by Arnold Plotnick, DVM, reprinted from "DogFancy", July 2001

When Diego stopped eating and started limping on his right rear leg, Carlos Alva of New York figured his 6-year old Labrador Retriever has simply overexerted himself in the park. But Diego's loss of appetite surprised and concerned him. "I've never seen him refuse a meal," Alva says. Diego had a fever, and his pain was localized to his right knee. I suspected a ruptured ligament but ruled it out during the orthopedic exam. X-rays showed no fractures. Because fever often suggests an infectious disorder, we performed a complete blood count, chemistry panel and urinalysis - all of which came back normal. Next, we tested for evidence of tick-borne diseases that could cause arthritis. "We stroll through the woods all the time," Alva says. "I pull ticks off of him now and then." Diego tested negative for two of them - ehrlichiosis and Rocky Mountain Spotted Fever- but strongly positive for Lyme disease. Canine Lyme disease is mainly a regional problem that takes its name from the two where it was discovered - Old Lyme, Conn. Most cases surface in the Northeast and Mid-Atlantic states. A few cases are reported in the Midwest and Pacific Coast. Even in epidemic areas, the proportion of dogs that develops clinical disease is low. In highly endemic areas, as many as 75 percent of dogs might show evidence of exposure to infected ticks, yet only about 5 percent of them develop clinical symptoms - primarily acute episodic arthritis, poor appetite, lethargy, and swollen lymph nodes. One or more joints can be involved, and they're typically swollen, hot, and painful. Left untreated, a dog's lameness can resolve itself, with occasional reoccurrences several weeks or months later. The disease mostly affects the muscoloskeletal system but sometimes causes myocarditis, an inflammation of the heart muscle, and nephritis, an inflammation of the kidneys. A positive diagnosis requires four criteria: exposure to deer ticks clinical symptoms a blood test showing antibodies to the Lyme organism dramatic response to antibiotic therapy Diego had satisfied the first three. Veterinarians typically treat Lyme disease with antibiotics, such as doxycycline (a tetracycline derivative) and amoxicillin (a penicillin). Dogs usually respond within a day or two. "I popped Diego an amoxicillin tablet when I got home and another one 12 hours later," Alva says. "By the time his next dose was due, he was walking normally and barking for food again." Diego had satisfied the fourth criterion, confirming he had Lyme disease. Dogs don't seem to transmit the disease to each other or to humans. WHile it's possible for a dog to introduce deer ticks into a household, veterinarians have never documented such a case. Early detection and removal of ticks are your best defense. You can reduce your dog's exposure risk to Lyme disease by using tick repellents and by grooming dogs daily. There are several commercial Lyme disease vaccines, but the disease has a low incidence of infections and high treatability, while the vaccine exposes dogs to potentially adverse reactions. Some veterinarians recommend tick collars containing amitraz, a topical antiparasitic agent used primarily to treat mange mites. "I can't stop taking Diego to the park," Alva says. "He'd be miserable if I did that. But I got him a brand new tick collar, and I check him for ticks every day."

Arnold Plotnick, DVM, is vice president of
the American Society for the Prevention of Cruelty to Animals'
Bergh Memorial Animal Hospital in New York.