Texas A&M: Horse Mortality Incident Traced to Pesticide

Testing at the Texas A&M University College of Veterinary Medicine and Biomedical Sciences and the Texas Veterinary Medical Diagnostic Laboratory has yielded evidence that the toxic principal responsible for the recent deaths of more than two dozen horses at Carousel Acres Equine Center in Brazos County, Texas, was in all likelihood phosphine gas.

Phosphine is a gaseous product released from a highly toxic fumigant pesticide that was reportedly applied by Carousel Acres to the feed bin to kill weevils. H Richard Adams, DVM, PhD, dean of the Texas A&M College of Veterinary Medicine and Biomedical Sciences, indicated necropsies on three of the horses that died at the Texas A&M veterinary clinic all showed the presence of phosphine gas in their stomach.

 "Considering that the stable feed bin was reportedly treated with a fumigant pesticide that releases phosphine gas as its toxic principal, and considering that phosphine gas was detected in the horses' digestive tracts after death, the pesticide certainly appears to be the etiologic agent, the causative factor, responsible for this tragic situation," Adams said.

"So far, necropsy examination of the animals and toxicologic testing of bodily materials have not revealed any apparent toxicants beyond the phosphine," Adams said.

"This appears to have been an unfortunate on-farm accident attributable to the pesticide application. Contrary to some early misleading speculation, there is no indication that the feed product itself was defective when it was delivered to the farm."

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