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Background: In 2020, a novel neurologic disease was observed in juvenile Quarter Horses (QHs) in North America. It was unknown if this was an aberrant manifestation of another previously described neurological disorder in foals, such as equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM). Hypothesis/Objectives: To describe the clinical findings, outcomes, and postmortem changes with Equine Juvenile Spinocerebellar Ataxia (EJSCA), differentiate the disease from other similar neurological disorders, and determine a mode of inheritance. Animals: Twelve neurologically affected QH foals and the dams. Methods: Genomic DNA was isolated and pedigrees were manually constructed. Results: All foals (n = 12/12) had a history of acute onset of neurological deficits with no history of trauma. Neurological deficits were characterized by asymmetrical spinal ataxia, with pelvic limbs more severely affected than thoracic limbs. Clinicopathological abnormalities included high serum activity of gamma‐glutamyl transferase and hyperglycemia. All foals became recumbent (median, 3 days: [0–18 days]), which necessitated humane euthanasia (n = 11/12, 92%; the remaining case was found dead). Histological evaluation at postmortem revealed dilated myelin sheaths and digestion chambers within the spinal cord, most prominently in the dorsal spinocerebellar tracts. Pedigree analysis revealed a likely autosomal recessive mode of inheritance. Conclusions and Clinical Importance: EJSCA is a uniformly fatal, rapidly progressive, likely autosomal recessive neurological disease of QHs <1 month of age in North America that is etiologically distinct from other clinically similar neurological disorders. Once the causative variant for EJSCA is validated, carriers can be identified through genetic testing to inform breeding decisions. [ABSTRACT FROM AUTHOR]

Background: Comprehensive descriptions of equids with granulocytic anaplasmosis (EGA) with neurologic or muscle disease and other atypical presentations are scarce in the literature. Objective: Describe the clinical signs, laboratory findings, treatment, and outcome of equids with EGA with emphasis on neurologic and muscle disease. Animals: Thirty‐eight horses, 1 donkey. Methods: Retrospective study. Equids with EGA were included. The electronic data base was searched from January 2000 to December 2022 using the words anaplasmosis, ehrlichiosis, granulocytic, and rickettsia. Signalment and clinical data were reviewed. Data were evaluated for normality using Shapiro‐Wilk test. Parametric and nonparametric statistics were used for normally and non‐normally distributed data. Results: Common (41%) and other (59%) presentations were seen in horses ≥ 4 years of age (median, 14 years) with an overrepresentation of males (77%). Neurologic disease was common (41%), mainly presenting as diffuse symmetrical proprioceptive ataxia. Brain disease was less common manifesting as obtundation and cranial nerve deficits. Muscle disease was less common, with QH breeds with the variant causing myosin heavy chain myopathy (MYHM) having severe disease. Cavitary effusion, cardiomyopathy and disseminated intravascular coagulation (DIC) were uncommon. Clinical laboratory results varied depending on disease stage. Muscle enzyme activities were significantly higher in horses with muscle disease. Outcome was favorable with prompt tetracycline treatment. Death and long‐term sequelae were not reported. Conclusions and Clinical Importance: Common and atypical presentations of EGA have a favorable outcome with prompt tetracycline treatment. Quarter horse breeds with muscle disease should be genotyped for MYHM. [ABSTRACT FROM AUTHOR]

Background: Omega‐3 fatty acid and alpha‐tocopherol supplementation reduces gastric ulcer formation in humans and rodents; however, efficacy of prevention in horses is unknown. Equine Omega Complete (EOC) is an oral supplement containing omega‐3 fatty acids and alpha‐tocopherol. Hypothesis/Objective: Determine if EOC supplementation prevents gastric ulcers and increases serum alpha‐tocopherol concentrations in healthy horses. Animals: Nine thoroughbred geldings; 5‐13 years old. Methods: Prospective randomized block design, repeated in crossover model. Horses were administered EOC, omeprazole, or water PO for 28 days. Horses underwent an established gastric ulcer induction protocol from days 21‐28 via intermittent feed deprivation. Gastroscopies were performed on days 0, 21, and 28. Serum alpha‐tocopherol concentrations were measured on days 0 and 28. The effects of treatment and time on ulcer grades were assessed with ordinal logistic regression, with significance at P‐value <.05. Results: Ulcer grades increased during ulcer induction in control and EOC but not omeprazole groups (P =.02). Grades increased in EOC‐treated horses after ulcer induction from a median of 1 [95% confidence interval 0‐2.5] (day 0) to 2.5 [1.5‐3.5] (day 28) and were similar to the control group (P =.54). Serum alpha‐tocopherol increased in EOC‐treated horses from day 0 to day 28 (mean 2.2 ± 0.43 μg/mL to 2.96 ± 0.89 μg/mL; P <.001) with high individual variation; this increase was not different from omeprazole or control groups. Conclusion and Clinical Importance: Supplementation with EOC for 28 days did not prevent gastric ulcer formation nor increase alpha‐tocopherol concentrations relative to the control group. [ABSTRACT FROM AUTHOR]

The Wellness Ready Test (WRT) is a lateral flow, stall-side assay that measures equine insulin in whole blood and requires validation before recommending clinical use. We evaluated intra- and inter-assay precision and linearity and compared the WRT with a radioimmunoassay (RIA). Tested concentrations ranged from <139 to >695 pmol/L (<20 to >100 μIU/mL). For 20 replicates at each insulin level, intra-assay CVs of the WRT for insulin were 13.3%, 12.9%, and 15.3% at low (139–278 pmol/L; 20–40 μIU/mL), intermediate (278–417 pmol/L; 40–60 μIU/mL), and high (>417 pmol / L ; >60 μIU/mL) concentrations, respectively. For 10 replicates at each level (3 assay lots), inter-assay CVs were 15.9%, 11.0%, and 11.7%, respectively. In the weighted linear regression of 5 measured insulin concentrations against expected concentrations, R 2 = 0.98, slope = 1.02, and y-intercept = 14.4 pmol/L (2.08 μIU/mL). The Spearman correlation coefficient (rs) was 0.90 (95% CI: 0.85–0.94) between the WRT and RIA; the WRT = f(RIA) Passing–Bablok regression yielded the fit, y = 1.005x + 24.3 pmol/L (3.50 μIU/mL). The WRT result averaged 10.4% higher than the RIA result, with targeted bias of 25.9, 26.1, and 26.7 pmol/L (3.74, 3.76, and 3.84 μIU/mL) for cutoffs used to diagnose insulin dysregulation of 312, 347, and 451 pmol/L (45, 50, and 65 μIU/mL). Assay clinical sensitivities, specificities, and accuracies determined at the 3 selected clinical cutoffs and using the RIA as gold standard were 87–95%, 92–96%, and 91–95%, respectively (n = 99 samples). Observed total error was 28.4–30.4%. The WRT had acceptable precision, excellent linearity, and good association with the RIA. [ABSTRACT FROM AUTHOR]

Summary: This report describes a case of septic discospondylitis in an 11‐year‐old American Miniature stallion. Key imaging features are described here and include Fast Spin Echo T2/STIR hyperintensity on MRI of the intervertebral disc space and surrounding soft tissues as well as vertebral endplate destruction. Spinal cord deformation was seen concurrently and is considered likely secondary to either associated inflammatory granulation tissue or disc herniation. These findings most likely explain the apparent cervical pain and spinal ataxia grade 2/5 due to cervical spinal cord disease in this case. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Veterinary Journal / Revue Vétérinaire Canadienne is the property of Canadian Veterinary Medical Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Sidewinder gait in horses is poorly understood and characterized by walking with the trunk and pelvic limbs drifting to 1 side. Hypothesis/objectives: To report causes, clinical and diagnostic features. Animals Horses examined at 2 institutions. Materials and Methods: Retrospective study (2000‐2019). Cases with sidewinder gait, neurological and orthopedic examination, and diagnostic work up or postmortem evaluation were included. Descriptive statistics were performed. Results: Twenty‐four horses (mean age 18.9 years) of various breeds and both sexes were included. Onset was acute (N = 10), subacute (N = 6), and insidious (N = 8). Electromyography and muscle biopsy supported neurologic disease and further aided in localizing site of lesion (N = 9/9). Neurologic causes included dynamic thoracolumbar spinal cord compression (N = 5), equine protozoal myeloencephalitis (N = 4, confirmed and presumed [2 each]), thoracic myelopathy of unknown etiology (N = 4), gliosis (N = 2), and thrombosis of thoracic spinal cord segments (N = 1). Non‐neurologic causes included osteoarthritis of the coxofemoral joint (N = 4), multiple displaced pelvic fractures (N = 2), bilateral rupture of the ligamentum capitis ossis femoris (N = 1), and severe myonecrosis of multiple pelvic limb muscles (N = 1). Case fatality was 79%. Conclusion and Clinical Importance: Sidewinder gait is usually observed in older horses and can have neurologic or musculoskeletal etiologies. Electromyography can be used as a diagnostic aid to determine neurologic versus non‐neurologic disease and further localize those of neurologic origin. The condition often has a poor prognosis for function and life. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Veterinary Journal / Revue Vétérinaire Canadienne is the property of Canadian Veterinary Medical Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]