An alternative to a widely accepted vaccination protocol in cats could literally move the needle for feline cancer treatment, according to University of Florida researchers.
“One to 10 cats out of every 10,000 vaccinated against infectious diseases develop cancer at the vaccine injection site,” said Julie Levy, D.V.M., Ph.D., the Maddie’s Professor of Shelter Medicine at the University of Florida College of Veterinary Medicine. “It’s still important to vaccinate because death from these infections is much more common than the cancer, but unfortunately this complication is one that does affect thousands of cats each year.”
When administering vaccinations, veterinarians typically follow the current recommendations of the American Association of Feline Practitioners, giving the injections below the elbow or the knee joint in the leg. That protocol is based on the understanding that the most effective treatment for cancer that occurs near vaccine injection sites is radical surgery – amputation of a limb.
“Many cat owners elect not to pursue the most effective treatment — radical surgery of the tumor — because excision of tumors in the limbs and torso is often disfiguring, painful, and expensive,” Levy said.
But in a report published online this month by the Journal of Feline Medicine and Surgery, Levy and a national team of experts in infectious disease and vaccinology report that administering vaccinations in the tip of the cat’s tail appears to be as effective as vaccines at traditional sites. The researchers say tail vaccination would make surgical treatment of any cancer occurring near the site much easier, less invasive and less disfiguring for the animal, which could encourage more owners to treat the disease in their pet when it occurs.
As a first step in amassing information for the study, the researchers developed a questionnaire that was sent to veterinary oncologists practicing around the world. Oncologists were asked to rank 11 potential vaccination sites, and to note their top three preferred sites, considering only surgical treatment of sarcomas that might develop at those sites.
When the tail emerged as a favored site, the team performed a trial to see if cats would even allow it to be done to them.
Sixty cats that had come for spay or neuter services through the Operation Catnip trap-neuter-return program at UF were enrolled in the study. Only cats that were tame, outwardly healthy, had a full-length tail and were brought by a caregiver who committed to returning the cat in one or two months for further evaluation were selected for the study, the researchers said.
The study showed that cats tolerate tail vaccination at least as well as the currently recommended injection site in the hind leg.
“Dr. Levy’s study is very important for a number of reasons,” said Julius Liptak, B.V.Sc., a surgery specialist and a founding fellow in surgical oncology with the American College of Veterinary Surgeons.
“Firstly, it is important that vaccinations in the tail are effective in providing the necessary immunity against infectious and communicable diseases,” he said. “Secondly, vaccinations in the tail are easy to perform and well tolerated by cats, which will hopefully mean that general practitioners will be willing to change their vaccination protocols and try this new location.”
Most important from a cancer treatment perspective, “If vaccinations on the end of the tail become a widely adopted practice, then amputating the tail is a much easier and less traumatic procedure, which will hopefully result in a much greater potential to cure this disease,” Liptak said.
Levy’s research team included UF veterinary student Cleon Hendricks, a Merial Scholar, as well as serology experts Edward Dubovi, Ph.D., of Cornell University, and Cathleen Hanlon, V.M.D., Ph.D, of Kansas State University, who tested blood samples from the cats for antibodies before and after vaccination.