What You Need To Know When Vaccinating Your Cat (Part 4)

The goal of vaccination is to create immunity in response to an infectious disease risk.  In this 5 part series, we’ve talked about Immunity vs. Vaccination, Vaccination Risks and Minimizing Vaccination Risks. The next tool for your “decision toolbox” is learning about specific Feline Infectious Diseases and Prevention.

Feline Infectious Diseases and Prevention

There are only two “Core Vaccines” for cats:  FVRCP (“distemper”) and Rabies.


Panleukopenia (commonly known as “Feline Distemper,” and the “P” in FVRCP) was, not so long ago, a common and dreaded veterinary hospital visitor, highly contagious and overwhelmingly fatal.  It is a resilient organism that, like human cold viruses, does not die quickly when exposed to air.  It can sneak into your house on your clothes or shoes.  It is still an epidemic in the feral cat population, but vaccination has made it a relative rarity in pet cats today.  The flip side, somewhat less awesome, is that the long-standing veterinary model of vaccinating annually for Panleukopenia has probably created a whole panoply of different epidemic non-infectious diseases which are no less fatal than Panleukopenia itself – just much tougher to recognize.

Panleukopenia is absolutely something you want your cat protected against, and unless your cat has survived an exposure, vaccination is necessary to get that protection — but annual vaccination is not.  We know now that most cats who have once acquired a good immunity to Panleukopenia will retain for most or all of a lifetime.  As a result, the American Association of Feline Practitioners (AAFP) now recommends that Panleukopenia vaccination in adult cats be repeated every THREE years, rather than annually, and some Panleukopenia vaccine products are now labeled for every three-year administration.

This is a good first step, but we can do better.  There is an excellent titer test for Panleukopenia, and protective antibody levels are well-established.  A cat who already possesses a protective level of antibody stands to gain nothing from vaccination except the associated risks.

In the absence of any other alternative, if your cat has EVER been vaccinated for Panleukopenia, you are statistically better off to assume your cat is protected than to re-vaccinate.

Feline Viral Rhinotracheitis (FVR) and Calicivirus (C)

Feline Viral Rhinotracheitis (FVR) and Calicivirus (C) antigens are commonly included in the combination vaccine often referred to simply as “the distemper vaccine,” or FVRCP.  While almost never fatal, both FVR and Calicivirus cause much preventable suffering.  Vaccination against these two viruses can be of great benefit for cats who have not already been infected; and in some cases, when given intranasally, can aid in the medical management of cats who have chronic eye, nasal and/or oral problems as a result of infection.

There are antibody tests for both FVR and Calicivirus, but they are not generally as useful as the Panleukopenia titer test.  “Protective” levels are not established for either virus.  In the case of FVR, that is because there is no completely protective immunity – infection is not completely prevented in cats with high antibody levels, but is less likely.  For Calici, definitive studies establishing protective titers have not been done.

What we can tell from FVR and Calici titers is that a level below a certain point corresponds to high susceptibility to infection; and like Panleukopenia, these are tough viruses that don’t require direct contact for transmission, so indoor cats are at risk.  The expense of these two titers combined with their limited usefulness makes a decision to run them much less of a slam-dunk than a Panleukopenia titer, but even so, titering remains a useful choice for cat parents who prefer to take every precaution.

For cats who need periodic boosters against FVR or Calici, but do NOT need vaccination against Panleukopenia, there are vaccine products that contain antigens against only those two, and at least one of those products is a lower-risk intranasal vaccine.

Feline Infectious Diseases


Rabies vaccination is required by law in most jurisdictions worldwide.  Stringent rabies laws exist largely to help prevent human infection, and also to protect against disease in domestic animals and to prevent the spread of rabies to non-endemic areas by transport of infected or susceptible animals.

Cats are unusually susceptible to the rabies virus.  In some states, the domestic pet cat has become the most commonly reported rabid animal species each year.  Indoor cats, while at lower risk, do contract rabies periodically, most often during escapes outside or by exposure to bats that get into houses through chimneys, vent pipes and the like.  Protection is an important concern for all cats.

The pharmaceutical company Merial makes a vaccine that is considered the safest on the market for cats.  It is non-adjuvanted, and comes in a one-year and a three-year formulation.  This is the only non-adjuvanted rabies vaccine product currently on the market.

Two titer tests are available that use different methodologies and have different applications; however, neither is accepted as a substitute for current vaccination by any jurisdiction I am aware of.

Rabies Exemption Certificates can be issued by veterinarians in some states (including Colorado), when, in the vet’s best medical judgment, the pet is at an unacceptable risk of harm from a rabies vaccination.  Rabies Exemption Certificates cannot ethically be issued to pets with an ongoing risk of exposure, such as cats who go outside.  Exemption certificates do not exempt a cat from quarantine or euthanasia requirements should a human be bitten, but they do exempt the cat parent from fines and other legal consequences for not having proof of a current rabies vaccine.


You’ve learned about feline infectious diseases and now the final tool you need for your “decision toolbox” is a list of all the other available vaccines for cats.  We’ll discuss these in the last part of our 5 part series on what you need to know when vaccinating your cat.

Why Dental Work Is Important For Your Cat
Cats Are Not Small Dogs
Your Cat and Vaccination: Immunity vs Vaccination
Your Cat and Vaccination: Vaccination Risks
Your Cat and Vaccination: Minimizing Feline Vaccination Risks