Bronchoalveolar lavage fluid cytology and airway hyper-reactivity in clinically normal horses.

OBJECTIVE: To characterise the relationship between bronchoalveolar lavage fluid (BALF) cytology and pulmonary function testing with histamine bronchoprovocation (HBP) methods in a population of clinically normal horses. DESIGN: Cross-sectional study METHODS: Clinically normal adult horses (n = 33) underwent pulmonary function testing and HBP with a commercial flowmetric plethysmography system. BAL was performed 1-5 days later. Statistical analysis was used to assess associations between BALF cell concentration, relative inflammatory cell percentages and categorisation, and airway hyper-reactivity (AHR). RESULTS: AHR (PC35 ≤ 8 mg/mL) was demonstrated in 17 (52%) of the horses. Using current definitions, BALF cytology was consistent with inflammatory airway disease in 14 (42%) of the horses and 7 of those demonstrated either mastocytic and/or eosinophilic responses. There was no correlation between total inflammatory cell counts or relative percentage and AHR. No statistical association was found between BALF inflammatory cell categories and AHR. CONCLUSION: A direct association between cytological evidence of airway inflammation and AHR was not identified in this population of clinically normal horses. Determining the presence and measuring inflammatory cell mediators in BALF may more accurately reflect AHR. In addition, normal values for cell proportions in BALF may vary between different populations of horses and more appropriate regional reference ranges should be established.

Hypertrophic cardiomyopathy in a Clydesdale gelding.

CASE REPORT: A 7-year-old Clydesdale gelding was referred with a history of progressive lethargy and ventral oedema. The horse developed diarrhoea after treatment with antibiotics by the referring veterinarian. History, clinical signs, imaging and laboratory findings were consistent with hypertrophic cardiomyopathy complicated by antibiotic-associated colitis. Progression of clinical signs prompted euthanasia and the antemortem diagnosis of hypertrophic cardiomyopathy was confirmed at postmortem examination. CONCLUSION: Primary HCM is reported as rare in horses, but specific descriptions are lacking. The history, clinical, laboratory and postmortem findings in this case supported a diagnosis of HCM, complicated by antibiotic-associated colitis.

Elapid snake envenomation in horses: 52 cases (2006-2016).

BACKGROUND: Snake envenomation is a cause of morbidity and mortality in domestic animals worldwide. The clinical features of crotalid snake (pit viper) envenomation are widely reported and well described in horses but elapid snake envenomation is poorly characterised. OBJECTIVES: To describe the presentation, clinical and laboratory findings, treatment and outcome of horses with a diagnosis of elapid snake envenomation in Australia. STUDY DESIGN: Retrospective case series. METHODS: Medical records of horses with a diagnosis of elapid snake envenomation (2006-2016) at several university and private veterinary practices were reviewed. Inclusion criteria comprised one or more of the following: 1) observed snakebite, 2) positive snake venom detection kit (SVDK) result, 3) appropriate clinical response to treatment with antivenom or 4) supportive post-mortem findings. RESULTS: Fifty-two cases met the inclusion criteria. Most cases (94%) demonstrated clinical signs of neurotoxicity, characterised by generalised neuromuscular weakness. Associated neurologic signs included staggering gait, muscle fasciculations, recumbency, mydriasis, ptosis and tongue paresis. Concurrent clinically important conditions included rhabdomyolysis (50%) and haemolysis (19%). Of 18 urine samples evaluated with a SVDK, only three (17%) were positive. Overall survival was favourable (86%) among 49 horses who received antivenom. Eighteen surviving horses (43%) required more than one vial of antivenom. MAIN LIMITATIONS: Possible cases within the searchable database were not included if horses died acutely or responded to symptomatic treatment without receiving antivenom. CONCLUSIONS: Elapid snake envenomation is primarily a syndrome of neuromuscular weakness. Supportive anamnesis or an obvious bite site is rarely encountered. In endemic areas, this diagnosis should be considered for horses with generalised neuromuscular weakness, altered mentation, rhabdomyolysis and/or haemolysis; especially during spring and summer months. Diagnostic suspicion is best confirmed by response to treatment with antivenom.

Retrospective survey of bronchoalveolar lavage fluid cytology in Western Australian horses presented for evaluation of the respiratory tract: effect of season on relative cell percentages.

OBJECTIVE: To characterise the cytological changes in equine bronchoalveolar lavage (BAL) samples over multiple years to determine if the prevalence of a relative mast cell response was influenced by season. METHODS: Medical records of 228 horses with clinical signs consistent with non-infectious respiratory disease or poor performance where a BAL was performed were reviewed retrospectively. BAL fluid cytology and categorised clinical variables were analysed using a Chi-square test to determine associations. RESULTS: The predominant signalment was a racing horse between 2 and 6 years of age, and poor athletic performance was the most common presenting complaint. Based on published criteria, 69.7% of horses had abnormal BAL cytology. The presence of nasal discharge was the only clinical finding that differed significantly between horses with abnormal and normal cytology. The most common cytological derangement was a mixed cell response (26.7%), the majority of which comprised elevated percentages of neutrophils and mast cells. A solely neutrophilic response or mast cell response occurred with equal frequency (18% and 18.95%, respectively), and an isolated eosinophilic response was noted in 6.1% of cases. Of the horses with cytology consistent with non-infectious lower airway inflammation, 58.4% had increases in the relative percentage of mast cells. Cell profiles were significantly associated with season, with mastocytosis occurring more commonly in spring, whereas eosinophilic and neutrophilic responses were more common in summer. CONCLUSION: In this study, a relative mast cell increase was the most common cytological profile in horses with lower airway inflammation and was associated with season.

Tiger snake (Notechis scutatus) envenomation in a horse.

BACKGROUND: A 7-year-old Thoroughbred gelding presented with muscle fasciculation, reluctance to move, profuse sweating, tachycardia, tachypnoea and a localised, unilateral swelling on the muzzle. History and physical examination were suggestive of snake envenomation. METHODS: A sandwich ELISA for the detection of snake venom was performed on serum and urine samples. RESULT: The test performed on urine confirmed a diagnosis of tiger snake envenomation. CONCLUSION: The response to treatment with antivenom and supportive medical therapy was excellent.