UC Davis Center for Equine Health

Coronaviruses are known to cause illness in a variety of species and tend to attack specific organ systems such as the respiratory or gastrointestinal tracts. Genetically, equine coronavirus (ECoV) appears to be a close relative of bovine coronavirus. There is currently no evidence that equine or bovine coronaviruses are likely to be infectious to humans. However, it is always advisable to follow basic biosecurity protocols when handling sick animals.

Historically, ECoV was thought to occur only in foals, but it has been increasingly reported in adult horses. It is highly contagious and transmitted between horses through exposure to contaminated fecal material. Equine coronavirus is most commonly diagnosed in the winter.

Research projects are underway to learn more about ECoV.

Clinical Signs

Equine coronavirus has a short incubation period, between 48 and 72 hours. Clinical signs include fever (38.6 to 41 degrees C), anorexia (going off feed), and lethargy. Approximately 10 to 15 percent of cases develop gastrointestinal signs such as colic and diarrhea. A small number of affected horses (seven percent) develop severe complications such as shock, organ failure, and neurological impairment.

Clinical signs generally persist for up to one week and horses can shed the virus in their feces for up to 21 days.

Some horses remain subclinical, showing no clinical signs.

Diagnosis

Equine coronavirus is diagnosed based on the clinical presentation, abnormal bloodwork, and the exclusion of other causes. Infection is confirmed by quantitative PCR (qPCR). Other diagnostic techniques such as immunohistochemistry, electron microscopy, and antigen capture ELISA may be used, but are less sensitive than qPCR.

Horses that present with sudden onset of fever, lethargy, and anorexia, but do not have any respiratory signs, should be tested for ECoV. It is recommended to submit both respiratory and fecal samples to the diagnostic laboratory.

Treatment

There are currently no antiviral drugs for ECoV. The disease has a high morbidity but low mortality. Most adult horses recover within a few days without specific treatment. Supportive treatment is recommended as needed and may include nonsteroidal anti-inflammatory drugs (NSAIDs) such as flunixin meglumine (banamine) or phenylbutazone (bute), fluids and electrolytes, and gastrointestinal protectants.

Prognosis

The prognosis for horses diagnosed with ECoV is good. Most horses make a full recovery.

Prevention 

There is no licensed vaccine for ECoV. The best way to protect horses from infection is by adhering to biosecurity protocols. This includes practicing good hygiene, minimizing nose-to-nose contact between horses, cleaning stalls properly, monitoring horses for illness, and isolating sick horses.

Although no definitive data exists, ECoV likely has a short survival time in the environment (up to two or three days), but this depends on the ambient temperature and humidity, as well as the biological material surrounding the virus. Equine coronavirus is known to be susceptible to many commonly available disinfectants, and disinfection should be a key part of biosecurity protocols.

It is also important to enforce good biosecurity practices at events that bring together large groups of horses.

Printed with the kind permission of the UC Davis Center for Equine Health. The UC Davis Center for Equine Health is dedicated to advancing the health, welfare, performance and veterinary care of horses through research, education and public service. 

The best way to protect horses from infection is by practicing good hygiene, minimizing nose-to-nose contact between horses, cleaning stalls properly, monitoring horses for illness, and isolating sick horses. Photo: Shutterstock/Grigorita Ko