Why should we vaccinate our pets?

  • Veterinary vaccines prevent common infectious diseases that cause severe and life threatening illness.
  • They benefit us as well by controlling diseases that can affect both pets and humans such as Rabies and Leptospirosis.
  • This makes vaccination a very cost-effective procedure in veterinary medicine.

How do vaccines work?

  • Survivors of a dangerous infection develop specific resistance to the same disease through a process known as “immune memory”.
  • Immune memory prompts faster and stronger future attacks against the same microbe making the animal immune to its disease.
  • Vaccines harness immune memory to prevent disease by pre-emptively inducing it BEFORE a natural exposure.
  • This is accomplished with a high degree of safety by using harmless, altered versions of microbes to simulate a real infection.

Why are vaccinations especially important in puppies and kittens?

  • Puppies and kittens have immature immune systems that make them highly vulnerable to severe infectious complications.
  • At birth they receive limited protection from maternally derived proteins known as antibodies.
  • These immune proteins are transferred by the placenta or in the mother’s milk.
  • They provide significant protection by binding, inactivating and killing many disease-causing organisms.
  • Unfortunately, they decrease progressively after birth and disappear by 16-20 weeks of age.
  • As the mom’s antibodies wane, newborns become increasingly susceptible to infections.
  • Vaccination helps them survive this critical period by safely “jump-starting” their immune system against the most dangerous diseases.

Why do puppies/kittens need a series of vaccines?

  • Maternal antibodies in very young animals interfere with vaccines by binding to and hiding them from the immune system.
  • Depending on the exact antibody level, this interference usually results in inadequate immunization after a single dose.
  • Giving multiple vaccine doses (usually 3) during the critical period between 8 to 16 weeks of age helps each puppy and kitten reach an optimal level of protection.

Why vaccinate adult animals?

  • Although puppies and kittens fare the worst, adult animals can also suffer significant illness from preventable infectious diseases.
  • For diseases with strong public health concerns, such as Rabies, vaccination is legally required.
  • For others such as Bordetella, (Canine “Kennel Cough”) vaccination is required by many groomers and boarding facilities.

Why are booster vaccinations required in adults?

  • Vaccine-induced immune memory decays over time and may eventually fail to be protective.
  • Adult vaccine boosters will bolster and amplify waning immunity to help prevent disease breakthrough in mature animals.
  • In the case of Rabies, vaccine boosters at specified intervals (1 or 3 years) are legally required.
  • In the case of Bordetella bronchiseptica, up to date-status boosters are required by many groomers and boarding facilities.

 What vaccines should I get for my pet?


Core vaccines: Protect against life-threatening diseases with a high risk of exposure regardless of the pet’s lifestyle. With rare exceptions these are highly recommended for the vast majority of dogs/cats.

Non-Core Vaccines: Protect against diseases whose exposure risk depends on a pet’s environment and lifestyle. These are considered appropriate for dogs/cats under specific circumstances. Examples of these include:

  • For dogs:
    • Bordetella vaccination for dogs that visit boarding and grooming facilities or other areas where many dogs congregate.
    • Leptospirosis vaccination for dogs that make contact with contaminated water.
    • Lyme vaccination for outdoor dogs in certain areas exposed to deer ticks.
    • Rattlesnake vaccination for outdoor dogs in areas where rattlesnakes are prevalent.
  • For cats:
    • Feline Leukemia Virus for cats with outdoor lifestyles or in multi-cat environments.
    • Feline Bordetella vaccine for cat’s that visit boarding facilities.

Are pet vaccines safe? Are there any side effects?

  • Pet vaccinations have an excellent record of safety and tolerability.
  • Most vaccinated dogs and cats suffer no symptoms or complications.
  • Awareness of possible side effects helps to assure an appropriate response if they occur.
  • Most complications from vaccines are considered mild and self-limiting.
  • VERY RARELY, THEY MAY BE SUDDEN, SERIOUS AND POTENTIALLY FATAL. See Emergency reactions and aftercare.

What are the most common vaccine-related complications? How should they be managed?

  • Common symptoms are “flu-like” in nature and may include: lethargy, poor appetite, mild fever and injection site pain.
  • These are not serious and tend to subside in a day or two. They rarely require treatment.
  • It’s prudent to seek veterinary advice if symptoms are debilitating, worsen or last longer than 3 days.

What are some other complications? How should they be managed?

  • Less commonly, a lump may form at an injection site.
  • This occurs after variable time periods (usually weeks to months).
  • Lumps may contain sterile fluid (seroma), inflammatory tissue (granuloma) or pus (abscess).
  • Medical intervention may be required for diagnosis and/or treatment.
  • Another rare local reaction is hair loss over an injection site that may be permanent.

What are the most serious vaccine reactions? How should they be managed?

  • Serious to life-threatening complications are very rare and can be immediate or delayed.

Immediate reactions

  • The most serious immediate complication is a severe allergic reaction.
  • This can occur suddenly and may progress quickly to respiratory distress, shock and death.
  • Although serious, it responds very well to prompt treatment.
  • Most pets can make a complete recovery.
  • Symptoms may include any or all of the following: facial or generalized swelling, hives (skin welts), breathing difficulties, repeated vomiting/diarrhea, marked lethargy and weakness, seizures and collapse.
  • Any of these symptoms is serious and requires prompt veterinary attention.

Delayed reactions

Although definitive proof is lacking, some evidence implicates vaccinations with two very rare delayed complications: Autoimmunity and Vaccine Associated Sarcoma.

  • Autoimmunity: Results from a misguided immune-system attack on the body tissues.
  • Disease severity varies from mild to life threatening depending on the exact tissues involved and the strength of the attack.
  • Autoimmune diseases possibly associated with vaccines include disorders of:
    • Platelets (thrombocytopenia)
    • Red blood cells (immune-mediated hemolytic anemia)
    • Joint(s) (arthritis/polyarthritis)
    • Blood vessels (vasculitis)
    • Nervous system (neuritis/encephalitis)
  • Vaccine-Associated Sarcoma: Is a very rare malignant tumor seen mostly in cats. It is estimated to occur in 1 to 2 out of every 10,000 vaccinated cats .
  • It presents as a fast growing lump under the skin appearing months to years after vaccination.
  • This is a life-threatening complication that requires extensive surgical and medical intervention. Despite treatment it is usually fatal.