Circovirus Linked to Multiple Deaths of Michigan Dogs

Patrick Mahaney, VMD, CVA, CVJ
Published: October 08, 2013
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As of late (i.e., the latter half of 2013), there’ve been reports of outbreaks of illnesses having serious health consequences for animals or people. I recently wrote about two of them in my petMD Daily Vet column:

Can a Dolphin Virus also Infect Humans? and Could Your Pet Have a Brain-Eating Amoeba?

Recently, reports of what seems to be an emerging virus have come from multiple states, including California, Michigan, and Ohio. As of October 3, 2013, circovirus has been confirmed in two dogs that have died in Ann Arbor, Michigan. Another four dog deaths in Ann Arbor are suspected to have been in part due to circovirus related illness.

So, let’s get right down to it and discuss what is currently known about this virus.

What Species is Circovirus Known to Infect?

Circovirus is currently known to infect birds, dogs, and pigs. Infection in the pig world is quite common, as Porcine circovirus 2 can affects piglets shortly after they are weaned (cessation of nursing). Delayed growth, body tissue wasting, and death are associated with infection in pigs.

Many species of birds can be infected, as circovirus causes infectious anemia in chickens, and beak and feather diseases in psittacines (budgies, cockatiels, finches, parakeets, and parrots).

The canine variety of cirvovirus, CaCV-1 strain NY214, is closer in genetics to the virus infecting pigs than it is to the bird virus. It was first discovered during a 2012 Columbia University study (Complete Genome Sequence of the First Canine Circovirus). It was then diagnosed in a dog suffering from diarrhea and hematemeis (vomit containing blood) that had been brought in for evaluation at the University of California, Davis (UC Davis) Veterinary Medical Teaching Hospital. The virus was also discovered in the feces of 14 of 204 dogs that were not suffering from digestive tract upset; a finding that shows it can be present and not cause illness.

What Are Common Clinical Signs of Circovirus Infection?

Besides the diarrhea and vomit as mentioned above, other clinical signs include:

  • Decreased appetite (anorexia)
  • Decreased water consumption
  • Lethargy (depression, decreased moving, etc.)
  • Delayed capillary refill time (the time it takes for blood to refill the gums after a finger presses out the blood. It should be < 2 seconds: try it on your pooch)
  • Pale pink mucous membranes (gums) and tongue
  • Vasculitis (inflammation of blood vessels, which can manifest in skin lesions)

As there are many other causes of the same clinical signs in dogs, it is important that veterinarians don’t immediately jump to the diagnosis of canine circovirus and consider all potential options (bacterial, parasitic, and other viral infections, toxicity, foreign body consumption, cancer, etc.) when performing their clinical workup (blood, fecal, urine, other testing).

How is Circovirus Spread?

Circovirus is commonly spread through body fluid secretions, including those from the digestive and respiratory tract, such as saliva, vomit, diarrhea, and nasal secretions.

Infectious organisms affecting our canine (and feline) companions have a tendency to emerge in areas where populations of susceptible hosts congregate. Therefore, shelters, day care facilities, dog parks, breeding facilities, and veterinary hospitals are all sites where bacteria, fungi, parasites, and viruses can be transmitted from one animal to another.

How is the Diagnosis of Circovirus Achieved?

Circovirus diagnosis is achieved based on a PCR (Polyerase Chain Reaction) test on body tissues. If deemed appropriate, a veterinarian can perform canine circovirus testing through the MSU Diagnostic Center for Population and Animal Health.

Collecting data about this emerging disease is important, so please consent to testing for circovirus should your veterinarian deem it appropriate based on clinical suspicion.

Can Circovirus Infection Be Prevented?

There is currently no vaccination available for canine circovirus. Unfortunately, development of vaccinations takes years and the diagnosis of circovirus in dogs is a recent event.

Realistically, there may never be a vaccination available to prevent dogs from being infected with circovirus. Therefore, it’s vital that owners focus on preventing infection with microorganisms instead of treatment. Prevention comes down to using common sense and caution when planning your dog’s interaction with other canines.

Locations where dogs congregate can be hot zones for infection, as bacteria, viruses, and parasites are exchanged via direct contact or from body secretions. As a result, having your dog frequently spend time in these places isn’t really in his best interest from a standpoint of health. Dogs that do socialize with others of their and other species should be vaccinated according to the recommendations of their veterinarians and have frequent physical examination and diagnostic testing to monitor for the development of disease that may not be apparent to the naked eye.

Can Circovirus Be Spread to Humans?

Currently, there have been no reports of humans being infected with circovirus. Yet, as there are many zoonotic diseases (those that transmit from one species to another), including some which have origins in swine and birds, the potential exists for humans to be infected with circovirus.

Infection with the swine variety of circovirus is more likely than with the dog variety, as humans and pigs are closer in their genetic relation than dogs (see Human to Pig Genome Comparison Complete). I wrote about zoonotic transmission of a virus containing bird and pig genetic material in the following article: Swine Flu Pandemic Over But H1N1 Hybrid Virus Emerges

You can focus on disease prevention by:

  • Washing your hands frequently with soap and water
  • Preventing your dog from licking your face or areas of the body having mucous membranes, such as the nose or eyes
  • Scheduling a wellness examination with your veterinarian every 6 to 12 months
  • Limiting your dog’s access to areas well-traveled by other canines

Dr. Patrick Mahaney

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