Ask the Vet: Calling the Shots For Your Pet

we vaccinate our pets for the same reason we vaccinate our children: to protect them against serious diseases that can potentially be fatal. also, some of these diseases are transmissible to people (i.e., zoonotic). as with people, vaccination may not entirely prevent the disease, but it will reduce the severity of infection. in general, dog diseases do not affect cats, and cat diseases do not affect dogs.

puppies and kittens should receive a series of vaccinations every three weeks from the time they are six to eight weeks old until they are between three and four months old. the first vaccine for a kitten is called either a "3 in 1" or a "4 in 1," or fvrcp, and it gives protection from viruses that cause serious upper respiratory symptoms that can become much more severe than just a "kitty cold." the vaccine also protects from panleukopenia, a gastrointestinal virus that causes vomiting and diarrhea and which can be fatal. if a kitten begins receiving vaccinations after three months of age, only one or two doses are necessary because the immune system is considered fully developed, and not dependent on the mother for maternal antibodies.

the first vaccine for a puppy is called a "5 in 1" or da2pp, and it gives protection against five very severe diseases, including distemper and parvovirus, both of which are highly contagious to other dogs and can be fatal. when a puppy is older than three months, the combo vaccine should also include leptospirosis, a disease that affects the liver and kidneys, which can be fatal, and is contagious to people. leptospirosis is found everywhere, cities and suburbs, and is carried by many species, including raccoons, small mammals and cockroaches.

all dogs and house cats need a rabies vaccine if they are older than four months of age. this is mandated by new york state law. the rabies vaccine must be boostered no later than one year after the first vaccination was given, then the vaccine is given either annually or every three years, depending on the type of vaccine your vet uses.

adult dogs and cats should receive boosters of their core vaccinations (fvrcp for cats and da2pp for dogs) either annually or every three years, depending on the vaccines used by your vet.

there are also "lifestyle" vaccines for pets at higher risk of contracting certain diseases. dogs that are social with other dogs (play in dog parks, go to doggy day care or the groomer, or are boarded frequently) may need to be vaccinated against bordatella bronchiseptica, which causes "kennel cough," or canine influenza. dogs that play in the woods may need to be vaccinated against lyme disease. check with your veterinarian.

in general, all vaccinations are very safe, and most pets have no reactions at all. however, some pets may experience transient lethargy, decreased appetite, soreness or mild swelling at the injection site. occasionally, more severe reactions occur, such as vomiting, hives, facial swelling or, in rare instances, trouble breathing. if any of these more severe signs occur, you should seek immediate veterinary attention for your pet.

-- dr. kathleen a. dunn, dvm, is a staff veterinarian at the north shore animal league america.