Canine Lyme Disease

Canine Lyme disease is transmitted by ticks and is the most common tick-borne disease in the U.S. This page looks at canine Lyme disease symptoms and treatment including Lyme disease vaccine.

Lyme disease is caused by the spirochete bacteria Borrelia burgdorferi, and was first recognized in 1975. The spirochete is acquired through the bite of an infected tick. Lyme disease is the most common tick-borne disease in the U.S.A. Currently, most cases of Lyme disease occur in wooded locateds in the Northeast, upper Midwest, northern California, and the Pacific Northwest.

The deer tick is the primary carrier of the spirochete bacteria in Northeast and upper Midwest, whereas the Western black-legged tick is the primary carrier in the western United States. The principal reservoir for the spirochete bacteria is the white-footed mouse. Birds can also habor the spirochete. The white-tailed deer carries the tick, but not the spirochete bacteria.

Lyme disease can affect not only dogs but also humans. The disease cannot be transmitted from dogs to people; however, dogs can spread the ticks infected with the bacteria. An infected dog usually poses no risk to people in the same family (other than the fact that the dog is a reservoir of infected ticks). Once a tick has had a full meal of blood, it will detach and not bite another mammal. The only risk comes from ticks that have not had a complete meal and are detached, in which case they could possibly bite a human and cause infection.

Transmission of Canine Lyme Disease

Lyme disease in dogs is transmitted through tick bites and therefore is more prevalent during tick season (from May through August), peaking in the month of July. However, ticks can be active any time the temperature is over 32°F (0°C).

The spirochete is transmitted by the saliva of ticks while being attached to a dog and having a blood meal. However, ticks must be attached to the host for about 24 to 48 hours before the transmission of the spirochete occurs. In other words, if a tick dies or is removed before 48 hours, transmission of the bacteria will not occur. It shows the importance of regular daily checking of your dog for ticks during tick season, and the immediate removal of ticks once they have been spotted.

The good news is, even if an infected tick attaches to a dog for more than 48 hours, the dog may not necessarily develop Lyme disease. It has been found that only about 10% of dogs who are exposed to the spirochete will contract canine Lyme disease.

Canine Lyme Disease Symptoms

The symptoms of Lyme disease in dogs usually occur two to five months after a bite from an infected tick.

One of the classic canine Lyme disease symptoms is the sudden onset of lameness. Very often, lameness is the only sign of the disease. One or more of the joints may become swollen and painful to the touch. The lameness may last for only a few days. However, in some cases it may persist or recur for months.

Other common symptoms include:

Fever (103°F to 105°F)
Lethargy
Weakness
Appetite loss
Weight loss
Swollen lymph nodes

In some cases, dogs infected with Lyme disease may develop severe kidney problems and, in rare cases, an cardiac syndrome. Both of these problems are difficult to treat and can be fatal.

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Canine Lyme Disease Diagnosis

Diagnosis is based on blood tests to determine if a dog has been exposed to the spirochete. However, many dogs show positive test results, but are not actually infected with the disease. It means that they have been exposed but have fought off the infection; therefore, they have antibodies to the spirochete in their blood but not the disease.

In addition, there is another blood test (C6 antibody test) that can distinguish between dogs with vaccine immunity and dogs with natural exposure.

The above blood test results will be interpreted in combination with other information (such as clinical signs, and history of tick exposure) in order to arrive at a correct diagnosis.

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Canine Lyme Disease Treatment

Lyme disease in dogs is treated using antibiotics such as amoxicillin and doxycycline which must be given for a minimum of 2 to 4 weeks.

In some cases, dogs with Lyme disease may develop chronic infections, although the vast majority of infected dogs respond rapidly to antibiotic treatment.

Canine Lyme Disease Prevention

Tick Control: The best prevention of Lyme disease in dogs is tick control, such as immediate removal of ticks from the dog, as well as using dog tick preventive medicine to repel and kill ticks.
Vaccination: There is also a vaccine that can prevent Lyme disease in dogs. However, some veterinarians do not recommend the use of the Lyme vaccine because it is not 100% effective and because of the problem of over-vaccination. Therefore, vaccination may only be advisable for dogs living in tick-infested areas. Discuss the necessity and the pros and cons of this vaccination with your vet.