Horses at low risk of Covid-19 infection, but we need to know more

The novel coronovirus that causes COVID-19.
The novel coronovirus that causes COVID-19. © NIAID-RML

As the Covid-19 pandemic rages around the world, infectious equine disease expert Professor Peter Timoney takes a look at its impact and how many aspects of coronavirus remain to be explained.

Since the discovery of the novel coronavirus (SARSCoV-2), causal agent of the highly contagious and frequently life-threatening disease of humans designated Covid-19 in December 2019, the virus has spread very rapidly around the globe. The exponential increase of cases in affected countries and the alarming case-fatality rate has resulted in a pandemic of unprecedented proportions, in terms of its health and economic impact on human populations worldwide.

Peter Timoney, MVB, MS, PhD, FRCVS
Peter Timoney. © Gluck

Of the seven coronaviruses known to infect humans, three are of major public health significance: severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS) and coronavirus 2019 (COVID-19). Other members of the coronavirus family can cause respiratory or intestinal disease in a range of domestic species, including horses, swine, cattle, cats, dogs and chickens. SARS-CoV-2 is genetically and otherwise uniquely distinct from these other coronaviruses, none of which are known to be human pathogens.
There are many aspects of the biology of SARSCoV-2, including its host range, epidemiology, pathogenesis and nature of the immune response to the virus, that remain to be fully elucidated.

The pandemic of Covid-19 has had significant implications for the US horse industry. A point of continuing concern for many in the industry is whether SARS-CoV-2 is capable of infecting and perhaps causing disease in horses.

At the present time, there is no evidence confirming the susceptibility of horses to infection.

This is supported by the outcome of a recent study undertaken to determine conservation of the angiotensin-converting enzyme 2 (ACE2) across 410 vertebrates including 252 mammalian species, and the likelihood of it functioning as a SARS-CoV-2 cell receptor. The horse was ranked low risk in predicted susceptibility to infection based on the binding characteristics of its ACE2 compared to the human homologue. In the current absence of any information to the contrary, it is not possible to speculate on the potential risk of horse-to-horse transmission of the virus and whether horses might play a role in transmitting the virus back to humans.

Aside from the primary consideration of its potential to affect the health of the horse, Covid-19 has had a major impact on the economy of the horse industry in Kentucky and the USA. Virtually all sectors of the industry have been negatively influenced by the current pandemic. Racing, equestrian events, and horse shows have been cancelled or postponed to a later date. Horse sales and other ancillary businesses have been similarly affected. This has inevitably resulted in layoffs or furloughing of workers who would otherwise be employed at racetracks, equine sporting events, sales, etc. The economic fallout from this pandemic also has affected people who buy horses or wager at racetracks.

Horse breeding has been allowed to take place subject to stringent precautionary measures to prevent further spread of SARS-CoV-2. This is predicated on maintaining an enhanced level of biosecurity in all aspects of breeding shed activity and in following approved standard practices including social distancing by personnel. While much attention has been focused on centers of horse racing and breeding across the country, the financial repercussions of Covid-19 have also been acutely felt by owners of smaller horse farms/ businesses, etc., whose livelihoods are dependent on the sustainability of the equine industry.

It is way too soon to predict what the overall impact of the pandemic will have on the nation’s equine industry in all its aspects from racing, equestrian events, horse shows, breeding, sales and a variety of ancillary businesses. What is certain, however, is that the horse industry will survive and, given time, thrive again and regain its former prominence and importance to the nation’s economy.

Article courtesy University of Kentucky College of Agriculture, Food and Environment.

» Earlier article: Equine Coronavirus and Covid-19: No evidence of horse-human spread

Professor Peter Timoney

Professor Peter Timoney, MVB, PhD, FRCVS, is the Frederick Van Lennep Chair in Equine Veterinary Science at the Gluck Equine Research Center.

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