What do we know about the potential COVID-19 threat to and from horses, cats and dogs?
By: Dr. David Marlin
At the time of writing, there have been 1,029 scientific papers published on COVID-19 – two papers in 2019 and 1,027 in 2020! This illustrates how acute the emergence of this pandemic has been. I certainly can’t claim to have read all of these, but I have read a lot, especially the ones I consider to be most relevant relating to aspects such as origin, transmission, disinfection, strain mutation, management and treatment.
As an asthmatic, I have been taking both a professional and personal interest in the COVID-19 pandemic.
Many animal owners will be facing some anxiety at this time, especially as there is a lot of misinformation circulating about where COVID-19 came from and its potential to jump into animals or for animals to transmit the disease. Diseases that can be spread from animals to people are referred to as “Zoonoses,” and include diseases such as rabies, Lyme disease, malaria, Salmonella, Ebola, Swine flu and West Nile virus.
Knowing horse, dog and cat owners, they are more likely to be concerned about passing COVID-19 onto their animals than catching it from them.
Where Do We Think COVID-19 Came From?
The likely origin is a live-animal market in Wuhan, China, but it may also be possible that it was brought to the market by an infected person. There are no definite answers yet, but most research supports the theory that it originated in the Rhinolophus or Horseshoe bat and was passed to people via another animal.
For a while, it was suggested that the intermediate-host may have been the Pangolin or scaly anteater, which is found in parts of Africa, India, and the Far-East, including Southern China. A paper published on the Feb. 27, 2020 in the Journal of Medical Virology, however, concluded it could not. But whatever the origin, this is a zoonotic disease.
Transmission From Humans to Horses, Dogs or Cats?
It’s early days and information is limited, but last week I was in contact with Dr. Richard Newton, Director of Epidemiology and Disease Surveillance at the Animal Health Trust. He is an expert in viral diseases of animals. Richard is also in touch with many vets and scientists working in this area around the world through the Veterinary Infection Control Society Listserver managed by Colorado State University: “This is topical, but as with many of these issues, there is, unfortunately, a dearth of evidence on which to base any firm guidance. There is no evidence that I am aware of that horses or farm animals are susceptible or can act as a source of infection for humans.”
The situation with dogs is slightly different at this stage, because, in Hong Kong, they did identify an animal that was owned by somebody who was subsequently confirmed to be infected with COVID-19 and detected SARS-CoV-2 as a weak positive by RT PCR. But there are many questions as to whether this was a true infection or the animal was acting as a fomite [carrier e.g. on the coat or paws] for the virus.”
In addition, IDEXX Laboratories in the USA announced (on March 13) that they have been testing thousands of dog and cat samples for COVID-19 and to date there have been no positives. IDEXX also has labs across Canada, Australia, New Zealand, Japan, South Korea, South Africa, Brazil and Europe and have said they will continue to test for COVID-19.
At the present time, considering all available information, person-to-person transmission is the cause of the spread of COVID-19 beyond Wuhan and that the Center for Disease Control (CDC), the World Health Organization (WHO) and World Organization for Animal Health (OIE) are all in agreement that there is no evidence of pet-to-pet or pet-to-animal transmission of COVID-19. Neither is there any current evidence of people infected with COVID-19 transmitting this to animals.
If you want to be cautious, the best advice at this time given the lack of knowledge is that if you become infected with COVID-19 you should limit contact with your animals as much as possible. If you are infected and have no choice, wear a face mask and latex gloves and avoid stroking or touching them or their food as much as possible and wash your hands before and after any contact.
It’s perhaps hard to imagine that the coronavirus strain COVID-19, also referred to as SARS-CoV-2, only began to emerge in China at the end of 2019, when we look at what is happening today. At the time of writing, (3/18) there are 175,438 confirmed cases and have been 6,713 deaths worldwide attributed to the COVID-19. And these are only the ones we know about. As many people showing less severe symptoms which could be due to COVID-19 infection are not being tested, it has been estimated that the current true number of cases could be 10 to 20 times higher.
Again, at the time of writing, we seem to have polarized behavior. There are people who are panic buying and self-isolating while others are out in pubs and restaurants in numbers. The latter may be underestimating the risk of infection, unaware of the consequences, concluding that, at this stage, the risk of infection is still relatively low, in denial or simply resigned to becoming infected and believing they will recover.
Social media is playing an interesting role at this time and there is a mass of information circulating about COVID-19. Some good, some bad, some potentially very harmful and some ridiculous. And as often happens, bad information seems to disseminate better than good. This can often be because the poor information is written in a style people find easier to relate to or more sinisterly, poor information is used as click-bait to drive people to sites that generate income through advertising revenue.
Article provided by Haygain. Author Dr. David Marlin is a scientist with over 25 years experience in physiology and biochemistry. David is the author of over 200 scientific papers and book chapters and he has written a variety of articles for Haygain on equine health, in particular respiratory health. Haygain manufactures Haygain Hay Steamers and ComfortStall Sealed Orthopedic Flooring. For more information, visit www.haygain.com.