Hemolytic-uremic syndrome in a postpartum mare concurrent with encephalopathy in the neonatal foal.

A postpartum mare and foal were presented for evaluation of fever and lethargy in the mare. The mare was diagnosed with endometritis and initially responded well to treatment. On the second day of hospitalization, the mare developed renal insufficiency characterized by oliguria, azotemia, hemolysis, and thrombocytopenia. Concurrently, the foal developed rapidly progressive central nervous system signs culminating in refractory seizures. Both animals failed to respond to treatment and were euthanized. Thrombotic microangiopathy involving glomeruli was evident on microscopic examination of the mare's kidneys. Microscopic evidence of brain edema was the principal postmortem finding in the foal. No specific etiology was confirmed in either case. Notably, Escherichia coli 0103:H2 was isolated from the mare's uterus and the gastrointestinal tracts of both animals. To the authors' knowledge, this is the first report in which an organism implicated as a cause of hemolytic-uremic syndrome was isolated from an animal with clinical signs and postmortem findings consistent with the disease.

Immunologic responses to West Nile virus in vaccinated and clinically affected horses.

OBJECTIVE: To compare neutralizing antibody response between horses vaccinated against West Nile virus (WNV) and horses that survived naturally occurring infection. DESIGN: Cross-sectional observational study. ANIMALS: 187 horses vaccinated with a killed WNV vaccine and 37 horses with confirmed clinical WNV infection. PROCEDURE: Serum was collected from vaccinated horses prior to and 4 to 6 weeks after completion of an initial vaccination series (2 doses) and 5 to 7 months later. Serum was collected from affected horses 4 to 6 weeks after laboratory diagnosis of infection and 5 to 7 months after the first sample was obtained. The IgM capture ELISA, plaque reduction neutralization test (PRNT), and microtiter virus neutralization test were used. RESULTS: All affected horses had PRNT titers > or = 1:100 at 4 to 6 weeks after onset of disease, and 90% (18/20) maintained this titer for 5 to 7 months. After the second vaccination, 67% of vaccinated horses had PRNT titers > or = 1:100 and 14% had titers < 1:10. Five to 7 months later, 33% (28/84) of vaccinated horses had PRNT titers > or = 1:100, whereas 29% (24/84) had titers < 1:10. Vaccinated and clinically affected horses' end point titers had decreased by 5 to 7 months after vaccination. CONCLUSIONS AND CLINICAL RELEVANCE: A portion of horses vaccinated against WNV may respond poorly. Vaccination every 6 months may be indicated in certain horses and in areas of high vector activity. Other preventative methods such as mosquito control are warranted to prevent WNV infection in horses.