Canine brucellosis confirmed in six Michigan counties

OKEMOS, MICH. — A Brucella canis outbreak in Michigan should not be pinned on venereal transmission, cautions the Michigan Veterinary Medical Association (MVMA).

Though venereal transmission is most commonly believed to spread canine brucellosis, MVMA says infection can cross mucous membranes and frequently is spread by licking, ingestion and through shedding from bodily fluids like urine. The risk of spreading B. canis is high among dog populations, but also is a danger to pet owners and public health, MVMA says.

The outbreak in Michigan already has been confirmed in six counties and strongly suspected in another 10, MVMA adds.

Cheri Johnson, DVM, MS, Dipl. ACVIM of the College of Veterinary Medicine at Michigan State University, writes in the association's journal that B. canis can often be difficult to detect because it's slow-growing and may not be detected in the 48-hour incubation period typically used for human blood cultures, also antibiotic therapy can cause negative culture and titer results even though B. canis is still present in dogs.

Once infection is confirmed, the most effective method to control spread is culling, Johnson adds.

"The evidence of all the studies of spontaneously occurring infection have shown that B. canis is not eliminated from the colony, even when infected animals are strictly isolated and regardless of treatment, until infected animals are actually culled," Johnson says.

"To avoid euthanasia, well-intended but misguided rescue organizations in Michigan have rescued dogs from infected kennels and adopted them out as pets to unsuspecting owners, whose veterinarians will be equally unsuspecting."

Johnson adds, "Because the chance of successful treatment is so unlikely and because infected animals remain a source of infection for other dogs and unsuspecting people, treatment is ill advised."

B. canis infection in people is traced back to a person's own pet, Johnson adds, citing serologic surveys from outbreaks in Argentina, California, Pennsylvania and Texas.