JANUARY 2023 VOLUME 32, NO.1
A PUBLICATION BY THE UNIVERSITY OF KENTUCKY DEPARTMENT OF VETERINARY SCIENCE, MAXWELL H. GLUCK EQUINE RESEARCH CENTER FUNDED BY:
EQUUS / STANDARDBRED STATION, INC. M&J INSURANCE
IN T HIS IS S U E INTERNATIONAL Fourth Quarter 2022.......3 Botulism in Horses ......4,5 NATIONAL Toxicologic causes of abortion and stillbirth in horses in North America.............6,7 KENTUCKY Cervical pole necrosis of the equine placenta.....8,9
TH A N K YO U SPON SO RS
C O MME N TARY Investigating cases of toxicant exposure and why there is no single ‘tox screen’ In cases of sudden death, abortion or neurologic diseases, a toxicant is often included in the list of possible causes of disease. If toxicants are suspected, a complete history and potential list of possible toxicants will help guide testing. No true ‘comprehensive’ toxicant screen exists in human or veterinary toxicology. Even in human toxicology laboratories, “routine” or “comprehensive” toxicology screens are generally limited to ethanol (alcohol) and therapeutic and illicit drugs and medications, which vary according to regional prevalence. Horses have a wider range of potential for exposure to toxicants, which varies based on their environment and management practices. When possible, a veterinary toxicologist should be consulted prior to sample submission to provide input on likely toxicants; advise on sample collection and handling; and assist with selection of appropriate analyses. Clinical signs, physical examination findings and results of routine laboratory analyses (e.g., CBC, serum chemistry, urinalysis) in toxicoses are often nonspecific and indistinguishable from non-toxicologic causes of disease. A thorough and detailed history is therefore one of the most important tools in identifying potential toxicant exposures. For example, a history of multiple sick or dead animals with similar signs over a short period of time is one of the most common indications of potential toxicant involvement. Important details include recently opened bags of feed or new bales of hay; new medications or supplements; new water sources or interrupted access to water; recent movement to a new barn or pasture;
recent weather changes or severe weather events; recent nearby landscaping, tree trimming, or gardening; recent nearby application of pesticides, fertilizers or other agricultural chemicals; and any other changes on or near the farm (e.g., construction, drilling or mining activity). Once potential toxicants are identified, analytical confirmation can be considered. Analytical techniques exist for some, but not all, toxicants. A veterinary toxicologist can direct testing to ensure the correct sample is chosen for the most appropriate test. In many cases, analysis can confirm exposure but data on relevant blood or tissue concentrations is lacking. Therefore, the combination of clinical signs and confirmation of exposure will lead to a presumed diagnosis of intoxication. Importantly, most analyses available at veterinary diagnostic laboratories require an idea of what class of toxicant is suspected. For example, a request to test for “rodenticides” or “rat poison” alone is insufficient to determine what analyses are appropriate. Several laboratories have a method that can measure warfarin, diphacinone, brodifacoum and other anticoagulant rodenticides. Thank you for enrolling in our online Equine Disease Quarterly. Please feel free to share this publication in the equine community. Others may enroll visiting https://tinyurl.com/EDQemail. You may also email EDQ@uky.edu to be added to the listserv or for additional questions.
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