Viruses and vaccines for your cat: A guide for cat owners

Many cat owners overlook the importance of vaccines for their pets, especially if they only reside indoors. Contrary to popular belief, there are many highly contagious and potentially deadly infectious diseases that cats can catch whether indoors or out that are prevented by vaccines. Read on if you have ever wondered:

• When should I vaccinate my cat?
• At what age should kittens get vaccinations?
• What can my cat be vaccinated against?
• What contagious diseases don’t currently have vaccinations?
• Can my cat have a bad reaction to a vaccine?
• What core vaccines does my cat need to stay healthy?

Vaccines are used to boost the immune system against certain diseases. Many of the diseases that we vaccinate cats for can be life-threatening, even for kittens or indoor cats. Preventive care such as vaccination and regular visits with a veterinarian are essential to provide disease protection for your cat.

Some vaccines can be given as early as six weeks of age, and cats older than sixteen weeks of age can receive any vaccine that is labeled safe for healthy adult cats. Your vet will determine the best vaccine schedule for your cat or kitten based on their individual lifestyle and history. Any cat receiving a vaccine needs to be healthy and will typically receive a full physical exam from a veterinarian before receiving the vaccination. It’s important to not only receive the first round of vaccines early in life but also ensure your cat gets booster vaccines throughout their life according to your vet’s recommendations.

At what age should kittens be vaccinated?

Kittens are especially vulnerable to many diseases, as their immune systems are not fully developed. They receive antibodies from their mothers, which provide some degree of protection against infectious diseases, but these antibodies also interfere with the effectiveness of vaccines. To compensate for the impact of maternal antibodies, multiple boosters are required until a kitten develops its own robust immune system. Veterinarians vaccinate kittens beginning at six to eight weeks of age and give boosters every three to four weeks until the kitten is approximately four months old.

There are core vaccines that are recommended for every cat, as well as risk-based or non-core vaccines that are given based on a cat’s lifestyle. All cats, including indoor-only cats, should stay up to date on all core feline vaccines, as they prevent deadly and highly contagious diseases.

There are two core feline vaccines that all cats, regardless of their lifestyle or location, should stay up to date on throughout their lives: the FVRCP combination vaccine and the rabies vaccine.

The FVRCP three-in-one vaccine components include panleukopenia, feline herpesvirus, and feline calicivirus.

Panleukopenia (feline distemper virus)

Feline panleukopenia is a highly contagious and deadly viral disease in cats that causes vomiting, diarrhea, fever, and loss of appetite. Some cats that contract the virus die suddenly, and kittens are highly susceptible to the disease.

Feline herpesvirus (viral rhinotracheitis)

Feline herpesvirus is a contagious upper respiratory virus that causes sneezing, fever, eye and nasal discharge, conjunctivitis, eye inflammation, and lethargy. Kittens are highly susceptible to this viral disease, and it can be deadly for kittens and cats with compromised immune systems.

Feline Calicivirus

Calicivirus is highly contagious and is a major cause of respiratory infections in cats. Symptoms can range from sneezing, eye and nasal discharge, and lethargy to sores on the gums, lameness, coughing, and inflammation of the liver, pancreas, blood vessels, and other organs in the body. Calicivirus cases progress to severe levels of infection in up to half of cats who contract it.

Rabies virus

Rabies is a severe disease spread through bites from infected animals. It has a nearly 100% fatality rate. Cases of rabies are uncommon in populations of cats where vaccination rates are high. In many countries, a rabies vaccination is legally required for all pet dogs and cats because of the danger rabies presents to humans. Symptoms of rabies in cats include aggression, drooling, loss of coordination, paralysis, and coma.

Other vaccines are given based on a cat’s individual lifestyle and risk of exposure. Many of these vaccines are recommended for cats that live in high-population shelters or go outdoors, since solitary and indoor-only cats are at low risk of contracting the viruses or infections that correspond to the non-core vaccines. However, in areas where the prevalence of the diseases is high, your veterinarian may recommend vaccination for your indoor cat in case they escape or their lifestyle changes.

Feline leukemia virus

The feline leukemia virus, or FeLV, is one of the leading causes of virus-associated death in cats. The virus is spread through bodily fluids and the milk of infected cats. The disease is highly contagious and cats can catch it from direct contact, even a casual touch from an infected cat. Clinical signs include anemia, immune suppression, and cancer, with a high chance of death in the first three years after contracting FeLV.

Bordetella bronchiseptica (kennel cough)

Bordetella bronchiseptica is one of many infectious agents responsible for kennel cough, which is a particularly common upper respiratory tract infection in dogs. It is more common in shelter situations where large populations of dogs and cats are housed together. Symptoms of this respiratory infection include coughing, sneezing, and discharge from the nose and eyes. A vaccine may be considered for cats who are at high risk of exposure to this highly contagious disease.

Chlamydophila felis (feline chlamydia)

Chlamydophila felis is the bacteria that causes feline chlamydia, which is characterized by pink eye and upper respiratory symptoms such as sneezing, eye and nasal discharge, and cough. The bacterial infection is most prevalent in households with more than one cat or other areas where multiple cats live.

Feline infectious peritonitis (FIP)

Feline infectious peritonitis, or FIP, is a fatal viral disease that comes from a mutated feline coronavirus. The regular, unmutated feline coronavirus is very common, highly contagious, and usually doesn’t cause illness, but in some cases the virus mutates and causes FIP. Evidence suggests the mutated form is not contagious. Scientists and veterinarians are still unsure why it mutates into FIP in some cats. FIP vaccinations do exist but are not highly effective and as such, are not usually recommended. Symptoms of FIP are vague and nonspecific in the beginning and include lethargy, diarrhea, and reduced appetite. As it progresses, FIP may lead to a “wet form” that involves fluid in the abdomen or chest and difficulty breathing, or a “dry form,” which presents as loss of coordination and seizures.

Feline Immunodeficiency Virus (FIV)

Feline immunodeficiency virus suppresses the immune system of infected cats. Cats that are FIV positive may appear normal for several years before experiencing severe infections from normally harmless disease-causing organisms.  FIV is very common and is primarily transmitted through bite wounds. There is no cure, but cats with FIV have a good chance of living a long life as long as they are not also infected with FeLV. A vaccine is available, but it interferes with interpreting test results and is usually not recommended.

Feline giardia

Giardia is an intestinal infection in cats, dogs, and humans. Signs of illness include foul-smelling diarrhea, lethargy, weight loss, and reduced appetite. Cats can catch giardia by ingesting the parasite in stagnant water or inhaling it in contaminated areas outdoors. They can also catch it from another infected pet in the home, and the infection is fairly common in dogs. The feline giardia vaccination is generally not recommended as there is limited data to support the effectiveness of the vaccine in cats.

There are many contagious diseases that cats can catch that cannot currently be prevented by vaccines. Some of these diseases include:

• Tick-borne illnesses
• Some strains of Feline immunodeficiency virus (FIV)
• Ringworm (dermatophytosis)
• Internal parasites

Most contagious diseases can be prevented by avoiding contact with other infected cats.

Vaccines are safe for the vast majority of cats and extreme reactions are rare. It is important for cat owners to know the difference between a vaccine reaction and the body’s natural immune response to a vaccination. It’s normal for a cat to feel sore or tired after a vaccination while their immune system is doing its job to protect them in the future. Negative vaccine reactions include:

• Hives
• High fever
• Abscess at injection site
• Facial swelling
• Anaphylaxis

Cats can also develop feline injection site sarcomas, or FISSs, where a cancerous tumor forms in the soft tissue around an injection site. “Injection site sarcomas are very rare and it is currently under investigation why this occurs in some cats,” states Vetster veterinarian, Dr. Jo Myers. “Overall, the health risks of deadly diseases such as feline leukemia virus and rabies outweigh the low risk of negative vaccine reactions and FISSs.”

All cats should receive the core vaccinations since the viruses and infections they protect against are highly contagious and often lethal. In addition, the rabies vaccine is legally required in many countries around the world. Other available vaccines are risk-based. A cat owner should discuss their individual cat’s lifestyle with a veterinarian to determine which vaccinations their cat may need. If you would like to connect to a veterinarian to talk about your cat’s vaccine needs, you can book an online virtual care appointment with Vetster from home.

Does my indoor cat need vaccines?

All cats, even those who live indoors, should receive all of the core feline vaccines, including vaccines for panleukopenia, feline herpesvirus, calicivirus, and rabies. The first two feline leukemia vaccines are highly recommended for all kittens. These diseases are highly contagious through airborne particles or direct contact with other cats. The rabies vaccine is also required by law in many countries around the world.

What is the most common viral infection in cats?

Feline leukemia virus (FeLV) and Feline immunodeficiency virus (FIV) are among the most common viral infections of cats. Upper respiratory tract infections caused by herpesvirus, panleukopenia, and calicivirus are also common.

What are the most important vaccinations for cats?

The rabies vaccination is the most important vaccine from a public health standpoint since vaccinating pets protects people from this fatal disease. The other core vaccination that all pet cats should receive for their protection and the protection of other cats around them is the 3-in-1 distemper combination vaccination for panleukopenia, feline herpes virus, and calicivirus. Even though it is considered non-core, the initial series of feline leukemia virus vaccine is recommended for all kittens.