Gretchen Wilson DVM
Blame it on global warming (warmer winters), less snow, increased deer populations, or natural tick population cycles; Lyme disease caused by a Borrelia species and spread by feeding ticks, is on the rise and has been for several years. Canines typically do not show symptoms of early infection as humans do. Instead, they commonly develop fever, lamenesses, arthritis, swollen and painful lymph nodes, and general soreness 2 to 6 months after contracting the disease. Less often, some animals go on to develop neurologic disease , severe, generally fatal kidney disease or heart complications.
This upsurge in Lyme disease cases was first noted in our clinic in 2004 with about 60 cases. In the ten years previous to that added together, we had not seen nearly 60 cases. In 2005, we saw double that number. This year, we already have diagnosed 41 positives for Lyme disease, many with the typical symptoms, some seemingly normal. The test only tells us that they are exposed and may or may not develop signs of disease.
The drugs used to treat Lyme disease remain the same as in recent years. However, the suggested dosage of doxycycline has doubled and the length of the treatment has increased. Current research indicates that the Borrelia organism may never be completely eliminated from the system, simply retreating into tissues like cartilage that have a poorer blood supply to carry the antibiotics. Here, it repeatedly changes its capsule components to evade the immune system of its host. Interestingly, the antibody defenses created by the dog in response to Lyme vaccines, only work within the tick itself. As the first antibody laden blood is ingested by the tick, these immune defenses interfere with functions of the Borrelia within the tick, blocking transmission to the dog.
Unfortunately, the Borrelia organism that causes Lyme disease has some new tick-born friends in our state with increasing numbers of cases as well. Our bumper crop of varying species of ticks is busily infecting animals (and people) with Erlichia, Anaplasmosis, Babesia, and Rocky Mountain Spotted Fever as well. These may cause different combinations of the symptoms of Lyme disease listed above as well as more cases of neurological disease, eye lesions, and bleeding and blood disorders. Some dogs are found to be positive for more than one of these diseases.
Short of moving out of the area, we do have some things that will greatly decrease the chances of infection with any of these organisms. First of all, limit exposure. Ticks come out of tall grass, so, if plausible, mow or spray areas frequented by yourself and your pets. Do not depend upon being able to find and remove ticks before the 24 to 48 hours of attachment thought necessary for disease transmission. Many animals are infected by immature forms or small species that are very difficult to see even in short-coated pets. Spray any attached tick with a tick killing product before removing it. You will be more likely to get all of the head. Veterinarians often have to finish removing embedded tick heads that have caused severe inflammation.
Begin to vaccinate as early as 9 weeks of age and yearly for Lyme disease in dogs, even if you do not think they will find ticks. We have had to treat Chihuahuas and poms and other small house dogs that owners thought were never exposed. For dogs or cats, as young as 8 weeks, use fipronil (Front-Line Plus®) spot-on treatment monthly, avoiding bathing or swimming for a few days before or after application. In the last couple of years, we have seen ticks all through the winter months. It is very important to continue application throughout the year, especially for outdoor pets. Most of the cases we are seeing now were probably infected during this past winter.
Remember that with fipronil, the tick needs to bite the dog to be killed. So, if your pet is in a severe exposure situation, also use a flea and tick collar containing amitraz (Preventic®) to repel ticks even before they bite (and before they are carried into the house, potentially exposing you and your family).
Veterinarians have a simple in-house test for Lyme and erlichiosis (also includes heartworm). By the middle of this summer, this test should also include anaplasmosis. This test diagnoses current infections in pets that are ill and symptomatic, but also is an important screening tool to let us know of a problem during the 2 to 6 months before signs of disease are likely to appear. This increases likelihood of successful treatment and may even allow your veterinarian to prevent the death of your pet. Remember that this article pertains primarily to dogs and somewhat to cats, but we hope all of you out there are taking proper precautions for yourselves as well!