Introduction
Cat vaccines are crucial in preventing many life-threatening infectious diseases that cats are vulnerable to. Vaccines work by stimulating the immune system to produce antibodies against specific viruses and bacteria that cause disease. Although vaccines are not 100% effective, vaccinated cats typically develop strong immunity and protection if exposed to these pathogens. The most critical cat vaccines defend against highly contagious and potentially fatal illnesses like rabies, panleukopenia (feline distemper), rhinotracheitis and calicivirus. Routinely vaccinating cats, especially as kittens, is imperative for safeguarding both individual and community feline health.
This article provides an overview of the core and non-core feline vaccines, recommended vaccination schedules, associated risks and the importance of staying up-to-date on vaccinations for all cats.
Core Cat Vaccines
There are four core vaccines that all cats should receive:
Rabies
The rabies vaccine is considered a core vaccine because rabies is fatal if contracted. Rabies is spread through the saliva of infected animals and can be transmitted through bites and scratches. The rabies vaccine is a killed vaccine that is highly effective at protecting cats from the rabies virus. It is required by law in most jurisdictions.
Panleukopenia
Feline panleukopenia, also known as feline distemper, is a highly contagious and life-threatening disease caused by the feline parvovirus. It attacks and kills white blood cells, leaving cats susceptible to secondary infections. The panleukopenia vaccine contains a modified live virus that stimulates immunity against the disease.
Rhinotracheitis
Feline viral rhinotracheitis is an upper respiratory infection caused by feline herpesvirus-1 (FHV-1). It causes severe symptoms like nasal discharge, sneezing, coughing, mouth ulcers, and eye inflammation. The modified live rhinotracheitis vaccine helps prevent this highly contagious respiratory disease.
Calicivirus
Feline calicivirus is another major cause of upper respiratory infections in cats. Symptoms include oral ulcers, nasal discharge, pneumonia, and lameness. Like FHV-1, calicivirus is extremely contagious between cats. The vaccine contains inactivated or modified live virus to stimulate immunity against this respiratory pathogen.
Rabies
The rabies vaccine is critical for all cats and required by law in most areas (Source 1). Rabies is a fatal viral disease that affects the central nervous system. It is primarily spread through the bite or scratch of an infected animal. The rabies virus is present in the saliva of infected animals and can be transmitted when an open wound is exposed. Once symptoms appear, rabies is almost always fatal. Early symptoms include fever, seizures, and behavior changes. As the disease progresses, infected animals experience paralysis, inability to swallow, excessive salivation, and death (Source 2).
There is no effective treatment once clinical signs occur. However, the rabies vaccine provides effective protection by stimulating immunity before exposure to the virus. Vaccinating cats is critically important because rabies can spread between wildlife, pets, and people. Cats are natural hunters and can come into contact with rabid wildlife, exposing owners as well through bites and scratches. Vaccinating cats protects individual pets, helps stop the spread to people, and aids in the control of rabies in wildlife populations (Source 3).
Panleukopenia
Panleukopenia is caused by the feline parvovirus and is highly contagious among cats. The virus attacks and kills dividing blood cells, resulting in a severe drop in white blood cells (leukopenia). This leaves cats extremely vulnerable to secondary infections. Panleukopenia also causes severe gastroenteritis, with symptoms like vomiting, diarrhea, dehydration, fever and rapid weight loss. It has a very high mortality rate if left untreated, especially in kittens. Kittens less than 5 months old have the highest risk of contracting panleukopenia and the highest fatality rates, which can exceed 90% in untreated cases. The panleukopenia vaccine provides effective protection by exposing cats to a modified version of the virus to stimulate antibody development.
Sources:
https://vcahospitals.com/know-your-pet/feline-panleukopenia
https://www.avma.org/resources-tools/pet-owners/petcare/feline-panleukopenia
Rhinotracheitis
Feline viral rhinotracheitis (FVR) is caused by feline herpesvirus type 1 (FHV-1). This herpesvirus infection targets a cat’s upper respiratory tract and is highly contagious among cats (1). FHV-1 spreads through direct contact, respiratory secretions, and contaminated objects. The virus can survive in the environment for several weeks. Most cats encounter FHV-1 at some point in their lives. Without vaccination, over 80% of exposed cats develop acute upper respiratory infection. Symptoms include fever, sneezing, eye and nasal discharge, sores in the mouth, and lethargy. Some cats recover fully while others become lifelong carriers. The virus remains dormant in nerve tissue but can reactivate during periods of stress. Reactivated infections tend to be milder but perpetuate viral transmission. Vaccination is critical to control FHV-1 infection in the cat population. The FVRCP vaccine protects kittens and cats against disease from exposure to this highly contagious virus (2).
Sources:
(1) https://www.broadstreetvet.com/site/blog/2022/10/15/fvrcp-vaccine-for-cats
(2) https://www.fallsroad.com/site/tips-resources-blog-baltimore-vet/2021/04/23/fvrcp-vaccine-for-cats
Calicivirus
Calicivirus is one of the most common upper respiratory infections in cats. The feline calicivirus causes oral and respiratory disease. Typical symptoms include oral ulcers, sneezing, nasal discharge, conjunctivitis, and sometimes lameness. While most cases are relatively mild, some strains can cause a more severe disease known as virulent systemic feline calicivirus (VS-FCV), which has additional symptoms such as skin ulcerations, pneumonia, and limping.1
The calicivirus is very contagious and spreads through direct contact, respiratory secretions, and contaminated surfaces. The FVRCP vaccine is considered a core cat vaccine because it provides necessary protection against calicivirus and prevents more severe illness. However, the calicivirus mutates quickly, so vaccines may not protect against all strains. Even vaccinated cats can contract calicivirus, but symptoms are usually less severe.2
Most cats with an uncomplicated calicivirus infection can be treated at home with rest, hydration, and sometimes medications prescribed by a veterinarian. However, cats with VS-FCV may require intensive hospitalization and treatment. There is no cure for calicivirus, so prevention through vaccination is important.
Non-Core Vaccines
In addition to the core vaccines, there are some other important but non-core vaccines for cats:
Feline Leukemia Virus (FeLV): This virus weakens the immune system and increases the risk of other diseases. It spreads through saliva, urine, feces, and milk from an infected cat. Vaccination is recommended for outdoor cats or those with exposure to infected cats. https://vcahospitals.com/know-your-pet/vaccines-for-cats
Chlamydia felis: This bacterium causes conjunctivitis, pneumonia, and other respiratory infections in cats. The vaccine may be recommended for cats going into shelters or breeding catteries where exposure is higher. https://www.aaha.org/aaha-guidelines/2020-aahaaafp-feline-vaccination-guidelines/noncore-vaccines-for-pet-cats/
Feline Infectious Peritonitis (FIP): This deadly coronavirus disease has no known cure. An intranasal vaccine may help reduce the risk in higher risk populations like shelters, catteries, and multi-cat households. More research is still needed on its efficacy. https://www.riverstonevetgroup.com/services/blog/what-are-core-and-non-core-vaccines-cats-your-questions-answered
Vaccine Schedule
The core vaccines, including rabies, panleukopenia, rhinotracheitis, and calicivirus, have an established vaccine schedule for kittens and adult cats recommended by veterinarians and experts like the American Association of Feline Practitioners (AAFP).
For kittens, the schedule is:
- 6-8 weeks: First FVRCP (rhinotracheitis, calicivirus, panleukopenia) vaccine
- 9-12 weeks: Second FVRCP vaccine
- 12-16 weeks: Rabies vaccine
For adult cats, the schedule is:
- Rabies vaccine every 1-3 years depending on state laws
- FVRCP vaccine every 3 years
Some vets may recommend annual boosters for the FVRCP vaccine instead of every 3 years, especially for outdoor cats at higher risk of exposure. Cats with potential exposure to feline leukemia virus may also get that vaccine annually. Discuss the vaccine schedule with your veterinarian to customize it for your cat’s lifestyle and risks.
Following this standard schedule provides the best protection against severe illness from these dangerous and highly contagious feline diseases.
Sources:
https://www.petmd.com/cat/wellness/essential-cat-vaccinations
Risks
Like any medication, vaccines do carry some risks. However, the risks are minimal compared to the benefits vaccines provide. Some potential side effects of cat vaccines include:
- Soreness, swelling, or lumps at the injection site. This is relatively common but should resolve within a few days. Gently massaging the area can help.
- Mild fever, lethargy, decreased appetite for a day or two. This is not uncommon as the immune system responds to the vaccine.
- Severe allergic reaction (anaphylaxis). This is very rare but can be life-threatening if not treated promptly with epinephrine.
- Sarcomas (cancerous growths) have been reported in a small number of cats at injection sites. However, they are extremely rare, estimated at 1-10 cases per 10,000 vaccinated cats. [1]
While concerning, the risks associated with cat vaccines are minimal compared to the potentially devastating illnesses they prevent. Overall, the benefits far outweigh the risks. Talk to your veterinarian if you have any concerns.
Conclusion
After examining the core and non-core cat vaccines, the rabies vaccine emerges as the most critical for pet cats. Rabies is nearly always fatal once symptoms develop, and vaccination is the only reliable prevention method. Though rabies has become rare in areas with vaccination protocols, it still poses a deadly threat if ignored. All pet cats should receive the rabies vaccine on the standard schedule to protect both themselves and their human families from this devastating disease. While the other core vaccines help prevent common feline illnesses, rabies stands out as a uniquely dangerous zoonotic disease requiring vigilance. Staying up-to-date on the rabies vaccine is the most important step cat owners can take to safeguard their pet’s health and safety.
