Canine Circovirus: Our Current Knowledge

Some angst is brewing amongst dog lovers because of a newly discovered infectious agent called canine circovirus. This angst is justified as circovirus is suspected to be the cause of recent severe illness and even death in some dogs.

When I first heard about canine circovirus I thought back to an email I received three to four months ago from a reader inquiring about dogs in her area (I cannot recall where she lives) who were reported to be dying from hemorrhagic gastroenteritis (HGE). I responded by telling her that dogs affected by the disease veterinarians refer to as HGE are expected to fully recover, assuming they receive appropriate medical treatment. I raised the notion that perhaps these dogs had something other than the traditional version of HGE. Looking back, I’m wondering if this “something else” was canine circovirus.

What is circovirus?

Circovirus have been around for a long time, but documentation of this microorganism in dogs is new. Pig farmers are all too familiar with circovirus which causes poor growth, a “wasting away” syndrome, and death in piglets. Circovirus can also cause disease in a variety of bird species.

While the circovirus found in dogs resembles pig circovirus, they are not identical. This canine version was first discovered in June, 2012. At that time it was not determined to be a cause of disease, simply an incidental finding in healthy dogs.

In April, 2013 circovirus was first reported as a possible cause of illness in dogs by researchers in California. Most recently, circovirus was found in the feces of a number of sick dogs in Ohio. These dogs had severe vomiting, bloody diarrhea, and lethargy. Some of these dogs passed away in spite of aggressive therapy.

Although circovirus has been isolated from apparently healthy dogs, the consensus now is that this virus is very likely a “player” in the severe gastrointestinal illnesses reported in California and Ohio. Whether the symptoms these dogs exhibited were due solely to the circovirus or the virus acting in conjunction with another microorganism is unknown.

Route of infection

The route of canine infection isn’t known with certainty, but it is suspected that circovirus is spread directly between dogs via feces or vomited material. Circovirus in pigs can be spread through respiratory secretions. This route of contagion has not been ruled out in dogs. Some of the Ohio dogs who tested positive for circovirus were recently boarded or spent time at doggie daycare.

What should you do?

Symptoms thought to be caused by canine circovirus are lethargy and severe vomiting and diarrhea. These are nonspecific symptoms, meaning they can occur with a wide assortment of medical issues. If your dog has severe vomiting and diarrhea, it is important to get your veterinarian involved. Prompt treatment prevents dehydration and hastens recovery, whatever the underlying disease.

If your dog is a frequent flyer at a boarding kennel, doggie daycare facility, or dog park I encourage you to be just as “heads up” as you normally would be to protect your dog’s health. Inspect the facility for cleanliness, proper sanitation measures, and the presence of healthy appearing animals.

The bottom line

A new canine virus has been discovered and our current understanding of its behavior and significance is very limited. Mores studies of canine circovirus are in progress and I am confident we will have much more certain information in the near future. For now, no need to do anything more than take good care of your dogs- something I get the feeling you are already doing! I will keep you apprised of any new developments.

Prior to this, what have you heard about canine circovirus?

Best wishes,

Nancy Kay, DVM

Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet
Recipient, Leo K. Bustad Companion Animal Veterinarian of the Year Award
Recipient, American Animal Hospital Association Animal Welfare and Humane Ethics Award
Recipient, Dog Writers Association of America Award for Best Blog
Recipient, Eukanuba Canine Health Award
Recipient, AKC Club Publication Excellence Award
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Please visit to read excerpts from Speaking for Spot and Your Dog’s Best Health.   There you will also find “Advocacy Aids”- helpful health forms you can download and use for your own dog, and a collection of published articles on advocating for your pet’s health. Speaking for Spot and Your Dog’s Best Health are available at,, local bookstores, and your favorite online book seller.






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11 Comments on “Canine Circovirus: Our Current Knowledge

  1. I have only just read your post Dianna, sorry for that.

    But I’m the Englishman with the Irish name, that can’t spell in American (or truthfully in British either) . ‘Ann Arbour’, see above, should, of course be ‘Ann Arbor’. It sounds lovely.

    Well, I think circovirus is indeed a problem now in birds but it will be a different strain.

    The big problems are in pigs or hogs or swine, and much covered up.

    That dogs shoud get it in Ohio seems to be more than a co-incidence.

    All the big pig producing areas that’s US, British and others have circovirus. Circovirus is not nice.

    Now you have a brave lady veterinarian who has spoken out. That can’t be easy in pig country. I think she is just great.

    Here, once she had survived tha attacks, she would be Lady Lindsay Ruland. She would get the best table in any restaurant for life. But Americans are not allowed British titles, of course

    Look after that lass. We do not get too many like that anywhere.

    Regards Pat (m)

  2. Well it scares me, Taylor.

    Other diseases seem to travel with circovirus, and they are the ones needing antibiotics. The problem is then that antibiotic resistant forms emerge for which there is no treatment.

    Circovirus seems to knock out or damage the immune system.

    As of now, the veterinarians in Ohio seem divided, and to be frank, the officials do not tell the same story on matters factual.

    But that’s not all bad – at least the problem is well and truly out from under the carpet.

    Regards from England – and best wishes. Let’s hope that courageous vet at Ann Arbour has it wrong, she will hope that too.

    Pat Gardiner

  3. Wow Pat, I just looked up porcine circovirus… That is some scary stuff right there!!

  4. Thank you Terry for being heads up and responding to my blog post. Perhaps the veterinarian caring for these Arizona dogs will consider circovirus as a possible cause.

  5. I am the person whio wrote the inquiry to Dr Kay when my friend’s dog , a small yorkie, died from what was then believed to be HGE. The dog lives in southern Arizona. As we both belong to groups where we discuss care of yorkies and other small dogs and have heard of other cases around the country of sudden death caused by symptoms that are ‘apparently’ HGE, we were concerned with Dr Kay’s original reply that dogs if given proper medication should recover. However, in small dogs, rushed to the vets, the onset of symptoms and sudden death were within a few hours, not days. I am forwarding this latest notice from Dr Kay to my friend in Arizona, and to her vet, in hopes there is something in the vet charts or a clue that can help the small dogs. Thank you for your considerate followup

  6. Great information. I shared on the Happy Tails group page. Questions:, can this be detected in stool or blood for a definitive diagnosis? Would that determine treatment or is this just treated with palliative measures? I assume there’s no vaccine. – ?

  7. I think I remember that I read there is only one lab in the US that tests for this virus in dogs or for all species? If that’s the case, isn’t it more likely that this virus has been around for some time and simply has not been tested for?

  8. Prior to this article or prior to this latest situation? Prior to the latest situation – no, haven’t heard of it.

  9. Thank you for posting this. I have been hearing about it but did not know what it was.

    I do have a question regarding this disease in birds- do you know if this is present in wild species and can it be transferred to our pet birds? I did look it up but there is so much info out there, I trust resources you would be able to provide.

    Thank you!

  10. By sheer chance in 2000, I got invoved in porcine circovirus in England

    PCV is the ghost at the feast. It is a genuine nightmare, in Britain as well as the US. Our initial outbreak was in 1999 and, frankly, covered up.

    There are many unexplained deaths of dogs all in pig country, including at the Queen’s estate at Sandringham.

    You can’t get worse than that.