James T. Williams, DVM, Novato, CA, has responded to questions about coronaviruses in horses from horse owners in the following way:
Horse isolated in stall
It would be possible to get the coronavirus 19 from a horse if an infected human coughed droplets onto a horse's coat and a human then got those droplets on his hands and became infected.
© 2018 by Smerikal New window.
I have been asked if the coronavirus 19 (COVID 19) is contagious to horses and from horses to humans. The short answer is no. However it would be possible to get the coronavirus 19 from a horse if an infected human coughed some droplets onto a horses coat and an uninfected human then got those droplets on their hands to become infected.
This is the same method of spreading the coronavirus by an infected person coughing on a countertop and another person touches the countertop and then their nose and mouth transferring the virus. If we all use common sense, something not too common, this scenario with a horse is unlikely but possible.
In general, most if not all viruses are species specific. Horses have their own Equine Coronavirus. The symptoms are high fever, 104-105, loss of appetite, lethargy and diarrhea or soft stools. It lasts 4 to 5 days and with supportive care, usually the recovery is uneventful.
However there have been deaths but rarely. It is not contagious to humans and is spread from horse to horse thru exposure to infected feces.
According to information by Cornell University Animal Health Diagnostic Center, 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 United States, Europe and Japan, with its rising incidence being associated with increased awareness and testing. Equine coronavirus manifests as an enteric disease in the horse. Seroprevalence of equine coronavirus in the Unites States has been estimated at 9.3% (Kooijman et al., 2017).
Transmission
Transmission of equine coronavirus is via the fecal-oral route. Although beta coronavirus commonly causes enteric and respiratory symptoms in cattle, the prevalence of equine coronavirus in the nasal secretions of horses with fever and respiratory disease is low (Pusterla et al. 2015). This finding may suggest a lack of tropism by equine coronavirus for the equine respiratory tract epithelium.
Incubation Period
Clinical signs of equine coronavirus are seen 48-72 hours after exposure and fecal viral shedding begins 3-4 days after exposure. Peek shedding is documented 3-4 days after the development of clinical signs (Pusterla et al, 2018). This timeline of shedding may cause horses to test fecal PCR negative during the very early stages of clinical disease.
Duration
Clinical signs generally resolve in several days to 1 week with supportive care and outbreaks typically last for about 3 weeks (Pusterla et al., 2013). Fecal viral shedding has been documented to more commonly range from 3-25 days, however cases have been documented to shed as long as 99 days (Goodrich et al. 2018) and anecdotal reports suggest intermittent shedding may occur.
Asymptomatic shedders do exist and may be a source in the spread of disease (Pusterla et al, 2018). These horses will not show clinical signs but are in fact shedding the organism in their manure.
Survival in the environment is unknown. Although a direct comparison cannot be made, human coronaviruses have been shown to survive longest at cooler temperatures (39.2F) for 14 days in waste water and 17 days in feces.
Age Distribution
Equine coronavirus is seen as a mono-infection in horses, usually older than 2 years of age. When seen in foals, equine coronavirus has been documented as a co-infection with Rotavirus or Clostridium perfringens (Pusterla et al., 2018).
Seasonality
More commonly seen during the cold weather months (in the Northeast areas), October through April, but cases are also diagnosed in the heat of the summer.
Common Clinical Signs and Bloodwork Abnormalities
- Anorexia
- Lethargy
- Fever (101.5-106F)
- Changes in fecal character (soft formed); in severe cases profuse diarrhea can occur but is not routinely seen
- Mild colicy-like signs (laying down; looking at sides)
- Leukopenia secondary to neutropenia or lymphopenia. The hemogram can be unremarkable.
- Hypoalbunemia
- Neurologic abnormalities (ataxia, depression, recumbency) secondary to hyperammonemia. Hyperammonemia-associated encephalopathy can be seen in severe cases secondary to increased ammonia production by the overgrowth of urease-producing bacteria or secondary to increased ammonia absorption through the disrupted intestinal mucosal barrier.
Morbidity
Morbidity ranges from about 10-83% and death is typically rare. When death occurs it is thought to be secondary to complications associated with gastrointestinal barrier disruption leading to septicemia, endotoxemia and hyperammonemia-associated encephalopathy (Pusterla et al., 2018).
Case Management
Treatment most often is supportive, which may include fluid therapy and non-steroidal anti-inflammatories. More severe cases may require extensive treatment or hospitalization.
Press release: Cornell University Animal Health Diagnostic Center