Dog Vaccinations – A Basic Understanding of Canine Vaccines

We all know that dogs need vaccines to keep them healthy, but how well do you understand which vaccines your dog needs and why?

Vaccines prepare the immune system to fight a specific disease. A vaccine contains antigens – proteins that look like the disease-causing organism, but are not capable of actually causing disease.

When the immune system is exposed to these antigens, it learns to recognize them and attack the organism if it is encountered in the future. When an animal is vaccinated against a disease, its immune system is prepared to recognize and respond to that disease in the future.

In veterinary medicine, vaccines are broken down into two categories: core and noncore.

Core vaccines are vaccines that should be given to all dogs, regardless of their lifestyle. These vaccines are essential because they protect against serious diseases that pose a threat to all dogs.

Noncore vaccines are not recommended for all dogs. Noncore vaccines protect against diseases that only some dogs are considered to be at risk of acquiring. A decision regarding which noncore vaccines, if any, to give your dog should be based on a careful assessment of your dog’s lifestyle and risk factors.

Core vaccines: required for all dogs

Rabies Vaccine

Rabies is a virus, spread by the bite of a rabid animal. This virus affects the brain and is always fatal in pets. Dogs with rabies develop anxiety, paralysis, increased salivation, and aggression. Typically, they die within a few days of developing signs of the disease.

In addition to being fatal to our pets, rabies is a zoonotic disease. This means that it can pass from animals to humans. Rabies is almost always fatal in humans, unless treated promptly with post-exposure vaccinations. Because rabies is a serious zoonotic disease, rabies vaccination is required by law in most locations.

Puppies receive their first rabies vaccine between 12-16 weeks of age. They receive a booster vaccine one year later, then every 1-3 years for the rest of their life. (Local laws determine the frequency of booster vaccines in adult dogs.)

Distemper/adenovirus/parvovirus/parainfluenza vaccine

(a.k.a. DAPP, DHPP, distemper-parvo, “5-way,” “5-in-1”)

The DAPP vaccine protects against four separate viruses. Each of these viruses is easily transmitted between dogs and can cause significant disease.

Distemper is an often-fatal virus that is spread through the air or contaminated objects. It attacks the respiratory tract, gastrointestinal tract, and nervous systems. Signs of distemper include discharge from the eyes and nose, sneezing, vomiting, diarrhea, seizures, paralysis, and death. Distemper is less common now than it was in earlier years, thanks to widespread vaccination, but outbreaks still occur.

Adenovirus is a virus that can cause either upper respiratory infection or liver disease, depending on the strain involved. The DAPP vaccine offers protection against both strains of adenovirus. Canine adenovirus 1 leads to liver disease, fever, abdominal pain, vomiting, and diarrhea. Canine adenovirus 2 causes respiratory disease, leading to coughing, conjunctivitis, and lethargy.

Parvovirus, or parvo, is a virus that affects the gastrointestinal tract and immune system. Signs of parvovirus include decreased appetite, vomiting, and severe diarrhea. Affected dogs often die within 2-3 days without treatment; even with aggressive treatment, fatalities may still occur. Parvovirus is shed in the feces of infected dogs, and it may remain in the soil for over one year. Because it can be so widespread in the environment, parvovirus is a serious threat to the health of unvaccinated puppies.

Parainfluenza is an upper respiratory virus that is often associated with cases of kennel cough. This virus is airborne and can spread easily between dogs. Although parainfluenza is not as life-threatening as the other viruses included in the DAPP vaccine, it is a widespread illness.

Puppies should receive DAPP vaccinations every 3-4 weeks from the time they are 6 weeks old until they reach 16 weeks old. After completing this initial puppy series, they should receive a booster vaccine one year later and then every 3 years for the rest of their life.

Non-core vaccines: lifestyle-dependent

Bordetella vaccine

(a.k.a. “kennel cough” vaccine – this is a misnomer, as there are many viruses/bacteria that can cause kennel cough)

Bordetella bronchiseptica is a bacterial organism that is commonly involved in kennel cough. Dogs infected with Bordetella develop coughing, lethargy, and occasionally vomiting. Bordetella is airborne and therefore it spreads easily between dogs.

This vaccine is recommended for dogs that are frequently exposed to other dogs. This includes dogs that are boarded in kennels, dogs that go to the groomer, dogs that attend dog shows or dog parks, etc.

Leptospirosis vaccine

(a.k.a. lepto vaccine)

Leptospirosis, a potentially-fatal bacterial infection, causes severe liver and kidney disease in dogs. Leptospirosis is also a zoonotic disease, meaning that infected dogs can pass this disease to their owners.  Leptospirosis is acquired through contact with the urine of an infected animal (wild or domestic).

Dogs at high risk of leptospirosis include dogs living in rural areas, dogs exposed to wildlife or farm animals, and dogs who drink from lakes or streams. Some urban areas are also experiencing a rise in leptospirosis cases, spread by rats and other rodents. Talk to your veterinarian to determine whether leptospirosis vaccination is recommended in your area.

Lyme vaccine

Lyme disease is a bacterial infection, spread by ticks. The signs of Lyme disease in dogs are variable, ranging from fever and lethargy, to shifting-leg lameness, to signs of kidney disease.

Dogs that spend time Lyme-endemic areas and dogs that are exposed to ticks should be vaccinated against Lyme disease. Lyme disease is most common in the mid-Atlantic and New England, but the disease is spreading to the Midwest and throughout the Eastern United States. Talk to your veterinarian to determine whether Lyme disease is a risk in your area.

Canine influenza vaccine

Canine influenza is an upper respiratory virus of dogs, that can potentially progress to pneumonia and death. Periodic outbreaks occur in various areas of the country and there are some regions in which canine influenza poses a consistent threat.

The canine influenza vaccine is recommended for dogs living in areas where canine influenza circulates within the population, dogs who frequently travel (especially those attending dog shows), and other dogs whose lifestyle places them at risk. Your veterinarian can help you assess your dog’s risk of canine influenza and determine whether the vaccine is appropriate.

Small Husky puppy is receiving a shot from the vet.

What are the side effects of vaccines?

Many pet owners have concerns about vaccine side effects. It can be helpful to think of these effects in two categories: normal/expected immune response vs. adverse (negative) reaction.

Vaccines are designed to stimulate the immune system; therefore, some degree of immune response is normal or expected with vaccines. This immune response may include lethargy, decreased appetite, a low-grade fever, and tenderness at the vaccine site. These effects are a sign that the body is responding to the vaccine (think of how you feel when you’re “fighting off an illness”), and should not be confused with an adverse reaction.

A very small number of dogs (less than 0.05%) may experience a true adverse reaction to a vaccine. This reaction may include vomiting, diarrhea, hives, facial swelling, breathing difficulties, or collapse/fainting. Although these reactions are uncommon, they do require immediate treatment and will likely result in changes to your dog’s vaccine protocol in the future.


If you have any concerns regarding your pet’s vaccinations, please talk to your veterinarian. Your veterinarian can work with you to design a vaccine program that will maximize your pet’s health over the course of his lifespan.

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