By: Shannon Darby, DVM, DACVIM & Ben Buchanan, DVM, DACVIM, DACVECC
Do horses get Coronavirus?
Yes. Like other species, horses have their own Coronavirus called Equine Coronavirus. Horses do not get COVID-19 which is a disease caused by the SARS-CO 2 virus.
What is Equine Coronavirus?
Equine Coronavirus (ECoV) is an emerging equine specific gastrointestinal disease that was first described in 2010. It is caused by a β-coronavirus and has been diagnosed in horses all over the world. Coronaviruses as a group are single stranded RNA viruses that are named for the crown-like spikes on their surface, and are further divided into subtypes (alpha, beta, gamma, delta). Coronaviruses are enveloped, which means it is surrounded by a membrane. This membrane makes them more susceptible to disinfectants and less stable in the environment, compared to nonenveloped viruses, which are inherently stronger and more resilient.
How is ECoV transmitted?
Not everything is known about ECoV. We do know ECoV can be spread to other horses via fecal-oral transmission. Affected horses shed ECoV in their feces and then susceptible horses ingest the virus from the environment. Transmission can occur from horses eating and defecating in the same area and via fomites (shared personnel or equipment).
What are the signs of ECoV?
In adult horses, ECoV causes a self-limiting disease characterized by fever, depression and anorexia. Less common symptoms include changes in fecal consistency (soft manure or diarrhea) and/or colic. Additionally white blood cell counts often fall early in the course of the disease. Rarely, ECoV has been associated with septicemia, endotoxemia, severe necrotizing inflammation of the intestine and fatal neurologic disease (hyperammonemic encephalopathy).
Can ECoV cause disease in foals?
In foals with diarrhea and fever, detection of ECoV in feces is challenging to interpret as it can also be detected in the feces of healthy foals. Coronaviruses may not commonly have enough pathogenic potential to cause primary disease but may predispose the young animal to secondary infections. Thus, in diarrhetic foals, coronaviruses are often found with other pathologic agents.
How serious are outbreaks of ECoV?
Outbreaks have been described at boarding and competition facilities. Most commonly, outbreaks are associated with moderate case morbidity rate, but low case mortality rate (0-7, but up to 27%). There are varying clinically ill rates during outbreaks, with 4-83% of infected
horses remaining asymptomatic. Outbreaks with higher case fatality rates seem to be associated with acute onset of neurological signs. Varying fatality rates in reported outbreaks are likely multifactorial and reflect host or environmental factors, or the virulence of the viral strain.
What is the timeline of ECoV disease and fecal shedding?
For individuals, clinical signs generally resolve with supportive care within several days to one week. Outbreaks typically last for a couple weeks. Although fecal shedding of ECoV ranges from 3-25 days, it has been documented to last up to 99 days. Intermittent shedding has been reported and asymptomatic shedders can contribute to spreading the disease.
How common is it?
While outbreaks of ECoV are sporadic, one study investigated the seroprevalence of the virus in healthy adult horses in the United States. Seropositivity in this study was 9.6% and risk factors associated with seropositivity were: residence in the Mid-Western region, the draft horse breed, and use as farm/ranch horse. ECoV cases are more common during the colder months of the year (October to April).
How to diagnose it?
Fecal samples are the most common method of testing to detect the virus.
How to treat ECoV?
With most cases of ECoV, general supportive care is required. For rare cases that progress to severe gastrointestinal or neurological disease, hospitalization is recommended.
How to prevent it?
ECoV should be on the differential list for any horse, or group of horses, demonstrating fever, lethargy, anorexia, and gastrointestinal disease. Affected horses should be isolated from others immediately and veterinary evaluation and diagnostic investigation should be performed. On farms experiencing an outbreak, stopping the movement of horses around the farm (no turnout) or horses coming and going will help. Horses need to be kept in the same stall. Recent outbreak studies have demonstrated the importance of both asymptomatic animals and farm personnel in the maintenance and transmission of the virus. There is not a vaccine for ECoV.
How to clean when ECoV has been diagnosed?
It is currently unknown how long ECoV can persist in the environment. Although not a direct comparison, similar human coronaviruses can survive up to 2 days in wastewater, 3 days in feces and 17 days in urine at room temperature. EcoV is susceptible to many common disinfectants, including bleach. Many disinfectants are inactivated by organic matter (manure, shavings, etc) so facilities and equipment should first be cleaned and free of organic debris, and then disinfected. Various facility materials may be more challenging to disinfect; impervious
materials like plastic and varnished wood are the most readily cleaned surfaces. For more information about disinfectants, see the BVEH Biosecurity Guidelines.
Can I get ECoV? What about my dogs?
ECoV is only causes infections in horses. It has never been diagnosed in people or other animals around horses (like barn cats and dogs). People and pets have their types of coronavirus that is not contagious to horses.
References:
Giannitti F, Diab S, Mete A, et al. Necrotizing Enteritis and Hyperammonemic Encephalopathy Associated With Equine Coronavirus Infection in Equids. Veterinary Pathology. 2015;52(6):1148-1156. doi:10.1177/0300985814568683
Schvartz G, Tirosh-Levy S, Barnum S, et al. Seroprevalence and Risk Factors for Exposure to Equine Coronavirus in Apparently Healthy Horses in Israel. Animals (Basel). 2021;11(3):894. Published 2021 Mar 21. doi:10.3390/ani11030894
Human Coronavirus Types. National Center for Immunization and Respiratory Diseases (NCIRD), Division of Viral Diseases. 2020 Feb 15. https://www.cdc.gov/coronavirus/types.html
Smith, B. P., Van Metre, D. C. 1., & Pusterla, N. (2020). Large animal internal medicine. Sixth edition. St. Louis, Missouri: Elsevier Mosby.
Pusterla N, Vin R, Leutenegger CM, Mittel LD, Divers TJ. Enteric coronavirus infection in adult horses. Vet J. 2018;231:13-18. doi:10.1016/j.tvjl.2017.11.004
Fielding CL, Higgins JK, Higgins JC, et al. Disease associated with equine coronavirus infection and high case fatality rate. J Vet Intern Med. 2015;29(1):307-310. doi:10.1111/jvim.12480
Goodrich EL, Mittel LD, Glaser A, Ness SL, Radcliffe RM, Divers TJ. Novel findings from a beta coronavirus outbreak on an American Miniature Horse breeding farm in upstate New York. Equine Vet Educ. 2020;32(3):150-154. doi:10.1111/eve.12938
Kooijman LJ, James K, Mapes SM, Theelen MJ, Pusterla N. Seroprevalence and risk factors for infection with equine coronavirus in healthy horses in the USA. Vet J. 2017 Feb;220:91-94. doi: 10.1016/j.tvjl.2017.01.007. Epub 2017 Jan 12. PMID: 28190504; PMCID: PMC7110631.
