Lathyrus hirsutus (Caley Pea) intoxication in a herd of horses.

BACKGROUND: Caley Pea (Lathyrus hirsutus) is potentially toxic to horses, but large case series are not reported. OBJECTIVES: To describe the clinical signs of horses intoxicated with Lathyrus hirsutus and speculate on the neuroanatomical lesion localization and pathogenesis based upon the observed clinical signs. ANIMALS: Twenty-two of 25 horses ranging in age from 6 to 34 months were affected. Five affected horses were presented to the OSUCHVS for evaluation and treatment after having been attended at the ranch by a local veterinarian (ALA). An additional horse that had been euthanized was also presented for necropsy. METHODS: A case series is presented. Diagnostic evaluation included: physical examination, complete blood count, serum biochemistry, CSF analysis, EMG, ERG, upper airway endoscopy, muscle biopsy, and serum vitamin E analysis. The grain ration consumed by the affected horses was analyzed for ionophores and cultured for fungi: the hay was examined for toxic plants. RESULTS: Bermuda grass hay consumed by the horses contained large quantities of mature Lathyrus hirsutus. Acute clinical signs conform to earlier descriptions of Lathyrus hirsutus intoxication in cattle. Residual neurologic signs were characterized by incoordination in the rhythmicity of multiple gaits. Evidence of mild neurogenic muscle atrophy was recognized in 1 of 5 horses biopsied. CONCLUSIONS AND CLINICAL IMPORTANCE: Caley Pea intoxication may occur within days of seed pod consumption. The neurologic signs are unique and suggest involvement of the upper motor neuron system and regions of the spinal cord influencing voluntary motor movement. Drought conditions during plant growth may increase the risk of toxicosis.

Effect of repeated oral administration of hypertonic electrolyte solution on equine gastric mucosa.

REASONS FOR PERFORMING STUDY: Electrolyte supplementation is common in horses during endurance competitions, but the effect on the gastric mucosa is unknown. HYPOTHESIS: Repeated oral administration of hypertonic electrolyte solution is associated with exacerbation of gastric ulcers in mature horses. METHODS: The study design was a randomised, blinded, crossover trial. Fourteen horses were divided randomly into equal groups and administered either 60 ml water (placebo) or 56.7 g commercial electrolyte supplement mixed with 60 ml water by dose syringe orally once an hour for 8 h. The minimum concentration of individual constituent electrolytes/28.35 g dry commercial product used was: sodium (5528 mg); chloride (11,886 mg); potassium (3657 mg); calcium (754 mg); and magnesium (153 mg). Gastric lesions were scored prior to and after oral treatments, and analysis of variance procedures were then performed. RESULTS: Administration of hypertonic electrolytes resulted in a significant increase in mean ulcer number (P = 0.0174) and severity (P = 0.0006) scores in the nonglandular stomach. Mean ulcer number score was 3.6 and mean ulcer severity score 2.7 after hypertonic electrolyte treatment. CONCLUSIONS: Oral hypertonic electrolyte administration to horses in this model was associated with exacerbation of gastric ulcers. POTENTIAL RELEVANCE: Our findings suggest that one schedule of electrolyte supplementation used commonly in endurance horses may be harmful to the gastric mucosa.