A seasonal idiopathic hepatitis syndrome in horses presented to a Midwestern veterinary teaching hospital.

OBJECTIVE: To report history, clinical examination findings, clinicopathologic findings, diagnostic test results, treatment, and outcome in horses with a novel idiopathic hepatitis syndrome. ANIMALS: 13 client-owned horses. PROCEDURES: Medical records of horses that were presented with fever and increased blood liver enzyme activity over a 16-month period were reviewed (December 1, 2020, to April 1, 2022). Collected data included signalment, history, clinical and clinicopathologic findings, diagnostic test results, treatment, clinical progression, and short-term outcome. RESULTS: Affected horses were presented between December and April of each of the 2 seasons investigated. The majority of horses developed cyclic fevers over the course of 3 weeks, during which time histologic evidence of hepatitis was observed. Histologic lesions included hepatic necrosis, neutrophilic to lymphohistiocytic inflammation, biliary epithelial injury, and portal fibrosis. Systemic inflammation was evidenced by increased serum amyloid A concentration and leukon changes. No horse developed signs of hepatic insufficiency, and all horses clinically recovered. Return of serum activity of GGT to within the reference range occurred within 16 weeks in most horses. Histologic lesions remained evident up to 27 weeks after initial presentation in 1 horse. CLINICAL RELEVANCE: Although an etiologic agent has not been identified, an apparently seasonal equine hepatitis syndrome was characterized by fever, systemic inflammation, increased liver enzyme activity, and histologic evidence of hepatitis. An infectious cause is suspected on the basis of histology and outcome.

Effect of needle brand, needle bevel grind, and silicone lubrication on contamination of joints with tissue and hair debris after arthrocentesis.

OBJECTIVE: To assess contamination of joints with tissue and hair debris after arthrocentesis. STUDY DESIGN: Experimental. ANIMALS: Fetlock joint tissues (n = 6 horses). METHODS: Soft tissue flaps including joint capsule were dissected from the dorsal aspect of fetlock joints of 6 anesthetized horses leaving an intact proximal base ("live" model) or with complete excision and immediate mounting to a wooden frame ("fresh" model). Needles were inserted through joint tissues and saline solution was flushed through them into tissue culture plate wells, and then examined for tissue and hair debris. Nine needle types were assessed; variables included needle brand, needle bevel grind, needle size, and silicone lubrication. RESULTS: No significant difference was detected between "live" and "fresh" models for hair or tissue contamination. Compared to 20 g hypodermic needles, 19 g lubricated and 19 g non-lubricated needles had a significantly greater odds ratio (OR) for hair contamination. Nineteen-gauge non-lubricated needles had a significantly greater OR for hair contamination than 19 g lubricated needles. No significant differences in ORs were identified between type of needle bevel grind, brands of disposable hypodermic needles, or brands of spinal needles for hair or tissue contamination. CONCLUSIONS: Nineteen-gauge needles significantly increase the risk of joint contamination with hair compared to 20 g needles; non-lubricated 19 g needles have the greatest risk. All other needle types tested in this study have similar risks for tissue and hair contamination after arthrocentesis.