Are vaccines necessary for my cat? If so, which are most important?
Vaccines have been an integral part of preventive health care programs for several decades. No other medical development has been as successful as vaccination in controlling deadly diseases in companion animals.
Vaccination is a medical procedure, and the decision to vaccinate is made based on the risks and benefits for each individual cat. To not vaccinate our pets is not an option. The goal is to devise a reasonable strategy for vaccination that maximizes our ability to prevent infectious disease while minimizing the occurrence of adverse events associated with vaccination.
Vaccinations can be divided into two broad categories: core vaccines – those recommended for all cats, and non-core vaccines – those that may or may not be necessary, depending on the individual cat’s lifestyle and circumstances. Currently, vaccines against panleukopenia, herpesvirus, calicivirus, and rabies fall into the core vaccine category.
The most commonly used vaccine against panleukopenia, herpesvirus and calicivirus is a multivalent vaccine: it contains viral antigens for several diseases together in the same dose, and is commonly abbreviated as the “FVRCP” vaccine. (For those of you who’ve always wondered exactly what FVRCP stands for, it’s “Feline Viral Rhinotracheitis, Calicivirus, Panleukopenia”. Feline viral rhinotracheitis is a fancy way to describe the respiratory infection caused by the herpes virus. Panleukopenia is the illness caused by the panleukopenia virus. Panleukopenia is often (incorrectly) referred to as “distemper”. It’s confusing, I agree.) The rabies vaccine is usually a monovalent vaccine. It contains viral antigens for one virus: the rabies virus.
To reiterate: ALL cats should be vaccinated with the FVRCP vaccine and the rabies vaccine.
So, what exactly are we vaccinating against? Let’s start with the “FVR” part of the FVRCP vaccine: the herpesvirus.
Feline herpesvirus is a major cause of upper respiratory disease in cats. Herpesvirus infections are very contagious between cats. Most cats become exposed to the herpesvirus at some time in their lives, and the majority of exposed cats become infected. Cats typically develop a mild upper respiratory infection – sneezing, conjunctivitis (“pink eye”), runny eyes, nasal discharge – which often resolves on its own.
In some cats, the virus induces severe upper respiratory disease, and a few of these cats may develop persistent upper respiratory symptoms for years. The herpes virus can also cause a variety of eye disorders, and may cause skin disease as well. Cats of all ages are susceptible, however, kittens appear to be affected more severely than adults. A presumptive diagnosis is made based on evaluation of the cat’s history and clinical signs.
After a cat recovers from the initial infection, the virus remains in the body as a latent infection. The dormant virus can be reactivated during times of stress, crowding and concurrent illness, resulting in a recurrence of clinical signs. During these recurrences, infected cats shed the virus profusely in their eye, nasal, and oral secretions, increasing the risk of infecting other cats. There are currently no drugs that eliminate herpesvirus from the body.
The feline calici virus (the “C” in the FVRCP vaccine) is an important cause of upper respiratory and oral disease in cats. Respiratory signs caused by calicivirus (sneezing, ocular discharge, nasal discharge) tend to be milder than those caused by the herpesvirus, however, calici virus may cause ulcers on the tongue of cats and kittens. The virus is mainly transmitted by direct cat-to-cat contact, however, indirect transmission via contamination of the environment or through contaminated objects is also possible.
Acutely infected cats will shed the virus in oral, ocular, and nasal secretions for two or three weeks, although some cats become chronic carriers, and will shed the virus persistently for months or even years. Cats of any age are susceptible, although kittens are most susceptible. Cats housed in groups, such as in boarding catteries, shelters, and breeding colonies, are at increased risk for contracting calicivirus.
Panleukopenia (the “P” in the FVRCP vaccine) is a highly contagious viral disease caused by the feline panleukopenia virus (FPV). Cats infected with the virus often show signs of lethargy, poor appetite, fever, vomiting, and severe diarrhea. The word panleukopenia means “a decrease in white blood cells”, and that is what is seen on the bloodwork of affected cats. In young cats, the disease is often fatal. Queens, if infected during pregnancy, may give birth to kittens with a condition called cerebellar hypoplasia, a neurologic disorder that causes severe incoordination. The virus is spread mainly through contact with feces, however, the virus is very stable in the environment and can be spread via contaminated food bowls, water bowls, litter boxes, and health care workers. Treatment consists mainly of supportive care – hospitalization, fluid therapy, antibiotics, and nutritional support. With aggressive care, some cats survive the infection, however, most succumb to the virus.
Rabies is a viral disease that attacks the neurological system. Although most people tend to think of this as primarily a dog disease, in the past few decades the number of cases of rabies in cats have been much higher than that in dogs. How often the rabies vaccine should be given depends on the vaccine. Some are labeled for annual revaccination. Others are to be given every three years.
Vaccines against infectious diseases have done much to reduce sickness and death in companion animals, and vaccination is the cornerstone of preventive veterinary medicine. As with any medical procedure or decision, the advantages must be balance against the risks, and you and your veterinarian should discuss all of the options now available to determine the best vaccine protocol for your cat.