Manitoba’s veterinarians are tracking the incidence of Lyme disease in dogs to contribute to veterinary and public health official understanding of the geographic presence of this bacterial infection transmitted to animals and humans through deer tick bites.
A simple in-clinic blood test typically run in conjunction with heartworm testing identifies to veterinarians if a dog has developed antibodies to Lyme disease, meaning the animal has been exposed.
“This is an excellent opportunity for the veterinary community and our clients who bring their dogs in for checkups to help public health officials better identify areas in the province where Lyme disease is present,” said Dr. Richard Rusk, a veterinarian and physician with the University of Manitoba’s community health sciences department.
Dr. Rusk spearheaded the online Lyme disease survey where participating Manitoba veterinarians can record details of positive cases. “Lyme disease is not transmitted from dogs to people but if a dog is known to have been bitten by a deer tick, the people who own that dog are at risk of encountering deer ticks as well.”
Dr. Rusk is working closely with Manitoba Agriculture, Food and Rural Initiatives to share the information collected from Manitoba veterinarians.
Only about five per cent of the dogs exposed to Lyme disease will develop clinical signs of infection that may include a “bull’s-eye” or target-shaped rash around the tick bite, fever or decreased appetite. Some animals develop polyarthritis or inflammation of multiple joints. The nonresponsive chronic arthritis seen in some humans infected with Lyme disease has not been noted to date in dogs.
In dogs, early detection and treatment are important in preventing the more serious forms of this disease. Antibiotics have proven to be effective in treating Lyme disease.
Lyme disease is a bacterial infection caused by Borrelia burgdorferi, a spircochete (corkscrew shaped bacteria). Ticks acquire the bacteria by feeding on infected wildlife such as mice, deer, and other animals. About 10 per cent of Manitoba deer ticks have been found to carry the Lyme disease organism.
Some experts estimate that dogs are 50 per cent more likely to get Lyme disease than humans. Cattle, horses and cats have also been reported to be infected. Humans can also be infected with Lyme disease.
The incidence of infection in dogs and humans in our province is still relatively low. Also, only about five per cent of dogs that are exposed to Lyme disease will develop clinical signs of infection. It appears that the majority of dogs exposed to Lyme disease (95 per cent) will have a sufficient immune response to clear the infection without ever developing signs of illness.
Lyme disease can be treated with broad-spectrum antibiotics. Doxycycline is the antibiotic of choice, followed by amoxicillin. Treatment is usually administered for at least four weeks. The effectiveness of treatment for this disease frequently depends upon how quickly a diagnosis is reached and therapy begins. Early detection and treatment are important in preventing the more serious forms of this disease.
Lyme disease is transmitted by deer ticks, Ixodes scapularis, or related Ixodes ticks in other parts of North America. It is important to note that the organism that causes disease is believed to be transmitted after the tick has been attached for 24-48 hours. The more common wood tick (Demacentor variabilis) is not an effective transmitter of Lyme disease.