The Shots Your Pets Need

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Making sure that your pet is kept up to date on vaccines is part of being a responsible pet owner. However, recommendations can differ between clinics and even between pets, and vaccine schedules can be confusing. Many owners also have concerns about overvaccination, and no one wants to cause their pet more harm than good. That said, it is important to understand which diseases you need to protect your pet against and why. In all cases, it’s best to work with your veterinarian to weigh the risks and benefits.

What Are Vaccines?
The purpose of a vaccine is to protect your pet against acquiring a specific disease. Vaccines contain antigens, which are essentially small segments of a disease-causing organism that, when given to your pet, stimulate his or her immune system to produce protective antibodies against the disease. Most vaccines generate only a mild response from the immune system. However, it is possible for some pets to have more severe reactions. Your vet can advise you of these reactions and what type of symptoms to watch for.

What types of vaccines are there?
Vaccines are generally broken down into two categories: core vaccines and non-core vaccines. Core vaccines protect against diseases known to cause significant illness in dogs and cats, those that are highly contagious and those that may be transmitted to humans. These vaccines are generally recommended for every healthy pet. Non-core vaccines are usually reserved for pets who are at higher risk for acquiring a specific disease. The vaccines that your pet requires to stay healthy will depend on age, health and lifestyle. Your veterinarian can help you determine which vaccines are appropriate for your pet. (Get details about vaccines for dogs and vaccines for cats.)
 
Why does my puppy or kitten require a series of vaccines?
When puppies and kittens are born, they acquire protective antibodies from their mothers through nursing. Before or around 16 weeks of age, these antibodies fade and no longer offer immunity. Without testing, it is impossible to know the level of antibody protection each pet has at any given time (some stray puppies and kittens, for example, might not have had the opportunity to nurse). The purpose of the vaccine series is to provide immunization during a time when your pet might not be protected. Adhering closely to this schedule is extremely important for proper immunity. If you miss a vaccine appointment during this series, your veterinarian might recommend additional boosters to ensure that your pet is adequately protected.
 
What if I don’t know my pet’s vaccine history?
If your pet is an adult with an unknown vaccination history, such as a newly adopted dog or cat, he or she should essentially be treated as an unvaccinated pet. One rabies vaccination and two sets of each core vaccine generally will be recommended.

Why do vaccine schedules differ among clinics?
Depending on the veterinary clinic, certain vaccines might be recommended annually or every three years. While research exists to show that some core vaccines offer protection past their one-year booster, some veterinary practices still adhere to an annual vaccination schedule. Thus, it is not uncommon to find variation among clinics. It is best to keep your pet on a consistent schedule and defer to your veterinarian's recommendations.

Regardless of vaccine schedule, every pet should have a yearly wellness exam. Our pets age faster than we do, and regular veterinary check-ups are crucial for keeping optimum health and early detection of disease.

Should I be worried about vaccine reactions?
For commonly recommended vaccines, the risk of disease far outweighs the risk of any vaccine-associated complications. Most pets do not show signs of illness after a vaccine. Mild lethargy or itching in the area where the vaccine was given is common. In some cases, pets might have allergic reactions following vaccination. For this reason, it is best that owners schedule appointments when they are able to monitor their pet for 24 hours after vaccines are given.

Signs of a vaccine reaction can include vomiting, swelling of the face, difficulty breathing, lethargy or collapse. If your pet ever develops any of these signs following vaccination, seek immediate veterinary care. Generally, these types of reactions can be managed easily by your veterinarian. Pets that are known to have reactions can receive treatment before future vaccinations to minimize these responses.

When should my pet not receive vaccines?
There might be certain situations or medical conditions in which it is not safe for your pet to be vaccinated. If your pet is ever very ill, it is probably best to wait until he or she is healthy before receiving vaccines. The goal of any vaccination protocol is always to offer your pet the best protection for his or her health while minimizing the risk. Every case is unique, and vaccine requirements may vary over the course of your pet’s life as travel and other variables change. Always check with your veterinarian and defer to his or her recommendations.

Core Vaccines for Dogs

Canine Distemper and Adenovirus Vaccine
Distemper is an extremely contagious viral illness that can cause symptoms ranging from coughing and sneezing to vomiting and diarrhea, and even seizures. Infection with adenovirus leads to a condition called hepatitis (an inflammatory condition of the liver). Both of these viruses can cause significant illness in dogs, requiring lengthy treatment and supportive care. In many cases, infection can be fatal.

Puppies should be vaccinated for distemper and adenovirus every 3-4 weeks, beginning at 6-8 weeks of age, until they are at least 16 weeks of age. Adults should then be vaccinated at 12 months of age and every 1-3 years thereafter.

Canine Parvovirus Vaccine
Canine parvovirus, commonly known as parvo, is a highly contagious virus that destroys the lining of the small intestine. Symptoms include vomiting, diarrhea and lethargy. Parvo is an extremely serious condition. Dogs who become infected can require days of hospitalization receiving fluids and additional supportive care. Complications from parvo can include extreme dehydration and secondary bacterial infections which can be fatal. The virus is spread through the feces of infected dogs. Young, unvaccinated puppies are especially susceptible, although unvaccinated adult dogs can easily acquire the disease, too.

For best protection, puppies should be vaccinated against parvovirus every 3-4 weeks, starting at 6-8 weeks old until they reach at least 16 weeks of age. Dogs are then vaccinated at 12 months of age and every 1-3 years after that.

Canine Rabies Virus Vaccine
Rabies virus is the causative agent of a grave disease affecting the nervous system. Infection with rabies is universally fatal, meaning that animals who become infected will eventually die from the disease. Due to tightly regulated vaccination practices, the occurrence of rabies in domesticated dogs in the United States is rare. However, wild animals can serve as a reservoir for infection, so it is especially important that every pet be protected.

Rabies is most commonly spread by the bite of an infected animal. Rabies can be transmitted to humans; therefore vaccination for dogs is required by law. Every state has its own laws regarding rabies vaccination and licensure, so be sure to check the specific requirements in your area.

Puppies should receive a single rabies vaccine, generally around 12-16 weeks of age, which will be repeated at one year of age and then every 1-3 years after that.
 
Non-Core Vaccines for Dogs

Bordetella and Parainfluenza Vaccine
Bordetella bronchiceptica and parainfluenza are the bacterial and viral agents respectively involved in causing the upper respiratory disease in dogs commonly known as kennel cough. Although kennel cough is a highly contagious disease among dogs, symptoms are generally mild. Dogs most notably develop a rather dramatic-sounding hacking cough, often accompanied by sneezing and watery eyes. Some dogs might show more severe symptoms such as lethargy or a reluctance to eat or drink, and in some cases, secondary pneumonia is possible.

Like the common cold in people, kennel cough can be spread through the air and by coming into close contact with infected dogs. Dogs who take frequent trips to the dog park, grooming salons or doggy day care are more susceptible to acquiring kennel cough and should be vaccinated.

The recommended schedule for vaccination against kennel cough will depend on the type of product used, so check with your veterinarian. Please note that while the bordetella vaccine is generally considered by most veterinarians to be protective for one year, some kenneling and boarding facilities require it to be updated every six months.

Leptospirosis Vaccine
Leptospirosis is an infection caused by a microscopic organism known as a spirochete (a type of bacteria) that can cause liver and kidney disease in dogs and humans. While once thought to be primarily a rural disease, Leptospirosis is being diagnosed increasingly in dogs in urban and suburban areas.

Dogs generally acquire the disease by drinking or wading through contaminated water or by being exposed to infected wildlife (such as rodents, skunks and raccoons). Because the infection can be transmitted to humans, extreme care should be taken around any dog thought to have Leptospirosis. Several strains of Leptospirosis exist, so vaccination is not considered to be completely protective.

Talk to your veterinarian to see if your pet should be vaccinated for Leptospirosis.

Lyme Disease Vaccine
Lyme disease (also commonly known as tick fever) is an infectious disease of the blood that is transmitted by ticks. Lyme disease can affect both dogs and humans, although infected dogs cannot directly transmit the disease to people. Symptoms in dogs can include lameness, fever, depression and anorexia. Dogs who live near heavily wooded areas are more susceptible, however, any dog who comes into contact with an infected tick can acquire the disease.

Routine tick control is an important aspect of prevention against Lyme disease. Talk to your veterinarian to see if your pet should have additional vaccine protection.

Miscellaneous Vaccines for Dogs
Other, less common vaccines such as Giardia, canine influenza and the rattlesnake vaccine may be beneficial to some dogs in specific situations. As always, defer to your veterinarian for the best recommendations for vaccines for your pet.
 
Core Vaccines for Cats

Feline Viral Rhinotracheitis, Calicivirus and Panleukopenia Vaccine
Feline viral rhinotracheitis and calicivirus cause upper respiratory disease symptoms in cats such as fever, runny eyes and sneezing. Symptoms are generally mild, although kittens can develop corneal or oral ulcers and pneumonia. These viruses are spread through close contact with infected cats. Transmission can also be airborne, and spread, for example, through the droplets of a sneeze.

Feline panleukopenia is a highly contagious virus that causes a severe infection of the bone marrow and intestinal tract of cats, leading to fever, vomiting, diarrhea, dehydration and a dangerously low white blood cell count. The virus is spread through the feces as well as oral and nasal secretions of infected cats. Young kittens, especially strays who haven’t had an opportunity to be vaccinated, are particularly susceptible.

Kittens will generally receive a combination rhinotracheitis, calicivirus and panleukopenia vaccine beginning at 6 weeks old and then every 3-4 weeks until 16 weeks of age. After that, boosters are given every 1-3 years.

Feline Rabies Virus Vaccine
Rabies can affect cats just as it does dogs. Because wildlife can serve as a reservoir for infection, outdoor cats are particularly susceptible. Although indoor cats are at considerably lower risk for acquiring rabies, some states regulate feline rabies vaccine administration, so check with your veterinarian for recommendations.

A single dose of the rabies vaccine should be given to kittens at 12-16 weeks of age, at 12 months and then every 1-3 years thereafter.
 
Non-Core Vaccines for Cats

Feline Leukemia Virus Vaccine
Leukemia is a contagious viral disease of cats that can result in immune system suppression, blood abnormalities, and even cancer in some cases. Infected kittens will show signs of fever, lethargy and loss of appetite. Adult cats can carry the virus in their system for years and can be prone to chronic infections and illness resulting from a suppressed immune system.

Feline leukemia virus is highly contagious and can be spread by infected to non-infected cats through grooming, sharing food and water dishes or simply being in close contact. Every cat should be tested for feline leukemia virus before introducing new cats into a multiple-cat household. Outdoor cats are considered at high risk for infection and should be protected.

All kittens receive two sets of leukemia vaccine 2-3 weeks apart. After the kitten series, if a cat is to remain indoors and not exposed to other cats of an unknown health status, further leukemia vaccination is not necessary or recommended. Outdoor cats should be vaccinated annually.

Miscellaneous Vaccines for Cats
In special circumstances, vaccination against diseases such as FIV (feline immunodeficiency virus) or other conditions may be beneficial. Check with your veterinarian for his or her recommendations.

Sources
American Animal Hospital Association, "2011 AAHA Canine Vaccine Guidelines," accessed on August 14, 2013.

American Association of Feline Practitioners, "AAFP 2006 Feline Vaccination Guidelines," accessed on August 16, 2013.

Centers for Disease Control and Prevention, "Leptopirosis: Pets," accessed on August 14, 2013.

Cote, Etienne, DVM, DACVIM. "Clinical Veterinary Advisor: Dogs and Cats." (Missouri: Mosby, Inc, 2007), 140-141, 171-172, 315-316, 332-333, 380-381, 629-630, 799-800, 816-818, 939-940.