Author: Tracy Reis, DVM
Lyme disease in dogs is most prevalent in the Northeastern United States. The deer tick, which carries the bacteria Borrelia Burghdorferi, has a two-year life cycle. The female tick lays up to 2000 eggs, which hatch into nymphs in the spring. They then feed mainly on white-footed mice which can carry a heavy burden of bacteria without actually getting sick. This happens in the late spring through the fall. In the winter the nymphs go into a hibernation state, and then in the early spring emerge as adult ticks. The adult ticks are twice as likely to infect a host as a nymph because of the larger amount of bacteria they carry.
While most mammals and some birds can carry the disease subclinically, they are great hosts for the ticks to feed on to increase their bacteria load. Once a tick attaches to a dog, it has a greater chance of infecting the dog the longer it feeds on the dog. If the tick is on the dog for less than 12 hours, the incidence of illness is much less.
In addition to dogs, Lyme disease is the most common arthropod-borne disease in humans in the United States. However, in humans there are three distinct phases. In dogs there are two stages, acute and subacute. In the acute phase, the dog can have sudden lameness in one or more limbs, sometimes with severe pain, swelling and warmth of the joints, and may run a fever, be lethargic or inappetant. Once the dog has recovered, he may have a recurrence later on lasting several weeks. Initial lameness in dogs occurs 2-5 months after tick exposure.
The proportion of infected dogs that show clinical signs is much smaller than that of humans that are exposed. There may be breed, genetic or age predilections, but they are not known at this time. However, an infected pregnant dog will not pass Lyme disease to her pups, nor will the pups contract the disease from nursing.
There are four criteria to diagnosing Lyme disease definitively:
1) History of exposure to ticks in an area of known disease
2) Clinical signs of lameness with or without a fever
3) A positive antibody test
4) A quick response to antibiotics
The antibiotics of choice include doxycycline and other penicillin type drugs. Most dogs make a full recovery. If they have a recurrence, either from chronic disease or additional exposure to ticks, they will respond to the same antibiotics at the same dose. The best way to protect your dog is to keep him out of tick endemic areas, use topical tick repellents or get him a vaccination. However, the vaccination does not actually prevent the disease, and there is some question as to how effective this vaccine is compared to the possible side effects.
There have been no known cases of dog to human transmission or human infection caused by tick removal. Lyme is much more serious of a disease in humans than dogs, but can still be a painful illness for dogs.
A few natural homeopathic remedies have been used to help with joint pain, as well as red blood cell integrity. These include Carduus mar, Cortelus hor, Ferrum phos and Anconitum nap. Always talk to your veterinarian before starting treatment on your own. Lyme is a serious but treatable disease.