When the immune system is exposed to an infectious agent such as a virus or bacteria, it sets to work killing and eliminating it. One of the ways it does this is by making proteins called antibodies that specifically recognize that virus or bacteria and attach to it, flagging it for white blood cells to attack it. These antibodies will stay in the body for some time (months or years) after the disease has been eliminated, thereby acting like the immune system’s memory. Next time the animal is exposed to that virus or bacteria, the antibodies are already there waiting, so the virus or bacteria is flagged and eliminated much quicker than the first time, often before any signs of illness develop.

Vaccinations take advantage of this immune system memory by exposing the patient to an inactivated virus or bacteria to generate immunological memory without making the patient sick. Vaccinating your pet is one of the best things you can do to help keep them healthy.

Puppies and kittens require several vaccination ‘boosters’ to be given until they are about 16 weeks old. This is because they have maternal antibodies – antibodies they acquired from their mother’s breast milk. These maternal antibodies help protect newborns from infections, however they will also quickly flag and eliminate the vaccine virus and it will be eliminated before the puppy or kitten’s immune system has much chance to respond and develop its own antibodies. As the puppy or kitten gets older, it will have fewer and fewer maternal antibodies and therefore will develop more of its own immunological memory each time it receives a vaccination ‘booster’. By 16 weeks, most or all of the maternal antibodies will be gone so this is when we administer their final puppy or kitten ‘booster’.

There is no one-size-fits-all vaccination program. Our veterinarians will recommend vaccinations that are appropriate for your individual pet based on a risk/benefit assessment. Depending on your pet’s age, breed, lifestyle, travel and other factors, he or she may be at risk of exposure to some infections but not others. We will recommend vaccinating your pet against infections that he or she could be exposed to (examples are kennel cough, leptospirosis or feline leukemia). Also, there are some infections are always or almost always fatal, such as Rabies, Canine Distemper, or Feline Panleukopenia, therefore even a pet at a low risk of exposure should be vaccinated against these infections.


Immunological memory does not last forever. Also, different individuals will have a longer or shorter immunological memory. Therefore vaccinations do need to be given again at some point to renew antibody production and ensure continued protection against disease. The risk of not vaccinating again soon enough outweighs the risk associated with adverse effects, so we err on the side of vaccinating again sooner than later, however, recent research has proven that annual vaccination is not required for many diseases. Depending on the disease itself (memory is longer for viruses compared to bacterial infections), and the vaccination product used, as well as your pet’s vaccination history and age, the veterinarian will plan the revaccination interval that is ideal to keep your pet protected from disease, while also minimizing the risk of adverse effects. For most adult cats and dogs, this means viral vaccinations will be boostered every 3-4 years, and bacterial vaccinations will be boostered annually.

Rabies is transmitted through bodily fluids, usually from a bite wound, and can infect many different warm-blooded animals. Rabies infects the nervous system and causes behaviour changes, paralysis and eventual death.

Canine Distemper is transmitted through urine, feces, vomit and secretions, and can be transmitted by raccoons. It causes flu-like symptoms followed by damage to the liver and nervous system, causing seizures, difficulty walking, and is almost always fatal.

Canine Hepatitis is transmitted through bodily fluids and secretions. It causes severe liver damage that is almost always fatal.

Canine Parvovirus is transmitted through feces, and vomit, and causes severe diarrhea with vomiting. With intensive care and appropriate medications, many patients can be saved, but without treatment it is usually atal.

Canine Parainfluenza is transmitted through bodily fluids and secretions, and causes mild to severe respiratory disease (coughing, sneezing, pneumonia).

Leptospirosis is a bacterial infection transmitted through urine of many wild animals, and contaminated water (puddles, ponds etc). It damages the liver and kidneys, causing vomiting, inappetance, excessive drinking and urination. Recovery is possible if antibiotics and other treatments are started before the major organs are damaged too much. Many patients continue to have kidney impairment for the rest of their lives after recovering from leptospirosis.

Infectious Tracheobronchitis (AKA Kennel Cough) is caused by a combination of virus and bacteria and is transmitted through casual contact as well as through the air. It causes a cough that can vary from mild to severe and may even progress to pneumonia in some cases. Almost all patients recover but it could require a trip to the veterinarian for some medication. Natural immunity is not very long-lasting, so vaccination is still recommended if your dog has had kennel cough.

Lyme Disease is transmitted by certain species of ticks. It causes variable signs including lethargy, vomiting, lameness and joint swelling, and sometimes kidney disease. It is not usually fatal, but can cause chronic joint pain or kidney disease. Lyme disease is more prevalent in some areas of Canada and the USA, so your pet’s travel plans will dictate if this vaccination is necessary or not. Tick prevention is a good way to reduce your pet’s risk of lyme disease in our area.

Feline Viral Rhinotracheitis (Feline Herpesvirus) is transmitted through casual contact and the air. It causes eye infections, and upper respiratory signs like sneezing, coughing and sore throat. Adult cats usually recover but often require veterinary attention; however young kittens can become very sick and even die from this infection.

Feline Calicivirus is transmitted through casual contact as well, and causes more severe respiratory signs including pneumonia, as well as sometimes affecting joints. Adult cats often recover but usually require veterinary attention, however kittens and seniors can become very sick and die from this infection.

Feline Panleukopenia is transmitted through stool, vomit and secretions. It causes respiratory and severe gastrointestinal signs and is often fatal.

Feline Leukemia is often transmitted through bites but also sexual activity and saliva (mutual grooming, sharing food dishes). It infects white blood cells, causing poor immune function. Cats do not die from the leukemia virus itself but succumb to other infections or cancers because they cannot effectively fight off viruses or bacteria, or remove cancerous cells from the body.

Feline Immunodeficiency Virus is transmitted through bite wounds and sexual activity. It causes disease in a very similar to the leukemia virus. There is a vaccination but it does not provide sufficient immunity to protect cats from this virus so we do not recommend it. Vaccination will also cause a false positive when a cat is tested for this infection.