Circovirus Infections in Dogs: Guidance for Veterinarians
November 22, 2013 
FAQ for dog owners
Update November 22, 2013: There has been a media report about the possiblity of cats being infected with this virus. We have contacted the Michigan authorities with a request for more information.
Circovirus may be present as a primary or co-infection with other enteric pathogens, but there is still much to learn about its significance as an enteric pathogen. Li et al (2013) documented co-infection with circovirus and canine enteric coronavirus, Cryptosporidium spp, C. perfringens α toxin, Giardia spp, Salmonella spp, Campylobacter jejuni, or Campylobacter coli in 19 circovirus-infected dogs with diarrhea. Circovirus was detected in the feces of 19/168 dogs with diarrhea and 14 of 204 healthy dogs. Sixty-eight percent of dogs positive for circovirus were co-infected with at least one additional enteric pathogen.
Circovirus infection was rumored to be the cause of dog illnesses and several dog deaths in Ohio in late August/early September 2013, but the Ohio Department of Agriculture is no longer considering it a primary cause as of October 3, 2013. Listen to our podcast on the status of the investigation (Sept 23) and the investigative process.
In late September/early October 2013, similar illnesses were reported in dogs in Michigan. The Michigan Department of Agriculture and Rural Development is investigating the illnesses.
Please note, this information is based on a very limited number of cases and may change as more is learned about this new circovirus.
Case presentation: Dogs infected with circovirus may present with progressive vomiting, diarrhea (possibly hemorrhagic) and hematochezia. Ascites, pleural effusion, hypovolemic shock, bicavitary hemorrhage and disseminated intravascular coagulation may also be present. According to Li et al, circovirus “should be considered in cases of unexplained vasculitis in dogs.”
If you suspect circovirus infection, please contact your state animal health authorities regarding sample submission.
Pathology: According to the report published by Li et al, examination of tissues from all infected animals revealed fibrinonecrotizing vasculitis. The location and severity of affected vessels varied among the cases, with most cases demonstrating abnormalities in the intestine and kidneys. Affected organs included the intestine, urinary bladder, spleen, liver, lungs, kidneys, heart, pancreas, adrenal glands and meninges (in a dog with tetraparesis). Lymph node necrosis was also observed in several cases and all dogs had histiocytic or granulomatous lymphadenitis in Peyer’s patches. One dog hemorrhaged into the thoracic and abdominal cavities.
Treatment: At this time, there is no indication to treat these cases any differently than other enteric infections. Because of the virus’ association with fibrinonecrotic vasculitis, careful monitoring of coagulation and cardiovascular status may be necessary.
The AVMA would like to thank the American Association of Veterinary Laboratory Diagnosticians for their assistance in creating this resource.
FAQ for dog owners
Update November 22, 2013: There has been a media report about the possiblity of cats being infected with this virus. We have contacted the Michigan authorities with a request for more information.
Circovirus may be present as a primary or co-infection with other enteric pathogens, but there is still much to learn about its significance as an enteric pathogen. Li et al (2013) documented co-infection with circovirus and canine enteric coronavirus, Cryptosporidium spp, C. perfringens α toxin, Giardia spp, Salmonella spp, Campylobacter jejuni, or Campylobacter coli in 19 circovirus-infected dogs with diarrhea. Circovirus was detected in the feces of 19/168 dogs with diarrhea and 14 of 204 healthy dogs. Sixty-eight percent of dogs positive for circovirus were co-infected with at least one additional enteric pathogen.
Circovirus infection was rumored to be the cause of dog illnesses and several dog deaths in Ohio in late August/early September 2013, but the Ohio Department of Agriculture is no longer considering it a primary cause as of October 3, 2013. Listen to our podcast on the status of the investigation (Sept 23) and the investigative process.
In late September/early October 2013, similar illnesses were reported in dogs in Michigan. The Michigan Department of Agriculture and Rural Development is investigating the illnesses.
Please note, this information is based on a very limited number of cases and may change as more is learned about this new circovirus.
Case presentation: Dogs infected with circovirus may present with progressive vomiting, diarrhea (possibly hemorrhagic) and hematochezia. Ascites, pleural effusion, hypovolemic shock, bicavitary hemorrhage and disseminated intravascular coagulation may also be present. According to Li et al, circovirus “should be considered in cases of unexplained vasculitis in dogs.”
If you suspect circovirus infection, please contact your state animal health authorities regarding sample submission.
Pathology: According to the report published by Li et al, examination of tissues from all infected animals revealed fibrinonecrotizing vasculitis. The location and severity of affected vessels varied among the cases, with most cases demonstrating abnormalities in the intestine and kidneys. Affected organs included the intestine, urinary bladder, spleen, liver, lungs, kidneys, heart, pancreas, adrenal glands and meninges (in a dog with tetraparesis). Lymph node necrosis was also observed in several cases and all dogs had histiocytic or granulomatous lymphadenitis in Peyer’s patches. One dog hemorrhaged into the thoracic and abdominal cavities.
Treatment: At this time, there is no indication to treat these cases any differently than other enteric infections. Because of the virus’ association with fibrinonecrotic vasculitis, careful monitoring of coagulation and cardiovascular status may be necessary.
The AVMA would like to thank the American Association of Veterinary Laboratory Diagnosticians for their assistance in creating this resource.