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Equine Enteric Coronavirus

Equine Enteric Coronavirus - A Newly Emerging Disease of Horses

Illustration of a CoronavirusThe Veterinary Support Services group at the Animal Health Diagnostic Center at the School of Veterinary Medicine at Cornell University has recently received several calls regarding a relatively newly recognized illness in horses.  Equine enteric coronavirus has been on the rise in recent years in our area of the Northeast and it seems to be most prevalent during the colder months.  In 2013, we received 144 samples of which 38 were positive or suspect.  We have seen positive samples from several states including New York, Missouri, South Carolina, Connecticut, and Vermont.

Equine enteric coronavirus should be on your differential list for a horse whenever you see a fever (usually less than or equal to 104.0) accompanied by anorexia and lethargy.  It is transmitted by the fecal oral route and signs usually tend to resolve in 1-4 days although animals can continue shedding for several weeks.  For a more complete description of signs, characteristics of this disease, and appropriate sample submission for testing please take a look at the following fact sheet:

Equine Enteric Coronavirus

Overview:  Coronaviruses comprise a large group of RNA viruses that can cause both respiratory and enteric signs of disease in various species. They are further grouped based on genetic and serologic differences into alpha, beta and gamma coronaviruses. The equine coronavirus, a beta coronavirus, has been recently isolated from a number of outbreaks across the country. This is an enteric disease of the equine.  At this time there has been no association with a respiratory component although in cattle enteric and respiratory disease is common.   
Transmission:  Fecal-oral route  
Survival in environment:  Unknown
Age distribution:  Most often diagnosed in adults, usually older than 2 years of age.
Seasonality:  Seen during the cold weather months (in the Northeast areas), December through May.    

Polo ponies in stable

Common Clinical Signs/Blood test changes

  • Anorexia
  • Lethargy
  • Fever (usually </= 104.0)
  • Changes in fecal character; diarrhea not routinely seen
  • Mild colicy-like signs (laying down; looking at sides)
  • Neurologic abnormalities (ataxia, depression, recumbency) secondary to hyperammonemia
  • Leukopenia( neutropenia,lymphopenia)
  • Hypoalbunemia

Morbidity ranges from about 20-57% (Pusterla et al., 2013) and mortality  is typically rare ,but secondary complications including dehydration, diminished perfusion, and gastrointestinal translocation, can occur (Pusterla et al., 2013). Hyperammonemia and associated neurological signs may be cause for mortality.
Duration:  Signs generally resolve in 1-4 days with supportive care and outbreaks typically last for about 3 weeks (Pusterla et al., 2013). 

AHDC Sample Submission/Requirements

The sample is fresh feces submitted in an unbreakable leak-proof container to the laboratory by overnight courier on ice packs.  Samples must be kept chilled to prevent overgrowth of bacteria that may cause inhibition in the PCR testing.  Feces are tested by: Equine Enteric Corona PCR. Lag Time: 3-days. Any questions contact the lab and speak to the VSS, Drs. Mittel, Goodrich and Thompson at 607.253.3900.Horses in the stable

Biosecurity/ Control measures:

  • If beta coronavirus is on your differential list, encourage the barn to practice appropriate biosecurity measures to control the spread of the virus.
  • See the AAEP guidelines: for Biosecurity guidelines. 
  • Horses can continue shedding the virus in their feces for a few weeks (anecdotal reports have shown up to 21 days) from the onset of clinical signs. The virus is shed in the manure.  Encourage the farm to take precautions by using footbaths, individual thermometers, and disposable gloves between horses.  Attempt to isolate affected animals and handle them last and use separate manure handling equipment from the rest of the barn. Minimize traffic into/out of barn.

Recommended references:

Pusterla N. et al., 2013. Emerging outbreaks associated with equine coronavirus in adult horses. Veterinary Microbiology.  Vol 162. pp. 228-231

Oue, Yl, et al., 2011. Isolation of an equine coronavirus from adult horses with pyrogenic and enteric disease and its antigenic and genomic characterization in comparison with the NC99 strain.  Veterinary Microbiology. Vol 150. Pp. 41-48.

If you have questions, please contact the lab at 607.253.3900 and ask to speak with a veterinarian in VSS.