EQUINE CORONAVIRUS – A DECADE LONG JOURNEY TO INVESTIGATE AN EMERGING ENTERIC VIRUS OF ADULT HORSES DR. NICOLA PUSTERLA, DACVIM
In the VETgirl-Merck Animal Health large animal webinar, Dr. Nicola Pusterla, DACVIM reviews equine coronavirus in the webinar Equine coronavirus – A decade long journey to investigate an emerging enteric virus of adult horses.
KEY HIGHLIGHTS
1 THE VIRUS Equine coronavirus (ECoV) is classified within the Betacoronavirus 1 genus, along with human coronaviruses OC43, 4408 and HKU1, bovine coronavirus (BCoV), porcine hemagglutinating encephalomyelitis virus, canine respiratory coronavirus, mouse hepatitis virus, bubaline coronavirus and sialodacryoadenitis rat coronavirus. ECoV is genetically distinct from the human SARS-CoV-2 and there is no evidence to indicate that horses could contract SARS-CoV-2 or that horses may be involved in the spread of SARS-CoV-2 to other animals or humans. 2 CLINICAL PRESENTATION Over a decade ago, a Japanese research group investigated an unusual outbreak of fever and enteric signs in 2- to 4-year-old racing draft horses. It is of interest to notice that enteric signs were only reported in 10% of the horses, and a total of 132/600 horses (22%) became diseased. Additional outbreaks have since been observed and reported in the USA and Europe. Collectively, these outbreaks have been able to refine the clinical presentation of ECoV, one that is still perplexing considering the inconsistent development of enteric signs. The lack of enteric signs such as colic and/or changes in fecal character may specifically relate to the intestinal
between 17-57% and there are still yet undetermined host, viral, and environmental factors that impact susceptibility and outcome of ECoV infection. Of interest is the observation that clinical expression of ECoV infection is age-dependent with foals rarely developing clinical disease. Given the lack of documented outbreaks of ECoV at large breeding farms, it is possible that virus circulating between foals and breeding stock confers protection against clinical disease. (continued)
section affected by the virus. ECoV has been shown to cause enteritis in both foals and adult horses. While enteritis is consistently associated with diarrhea in foals, this condition may not affect the fecal character of infected adult horses. Horses infected with ECoV generally recover with minimal to no medical treatment within 2-4 days post-onset of clinical signs. While ECoV infection is often self- limiting, adult horses may occasionally require intensive care to resolve leukopenia, systemic inflammation and metabolic disturbances. Morbidity rates have been reported to range
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