Cat Flu Vaccine Side Effects

Vaccine side effects are an occasional complication of feline vaccinations, but are often minor problems when compared to the symptoms of cat flu. Caused by bacteria and viruses like the feline herpes virus (FHV-1), also known as feline rhinotracheitis virus, and feline calcivirus (FCV), so-called 'cat flu' can affect the respiratory system of cats of every age, with more serious consequences for young kittens or elderly cats with weak immune systems.

Causes of Cat Flu

The bacteria and viruses that cause cat flu are common and can be very contagious. FHV-1 and FCV are frequently the causes of cat flu, and once a cat has become infected with one of these viruses they can be carriers for life.  Even seemingly healthy cats may be carriers of cat flu and pass on the illness to other animals. While vaccinations cannot completely eliminate the chances of your cat becoming infected, they can decrease the likelihood of infection and prevent intense and prolonged symptoms.

The infection is spread through saliva and eye and nasal discharge and, as mentioned above, can be passed from healthy or sick cats. Kittens or older cats with weak or suppressed immune systems are more likely to become infected with the illness, along with cats that aren't vaccinated and are frequently in contact with other cats, such as those in pet shelters. Cats living in a stressful environment, such as those that are crowded, unsanitary and unsafe, may be more susceptible to all types of infections, including cat flu.

Symptoms of Cat Flu

Cat flu symptoms can vary and depend on which virus has caused the infection. While cat flu generally doesn't cause death in cats, kittens are more susceptible to serious complications due to their undeveloped immune systems and the dangers of dehydration and weight loss, which can develop quickly. Signs of cat flu must be addressed immediately by a veterinarian in order to prevent more severe health problems. Symptoms of cat flu to watch for include:

  • Mouth and tongue ulcers
  • Fever
  • Sneezing
  • Eye and nasal discharge
  • Coughing
  • Loss of appetite
  • Lethargy
  • Dehydration
  • Weight loss
  • Conjunctivitis, which could lead to eye ulcers

Cat Flu Vaccine and Side Effects

Talk with your vet's office about vaccinations and vaccine schedules for your cat, including future booster shots. Kittens should be vaccinated anywhere between 6 to 9 weeks of age and then again in regular intervals to be determined by your veterinarian. Standard feline vaccinations are available to vaccinate your cat against multiple diseases, including feline calicivirus and feline herpes virus.

Side effects are a potential but rare consequence of vaccinations, but are generally mild. Side effects of the cat flu vaccine may include:

  • Inflammation or pain at the site of injection
  • Lethargy
  • Lack of appetite
  • Lameness
  • Depression
  • Fever
  • Allergic reaction (this includes swelling and vomiting, and must receive immediate attention)

Some cats will be drowsy, pick at their food and will not quite be themselves for a couple of days after vaccinations. If your cat experiences any more serious changes in health or behavior, contact your veterinarian's office to determine if further attention is needed.