Wednesday, February 9, 2005

Vets find Lyme risk is great in dogs

Just as in humans, it’s hard to diagnose


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Alyce M. Brommels of Auburn, said her year-old Shih Tzu, Millie, was temporarily paralyzed by Lyme disease. Veterinarians say the full vaccination series consists of three shots. (T&G Staff / DAN GOULD)
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An Auburn resident was horrified when her Shih Tzu, which had been fine the day before, was suddenly paralyzed by Lyme disease. In another case, an Auburn selectman was surprised when her pug tested positive for exposure to Lyme disease, but showed no symptoms.

Veterinarians at Hillside Veterinary Clinic last month compiled results of thousands of blood tests they have been performing on dogs that have come to their clinic for testing for heartworm over the past three years.

Hillside veterinarian Kenneth C. Detora said he expected that 2 percent or 3 percent of dogs would test positive to exposure to an infected tick.

“We were shocked that 25 to 30 percent tested positive,” he said.

He was also surprised to find a few dogs tested positive for erlichiosis, another tick-borne illness that can strike dogs and humans and is usually found in the Southwest.

John R. Gaudion, practice manager for Hillside, said dogs that test positive have antibodies in their blood.

“They have been exposed; that is, they have been bitten by an infected tick, but they won’t necessarily develop disease. About 3 to 4 percent of dogs in our area develop symptoms of Lyme disease,” Mr. Gaudion said.

Lyme disease symptoms in a dog can come on suddenly and be severe, or they can be nonexistent, even when a dog tests positive for exposure.

Alyce M. Brommels of 9 Pine Valley Drive, Auburn, said her year-old Shih Tzu, Millie, had received a single vaccination against Lyme disease and was wearing a product to protect her from fleas and ticks last September when she suddenly showed severe symptoms.

“Millie had been slow to come downstairs one morning and then within hours became paralyzed. She couldn’t move,” Ms. Brommels said.

The small dog was rushed to Abbott Animal Hospital in Worcester, where she was given intravenous fluids and antibiotics after testing positive for Lyme disease, Ms. Brommels said. After a month of daily antibiotics, Millie appears to have made a full recovery, although veterinarians have warned Ms. Brommels that the dog could have a relapse.

Auburn Selectman Elizabeth L. Prouty’s fawn pug, Evie, 4, has never had any symptoms, but has tested positive for Lyme exposure for three years. Mrs. Prouty’s black pug, Ernie, tests negative.

“I’m glad I’m aware. Now, if Evie shows any symptoms, I would know to bring her right to the vet,” Mrs. Prouty said, adding that when she developed a stiff neck last year, doctors tested her for Lyme disease when they heard about Evie. Mrs. Prouty tested negative.

Mr. Gaudion said it is worrisome that so many pets in the area test positive for exposure to Lyme disease, but his concern goes further. “When a dog is exposed, there is a human at the other end of the leash,” he said.

Dr. Robert E. Bessette, whose practice is in infectious diseases for Fallon Clinic at St. Vincent Hospital at Worcester Medical Center, said human cases of Lyme disease in his practice have increased in the past two or three years, from about one case every few months, to one a week during the summer and fall.

“The expression of the disease is variable, and ranges from asymptomatic to Bell’s palsy, to multiple organ system involvement over weeks and months,” Dr. Bessette said.

The joints, heart, central nervous system and other systems can be involved, he said.

About 50 percent of people infected by Lyme disease bacteria develop a target-shaped rash around the site of the tick bite, but the other half show no such telltale signs, Dr. Bessette said.

Onset varies from days to a few weeks after exposure to the infected tick and may cause a wide variety of symptoms, from simple fatigue to severe health problems.

Or there may be no symptoms at all, he said, noting, “It presents a very challenging diagnostic dilemma.”

Treatment depends on the clinical presentation, he said. Antibiotics might be needed, with amoxicillin or doxycycline as the drugs of choice for treatment. Erythromycin or intravenous ceftriaxone might also be used, he said.

“Current, new recommendations are that if someone has been bitten or is suspected of having been bitten by a deer tick in an endemic area such as this area, risk can be decreased by taking two 200-milligram tablets of doxycycline once,” Dr. Bessette said.

No Lyme disease vaccine exists for humans, Dr. Bessette said.

One which had been on the market several years ago was withdrawn, he said, when it was found that its undesirable side effects outweighed its effectiveness.

An effective vaccine for Lyme disease is available for dogs, Mr. Gaudion said. Full effectiveness, which gives about 85 percent protection, is reached after three injections, he said.

The second inoculation is given about a month after the first vaccination, and the third shot is given six months later.

“Then it becomes part of the usual regimen, with a shot a year, like distemper and other vaccinations,” Mr. Gaudion said.

He said using good-quality flea and tick medication on a dog’s skin, as recommended by a veterinarian, is also helpful.

Mr. Gaudion said Lyme disease is spread only by a bite from an infected deer tick, not from a much larger dog tick or brown tick, nor from being licked by an infected dog.

He said the deer tick is tiny, about the size of the period at the end of this sentence, but can carry enough Borrelia burgdorferi bacteria to infect an animal or human.

Not all deer ticks are infected, he said. The deer is the deer tick’s primary host.

Dr. Bessette said the best way to avoid exposure is to wear light-colored long pants and long-sleeved shirts and tuck pants into socks, and check carefully for the tiny ticks after walking in woods or long grass any time of year.

Dr. Robert E. Bessette, whose practice is in infectious diseases for Fallon Clinic at St. Vincent Hospital at Worcester Medical Center, said human cases of Lyme disease in his practice have increased in the past two or three years, from about one case every few months, to one a week during the summer and fall.