Monday, August 18, 2014

Cats and Vaccinations - Frequently Asked Questions



Black cat licking veterinarian after exam  | Exclusively Cats Veterinary Hospital, Waterford, MI
"Thank you" kisses for Dr. Demos!
The most important reason that your cat should visit the veterinarian 1-2 times yearly is for the expert physical exam your pet's doctor performs. A proactive approach to your cat's health, focused on wellness and preventive care can be beneficial because illness and disease can be detected earlier, when treatments may be more successful and less costly. In addition to physical examinations and discussing your cat's diet and litterbox habits, when your veterinarian discusses your cat's health with you, he or she will likely recommend updating your cat's vaccinations.

What are vaccinations?

Vaccinations are injections of a substance that stimulates a cat's immune system, preparing the body to fight disease-causing organisms. Most vaccinations are developed for viral infections - diseases that cannot be treated with antibiotics. Some vaccines are developed for severe bacterial diseases, too.

Types of Vaccines -
  • Inactivated vaccines or "killed virus" vaccinations are vaccines that contain viruses that are unable to reproduce in the body. The majority of this type of vaccine contains adjuvants.
  • Modified-live vaccines contain viruses that can replicate, but do not cause clinical disease. While it is unlikely, it is theoretically possible for this type of vaccine to revert to virulence and cause disease.
  • Recombinant vaccines do not contain the whole virus, but specific parts of the virus DNA that the body's immune system recognizes as an invader, but that don't actually cause disease. These strings of proteins are either inserted into a non-disease-causing virus (vectored vaccine) or are inserted into bacterial DNA (called plasmids) so that antigens can be harvested and purified for use in vaccines (subunit vaccine).

Why do cats need vaccinations?

Vaccinations are very important to the health of your cat - the diseases we vaccinate for are diseases that do not respond well to treatment, and in most cases are deadly or produce life-long complications. Diseases like distemper are extremely long-lasting in the environment, lasting for years and can be brought into your home on your hands, feet or clothing if you come into contact with the virus particles in the environment. Additionally, the virus that causes distemper is resistant to disinfectants, can be passed to kittens through breast milk from the mother and can be acquired in utero. During the summer, cats that go outdoors are at higher risk because they are more likely to spend a longer or more frequent amount of time outdoors. Other diseases that we vaccinate for can be transmitted through the air. Rabies virus is transmitted by the bite of an infected animal, and despite common misconception, an infected animal is not always the raging, frothing creature that you see in the movies. Most skunks do not show signs or symptoms of infection, and any skunk that you encounter should be considered to be a carrier of rabies. In  companion animals, signs of infection may not show up for 10 days after the animal begins shedding the virus - so if your cat gets into a fight with a stray cat that seems healthy, that cat could be rabies positive, but may not be recognizably so until it has disappeared into the woods again.

But my cat doesn't go outside he doesn't need vaccinations!

Indoor cats are definitely at lower risk for communicable diseases, however there are many factors that still create risk for these cats. If you bring a new cat into the house from a rescue or shelter, you may be bringing disease into your home. A trip to the pet store to buy cat food may result in virus particles on your clothing that you can bring home to your cat. A friend with a sick pet may bring virus particles into your home while visiting. Airborn viruses can travel into your home through open windows and doors. You may bring virus particles in on your shoes after working in the yard. A stray cat may visit your screen door. Your cat may need to be boarded in an emergency situation, and would require vaccinations to do so.

In the case of rabies, the major carrier of this disease in Michigan is the bat. We very frequently receive phone calls from people telling us that they found a live or dead bat in their home, and most people do not know that a bat has access to their home until it is inside. Most bats are able to squeeze through extremely narrow openings; the little brown bat can enter a space (5/8" by 7/8") and the big brown bat can squeeze through an opening (1-1/4" by 1/2"). Bat bites are almost microscopic, so you would be unable to tell if your cat had been bitten by the bat. If your unvaccinated cat were to escape from your home and get bitten by an unknown animal, vaccination after the fact would not be guaranteed protection, and Michigan Public Health officials must proceed as though the animal that bit your pet was positive, euthanizing and testing your cat. If your unvaccinated cat bites a person, it could result in a 10 day quarantine at an animal shelter at your expense.

Rabies is a life threatening disease and in companion animals, there is no cure. The only definitive test for rabies requires euthanasia of the animal in question and examination of the brain tissue. By the time your pet starts showing signs of disease, you could already have been exposed. While rabies vaccinations are not required by law for cats in the state of Michigan, the safest thing to do for you and your cat is keep your pet's vaccines up to date.

For the health and safety of all of our patients and staff, all cats that come into our hospital for surgical or dental care or boarding must be up to date on vaccinations.


How often do cats need vaccinations?

The number and frequency of vaccines recommended for a cat is often a complex and individualized plan based on each cat's age, lifestyle, risk assessment and health status. However, there are some general guidelines that have been established by scientific study and experts in the field that are upheld by professional groups that specialize in feline medicine, such as the American Association of Feline Practitioners (AAFP) and the International Society of Feline Medicine (ISFM).  In some states, certain vaccinations and schedules are required by law.

Kittens are more susceptible to disease because their immune systems are not fully developed. Kittens raised by their mothers receive antibodies from their mothers, but these antibodies can interfere with vaccinations. Since we do not know for certain how long maternal antibodies remain active, or if every mother cat provides antibodies to all the major diseases, kittens need a series of vaccines to provide immunity. This series should continue until the kitten is at least 16 weeks of age. Additionally, any cat receiving a vaccination for the first time, no matter how old they are, will usually need a series of two vaccinations to ensure adequate protection.


It is recommended that even if a cat is not due for vaccination in a given year, they should be evaluated by a veterinarian at least annually, to ensure that health and risk status has not changed.

Cats should be tested for Feline Leukemia before starting the series of Feline Leukemia vaccinations because there is no medical benefit in giving a Leukemia vaccine to an infected cat. There are no negative side effects to vaccinating an infected cat, but this also eliminates the possibility of failing to recognize vaccine failure. If a previously untested cat who has been vaccinated for Feline Leukemia is later tested and is positive for Feline Leukemia, there is no way to tell if the Leukemia virus has been present long term or if the cat was recently exposed and the vaccine did not protect him. 

What are the possible side effects of vaccination?

The currently available feline vaccines do have an excellent safety record, however negative events following vaccination can occur. It is important to report these events to your veterinarian if they do occur, as veterinarians are requested to report adverse events to the manufacturer, as well as the USDA. It is also important to note that not all negative events that may follow vaccination can be directly said to be caused by the vaccine with 100% certainty. 

During the years 2002 - 2005, more than 1.25 million vaccines were given to cats at Banfield Hospitals across the US. In that time period, 51.6/10,000 cats had reactions within 30 days of vaccination (0.52%). Of these reactions, 54% experienced lethargy (weakness/tiredness) with or without fever, 25% experienced pain at the injection site, 10% experienced vomiting, 6% experienced facial swelling, 2% experienced generalized itching. Death occurred in 4 cats (0.04%) - two of these deaths were related to anaphylaxis (allergic reaction). Vaccines containing a Chlamydophila component were more likely to cause lethargy and fever than those without. Several other vaccine reaction studies report a rate of adverse reaction between 0.23% and 3% depending on the type of vaccination, the number of vaccinations given at one time, and the type of reaction being monitored.

Anaphylaxis or "allergic reaction" occurs rarely (about 1-5/10,000 cats).  It can be identified as vomiting, diarrhea, respiratory distress, facial itching or swelling, and collapse. Often, this type of reaction can be adequately controlled with the use of antihistimines or steroid medications or a different vaccine formulation.

Vaccine-associated sarcomas are a known problem, but the exact reasons that they form is not yet understood. Many suggest that the development of these tumors may result from inflammation or trauma at the injection site. Feline injection-site sarcomas (FISS) are rare, occurring in fewer than one out of every 10,000-30,000 cats, but the severity of this side effect is frightening to many people. In recent years, many precautions have been taken to minimize the trauma and inflammation caused by vaccination, and the frequency of this problem has significantly decreased. At Exclusively Cats, we give vaccinations in insulin syringes, to decrease the needle trauma associated with vaccination. We allow the vaccines to warm to room temperature before giving them, and we choose to use primarily non-adjuvanted vaccines. In addition, we vaccinate cats only as frequently as medically necessary to provide immunity, and we avoid vaccinating cats that have other compromising health issues (which is why we do not administer vaccinations without a physical exam). In addition, we use recommended vaccination sites low on the leg so that, in the eventuality that a sarcoma does develop, the limb can be amputated if necessary, to prevent the spread of the tumor to the rest of the body and prolong the life of your cat.

More about the diseases that we vaccinate for:
Feline Panleukopenia (also known as Feline Distemper, Feline Parvo, or Infectious Enteritis)
Feline Leukemia
(more to come...)