Dr. Matthew Smith DVM

Vaccines are an important part of a routine health care program for your pet. They can lessen the severity of future diseases and sometimes prevent infection all together. Experts agree that widespread use of vaccines within the last century has prevented death and disease in millions of animals. Vaccination is a medical procedure and should be done only after considering the lifestyle of each individual pet and his or her needs along with legal and other requirements. No vaccine can provide 100 percent protection from any disease but discussion of your pet’s vaccination plan with your veterinarian can provide you with the best protection current medical science can provide.

Our pets, just like us, have a natural immunity to many things. This natural immunity involves: skin, hair, tears, normal bacteria living on/in the body, mucus, stomach acid, certain blood cells, and chemicals produced by the immune system. Natural immunity is very helpful but is inefficient at fighting off a new disease to which the body has never been exposed. This is where “acquired” immunity comes in. Acquired immunity starts when the immune system is exposed to a new infectious agent: virus, bacterium or parasite. A complex series of reactions occurs where the immune system recognizes, processes, and reacts to the infectious agent. Antibodies are produced and new blood cells are created which assist the immune system in attacking the infectious agent. These cells and antibodies can remain in the system long after the disease is gone; the immune system has a memory that will help the body respond quicker if the infectious agent is found again. Vaccines stimulate this type of acquired immunity.

The majority of vaccines currently in use for cats and dogs are made from inactivated/killed or “modified live” viruses or bacteria. The chance of contracting a disease from the vaccine itself is nearly zero. The so-called killed vaccines are just like it says, dead viruses or bacteria that the immune system can still recognize but are unable to cause illness. The modified live vaccines are weakened forms of the original infectious agent. So, even if they do cause disease in very rare cases, it would be a much milder form of the disease that a normal healthy pet should be able to fight off on its own. The symptoms of illness many pets will show after vaccination are simply due to the immune system responding to the vaccine. It happens often in people too. Typically the symptoms are: fatigue, achiness, slight fever, and rarely vomiting. Your pet will usually be back to normal in a few days, however if symptoms are severe or last for more than 3 days you should visit a veterinary hospital. These types of symptoms are considered normal and do not mean your pet is allergic to the vaccines. True allergic reactions occur within 45 minutes of vaccination and usually involve swelling of the face and muzzle. If your pet’s face swells, return to the vet right away for an injection to calm the allergy. Facial swelling can be serious so it is best to supervise your pet for about an hour after vaccination. If you know your pet has had this reaction in the past, simply tell the vet and an injection to prevent it will be given before the vaccine. Serious adverse reactions to vaccinations are very infrequent.

Puppies and kittens are more susceptible to infections than a normal adult animal. They require a series of vaccines usually every 3-4 weeks starting around 6 weeks of age and ending around 16 weeks of age. The reason for this is that puppies and kittens have a certain amount of protection acquired from their mother via her blood while in the uterus and also her milk. This is called maternal antibody. The maternal antibodies can actually block the vaccines and prevent them from working. The reason we vaccinate every 3-4 weeks is because the maternal antibodies fade away at different times in each individual and we want to make sure the animal is protected before the maternal antibodies wear off and the pet is exposed to disease. As an added precaution, puppies and kittens should not be allowed around other animals of the same species (except healthy ones already in the household) until they have had the entire series of vaccines. As tempting as it is to show off your new baby pet to other animal owners you should avoid it until the vaccines are finished. You could be exposing your pet to diseases for which it has inadequate protection. Obviously you will have to take your pet to the vet at some point and there will certainly be other animals there; in a situation like this carry your pet and do not allow him/her to interact with other animals.

Historically, most vaccines were boostered (re-vaccinated) yearly in adult pets, however many studies have advocated for an extended interval between boosters in adults showing that major viral vaccines provide protection for up to three years in most cases. The acquired immunity from previous vaccines is still in the memory of the immune system. Only certain Rabies vaccines are licensed by the USDA as effective for three years, but vaccines manufacturers as well as researchers support the findings that other viral vaccines are effective for up to three years. The Rabies vaccine is the only one required by law. It is possible to test the blood, or serum, of a pet to see if the immune system still has an acquired immunity response to previous vaccinations. These are called antibody titers and can be performed at any veterinary hospital.

Veterinary research groups have provided the veterinary community with vaccine guidelines listing: “core” vaccines - those recommended for all pets, “non-core” vaccines – those recommend only for at-risk pets, and “not generally recommended” vaccines – those that are on the market but shown to have little or no benefit. Vaccines, while proven safe, are not without risk. So, only those vaccines that are needed for your individual pet should be given. Always discuss your pet’s needs with your vet. A Chihuahua being carried while shopping in Beverly Hills will require different vaccines than a Labrador Retriever hunting in the forests all over the country. Do keep in mind, however, that no matter the situation rabies vaccine is required by law in all dogs.

Every pet’s vaccine needs should be evaluated yearly. Certain vaccines, such as Bordatella/Kennel Cough are only protective for one year, and sometimes a pet’s lifestyle changes exposing him or her to new risks. For example: adult indoor house cats need only one combination vaccine every 3 years (commonly abbreviated FVRCP vaccine), however, if new cats are introduced into the household or the cat starts to explore the outdoors he or she will require additional vaccines.

Certain vaccines have bad reputations: feline leukemia vaccine causing skin tumors, canine lepto vaccine causing allergic reactions… However changes in the vaccine manufacturing process, taking proper precautions, and discussion with your vet can minimize or even eliminate risk. Feline leukemia is the leading viral killer of cats and is much more common than the tumors believed to be caused by the vaccine. So, at risk cats should be vaccinated for this virus.

The main vaccines for cats are:

1) FVRCP: a core vaccine combination of Feline Viral Rhinotracheitis (a herpes-type virus), Calici virus, and Panleukopenia virus (also called feline distemper). Start this vaccine as early as 6 wks of age and give every 3-4 weeks until 16 wks of age. Then give one year later. After that, as an adult cat, give once every 3 yrs.

2) Rabies: a core vaccine but really only needed for outdoor cats. The risk of exposure to the disease is very low for an indoor cat. Start this vaccine with a single dose at 12-16 wks of age, booster in one year and then give every 3 years. However, there are rabies vaccines that are only effective for 1 year, and, of course, local laws prevail. Rabies is not required in cats in California.

3) FeLV: a non-core vaccine for Feline Leukemia Virus. Like Rabies, this vaccine is only important for outdoor cats or cats in households with multiple cats.

There are other commercially available vaccines for cats, but they are either non-core or not generally recommended. The other non-core vaccines (except for FeLV) are only given in extreme circumstances such as cat breeding facilities during a disease outbreak.

The main vaccines for dogs are:

1) DA₂PP or DHPP: a core vaccine combination of Distemper virus, Adenovirus (or Hepatitis virus), Parvo virus, and Parainfluenza virus. Start this vaccine at 6 wks of age and booster every 3-4 wks until 16 wks of age. Give one year later and then booster every 3 years.

2) Rabies: a core vaccine required by law for ALL dogs. Give the first vaccine at 16 weeks, booster one year later, then once every three years. Note that there are some rabies vaccines that are only effective for one year although the three year vaccine is most common in dogs.

3) Bordatella: non-core, a bacterial disease commonly called Kennel Cough. The vaccine is often combined with Parainfluenza virus also found in the DA₂PP. Officially this is a non-core vaccine, but in my opinion it is important in any dog that is frequently around other dogs: dog parks, grooming/bathing salon, boarding in a kennel, training classes, etc. Start at 6-8 wks of age, booster in 3-4 wks, then give every year or every six months in high-risk situations.

Note: Corona Virus vaccination is very commonly done by veterinarians, but vaccine experts agree that it is essentially useless. The disease itself is uncommon and even if it does occur it is mild and the body will clear it without incident. Also, in studies of readily available corona virus vaccines, they were not able to significantly reduce the incidence of the disease. In fact, in these studies, the researchers had a hard time making even the unvaccinated dogs sick by deliberately exposing them to the virus. So, my advice is to refuse this vaccine.

The main thing to remember from this article is: Have your pet vaccinated regularly, but always discuss your pet’s individual needs before starting any vaccine program. Also, vaccines should be considered as only one important part of a comprehensive total health care plan.