Early last year, when Covid-19 was still a distant concern to most of us, there was a huge spike in the numbers of dog owners in the UK reporting sudden onset acute vomiting in their pets. The affected dogs were often having multiple bouts of projectile vomiting, and worryingly, seemed not to respond to normal treatment.

We reported the outbreak here, and thank you so much to all our readers who submitted case reports! A year on, the team at SAVSNet who investigated it have published their final report – and the results are really surprising.

Given the way it spread, it always seemed likely to be an infectious agent. But in their paper, the researchers were able to demonstrate that “Diet and vaccination status were not associated with the disease”. That left viruses and bacteria, and genetic testing on samples revealed an old “friend”, back in a different incarnation.

Variant Canine Enteric Coronavirus

Now, first of all, this is nothing to do with the human coronavirus that causes Covid. Dogs have their own species of the virus, and there are two major families – respiratory coronaviruses, and enteric (gut-attacking) ones. The new virulent vomiting bug appears to be a new variant of the enteric one, which rapidly swept across the UK in late 2019 and early 2020. 

As we are learning in the human pandemic, coronaviruses do occasionally mutate – and frequently the new viruses produced are either more infectious than the original. Occasionally, they may cause more severe disease too. This is what seems to have happened. 

“Original” Canine Enteric Coronavirus

The original virus is an alphacoronavirus (only very, very distantly related to the betacoronavirus that causes Covid), and typically causes mild to moderate vomiting and explosive diarrhoea in puppies and young dogs. In older dogs, mild signs aren’t uncommonly seen but most cases are asymptomatic. In fact, with the exception of young and unlucky puppies, most dogs recover rapidly and uneventfully.

It’s not even a particularly rare virus, with between 16 and 54% of dogs showing signs on blood tests of relatively recent exposure. The rare cases of severe haemorrhagic diarrhoea in young puppies appear to be largely due to mutant forms of the virus.

What’s the difference?

Well, the new variant seems to cause very severe vomiting – 5 or more times in 12 hours – and then a prolonged state of nausea and loss of appetite, with or without further vomiting. While the original strain tends to cause diarrhoea more, and symptoms usually only last 2-3 days, the variant seems to last 5 or more days, leaving dogs quite weak without veterinary attention. Many of these dogs became dangerously dehydrated, although fortunately, it seems that very few dogs died from the outbreak.

So what do I do if my dog seems to be sick?

A one-off vomit is probably nothing to worry too much about if your dog seems bright and fairly well in themself, and able to keep down water. A 12 hour starve with only water (ideally, a small bowl regularly topped up rather than a big container that they can fill their stomach on), followed by a bland diet for a few days is normally enough.

If however, your dog vomits repeatedly (more than twice in 12 hours), or if they show any other symptoms (weakness, lethargy, increased urination, change in gum colour, unusual behaviour etc), then call your vet for more advice.

The variant coronavirus doesn’t seem to be as bad this year, although there are scattered reports, so it may be that dogs are becoming immune to it. Alternatively, perhaps the virus outbreak has burned itself out. Either way, we need to be on our guard against all sorts of novel viruses these days!