SAN DIEGO -- A growing belief that too many vaccinations could weaken a pet's immune system is causing some animal experts to change their advice about how often to vaccinate cats and dogs.

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IMAGES: Can Vaccinations Make Pets Ill?

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FeedRoom

Too Many Shots?

At the Kensington Veterinary Hospital, animals are often screened before vaccinations with a Titer-A blood test showing a pet's immunity level. Veterinarians at the hospital often recommend only one vaccination at a time.

Some animal experts say all the vaccinations really are not necessary anyway.

"Over the last couple of years, the idea of annual vaccination has gone by the wayside for most vaccinations," said Dr. Keith Hilinski, president of the San Diego Veterinary Medical Association. "We found the immunity lasts for much more than a year. Therefore, we don't have to subject these patients to a poke and a pinch once a year."

Local pet owner Sherri Crispin wishes she had known about the potential risk before her dog was vaccinated. Just a few months after adopting Molly Mae, Crispin noticed something strange starting to happen.

"So she first started getting a few little weird bumps on the inside of her ear that I didn't think were normal," Crispin said. "Then she got a pretty big sore on the back of her neck."

Crispin said she took Molly Mae to several veterinarians, but no one could tell her what was causing the sores.

"Toward the end she wouldn't even get out of her bed," Crispin said. "I had to fed her from my hand. She looked like a leopard she had so many sores all over her body. I just couldn't find a vet that knew what it was."

Crispin finally learned that the problem was an auto-immune skin disease: the dog's body had been destroying its own skin. Crespin believes a cocktail of more than 5 vaccines given to Molly Mae before her adoption may have overwhelmed and confused the dog's immune system.

After thousands of dollars worth of treatments, Molly Mae survived.

The County Veterinary Medical Association recommends having pets examined once a year and talking to veterinarians about recommended vaccines and their risks. In some cases, a blood test may be a good option. They usually cost $50.