Study in Nebraska, Colorado Examines Outcomes in West Nile Virus Cases

As West Nile virus (WNV) continued to spread west across the United States, researchers examined the outcomes for 484 infected horses in Nebraska and Colorado. Owners of horses with WNV infection confirmed by laboratory testing were surveyed to obtain information on management, vaccination, clinical signs and the outcome of the infections.

Uncoordination, lethargy, muscle twitching and weakness were the most common clinical signs and 28 percent of infected horses died or were euthanized (76 percent of those that died) as a result of the infection. Horses 3 years of age or older and females were more likely to die compared with younger animals and males. Unvaccinated horses were twice as likely to die compared those that had been vaccinated at least once. Horses that were down and unable to rise were 78 times more likely to die. On average horses were affected for about 3 weeks and most (80 percent) of those that survived recovered completely.

Horses, donkeys and mules living in areas affected by WNV should be fully vaccinated (two doses, one month apart) at least 60 days prior to mosquito season.

—Salazar P et al. JAVMA 2004;225: 267-274.

Study Find Hoof Conformation Linked to Compressive Force on the Navicular Bone

Hoof conformation measurements were obtained from lateral radiographs of the right foot of 31 clinically normal Irish Draught-type horses. Using forceplate and 3-dimensional gait analyses, compressive forces exerted by the deep digital flexor tendon on the navicular…