Tick-Borne Lyme Disease Is Putting the Bite on Canines


August 04, 1991|By Beth Smith

In the fall of 1989, 4-year-old Rocky, a small, fluffy dog of possible Pomeranian parentage, began to limp occasionally. His owners, the Leedom family of rural Howard County, didn't pay too much attention at first. Rocky looked healthy and he didn't seem to be in pain.

But in the spring of 1990, with the limp coming and going and showing no signs of disappearing permanently, his owners took Rocky to Twin Oaks Animal Hospital in Ellicott City. Dr. Wendy Feaga wasted no time starting him on antibiotics. A few weeks later, a blood test confirmed her diagnosis. Rocky had Lyme disease.

Generally considered a disease that threatens humans, Lyme can cause "a small percentage of dogs to get very sick and die," says Dr. Michael Garvey, chief of the Department of Medicine at the Animal Medical Center in New York City, the Mayo Clinic for animals. "Without a doubt, Lyme is a serious disease."

And one that's growing. Although statistics aren't kept for dogs with Lyme disease, it's pretty much a given that if people in certain areas have Lyme disease, so do the dogs. Dr. Feaga says some researchers believe that dogs are infected with the disease five to 20 times more than humans. The extent of the problem is significant considering that in the human population, experts say, Lyme is second to AIDS as the fastest growing "new" disease in the United States.

Dr. Feaga, who has Lyme disease herself, sees about two to four Lyme cases a week in her veterinary practice. "Supposedly, heart worms is the big disease in dogs, but I see [only] one case of heart worms each year," she says.

When Rocky was brought in, she immediately suspected Lyme because of the intermittent lameness. Like most dogs with Lyme disease, Rocky responded quickly to treatment. If he hadn't been treated, the outcome could have been different. "Rocky might have been fine," says Dr. Feaga, "or he could have #F developed kidney disease, a rapid heartbeat, neurological symptoms like seizures, severe arthritis, or just become weaker."

IN THE SPREAD OF LYME DISEASE, deer -- who bring infected deer ticks into areas frequented by people and their pets -- are unwitted participants, but important ones. Charles County in Southern Maryland has the largest deer population on the western shore, and veterinarian Scott Cosenza at Mid County Veterinary Clinic in La Plata is feeling the effects. "In our practice, which is relatively small, we saw an explosion of Lyme disease in the middle of the summer of 1990. We were seeing about eight to 10 cases a week, which is significant for us. I would say that in our practice, the number of Lyme disease cases exceeds the numbers of cases we see for all other types of infections."

"But, one thing you have to realize," says Dr. Cosenza, "is that the disease in dogs was really not even described until the mid-1980s and diagnosing has only been going on for about four years." Because it is new, nothing is black or white. Symptoms can be vague.

The good news for pet owners is that many infected animals never exhibit any symptoms of the disease. "We are right in the middle of Manhattan," says Dr. Garvey at the Animal Medical Center in New York City, "but we draw patients from Westchester County and Long Island, real hot spots for Lyme disease in people. In some of these areas, 90 percent of the dogs had positive blood tests for Lyme, indicating they had been exposed to the disease. Obviously 90 percent of the dogs did not show symptoms of Lyme."

Lyme disease in dogs is very similar to the disease in man. In both, it is an infectious bacterial disease. Officially called Lyme borreliosis, the disease is transmitted in the eastern United States by the bite of a particular tick called Ixodes dammini or deer tick. Lyme is now the most common tick-borne disease in the country. In 1989, 8,552 cases of Lyme were reported, compared to 623 cases of Rocky Mountain spotted fever.

The deer tick is so small that it is almost impossible to find on animals and not easy to spot on man. And, since a tick bite is painless, a person can be dined upon by a tick, infected and then deserted by the culprit without even knowing it.

Deer ticks may be around even if deer are nowhere to be seen. Wild mice also carry the disease, and one might just decide to build its nest in a woodpile or shrubbery. Birds, suspected of helping to spread Lyme during their migratory flights, have been known to drop ticks at garden bird feeders. Some researchers call Lyme a "backyard disease."

In humans, early symptoms, usually appearing three to 33 days after the tick bite, can include flulike symptoms, general achiness, a fever, nausea, stiff neck, headache, fatigue. In 50 percent to 70 percent of the cases, a rash or skin lesion breaks out at the site of the tick bite.

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