The decisions people make about the health of a pet are often based on what pet-owner friends have done, what they have done in the past, and what the veterinarian recommends. Rarely do pet owners know instinctively what would be best for their pets. Currently, cat owners are faced with an even more unusual circumstance and one to which there are no easy answers. The veterinarians are divided and the traditional answer might not be good enough. Should they vaccinate their cats when the vaccine itself may pose a risk to the cat’s health?
The problem is that veterinarians have discovered that a specific form of cancer is associated with vaccinations. Sarcoma, a cancer of the connective tissue like tendons and ligaments, has been definitively linked to vaccinations. And, one of the most highly recommended cat vaccinations is a vaccine against another form of cancer, feline leukemia. For some cats, the risk of feline leukemia is almost zero and the vaccine can be avoided, but for cats that are at risk, the benefits of the feline leukemia vaccine outweigh the risks. Feline leukemia is an autoimmune cancer that develops from a virus.
In cats, as in humans, the immune system is the portion of the body that helps it fight off disease and illness. When a cat, or a person, develops an autoimmune disease, that disease suppresses the function of the immune system. “The immune system plays a pivotal role in maintaining your cat’s health. One of the most important functions of this highly complex system of specialized cells and molecules is to protect cats from disease and infection caused by foreign invaders” (Richard 1). Feline leukemia is a type of cancer that begins as a virus, specifically a retrovirus (Little 1).
The virus, which can easily be killed with bleach or basic cleaning supplies, can be passed from cat to cat via bites, scratches, shared litter boxes, blood transfusion or grooming, when the saliva of one cat touches another (PAWS 1). “Once a cat has been infected with FeLV, it has the virus and, at this time, there is no known way to eliminate it from the cat’s system. ” (PAWS 1). Though recent research has led to the realization that feline leukemia is not an automatic death sentence for cats, it can require the cat be euthanized, depending on other factors.
At the very least, it requires that cats be protected from other threats to their health (Little 1). Given the threat that feline leukemia poses to cat health, it would make sense that a vaccine would be a good thing. But research has shown that the vaccine is only effective 89 percent of the time (PAWS 1). The only thing that has proven to be 100 percent effective is to keep cats from being exposed to the virus. That means keeping them indoors all the time and keeping them away from other cats that might be infected.
Barring that, veterinarians recommend the vaccine, but the vaccine might have consequences of its own. Emerging research indicates that some cats, the number has not yet been identified, may have a particularly severe reaction to vaccines. While most reactions are like human reactions to vaccines, some are severe (PAWS 1). In the most severe cases, the site of the vaccine has been identified as the starting site for sarcoma (Hendrick 341). When sarcoma develops, the cat will begin with a tumor at the site of the vaccine and the cancer rapidly migrates to the connective tissues between the bones.
This cancer can be treated with surgery, but surgeons must be careful to get the entire tumor as sarcoma tumors are usually “rooted” and notoriously hard to get (Couto 33). Initially, this cancer can be more deadly than feline leukemia, but the percentage of cats that have this reaction to the vaccine is still very small. The percentage of cats exposed to feline leukemia that get the disease is very large. About 30 percent of those exposed will be able to fight it off with their natural immunities, but that means 70 percent of the cats who are exposed end up with feline leukemia and there is no known treatment or cure (PAWS 1).
The decision then to vaccinate makes sense if the cat cannot be kept indoors at all times and kept away from other cats that might be infected (Little 1). Cats cannot contract the virus from veterinarian’s offices or other locations that are routinely disinfected (Richards 1). Most pet owners should decide whether to have their cats vaccinated based on these seven criteria: 1) Your cat’s risk of exposure to the disease-causing organism (in part dependent on the health of other cats to which yours is exposed, and the environment in which your cat lives) 2) The consequence of infection
3) The risk an infected cat poses to human health (e. g. , rabies) 4) The protective ability of the vaccine 5) The frequency or severity of reactions the vaccine produces 6) The age and health status of your cat 7) Vaccine reactions your cat may have experienced in the past (Richards 1) Cats that are the highest risk of feline leukemia are those who live in a house with other infected cats and those who are allowed outdoors in urban areas (Little 1). In multiple cat households, the infection rate is near 70 percent and in urban areas, the infection rate for outdoor cats is presumed to be about 40 percent (Little 1).
Cats infected with feline leukemia show their first symptoms with sores in the mouth and often the first sign noticeable to their owners is an unwillingness to eat (PAWS 1). The disease takes several forms, but all are eventually fatal. It can settle in the abdomen, lungs or multicentric, meaning several places. As the disease suppresses more and more of the immune system, the cat becomes more susceptible to other infections and organ failure can also result (Little 1). “Cats that test positive for FeLV may live for months to years. Euthanasia of positive cats must be addressed on an individual basis in consultation with the veterinarian.
In many cases, it is possible and feasible to keep an infected cat and ensure good quality of life through the combined efforts of the owner and the veterinarian. “(Little 3) Though no pet owner likes to think that the preventative health care he is giving his pet could hurt her, it is obvious that in some cases that is exactly what happens. Cancer can result from vaccinations. However, the reaction and incidence of vaccine-related sarcoma is tiny when compared to the potential and likelihood of infection from feline leukemia. Especially in a multiple cat household, it is imperative that the pet owner vaccinate her cats.
Without the vaccine, a single exposure to the virus could wipe out a; the cats in a household. With the vaccine, it is unlikely any of them will get sick even with repeated exposure. Still, the experts agree that the only way to be100 percent safe is to make the cat an only cat and keep it indoors all the time. Even then, the risk of exposure is minimal, but still exists. Science has not yet found a way to prevent the vaccine-related sarcomas short of not giving vaccines and these sarcomas are not tied to any one vaccine. They are just as likely to form after a rabies vaccine as after a feline leukemia vaccine.
Since it is therefore impossible to be a responsible pet owner and completely eliminate the chance of a vaccine-related sarcoma, it makes sense that owners would try to eliminate any other threat to their pets, including feline leukemia. Ultimately though, veterinarians agree that the decision must be based on the individual owner and the individual cat. “Since young cats are at the greatest risk and their lifestyle is most likely to change in the future… it may be appropriate to suggest initial FeLV vaccination for all kittens, with subsequent annual vaccinations only for those that continue to be at-risk.
In any case, owners should discuss issues of FeLV testing and vaccination with their veterinarian so the best decision can be reached for each individual cat. “(Little 4) Works Cited . Couto, S. S. , S. M. Griffey, P. C. Duarte, and B. R. Madewell. “Feline Vaccine-associated Fibrosarcoma: Morphologic Distinctions” Veterinary Medical Teaching Hospital, University of California, Davis, CA. ;http://www. vetpathology. org/cgi/content/abstract/39/1/33;, December 1, 2007.
“Feline Leukemia Virus, Resource Sheet”, PAWS, ;http://www. paws. org/cas/resources/fact_sheets_cats/flv. php;, December 1, 2007. Hendrick, Mattie J. , Philip H. Kass, Lawrence D. McGill and Ian R. Tizard, “Postvaccinal Sarcoma in Cats” ;http://jnci. oxfordjournals. org/cgi/content/citation/86/5/341;, December 1, 2007. Little, Susan DVM. ‘Feline Leukemia Virus” The Winn Feline Foundation (2006) ;http://www. winnfelinehealth. org/Pages/FeLV_Web. pdf; December 1, 2007. Richards, James R. DVM. “Vaccine-Associated Feline Sarcoma Task Force: Feline Vaccines: Benefits and Risks” Americna association of Feline Practitioners and Cornell Feline Health, Cornell Univeristy, Ithaca, NY, 1997. ;http://www. avma. org/vafstf/rbbroch. asp; December 1, 2007