Morbidity and Mortality Associated with a Standardbred Yearling Sale

This study reported on illness and death after a 2002 Standardbred yearling sale. It highlighted the problem seen whenever horses gather, especially young horses. The article is titled, “Morbidity and mortality associated with a Standardbred yearling sale.” It was published in Equine Veterinary Education and is available on, where you can purchase access to read the entire article.


In the 2-week period following a Standardbred yearling sale, 5 horses from the sale died or were subjected to euthanasia. Three were confirmed as equine herpesvirus type 1 myeloencephalopathy (EHM), while EHM was suspected in 2. Clinical abnormalities were reported in 77 of 177 (43.5%) other yearlings during the 14-day period after the sale; however, no diagnostic testing was performed. Eleven secondary cases of suspected EHM in horses in contact with yearlings purchased at the sale were identified. No cases of EHM were identified associated with the same sale in 2003; however, there was no difference in morbidity with clinical abnormalities reported in 39/96 (41%) horses sold that year (P = 0.70). Yearling sales have an inherent risk of pathogen exposure and illness is common in purchased horses. Disease in these horses could have been associated with a wide range of respiratory pathogens; however, the incidence of confirmed or suspected primary and secondary EHM cases associated with the 2002 yearling sale highlight the potential for significant outbreaks of disease.


J.S. Weese, Department of Pathobiology, Ontario Veterinary College, University of Guelph, Ontario, Canada.

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