Feline Vaccination Risks

by Dr. Fern Slack, UCVC Medical Director and Feline-Exclusive Veterinarian

Feline Vaccination Risks: What You Need To Know When Vaccinating Your Cat (Part 2)

The goal of vaccination is to create immunity in response to infectious disease risk. The next tool for your “decision toolbox” is learning about feline vaccination risks. This is part 2 of a 5 part series on vaccinating your cat and what you need to know. If you missed it, part 1 focused on Immunity vs. Vaccination.

Risks of Feline Vaccination

Chronic Renal Disease:

Many, if not all, Panleukopenia (“Distemper”) vaccine products use a virus grown on feline kidney cell cultures, the Crandall-Rees Feline Kidney (CRFK) cell line. Cats who receive a vaccine grown on this cell line develop antibodies to renal proteins and can develop interstitial nephritis. Chronic interstitial nephritis (whether caused by vaccines or other issues) leads to chronic kidney disease in the cat. Many researchers now believe that the current nearly universal epidemic of chronic renal disease in the senior pet cat population is related to, if not a direct result of, what is, in effect, repetitive vaccinations against feline kidney cells.

We need to protect our kitties from Panleukopenia, but with this in mind, we should make every attempt to ensure immunity with the fewest vaccinations possible.

The current epidemic of inflammatory bowel disease, intestinal lymphosarcoma, pancreatitis, diabetes, arthritis, inflammatory hepatitis, and hyperthyroidism, as well as chronic renal failure, are now thought by many to be strongly influenced by overvaccination.

Repetitive Inflammatory Insults:

The term “inflammatory insult” refers to any assault on an organism to which the response is inflammation, such as a mosquito bite, an infection, a burn, a bee sting, or contact with an irritating chemical. Inflammation is part of a normal immune response, designed to get rid of the “insulting” element, essentially fighting fire with fire. Occasional inflammatory responses to noxious stimuli are part of life; our bodies are protected, not harmed, by them.

The problems appear when inflammation is repetitive or chronic; when noxious exposures happen regularly and inflammation is often induced or always present. Chronic inflammation is a leading precursor to cancer, not to mention being a major problem unto itself when affecting organs like the gut, liver, kidney, or skin.

The immune system of cats utilizes inflammation to a degree that makes humans look puny. Normally, this response serves them well. When noxious stimuli are encountered too frequently or are unnaturally strong, a systemic and chronic inflammatory response begins to develop. Continued exposures cause ever-stronger inflammatory responses leading to inflammatory disorders of many organ systems, even when those organs had no direct exposure. The current epidemic of inflammatory bowel disease, intestinal lymphosarcoma, pancreatitis, diabetes, arthritis, inflammatory hepatitis, and hyperthyroidism, as well as chronic renal failure, are now thought by many to be strongly influenced by overvaccination.

Vaccination is just one of many inflammation inducers that can cause or worsen these disorders, but it is a big one, and should be taken into account with every single vaccination decision.

Vaccine-Associated Fibrosarcomas (VAF):

These are rare but very malignant cancers that arise at the site of an injection. The incidence is estimated at 1 in 1000-10,000 vaccinations. Treatment must be both rapid and aggressive for any chance of success. The American Association of Feline Practitioners (AAFP) now recommends that feline vaccines be administered as far down the legs as possible; that way, if a tumor does occur, amputation of a limb can save a life.

Vaccine-associated fibrosarcomas have been most closely associated with adjuvanted vaccine products. Adjuvants are irritating chemicals added to killed vaccine products to induce local inflammation, bringing more lymphocytes to the vaccination site to respond to the vaccine antigen. (Live vaccines don’t need adjuvants.)

The most commonly used adjuvant is aluminum. Aluminum adjuvants are the most common association with VAFs. It is reasonable to conclude that the same chronic local inflammation that is the probable cause of VAFs is also a source of long-term systemic inflammation, and may, therefore, play a role in worsening systemic inflammatory diseases.

Adjuvanted vaccines should never be administered to cats unless there are no other alternatives – unlikely, since the only two vaccines most cats ever truly need (FVRCP and Rabies) are both available in non-adjuvanted formulations.

Allergic and Anaphylactic Reactions:

Allergic reactions, while unusual and usually mild in nature, can occur with any vaccine at any time. The more times we give a certain vaccine, the more likely that an allergic reaction will occur. If a cat has had an allergic reaction to a vaccine, there is near certainty of an allergic reaction to subsequent administrations, unless vaccination is preceded by treatment with antihistamines or steroids. A cat who has had an allergic reaction to a vaccine is also more likely to have an allergic reaction to a different vaccine. Successive allergic reactions tend to escalate in severity; a history of allergic reaction to a vaccine makes an anaphylactic reaction more likely.

Anaphylaxis is a severe, systemic, life-threatening allergic reaction. True anaphylaxis in cats is quite rare, but it does happen. Even with immediate treatment, death may ensue.

Vaccination may cause lesser reactions:

Lesser reactions may include transient lethargy and local hair loss. Most of these require no treatment and are not serious health problems, but they do signal that an inflammatory insult has occurred. The long-lasting effects of that, often totally hidden, are far more important.

*****

You understand the relationship of immunity to vaccination. You understand vaccination risks. And now you want to protect your cat from infectious disease while minimizing those risks. The next tool for your toolbox is a list of ways to minimize vaccine-associated risks. We’ll focus on this in the next part of this series.