A Canadian study highlights the susceptibility of yearlings to Equine Rhinitis A Virus (ERVA) and the ability of the disease to spread. The study, lead by Dr. Tanya Rossi of the University of Guelph, shows that horses between the ages of 1 and 2 are very susceptible to the virus and that farms should put targeted prevention strategies in place for this age group.
The study used 96 Standardbred racehorses, aged 1 through 5, that were housed at a training facility in Ontario. About half of the study horses were yearlings. Young racehorses often come down with viral respiratory infections; most heal without incident, though the airways can be affected for weeks or months.
The study team also included Drs. Terri O'Sullivan and Amy Greer, from the University of Guelph, and Alison Moore, with the Ontario Ministry of Agriculture, Food, and Rural Affairs. The team was hoping to describe the transmission of ERVA, as well as the clinical course of the disease. The team also wanted to identify the demographic, serological and contact network risk factors for the disease.
Complications of ERVA can include bronchopneumonia and asthma, both of which can shorten equine athletic careers and affect performance. Signs of ERVA can include cough, nasal discharge, fever and lack of appetite. Horses can shed the disease for a long period of time: 37 days or more. Horses are primarily infected with ERVA through contact with an infected horse.
The study horses were monitored for 41 days in the Fall of 2017. From blood tests completed during the study, 75 percent of respiratory cases related to ERAV, with 87.9 percent of the yearlings becoming ill. No horses over the age of 3 became sick, most likely because of immunity from previous exposure.
Many yearlings are bought at auction, then transported and introduced to new horses and routines. It is believed that these stresses may explain some of the relationship between age and disease. The study team recommended vaccination programs and isolation of new horses to help prevent ERAV in yearlings.
Read more at HorseTalk.
The study can be read here.
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