Veterinary science, in conjunction with industry, has done a great job developing vaccines that are very safe and effective preventive measures. Vaccines keep your pet protected from serious infectious diseases. Diseases that, just a few years ago, were epidemics are now less common. It’s not just a matter of more vaccines but also better vaccines that are more specific, provide longer protection and allow your veterinarian to make recommendations appropriate for your pet.


Not all dogs need to be vaccinated for all diseases all the time. There are two general groupings of vaccinations: those that target core diseases and those that target non-core diseases.

Core vaccinations
Core vaccinations prevent diseases that are extremely widespread in their distribution and are easily transmitted. These diseases are commonly fatal or extremely difficult to treat effectively. One core disease? rabies can be transmitted to humans with potentially deadly results. In summary, core diseases are the more contagious and severe diseases.

Core vaccines provide long-term immunity, making yearly vaccination unnecessary. Core vaccines include:

  • Canine distemper
  • Canine parvovirus
  • Canine adenovirus 1 infection
  • Rabies

Historically, these vaccines were recommended yearly but this is no longer the case. Duration of immunity from these vaccines has been proven to be at least 3 years. Rabies vaccines are sometimes administered more often based on state and provincial regulations. While not all vaccines carry a label that indicates they are effective for 3 years, current recommendations for core vaccines are that after the completion of an initial series, dogs should be revaccinated every 3 years.

Non-core vaccinations
Non-core vaccines protect against diseases that do not meet the core vaccine description. While all dogs are at risk for core diseases and must be vaccinated–risk of exposure, likelihood of infection, and severity of disease should be evaluated when making non-core vaccine recommendations. The indication for these vaccines should be based on a risk assessment that looks at local and regional incidence of the disease. The risk assessment should also take lifestyle into consideration. Non-core vaccinations may include:

  • Leptospirosis
  • Lyme disease
  • Canine cough complex
  • Canine influenza

These vaccines generally provide a shorter length of protective immunity, and dogs that are at risk for infection should be vaccinated every year.

How can you determine your dog?s risk of infection?
[Editor’s Note: Having a conversation with your veterinarian is the number one way you can determine your dog’s risk factors and which vaccines are recommended.]

Lyme disease is no longer limited to the Northeastern United States. It is transmitted by deer ticks associated with white tail deer. The populations of deer are expanding and with them the incidence of exposure. While exposure and infection do not always result in disease, dogs considered at risk should be vaccinated and tested annually.

Vaccination against leptospirosis should be considered for dogs who are exposed to wildlife environments like ponds, or when urban and rural wildlife share the environment with your dog.

Vaccination against canine cough includes bordetella and parainfluenza vaccines. These diseases are respiratory infections and as such are transmitted from dog to dog. Boarding facilities, dog shows, dog classes, and parks where dogs play are all potential risks. Dogs exposed to these environments should be vaccinated yearly.

Canine influenza is a relatively recently described disease and a relatively new vaccine. It should be administered yearly for dogs considered by your veterinarian to be at risk.

All dogs should be examined by a veterinarian at least yearly and a complete history and risk assessment should be performed. This will assure that your dog remains healthy and is appropriately vaccinated.


Few infectious diseases of cats have the emotional and physical impact of Feline Retrovirus infections more commonly referred to as Feline Immunodefficiency Virus (FIV) and Feline Leukemia Virus (FeLV). The incidence of FeLV and FIV is significant. The American Association of Feline Practitioners reports that in a study of 18,000 cats, ?2.3% were positive for FeLV and 2.5 were positive for FIV!? FIV is not typically fatal in cats but can produce carrier states that spread the disease for years.

Are these newly recognized diseases?
These viruses have existed for an unknown time. They likely mutated from a related virus of another species. FeLV has been recognized since the mid-1960s and FIV was first recognized in the mid-1980s.

How are these diseases spread?
Direct transfer with bodily fluids such as blood, saliva and urine transmits both of these diseases from cat to cat. FIV is primarily transmitted via deep punctures and scratches where saliva from infected cats enters the body.

My cat lives inside, does he need to be tested for FeLV and FIV?
Even though you consider your cat indoors, there are some considerations that may weigh on your decision. Many cat owners consider their cat an indoor cat because he sleeps in the house or spends very little time out of doors. The fact is that a cat should be considered indoors if it is indoors only or confined to a completely enclosed exercise area. Any free run of the yard or even walking on a leash means your cat is at least somewhat outdoors. If your cat has a gift for escaping through an open door or window they are at risk. If you have multiple cats and even one of them spends time out of doors, they are all susceptible to the risks of being out of doors to some degree. Finally, if you foster raise stray or orphan kittens in your home you effectively bring the outdoors in. There is also the possibility that for some reason in the future your indoor cat will become an outdoor resident. All of these factors place your cat to a degree of risk.

Fighting between cats is a particularly risky behaviour since exchanges of body fluids and bite wounds are common in cat fights. Testing newly acquired and at risk cats should be based on the recommendation of your veterinarian but with consideration of the risk factors discussed.

Is my cat at risk of FeLV and FIV?
In the case of FeLV, very young kittens are susceptible to infection in part because the virus can be transmitted from infected mother cats. All young kittens can be infected so regardless of where they are from, all kittens over 8-weeks of age should be tested when first presented for vaccinations. While both diseases can be transmitted in utero, this is more common with FeLV.

FeLV is relatively easy to transmit and should be considered a risk in kittens and young cats in particular. They are at a high risk of infection if exposed. Older cats are may become infected but are more able to clear the virus from their system except in massive exposures. For this reason it is recommended that all kittens and young cats under 1-year of age should be vaccinated.

FIV is not quite so black and white, but all cats should be tested when acquired. The greatest risk of infection is in 1-2 year olds, high risk cats presenting for their first or second year boosters should be retested for FIV.

Vaccination has been shown to protect very well against the two common strains of FIV. The primary argument against vaccination is that once vaccinated against FIV, infection cannot be distinguished from vaccination response using currently available testing. Cats considered to be at a high risk should be vaccinated after a discussion with the cat guardian. High risk cats include those living with known infected cats and cats known to wander and fight. All vaccinated cats should be permanently identified in the medical record and should be micro-chipped for permanent identification.

As is the case with all vaccinations, FeLV and FIV vaccinations aid in the prevention of retrovirus diseases and should be performed in healthy kittens and cats. No vaccination is 100% effective so exposure to unknown cats should be avoided.