This article is from the September 2020 Horse Deals magazine.

The Authors

The authors are both veterinarians who work in the Centre for Equine Infectious Disease at the University of Melbourne. Kirsten and James are both interested in infectious diseases of horses and are currently investigating antibiotic usage in animals in Australia.

Since early 2020 the world has been inundated with stories on coronaviruses. We have heard about infections spreading from bats to humans, about the previous SARS outbreak in the early 2000s and even about infections in camels that spread to people. But what are coronaviruses, what animals get infected and what does that even mean?

What are coronaviruses?

The coronavirus family of viruses infect a huge range of different animal species, from birds and bats, through to domestic animals and people. Often infections are sub-clinical (not associated with disease) or cause mild clinical disease, like the common cold in people. They commonly cause disease of the digestive or respiratory systems in our domestic animals, but occasionally they are the cause of severe disease syndromes, such as the current COVID-19 pandemic.

What is equine coronavirus (ECoV)?

Horses have their own distinct coronavirus strain (ECoV) that has been detected in many countries around the world, including Australia, since the mid-1970s. Equine coronaviruses attack the cells lining the digestive tract resulting in gastrointestinal disease. Horses become infected by ingesting the virus, which then travels through the stomach to infect cells of the small intestine. Equine coronavirus is shed in the manure of an infected horse and horses get infected by eating contaminated feed or pasture (faecal-oral route), or by contact with other contaminated items.

Common signs of ECoV disease

Many infected horses do not show any signs of disease. Those that do become ill most commonly show signs such as a fever, reduced appetite, lethargy, diarrhoea and colic. Disease is generally mild and may be seen in horses of any age. Researchers from the University of Melbourne found a low prevalence of ECoV in a case-control study of diarrhoea in Thoroughbred foals. From studies in adult horses in the USA and Japan, there is some evidence that draft horses are more susceptible to disease than Thoroughbreds. In rare cases, horses may exhibit neurological signs or develop complications.

What should I do if I think my horse might have equine coronavirus?

If your horse has a fever, is off-feed or has soft manure or diarrhoea call your veterinarian. While waiting for your veterinarian to attend, isolate your horse from other horses and prevent your other horses from any access to stables or pasture where your sick horse has been kept recently. Diarrhoea is always a concern in foals and adult horses. Severe diarrhoea can lead to rapid fluid loss, electrolyte imbalances and dehydration. In addition, inflammation of the intestinal wall can allow transfer of bacteria and their toxins into the bloodstream causing endotoxaemia.

Equine coronavirus is diagnosed using a PCR test that detects viral genetic material in a faecal sample. Other infectious causes of diarrhoea, such as Salmonella spp. and Clostridium difficile may also be ruled in or out using similar tests on faeces.

As with many viral infections, treatment entails supportive care, such as anti-inflammatory therapy and fluids via a nasogastric tube or intravenously.

Currently, there is no equine coronavirus vaccine available. However, equine coronavirus is closely related to bovine coronavirus, for which there is a vaccine available. Researchers at the University of California are investigating whether use of commercial bovine coronavirus vaccines in horses has the potential to provide protection against ECoV infection, but there is no available evidence to support the use of the cattle vaccination in horses at this point.

Can I get equine coronavirus from my horse?

There is no evidence that equine coronaviruses can infect people. However, it is possible that people can spread equine coronavirus between horses. Good biosecurity practices can reduce the risk of transmission and protect your horses from infection.

Can I get SARS CoV2 from my horse? 

The cause of the current pandemic, SARS CoV2, is classified as a betacoronavirus which is the same genus that contains equine coronavirus, bovine coronavirus and several coronaviruses of pigs. However, SARS CoV2 is genetically very different to the coronaviruses that infect our other domestic animals, including horses. Additionally, SARS CoV2 primarily causes respiratory disease and is spread by aerosol. There have been numerous reports that SARS CoV2 can infect domestic animals, such as cats, due to contact with SARS CoV2 positive humans. But there is no evidence that these animals are able to pass that infection back to humans, and there is no evidence that SARS CoV2 can infect horses.

Good Biosecurity Starts With You

• Handle healthy horses first (feeding, grooming, cleaning stables)

• Do not share tack and equipment between horses

• Wash your hands before and after handling each horse

• Isolate all new horses introduced onto the premises for three weeks

• Dispose of manure so as not to contaminate pastures or drinking water

Sign up to our newsletter