Lyme Disease In Dogs: What You Should Know
Lyme disease in dogs was first recognized in 1985, though it is believed to have existed in wildlife for years. It is caused by a spirochete bacteria called the Borrelia burgdorferi. It is primarily carried by the common deer tick in the Northeastern and upper Midwestern United States. In the western U.S. the Ixodes pacificus tick is the primary carrier.
Lyme disease is probably more prevalent today than it was in the past. Prior to 1900 much of the area in the East and upper Midwest was deforested for settlement, which removed deer as tick carriers. Now that some areas are being reforested, the deer population has increased, and so has the tick population.
In the U.S., most cases of Lyme disease occur between Massachusetts and Virginia. Some cases come from Minnesota and Wisconsin; a few come from California. Lyme disease in dogs is rare in the rest of the country.
Causes of Lyme Disease In Dogs
In the case of a deer tick, the tick goes through several stages from the time of hatching until they are adults. During the larva stage they typically feed on a small mammal such as a mouse. If that mouse is infected with the B. burgdorferi (Lyme disease) bacteria, then the larva will become infected. It will go on to become a nymph when it can feed on a dog (or human), and pass along the bacteria. Or, if it is not yet infected with the Lyme disease bacteria, it may become infected when it feeds on a deer or small mammal. When the nymph becomes an adult, it can feed on a larger mammal such as a dog or human, passing the Lyme disease on to them.
In order to pass Lyme disease to a dog or human, the nymph or tick needs to be attached for 48 hours. However, even if the tick carries the bacteria, the dog may not get the disease. According to studies, only about 10 percent of dogs that are exposed to a tick carrying Lyme disease actually get the disease. Once the tick is full, it detaches and doesn’t bite any other mammals. However, if the tick comes off before it is full, it may bite something else, such as a person.
Dogs infected by Lyme disease are not contagious in any way and they are not a danger to other dogs or people in the home.
Symptoms of Lyme Disease In Dogs
Symptoms of Lyme disease in dogs are unlike symptoms in humans and they do not occur right away. Symptoms usually appear two to five months after a tick bite. Symptoms to watch for include:
- Fever between 103 and 105
- Lameness
- Joints swelling
- Swollen lymph nodes
- Loss of appetite
- Lethargy
Some dogs may develop severe kidney disease, although this is not common. If your dog tests positive for Lyme disease you should also have a urinalysis test done to test kidney function, just in case. Heart problems and problems with the nervous system are also possible.
There is no rash or area of redness around the bite as with humans.
Diagnosis
In order to diagnose Lyme disease your vet will need to talk to you about your dog’s history of tick exposure. He or she will look for symptoms that may suggest Lyme disease. There are blood tests to confirm the presence of Lyme disease. However, many times the test may show a positive result when your dog does not have Lyme disease. In this case, your dog has probably been exposed to the bacteria but doesn’t actually have the disease. They may have overcome the infection on their own and have their own antibodies against the disease.
One test, the C6 antibody test, can show if your dog has produced his own antibodies or if your dog has antibodies because he’s been vaccinated against Lyme disease.
Your vet will probably prescribe antibiotics. If your dog has a quick response and improvement with the antibiotics, then he probably has Lyme disease. If he doesn’t improve quickly, then your vet will need to look for another cause for your dog’s problem.
Treatment of Lyme Disease In Dogs
Treatment of Lyme disease in dogs is usually done with tetracycline or a penicillin type antibiotic once the disease is diagnosed. Doxycycline or amoxicillin are usually used. The antibiotics must be given at least 14 days, with 30 days recommended. Sometimes antibiotics must be given longer than 30 days. Most dogs respond quickly, though in a few cases dogs have chronic symptoms and may have arthritis.
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