What Does It Mean if My Dog Tests Positive for Lyme?

Since ticks are almost everywhere, protect your dog against these disease-spreading parasites.
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If your vet informs you that your dog tests positive for Lyme disease, don't panic. Depending on what part of the country you live in, the majority of canines might have positive reactions. According to the Massachusetts Society for the Prevention of Cruelty to Animals, located in prime Lyme country, only about 10 percent of positive dogs ever develop clinical signs of the disease. Discuss your options with your veterinarian.

Lyme Disease

Named after the town of Lyme, Conn., where the disease first appeared in the 1970s, Lyme disease is a tick-borne illness that can result in systemic infection. Although people are also vulnerable to Lyme disease, canine and human symptoms aren't very similar. People are much more likely to suffer serious illness when exposed to Lyme's disease. The disease is spread primarily by the tiny deer tick, which injects the bacterial spirochete Borrelia burgdorferi into its victim.


The primary blood test for Lyme diagnosis is the C6, which detects against a specific protein by that name. If your dog's blood has antibodies, he's been exposed to the Lyme disease bacteria. It takes three to five weeks for antibodies to develop after a tick bite. This test is used in combination with additional tests that determine whether your dog has been exposed to other tick-borne diseases.


Dogs testing positive for Lyme disease might not display any symptoms, or might develop vague, intermittent symptoms that occur long after you've found a tick on your pet. Generally, dogs develop symptoms within six months of infection. Lameness in young dogs can result from Lyme disease. Other symptoms include joint swelling, fever, lymph node enlargement and lethargy. Seriously affected dogs might stop eating. Without treatment, some dogs might suffer from kidney failure.


Basic Lyme disease treatment consists of daily administration of the antibiotics doxycycline or amoxicillin for at least one month. Symptoms in affected dogs usually diminish within a few days of treatment initiation. Some dogs might require a longer course of antibiotics. Because most dogs testing positive for Lyme disease remain asymptomatic, the Companion Animal Parasite Council does not recommend treating dogs with no clinical signs of disease or prophylactically in cases of tick bite.


Your vet can recommend a monthly oral or topical medication to protect your dog against ticks and fleas. Depending on the region, your dog requires this medication seasonally or year-round. Inspect your dog for ticks on a daily basis. The MSPCA recommends using tweezers to grab the tick as close to your dog's skin as possible, then pull the pest straight out. Ticks must be attached and feeding on your dog for at least 48 hours to transmit Lyme disease.