prior to the start of the ride and values obtained during the ride (ie, T3 and T4). Only bicarbonate concentration at the 15-km mark of the ride was significantly associated with finishing status. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that significant changes in plasma sodium, potassium, and urea nitrogen concentrations can occur in endurance horses during transport to a competition and when horses are stabled overnight before an event. Additionally, a lower bicarbonate concentration following a steep climb early during the ride was associated with subsequent elimination.

Antimicrobial drugs play an important, often central, role in the therapeutic management of mature horses and foals with a variety of illnesses, including those requiring critical care. Antimicrobial use must be based on rational principles involving thorough patient evaluation and sound clinical judgment that indicate a high likelihood that the patient has a bacterial infection and that antimicrobials are indicated to promote recovery. The aim of antimicrobial treatment is to inflict an insult on infecting bacteria sufficient to kill the organism or render it susceptible to inactivation by natural host defenses or the local microenvironment without adversely affecting the patient.

The neurokinin-1 (NK) receptor antagonist, maropitant citrate, mitigates nausea and vomiting in dogs and cats. Nausea is poorly understood and likely under-recognized in horses. Use of NK-1 receptor antagonists in horses has not been reported. The purpose of this study was to determine the pharmacokinetic profile of maropitant in seven adult horses after single intravenous (IV; 1 mg/kg) and intragastric (IG; 2 mg/kg) doses. A randomized, crossover design was performed. Serial blood samples were collected after dosing; maropitant concentrations were measured using LC-MS/MS. Pharmacokinetic parameters were determined using noncompartmental analysis. The mean plasma maropitant concentration 3 min after IV administration was 800 ± 140 ng/ml, elimination half-life was 10.37 ± 2.07 h, and volume of distribution was 6.54 ± 1.84 L/kg. The maximum concentration following IG administration was 80 ± 40 ng/ml, and elimination half-life was 9.64 ± 1.27 hr. Oral bioavailability was variable at 13.3 ± 5.3%. Maropitant concentrations achieved after IG administration were comparable to those in small animals. Concentrations after IV administration were lower than in dogs and cats. Elimination half-life was longer than in dogs and shorter than in cats. This study is the basis for further investigations into using maropitant in horses.

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). Cmax 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 AUC0→∞ 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%. Cmax 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.

Since domestication, horses have been selectively bred for various coat colors and white spotting patterns. To investigate breed distribution, allele frequencies, and potential lethal variants for recommendations on genetic testing, 29 variants within 14 genes were investigated in 11,281 horses from 28 breeds. The recessive chestnut ea allele in melanocortin 1 receptor (MC1R) (p.D84N) was identified in four breeds: Knabstrupper, Paint Horse, Percheron, and Quarter Horse. After filtering for relatedness, ea allele frequency in Knabstruppers was estimated at 0.035, thus illustrating the importance of testing for mate selection for base coat color. The Rocky Mountain Horse breed had the highest allele frequency for two of the dilution variants under investigation (Za.f. = 0.32 and Cha.f. = 0.026); marker-assisted selection in this breed could aid in the production of horses with desirable dilute coats with less severe ocular anomalies caused by the silver (Z) allele. With regard to white patterning, nine horses homozygous for the paired box 3 (PAX3) splashed white 2 (SW2) allele (p.C70Y) and six horses homozygous for the KIT proto-oncogene, receptor tyrosine kinase (KIT) sabino 1 (SB1) allele (ECA3g.79544206A>T) were identified, thus determining they are rare and confirming that homozygosity for SW2 is not embryonic lethal. The KIT dominant white 20 (W20) allele (p.R682H) was identified in all but three breeds: Arabian (n = 151), Icelandic Horse (n = 66), and Norwegian Fjord Horse (n = 90). The role of W20 in pigmentation across breeds is not well understood; given the different selection regimes of the breeds investigated, these data provide justification for further evaluating the functional role of this allele in pigmentation. Here, we present the largest dataset reported for coat color variants in horses to date, and these data highlight the importance of breed-specific studies to inform on the proper use of marker-assisted selection and to develop hypotheses related to pigmentation for further testing in horses.

Author(s): Fielding, C Langdon; Mayer, Jennifer R; Dechant, Julie E; Epstein, Kira L; Magdesian, K Gary | Abstract: BackgroundTrauma from dog attacks has been associated with mortality rates as high as 23% in some species. However, the prognosis and clinical features of this type of injury have not been described in equids.Hypotheses/objectivesTo describe survival rate, signalment, clinical features, and biochemical results in equids presented for emergency care after presumed dog attacks. We hypothesized there would be differences between survivors and nonsurvivors.AnimalsA total of 28 equids presented for presumed dog attacks from 3 referral centers.MethodsA retrospective study was performed using data from 3 hospitals between 2008 and 2016. Survival was defined as survival at 14 days postdischarge. Variables were compared between survivors and nonsurvivors using a t test, Mann-Whitney U test, or Fisher's exact test as appropriate.ResultsOverall mortality rate was 21%. Ponies and miniature horses represented 16/28 (57%) of the animals in the study. Full-sized equids had a lower risk of nonsurvival as compared to smaller patients (odds ratio = 0.02; 95% confidence intervals = 0.00-0.27; P l .005). Animals with lower body temperatures had increased risk for nonsurvival (P = .0004). Increased admission blood lactate concentrations (P = .003) and decreased serum total protein concentrations (P = .006) were associated with nonsurvival.ConclusionsThe mortality rate in equids attacked by dogs was similar to what is reported for other veterinary species. Smaller equids and those with increased admission blood lactate concentration, lower body temperature, and lower total serum protein concentrations were less likely to survive.

Equine antimicrobial therapy has advanced over time with the availability of increasing pharmacokinetic and pharmacodynamic studies in horses, allowing for greater evidence-based clinical decision-making. However, many challenges to optimal antimicrobial therapy remain and further research is needed to address these areas. There are a limited number of approved antimicrobials for use in horses, which creates a need for compounded preparations for clinicians. Extra-label drug use is commonplace in equine practice, which warrants continual education of veterinarians about policies and updates. Performance and competitive horses have their own unique concerns when it comes to antimicrobial use and drug testing. In keeping with the use of a broader range of antimicrobials over time, antimicrobial resistance is emerging as an important issue facing veterinary medicine, including equine practice. Another challenge is that of drug interactions and adverse drug events for which there are little scientific data available for horses, especially for critically important diseases such as Rhodococcus equi infection. Finally, much progress has been made in the availability of equine-specific antimicrobial susceptibility break points. These aid clinicians in interpreting culture and susceptibility results and antimicrobial selection. Even with these advances, continuing education and further research are needed in this area.

Idiopathic hypocalcemia in Thoroughbred (TB) foals causes tetany and seizures and is invariably fatal. Based upon the similarity of this disease with human familial hypoparathyroidism and occurrence only in the TB breed, we conducted a genetic investigation on two affected TB foals. Familial hypoparathyroidism was identified, and pedigree analysis suggested an autosomal recessive (AR) mode of inheritance. We performed whole-genome sequencing of the two foals, their unaffected dams and four unaffected, unrelated TB horses. Both homozygosity mapping and an association analysis were used to prioritize potential genetic variants. Of the 2,808 variants that significantly associated with the phenotype using an AR mode of inheritance (PA,p.Ser875*) was significantly associated with the hypoparathyroid phenotype (Pallelic = 0.008). Affected foals were homozygous for the variant, with two additional affected foals subsequently confirmed in 2019. Necropsies of all affected foals failed to identify any histologically normal parathyroid glands. Because the nonsense mutation in RAPGEF5 was near the C-terminal end of the protein, the impact on protein function was unclear. Therefore, we tested the variant in our Xenopus overexpression model and demonstrated RAPGEF5 loss-of-function. This RAPGEF5 variant represents the first genetic variant for hypoparathyroidism identified in any domestic animal species., Author summary The Thoroughbred breeding industry in the United States produces a total impact of $6 billion. A lethal hypocalcemic syndrome was first described in young Thoroughbred horses in 1997. Affected foals suffer from seizures due to low blood calcium concentrations in the first few weeks of life. Our clinical evaluation of affected foals supported a diagnosis of primary hypoparathyroidism, and the disease appeared to be inherited as an autosomal recessive trait. Whole-genome sequencing of two affected foals identified a nonsense variant in RAPGEF5. Two additional affected foals were subsequently genotyped and also homozygous for the nonsense variant. Overexpression of the equine variant in frog embryos demonstrated loss-of-function. Genetic testing is now available to screen carrier Thoroughbreds and the disease was renamed equine isolated familial hypoparathyroidism (EIFH).

Splashed white is a coat color pattern in horses characterized by extensive white patterning on the legs, belly, and face often accompanied by blue eyes and deafness. Three mutations in microphthalmia-associated transcription factor (MITF) and two mutations in Paired Box 3 (PAX3) have been identified that explain splashed white patterns (SW1–SW5). An American Paint Horse stallion with a splashed white phenotype and blue eyes, whose parents were not white patterned, was negative for the 5 known splashed white variants and other known white spotting alleles. This novel splashed white phenotype (SW6) was hypothesized to be caused by a de novo mutation in MITF or PAX3. Analysis of whole-genome sequencing using the EquCab3.0 reference genome for comparison identified an 8.7 kb deletion in MITF on ECA16 (NC_009159.3:g.21551060-21559770del). The deletion encompassed part of intron 7 through the 3′ UTR of exon 9 of MITF, including the helix-loop-helix DNA-binding domain (ENSECAT00000006375.3). This variant is predicted to truncate protein and impair binding to DNA. Sanger sequencing confirmed the stallion was heterozygous for the MITF deletion. No single nucleotide polymorphisms (SNPs) or structural variants were identified in PAX3 or any of the other candidate genes that were unique to the stallion or predicted to affect protein function. Genotyping five of the stallion’s splashed white offspring, including one all white foal, found that they were also heterozygous for the deletion. Given the role of MITF in producing white pattern phenotypes, and the predicted deleterious effect of this mutation, this 8.7 kb deletion is the likely causal variant for SW6.

OBJECTIVE To describe clinical features and outcome of horses with severe large intestinal thickening diagnosed with transabdominal ultrasonography. DESIGN: Retrospective case series. ANIMALS 25 horses. PROCEDURES Medical records of horses that underwent transabdominal ultrasonography between 2003 and 2010 were reviewed. Horses were included if the wall of the large intestine was ≥ 9 mm thick in any of 6 abdominal zones. RESULTS Median age was 13 years (range, 3 to 28 years). Horses were initially examined because of colic, diarrhea, inappetence, weight loss, lethargy, fever, or hematuria. Severe large intestinal thickening (range, 9 to 46.6 mm; mean ± SD, 18.8 ± 6.8 mm) was the primary ultrasonographic finding in all horses. Thickened large intestine was more likely to be detected in ventral versus upper (ie, combined paralumbar and intercostal) abdominal zones and in right versus left zones. Eleven horses survived and had resolution of clinical signs, including the l horse treated surgically for colon torsion. An additional horse survived but continued to have intermittent colic. Ten horses were euthanized or died, including 3 horses with neoplasia and 3 with colitis. Three horses were lost to follow-up, including 1 horse with a cecal mass and 1 with hepatosplenic lymphoma. Severity of thickening and number of zones affected were not significantly different between survivors and nonsurvivors. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that in horses undergoing transabdominal ultrasonography, large intestinal wall thickness ≥ 9 mm may be detected in patients with a variety of conditions. Ultrasonographic examination of all abdominal zones was helpful to determine the extent of thickening and identify additional findings that helped prioritize differential diagnoses.

Background A new syndrome of hematuria in horses has been documented. Hypothesis/objectives Hemorrhagic cystitis is a novel cause of stranguria and hematuria in horses. This syndrome may be difficult to differentiate from bladder neoplasia because they share several clinical features. Animals Eleven horses with idiopathic hemorrhagic cystitis and 7 horses with bladder neoplasia. Methods Retrospective cohort study. Results Hemorrhagic cystitis was detected on cystoscopy of affected horses, with hemorrhagic and thickened apical bladder mucosa. Clinical signs and endoscopic appearance of the bladder resolved within 3-8 weeks. Histopathology of bladder mucosal biopsy specimens featured neutrophilic and hemorrhagic cystitis. Histopathology was suggestive of dysplasia or neoplasia in 3 horses with hemorrhagic cystitis, yet the horses experienced complete resolution, suggesting that small biopsy specimens obtained by endoscopy can be difficult to interpret. Horses with bladder neoplasia had lower hematocrits, were older, more likely to be female, and more likely to have a mass detected on ultrasonographic examination of the bladder than horses with hemorrhagic cystitis syndrome. Conclusions and clinical importance Hemorrhagic cystitis represents a novel differential diagnosis for horses with hematuria, and is associated with a favorable prognosis. Although histopathology may suggest a neoplastic process, affected horses should be monitored cystoscopically, because complete resolution of hemorrhagic cystitis occurs. The cause of this disease is unknown, and warrants investigation.