Dog Circovirus

A Virus Worth Watching
By Carole Howell, November 2014

It’s not new, but a member of the circovirus family, usually linked to diseases in pigs and some birds, is now showing up in dogs. Research data from the University of California Davis School of Veterinary Medicine suggests that this emerging virus, either alone or as a co-infection, may be a contributing factor in canine illness in California.

Data collection is underway in multiple regions of the country to determine if exposure to circovirus is common and widespread. Dog-to-human infection has not been documented.

“We know from looking at dog samples that were stored in our archives that canine circovirus has been around for at least five years,” said Patricia Pesavento, DVM. PhD, associate professor, Pathology, Microbiology, and Immunology at UC Davis School of Veterinary Medicine. “We are seeing it in dogs now because we are looking for it, and we have the tools to diagnose it now. The canine virus is not a modified strain of porcine circovirus, but is a completely different virus from the same virus family.” The good news is that circovirus does not always result in illness, being found in the stool of 14 of 204 healthy dogs screened.

“From what we know now, circovirus is not a major cause for concern, and the cases we’ve identified post-mortem seem to be isolated,” said Dr. Pesavento.

Among dogs that were sick and had circovirus in their tissues, vomiting and bloody diarrhea were the common symptoms, said Dr Pesavento. “However, diarrhea isn’t necessarily predictable, since two dogs had clinical signs that were limited to the central nervous system, and in those cases blood vessels in the brain were most affected. This reflects the fact that the virus seems to affect the vascular system.”

A symptom as non-specific as diarrhea could come from wide variety of common causes including other infectious agents, ingestion of foreign bodies or toxins, overeating rich treats, and even stress. Dr. Pesavento added that, among infectious agents, parvovirus is very common and can cause vomiting and bloody diarrhea.  

Circovirus is shed in feces, and transmission is presumably fecal-oral transmission. Doggie daycare and boarding facilities, where many dogs are gathered in one area, can be a prime source of infection for many illnesses, although the virus is not confined to boarding facilities.

To reduce the chance of any viral illness and to avoid infecting other dogs, apply the same simple measures that you would in a child attending daycare. Avoid contact with ill animals and contact with other dogs if your dog has symptoms of illness. Clean up your pet’s stool and avoid contact with other pet’s stool whenever possible.

“As you well know, dogs are not very picky about what they put in their mouths,” said Dr. Pesevento. “Monitor dogs carefully if they have ‘dietary indiscretion’ that causes vomiting or diarrhea that is mild and short-lasting. Blood in any vomit should be addressed quickly, said Dr. Pesavento.

Consult your veterinarian to get the correct diagnosis, including any laboratory testing. Prompt treatment, regardless of the cause, gives your dog a better chance of quick recovery and avoids infecting other animals.

“There is no circovirus-specific treatment, said Dr. Pesavento. “As with most viral infections, your veterinarian can treat symptoms with supportive fluid therapy or antibiotics to prevent secondary bacterial infections.”

A healthy pet is more likely to have a fully functional immune system to fight infections, so good preventive care is also important.

More than anyone, you know when your dog is not behaving normally. Prompt veterinary treatment can be critical to a good outcome, so address all illnesses early for the overall health of your pet.