‘COVID-19’ stands for ‘Coronavirus Disease 2019’, since it first emerged at the end of 2019 (in China). It is caused by a type of betacoronavirus now called SARS-CoV2 (Severe Acute Respiratory Syndrome -Coronavirus type 2).
There are many types of coronaviruses that affect different animal species. Many of them are rather benign so are carried and transmitted by the hosts without causing much harm. Many common ‘colds’ we suffer from are coronaviruses. Normally, they are ‘species specific’ meaning that a cat coronavirus only infects cats and a human coronavirus only infects humans, for example.
Coronaviruses in general have a high mutation rate, so can change and evolve rapidly. SARS-CoV2 is a novel virus, which appears to have evolved from a type of bat coronavirus. How this happened is not yet fully understood. Two main theories are a) a benign form made the jump to humans first then evolved into the nasty (pathogenic) type it is now; or b) it evolved to being pathogenic in the primary host then made the jump to humans. Direct bat to human transmission has not been documented, so it is likely an intermediate host was involved along the way, and two possibilities are pangolins (a type of anteater) or stray dogs. Among the first wave of human cases many were linked to a seafood and live animal market in Wuhan, then more and more humans were being infected that had no link to the market.
So, although in the early stages animal to human transmission has occurred, in its current state the main form of transmission is human to human.
Up to the point of writing (22 April 2020) there have been nearly 2,600,000 confirmed cases and nearly 180,000 recorded deaths. COVID-19 is spreading and killing so rapidly because it is a new virus, our immune systems have never been exposed to it before so we do not have any natural resistance to it.
Many people have great concern about this disease, not only for their own health and their loved ones, but for their pets as well. If it came from animals, surely they can be infected as well?
Below you will find a section of F.A.Q.s with a ‘bottom line’ answer if that is all you need, followed by ‘a bit more’ information including advice, and then some more ‘scientific stuff’ if that’s your thing.
Q1. Can my pets catch COVID-19?
A1. Bottom line: Currently, the evidence indicates that it is extremely unlikely that your pet would catch COVID-19, either from being outside (dogs exercising, cats free-roaming) or from you having COVID-19. You should continue to look after your pets as normal, observing good hygiene measures of washing your hands after handling them.
A bit more:
Because this virus is so new to the world we do not fully understand it, including whether it may still evolve into something which could be transmitted to animals and cause them to be ill. Therefore, we must exercise a certain amount of caution.
If you are ill with signs of COVID-19 (proven or presumed), in addition to the advice about self-isolation from people, it is recommended that:
- you get someone else in your household to look after the pets, if possible
- if this is not possible, you minimise direct contact with them, avoiding stroking, cuddling, grooming, kissing, being licked, and sharing food and bedding
- when you do need to handle them, cover your mouth and nose with a cloth face covering, and wash your hands before and after handling them
Please note this advice is cautionary, it is not an indication that your pets are definitively at risk.
Q2. Can my pet die of COVID-19?
A2: Bottom line: There have been no reported non-human deaths from COVID-19.
A bit more:
Consider those numbers above again – 2.6 million cases, 180,000 deaths (to date 22 April 2020). In many of the countries that have seen the largest numbers of cases, eg China, UK, Italy, Spain, USA, there are high percentages of pet ownership, and yet there have been no deaths in pets attributed to COVID-19, and no surge in non-fatal illness in pets either.
Scientific Stuff – What you may have heard about – explained:
- Two dogs tested positive in Hong Kong. Also, one cat in Hong Kong, one cat in Belgium and Nadia the tiger in New York Bronx Zoo have tested positive.
- It was then reported that one of the dogs had died, potentially giving the impression it had died of COVID-19. That dog, a 17-year-old Pomeranian, had multiple co-morbidities, and died a few days after being released back to its owner, having not shown any signs of the illness. It had been held in quarantine for a couple of weeks, during which it had been repeatedly swabbed; one can presume this was a stressful experience for the dog. Neither of the dogs nor the Hong Kong cat had shown any clinical signs of COVID-19. All these ‘positive’ animals had been quarantined from COVID-19 positive households. In total 27 dogs and 15 cats (as of 31st March) were quarantined and tested; out of 42 animals only 3 had positive test results.
- The Belgian cat belonged to a person infected with COVID-19 and developed respiratory and gastro-intestinal clinical signs. Its vomitus and faeces tested positive for SARSCoV2. However, due to the person self-isolating, the samples were taken by the owner, so could have been contaminated, and the cat was never checked by a vet or tested for other more common cat diseases which could have caused the signs it showed. It recovered after a few days.
- Nadia the tiger, along with 3 other tigers and 3 lions, all developed a dry cough and some inappetance within the same week. Nadia was the only big cat tested – bearing in mind a full general anaesthetic is required to do this. Samples taken from the trachea (windpipe) tested positive and were triple checked. It is assumed she was infected from a zookeeper who must have been an asymptomatic carrier. There are other big cats at the zoo which were not affected, and no other animal species at the zoo were affected. All the cats recovered uneventfully from this brief illness.
What does a positive test mean?
- In most of the cases some form of PCR (polymerase chain reaction) test was performed.
- Swabs are taken from the site of the body assumed to be affected – so in these cases the mouth and nose (dogs), trachea (tiger) and since the Belgian cat had vomiting and diarrhoea, vomitus and faeces were sampled.
- There are different types of PCR test with differing levels of accuracy. In general, they are highly sensitive – they can detect the tiniest amount of genetic fragments of the virus. PCR tests do not confirm if the virus is viable within the animal sampled. (NB viruses aren’t really living entities, they are bunches of genetic material (DNA or RNA) with some extra proteins to help them do their job – they hijack the host cells’ mechanisms to manufacture more virus elements, which burst out of the cells ready to be passed on).
- PCR tests can be positive because:
- a) the virus is present and viable in the host and able to replicate
- b) the virus is present, but is not viable – it cannot infect the host cells or it cannot replicate
- c) an infected person has contaminated the animal with their virus before sampling, or contaminated the sample after swabbing
- d) rarely, it could be contaminated at the lab doing the test.
- It is note-worthy that the Hong Kong animals all had serial ‘weak positive’ PCR results, so in the face of them having no clinical signs, this could indicate either contamination or scenario ‘b’ above.
What about Antibodies?
- Antibodies are manufactured by the immune system as a response to infection. They are made to target a particular infective agent, whether that is a bacterium, virus, protozoan or fungus.
- Not all infections trigger good antibody responses; the immune system deals with the infection in different ways (or not, if it is unable to).
- If a person or animal develops antibodies to SARSCoV2 it demonstrates that the virus has definitely infected the host, as the immune system has jumped into action and made antibodies.
- One of the two dogs in Hong Kong was shown to have developed antibodies, indicating its body mounted a response to the virus. However, that is still not a full indication that the infection in that one dog was significant, because the dog showed no clinical signs of illness. In this instance, there is no evidence the dog would act as a source of infection.
- Not all of the ‘positive’ animals have been tested for antibodies, so it is unclear how different animals react to the presence of the virus. Testing for antibodies requires taking a blood sample, so is more invasive than taking a swab.
Figure 1 shows how most viral infections work.
Other evidence available:
- There have been many studies performed using experimental infection of different animal species – when this is done, very high doses of the virus are inoculated – this does not reflect the dosing received by natural infection.
- It has been found that the virus could not replicate in dogs, pigs, chickens and ducks.
- In bats, ferrets and cats, the virus can replicate.
- There is also evidence that cats can develop antibodies -but at a low rate, and evidence of cat to cat transmission – but under very forced, unnatural conditions.
- These studies have only been performed on small numbers of animals.
- In summary, although this information could be of concern – the take-home message should be these experiments in no way mimic the conditions of a natural infection.
- Other evidence indicates strongly that dogs and cats are not considered a source of transmission:
- 2 large laboratories in the USA have PCR tested thousands of samples from dogs and cats, submitted for other tests – all of which have been negative for SARSCoV2
- 21 pets belonging to 20 French vet students were tested (PCR and antibody tests). Two students had tested positive for COVID-19 and 11 others had symptoms of the illness. None of the pets was positive by PCR or showed an antibody response.
Globally, research is ongoing in all different aspects of COVID-19, from studying the genome, to how it affects humans and animals, to potential treatments and vaccinations. Globally, we have only known SARSCoV2 for less than six months. Whilst an amazing amount of information has been obtained in that time, there is still a lot to learn.
About the author:
Claire Zentveld., BSc, BVM&S, GPCertFelP, MANZCVS (Medicine of Cats), MRCVS
The main thing to say about myself is I LOVE CATS! I am a cat ‘owner’ first and a vet second (We don’t really ‘own’ them, perhaps I should say ‘cat servant’). I completely understand the emotional upset of seeing your beloved cat when it’s sick or in pain, and also the difficulties of giving medication to a cat.
I graduated from Edinburgh University in 1999, with all good intentions of eventually working in wildlife conservation. As happens, life had other ideas, and the further education in Wild Animal Health just didn’t happen! All for the best, as working in small animal practice allowed me to be around the species I’ve always loved the most!
I was very fortunate to have studied under some world-renowned feline specialists at The Dick Vet School – such as the esteemed Danielle Gunn-Moore and Severine Tasker. So even as a baby vet, my interest in feline medicine was triggered. Over the years I have gravitated more towards feline-orientated professional development, as well as forming an interest in ultrasonography. In 2013 I passed the exam for a General Practitioner Certificate in Feline Practice (GPCertFelP), and in 2018, I passed another exam for a highly regarded qualification in the Feline Medicine world – the Membership of the Australian and New Zealand College of Veterinary Scientists (MANZCVS) -Medicine of Cats. This is the equivalent of a Masters degree.
I have worked in companion animal practice for 21 years now, changing through permanent positions and locum work, and spent two years at a referral centre in Hampshire, as a registrar in internal medicine. In 2019 I founded my own practice – Vet2Cat – a feline-only home-visiting practice based in Portsmouth and covering much of South Hampshire. Seeing cats in their own environments is so rewarding from a vet’s point of view: they are so much more likely to be more relaxed and behave naturally. Also assessing its environment and social relations with other cats can help with understanding and tackling issues, and this enables us to advise you on how best to help your cat. The practice is in its infancy still, and not yet financially self-sufficient, so I also offer consultancy work to other practices.
When I’m not vetting, I enjoy pilates, singing in a community choir and a good walk and a chat with a friend.
I share my life with my husband, Hugo and our two amazing cats Toots and Mikey – sister and brother. They bring joy to my life every day.