The California Veterinary Diagnostic Laboratory System isolated H3N8 influenza virus demonstrating recent antigenic drift from the A2 Kentucky and Alaska influenza viruses. An influenza outbreak that started in September has continued to spread. More than 250 cases have been reported from throughout California including private farms, breeding facilities, and at least one lay-up facility. High fever, nasal discharge, coughing, and limb edema have been reported. Acute and convalescent serology or viral detection from nasal swabs on the first one to two days of onset are useful diagnostic aids.
Three horses in Southern California on adjacent properties were positive for equine infectious anemia.
Nutritional cardiomyopathy was suspected, with fever progressing to anorexia over an 8-day period in a retired Thoroughbred stallion. The heart had severe necrosis with mineralization. Low selenium levels but normal vitamin E levels were found. Salmonella colitis was also present.
Peritonitis secondary to multisystemic Streptococcus equi infection was diagnosed in a 6-month-old foal with a history of "strangles" three months earlier. A 3-month-old Arabian foal died from polymicrobial peritonitis resulting from a urachal abscess. Combined immunodeficiency was not a predisposing factor in the Arabian foal.
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