Moulton resident Bryan Henderson thought he was doing the right thing by vaccinating his 15-year-old pet annually, until late 2011 when the cat developed a malignant tumor on her back.

Henderson’s veterinarian removed the lump, but it returned two months later. Biopsy results showed the mass was a vaccine-induced, high-grade sarcoma.

Henderson is among pet owners across the U.S. who have stopped or cut back on vaccinating their animals. After losing his longtime pet, Kitty, to the aggressive cancer last year, Henderson said he only allows his surviving cat to receive the federally mandated rabies vaccine, which is available in one- and three-year doses.

“The average pet owner doesn’t know that some vaccinations are maybe not as harmful or likely to cause cancer as other vaccinations,” Henderson said. “It’s all a matter of educating the public on something that’s not widely known.”

For years, pet owners vaccinated their animals annually, but the American Veterinary Medical Association and American Animal Hospital Association have adjusted guidelines and now recommend administering core vaccines every three years.

Alabama residents are not required to administer core vaccines, but doctors encourage owners to vaccinate their pets to stop the spread of common animal viruses, including distemper, hepatitis, parvo and feline leukemia.

Stephanie Maples, vet at Family Pet Health Care in Decatur, said clients can test their animal’s blood for antibodies to determine if yearly vaccination is necessary. The only problem with blood testing is the price, Maples said.

Maples said she saw more cases of fibrosarcoma in cats when she graduated from veterinary school 15 years ago, but the cancer is less common today.

Maples, who recommends booster shots every three years because of concerns about over-vaccination, said her clinic offers one- and three-year doses to meet the needs of different animals.

“Any time you give any medicine, any vaccine, any oral drug, the risk is just like it is in humans as it is in animals,” she said. “That’s a lot of the reason I push for three-year vaccines instead of one-year to try to alleviate any chance of effects from the vaccines.”

Steven Osborne, vet with Osborne Animal Clinic on Beltline Road, tells his clients to vaccinate their animals annually, but he said the average pet owner waits to vaccinate about 14 to 18 months between visits.

“With vaccines, we’re not dealing in perfection,” he said. “There are risks associated with everything you do, and vaccines are one of those things where you do a risk assessment.

“The good thing about vaccines is they enhance the animal’s ability to be protected against a lot of deadly diseases, but they’re not perfect, and they don’t protect you 100 percent in every case.”

A New England veterinarian was recently forced to close his pet hospital at PetSmart in Stamford, Conn., and is at risk of losing his state license after officials discovered he ignored vaccine manufacturer recommendations by giving smaller doses to dogs and cats.

Jennifer Zech, a part-time vet who works for Osborne and at Beltline Animal Clinic, moved to Alabama a month ago and has worked at practices in North Carolina and Michigan. Zech said she doesn’t like “cookie-cutter” medicine, so she practices conventional and holistic treatments.

“If you have a 15-year-old cat that never leaves the house, and you’re vaccinating it from diseases it could catch from other cats, that doesn’t make sense,” she said. “I think it is wise to tailor each vaccine to the patient.”

Decatur Animal Services Director Carol Wicks said the shelter receives about 4,000 animals annually, more than half of which are owner-surrendered. Although baby animals are vaccinated upon arrival, Wicks said the shelter delays vaccinating adult animals until the one-week holding period is complete.

Wicks said the decision to use one- or three-year vaccines is a “discussion that should go on between the pet owner and the veterinarian,” but she prefers to vaccinate her own pets every three years.

“It’s important for people to realize that no matter what the cost of vaccines are, it is far cheaper to vaccinate them than to treat a sick animal,” she said. “Animal diseases spread more readily than people may realize.”

Dishman Animal Clinic veterinarian Kelly Griffith said she recommends clients vaccinate their pets annually because she offers an on-site animal boarding facility where there is a higher likelihood of spreading germs and diseases.

“The biggest take-home point for pet owners who read about vaccines online or hear about them from other pet owners is they need to communicate with their vet and not just rely on the Internet for their only source of information,” she said. “Vets have gone to school, have gotten an education, receive continuing education on a yearly basis and still need to remain the main source of information and help when choosing pet vaccinations.”

Lucy Berry can be reached at 256-340-2442 or lucy.berry@decaturdaily.com.