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Vaccines: The Pros and Cons of Vaccinating Your Dog or Cat

In this expert guide, we discuss the pros and cons of vaccinating your dog or cat — and what to expect after your pet gets vaccinated.

pros and cons of vaccinating your dog or cat
Know the pros and cons of vaccinating your dog or cat. Photo: Skitterphoto

Vaccines save lives.

They have changed the face of contagious disease like almost no other modern medical discovery.

All animals and humans deserve to benefit from the protective power of vaccination when they are at risk for contracting a serious or fatal disease.


In this expert guide from Petful’s veterinary team, we discuss:

  • The pros and cons of vaccinating your dog or cat
  • Our top tip if you want to give as few vaccines as possible
  • Why you should think of your approach to vaccination as holistic but not selfish
  • What to expect after your pet gets vaccinated
  • What we know about vaccine reactions in pets
  • The 5 small dog breeds predisposed to vaccine reactions
  • How we treat vaccine reactions in pets — and how we can avoid them
  • Why you put everyone’s pets at risk when you refuse to vaccinate
  • Plus, our final thoughts on this controversial subject
You never know when a vaccination might come in handy when it comes to your pets. Photo: suju

Part 1: Pros and Cons of Vaccinating Your Dog or Cat

This is a controversial topic. But we feel it’s important for you to be educated on the subject and to know that you have many options.

Why do some people believe veterinarians have been guilty of “over-vaccinating” in the past?

Probably because this actually was true in the past.

Safe vaccinations and vaccination protocols for dogs and cats do not have a very long history when you think about it. And vaccine protocols are always evolving and changing depending on changing diseases and the pet population.

Think about vaccines in 3 categories:

  1. Rabies vaccine: The only vaccine required by law. There is a zoonotic potential, meaning humans can contract rabies from animals and the disease is fatal.
  2. Core vaccines: These include canine distemper, feline distemper (panleukopenia) and canine parvovirus. These diseases are extremely serious or fatal and are endemic (meaning they are everywhere).
  3. Non-core vaccines: These vaccines include canine Lyme disease, canine bordetella and feline leukemia, for example. Many factors go into deciding whether your animal needs non-core vaccines — where you live, the animal’s lifestyle, etc.


Please follow your state’s regulations on rabies vaccination. It’s the law.


Rabies vaccines are very safe, inexpensive and given infrequently if you follow the guidelines. If your pet is bitten or bites someone and is not up-to-date on their rabies vaccination, they will be placed under quarantine.

Rabies is still around and is fatal.

Core Vaccines

What about the basic dog and cat vaccinations your vet might recommend sometimes?

  • We used to recommend these be given annually.
  • But now we recommend they be given about every 3 years.

Why the change?

Vaccination protocols were set in the late 1940s and ’50s to vaccinate yearly for fatal diseases like distemper.

Studies showed that a third of puppies were not protected after a year, so the yearly protocol was instituted. The vaccine was less expensive to give than trying to test to see if the pet was still protected, so annual vaccination became the standard of care.

Over the next 40 years, vaccination became widespread and the diseases became controlled. It has become obvious that less vaccination is sufficient for adequate protection.

Tip: If you want to give the fewest vaccinations possible, ask your vet to run titers that are available for certain diseases like distemper and parvo. (A titer is a blood test that determines whether your animal is still protected by a previous vaccine.)

Non-Core Vaccines

Many veterinary vaccines on the market don’t have to be given to animals who are not at specific risk.

A simple example is the bordetella, or “kennel cough” vaccine for dogs. Only dogs who board in a kennel facility are required to have this vaccine.

That being said, your dog can contract bordetella on the street, in a dog park, in the veterinarian’s office, etc. The risk is simply higher in a kennel where there are lots of dogs under one roof.

Talk with your vet and decide if your dog should get this protection based on potential exposure.

Holistic or Traditional Medicine

Some people and vets who take a homeopathic or holistic approach to medicine think vaccines lower your pet’s immune system or cause disease. They advocate giving very few or no vaccines at all.

Traditional medicine says vaccines should be given to ensure the animal is protected against serious and fatal diseases, taking into account the potential risks of vaccination.


Many of you have probably experienced a time when your pet was lethargic, even possibly running a low-grade fever after a vaccination. Occasionally, a pet has a true anaphylactic reaction and the face or body swells, hives develop, etc.

These are considered vaccine reactions and we readily deal with them. This is different from the concerns of holistic medicine, where the belief is vaccination can do continual harm to a pet’s overall health.

Herd Immunity

Herd immunity is a level of immunity when a significant amount of a population is vaccinated to protect the entire population. This applies to animals and humans.

If enough of the population is not vaccinated, vaccine-preventable diseases will begin to occur, as has happened with childhood diseases because of parents who decline vaccination. In recent years we’ve seen a rise in measles, mumps and whooping cough because too many children have not been vaccinated.

In the late 1980s, some vet schools had a “parvo ward,” populated with dying puppies and dogs. Loaded up with IVs and monitors, medications being pumped into their little bodies, they suffered for days and often died.

Now, thank goodness, parvo is a rare disease. But when people decide that vaccination is not essential, the overall population is at greater risk and more cases are seen.

Both parvo and distemper are rarely seen in the vaccinated population today. But these diseases are not eradicated.

In areas of the country where dogs and cats are unvaccinated and the conditions are right for transmission (usually warmer climates), these deadly diseases are still seen regularly.

Educate Yourself

Think of your approach to vaccination as holistic but not selfish:

  • Consider the overall health of your pet, plus the risk factors, and go from there.
  • Discuss vaccine protocols with your veterinarian.

Also, vaccine clinics or going to a mega pet store for vaccines may not be help you or save you money in the long run. Why? Because you may be paying for unnecessary vaccines. If the vet has not discussed core versus other vaccines with you, the vet has done you a disservice.

Don’t buy “bundled” vaccines. Vaccinations shouldn’t be picked from a shopping list. You need to discuss pros and cons and tailor a health plan for your pet with your vet. You’re not going to be able to do this in a vaccine line at a Luv-My-Pup-Pup, where they do not love your pup — they love your money.

Example: Lyme Vaccine

Take the Lyme vaccine, for example, one of the most controversial vaccines.

Lyme is not a big problem in some parts of the country, and the vaccine is not 100% protective. So why would you get a Lyme vaccine for your Maltese who lives in a non-endemic area and spends 80% of the time in an air-conditioned room?

But maybe you have a Labrador Retriever in the Northeast, an endemic Lyme area. Buddy the Lab gets covered with ticks 10 months out of the year and spends 90% of his time running with deer and mice. A sincere discussion about the pros and cons of Lyme vaccination is appropriate.

Example: Feline Leukemia Vaccine

What about the feline leukemia vaccine?

Let’s say Mrs. Smith has Fifi, who sleeps in the bed and never goes out, and Dodo, who spends 75% of his time catting around and comes home for meals.

Fifi thinks Dodo is an idiot and never gives him the time of day. Mrs. Smith wants to vaccinate Fifi for leukemia because of the intensely low possibility that she might contract feline leukemia from Dodo.

This is a case where there is no right or wrong answer. But Mrs. Smith should have a clear and honest discussion with the vet about the danger and safety of the leukemia vaccine, the risks involved, her peace of mind and the necessity for that cat to be vaccinated. Mrs. Smith can then make her own educated decision.

Example: Rabies Vaccine for Cats

Another example is the rabies vaccination for cats:

  • The older vaccine has a small risk of causing a tumor at the site of the injection. It is labeled for a 3-year duration in many states. The older vaccines have something in them to boost their effectiveness. This is called an adjuvant. The inflammation caused by the adjuvant is what is thought to cause the tumors.
  • The newer vaccine has no adjuvant in it — and no chance of causing the vaccine-associated tumor. It has been proven to work just as well, but the drawback is that it’s labeled for only 1 year instead of every 3 years.

Some people seem outraged that the “less safe” vaccine is offered at all — and this is a no-brainer for them. They want no risk of a tumor, no matter how low the possibility.

Others scoff at the idea of the low tumor risk, take their chances and don’t want to be bothered thinking about annual vaccination. At least these folks are given a choice, and their decision is an informed one.

Is the tumor a big deal? Yes, it’s a BIG DEAL. It can be fatal.

These sarcomas that arise at the injection site are aggressive tumors. Studies suggest these tumors occur in anywhere from 1 in 1,000 cats to 1 in 5,000. We do not have enough information to give an exact number. Where the cat lives and the cat’s genetics may also be risk factors for tumor development.

Vets have been putting pressure on the pharmaceutical companies to make a safer rabies vaccine — and now they’ve done it. So, why isn’t everybody using it?

  • Inconvenience? The 1-year label for the rabies vaccines is a mild pain in the neck, but look at the alternative. Just come in every year for your rabies vaccine, particularly if your cat goes outdoors. Simple. A quick annual visit versus the possibility of a tumor eating away the leg of your cat? We don’t think there’s much of a decision there.
  • Expense? The safer vaccines are a bit more expensive — but not by much. In the grand scale of what veterinary bills can be, this is a pittance to pay for better safety.

We urge you to follow your state’s guidelines regarding rabies, particularly if your cat goes outside. But make sure you are giving your cat the newer, non-adjuvanted rabies vaccine.

should i vaccinate my pet
New vaccine protocols mean a safer unique vaccination plan for every individual pet. Photo: tamba09

Part 2: What to Expect After Your Pet Gets Vaccinated

How Many Trips to the Vet Do I Have to Make?

Some vaccinations occur frequently during the first year of your pet’s life.

Follow-up vaccinations are most commonly performed in 1- to 3-year increments.

If the frequency of vet visits or cost is a factor, talk this over with your vet. Most vets are concerned about the cost and try to suggest only those vaccinations they feel are necessary.

Possible Reactions

Vaccination reactions can range from mild to severe. There is no way to predict how your pet will react to a particular vaccination, but there are symptoms you can look for.

Mild reactions might include:

  • Discomfort at the injection site
  • Minimal fever
  • Less desire to eat or play
  • Sneezing
  • Swelling or firmness at the injection site or in the facial area (if this persists, you should see your vet)

Serious reactions to vaccinations are rare. They may include:

  • A severe change in behavior or actions within hours of the vaccination
  • A tumor might develop at the injection site within weeks or months after the vaccination.

What Should I Do If I Notice These Symptoms?

If you notice your pet is experiencing any of these symptoms or is acting abnormally, contact your veterinarian.

If your pet is reacting in a way that is very different or extreme, visit the nearest animal hospital for immediate assessment.

In the next section of this article, we take a deeper look at vaccine reactions in pets.

should i vaccinate my pet
A veterinarian doesn’t just pull out the same 2 vaccines every year for every pet. Photo: mathias-erhart

Part 3: Vaccine Reactions in Pets

Vaccinating your cat or dog used to be a pretty straightforward affair.

There was the required rabies vaccine and the “annual distemper vaccine.”

So what has changed? Well, a lot, actually.

What We Know

We know more about vaccine-preventable diseases and want to protect our pets.

Choosing vaccinations wisely, being aware of the proven and safest vaccines on the market, and tailoring individual vaccination protocols for every pet is key to protecting your pet and avoiding vaccine reactions:

  1. Vets and clients are aware of old protocols when pets received too many vaccines in a lifetime.
  2. We know more about vaccine reactions. Although they’re rare, we want to avoid them to the best of our abilities.
  3. The study of immunology in pets and people is still in its infancy. We know there is much we don’t know. What part vaccinations play in that puzzle is unknown.
  4. Every pet is now approached as an individual. A veterinarian doesn’t just pull out the same 2 vaccines every year for every pet. New and safer vaccine protocols and lifestyle and exposure to certain diseases dictate a unique vaccination plan for every pet.
  5. Pets are exposed to more contagious diseases because of emerging diseases, daycare facilities, dog parks, agility events and increasing pet travel in pet-friendly stores and hotels.
should i vaccinate my pet
Discuss your pet’s medical history with your vet before vaccination. Photo: jaminriverside

The Balancing Act

Veterinarians are charged with protecting your pet but also avoiding vaccine reactions whenever possible.

Although vaccine reactions are rare, we can cut down on reactions if we discuss your pet’s needs and assess their health status, breed, size, age and lifestyle before administering any vaccines.

What We Know About Vaccine Reactions

First of all, we don’t truly know how common vaccine reactions are because there is no requirement to report reactions.

People often don’t call the vet if they are not too worried about a vaccine reaction in their pets, and vets are not mandated to report vaccine reactions to manufacturers.

A few retrospective studies track vaccine reactions:

  • One study published by the Journal of the American Veterinary Medical Association found a reaction rate of 38 per 10,000 pets. This number included all kinds of reactions, mild and serious.
  • Another study of 57,000 dogs found a low incidence of any type of reaction, about 5 per 1,000 dogs.
  • In a study of 500,000 cats, vaccine reactions were 51 per 10,000 cats.

Most Vaccine Reactions Are Mild

Injection-Site Reactions From Vaccines

A lump at the injection site is usually self-limiting, causing mild pain, itching and/or swelling. These occur infrequently.

Rabies vaccines are probably over-represented in this category.

Long-Term Injection-Site Reactions From Vaccines

Dogs will occasionally develop hair loss or discoloration at the site of a vaccine, usually rabies.

If a lump from a vaccine lasts longer than 1–3 months, it should be biopsied or removed and biopsied.

Cats, in particular, can develop a vaccine-induced tumor. Advances in vaccine development make these serious tumors in cats rare.

Systemic Reactions From Vaccines

Some pets will develop lethargy or mild fever from a vaccine lasting a short time. These reactions are commonly reported to the vet.

More serious reactions, like GI, neurologic, or arthritic symptoms, are very rare. These typically resolve in a few days. Some pets require supportive care.

Allergic Reactions From Vaccines

Acute swelling, usually of the face or ears, or hives on the body, can usually be controlled with antihistamines. Severe anaphylaxis or death can occur in very rare instances.

should i vaccinate my pet
Most reactions to vaccines are mild for pets. Photo: PixelwunderByRebecca


Smaller and younger dogs are more likely to have a vaccine reaction.

One study found that 5 small breeds were predisposed to vaccine reaction:

The only large breed over-represented for reactions was the Boxer.

Certain young Weimaraners and Akitas have a rare condition not well understood. Affected dogs from 3 months to 3 years old can get very sick following vaccination with a modified live distemper vaccine. We use a recombinant canine distemper vaccine in these breeds.

Treating Vaccine Reactions

The vast majority of reactions are mild.

The dog or cat with a systemic reaction is under the weather for a day or so. They sleep more, don’t want to eat much and act tired. They may run a low-grade fever for about 24 hours. Cats tend to retire to a closet and sleep it off.

If an animal has severe vomiting or diarrhea or, of course, if the client is worried about any symptoms following vaccination, the pet is seen by the vet and treated symptomatically. The administration of SQ fluids, maybe some steroids, fever reducer and/or GI drugs and antihistamines is typical. Depending on the symptoms and the treatment plan, the animal usually stays in the hospital for the day for observation.

Learn a little more about pet vaccinations here:

How to Avoid Vaccine Reactions

  1. If a pet has had a vaccine reaction before, there are a few options. Always pre-treat that pet with antihistamines and possibly steroids for future vaccines. (Discuss this with your vet.)
  2. Pets with severe vaccine reactions should receive only a minimum of vaccines in the future or none at all, if that seems like a safer option.
  3. The more vaccines given at one time, the more likely a reaction may occur.

It is impossible to predict these reactions. Many pets don’t have repeat reactions, particularly if they were young when they had the first and only reaction.

Tip: Call your vet with any possible vaccine reaction so it can be noted in the animal’s record.

should i vaccinate my pet
Vaccines have helped keep both people and pets alive. Photo: philhearing

Part 4: When You Don’t Vaccinate, You Put Everyone’s Pets at Risk

When significant numbers in a population stop vaccinating, outbreaks of the disease occur and put the entire population, specifically the most frail members of the group, at risk.

This is what happened a few years ago in Disneyland with a measles outbreak.

When parents — as well as people who have pets — decide that the possible risk of a vaccine or vaccine reaction is not worth vaccinating, we lose herd immunity. There is a resurgence of the disease and, with enough cases circulating, even vaccinated individuals are at risk.

Many anti-vaxxers have chosen that the comfort and “wellness” of their own boy, Bichon or Burmese comes first. If their little precious might have a vaccine reaction, then they will do without the vaccine.

More Benefits Than Harm

Similar to parents not wanting to vaccinate kids, more and more people, particularly younger people, are leery of vaccines as “dangerous” to their pet.

It is true that every vaccine carries a low potential to cause a reaction, most mild but some serious.

This is why we advocate getting the minimum of vaccines, using the safest vaccines available and discussing risks versus benefits when tailoring a vaccine schedule for your pet.

Without our modern vaccines, however, people would still think it commonplace for a new puppy to die a horrific death from distemper, or a child to become deathly ill from measles.

Improvements for Animals

As for animals, we really don’t consider canine and feline distemper or rabies real threats because these diseases are all but eradicated, thanks to the power of vaccination.

The feline leukemia vaccine, too, has changed the world of cat medicine.

If we stop vaccinating, these diseases will re-emerge or become more prevalent.

Final Thoughts

With any luck, by vaccinating much less frequently than in the past, by checking vaccine titers if warranted, and by giving only essential vaccines to pets based on their lifestyle, veterinarians might lose the rap that the profession “over-vaccinates.”

We should all vaccinate to protect the lives of our own pets, but also to keep the entire pet population at large safe from deadly diseases.

Now that you know the pros and cons of vaccinating your dog or cat, we hope you’ll do the right thing:

  • Vaccinate when indicated and develop a complete wellness plan for your pet.
  • Remember to discuss your pet as an individual with your vet.


vet-cross60pThis pet health content was written by a veterinarian, Dr. Debora Lichtenberg, VMD. This article was originally published in 2012 and is regularly updated. It was last reviewed for accuracy by Dr. Pippa Elliott, BVMS, MRCVS, and updated May 1, 2020.

If you have questions or concerns, call your vet, who is best equipped to ensure the health and well-being of your pet. This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. See additional information.