If you’ve just brought home a new puppy or kitten, congratulations—and welcome to information overload.
Suddenly everyone has advice. Friends. Family. Breeders. The internet. Everyone has strong opinions about food, training, and—very quickly—vaccines.
You may be wondering:
- Which vaccines are actually necessary?
- Are pets overvaccinated?
- What if my pet has a reaction?
- Why are there so many visits and boosters?
If you’re feeling unsure, that’s normal. These are good questions, and they’re worth talking through.
In this article, we’ll slow things down and explain:
- What vaccines actually do
- How veterinarians think about risk
- Why boosters are part of one process—not “too many shots”
- And how to decide who to trust when opinions conflict
The Purpose of Vaccination
Let’s clear something up right away.
Vaccines are not a force field that blocks every illness forever.
Vaccines exist to train the immune system before it has to learn the hard way.
Without vaccines, immune systems learn by getting sick. Sometimes that works. Sometimes it doesn’t. In young puppies and kittens, it often doesn’t.
Vaccination gives the immune system practice without the risk of:
- Severe illness
- Long-term damage
- Or death
From a medical point of view, vaccines aren’t about perfection. They’re about reducing risk:
- Making illness less severe
- Reducing spread to other pets
- Preventing the worst-case outcomes
That’s why veterinarians focus so much on core vaccines—the diseases that are common, dangerous, or both.
How Veterinarians Decide Which Vaccines to Recommend
Not every pet needs every vaccine.
When veterinarians decide whether to recommend a vaccine, we usually ask two simple questions:
- Is the disease serious or deadly?
- Is the disease common or easy to catch?
If the answer is yes—and the vaccine is safe and effective—we recommend it.
That’s where the idea of core and non-core vaccines comes from.
- Core vaccines protect against life-threatening diseases and are recommended for almost all pets.
- Non-core vaccines depend on lifestyle and location.
For example:
- We don’t recommend Lyme vaccine for dogs who live only in Florida.
- Indoor-only cats may not need feline leukemia virus (FeLV) vaccine after kittenhood.
The goal isn’t “more vaccines.”
The goal is the right protection for your pet’s real-world risk.
“But I’ve Heard About Vaccine Reactions…”
You probably know someone who knows someone whose pet had a bad reaction to a vaccine.
Vaccine reactions do happen—but they are uncommon, and most are mild. The vast majority look like allergic reactions and are treated quickly with medications like antihistamines or steroids.
When you step back and look at the millions of vaccine doses given safely to pets every year, the risk becomes much clearer.
It’s also important to know this: veterinarians don’t give every vaccine ever created.
Some vaccines—like those for feline immunodeficiency virus (FIV) or canine adenovirus type-1 (CAV-1)—were developed years ago but are no longer routinely recommended because safer or more effective options exist.
Good medicine evolves. Vaccine recommendations change for the same reason they exist in the first place: to reduce risk, not add to it.
What About Combo Vaccines? Doesn’t Combining Vaccines Increase Risk?
This is a really common concern—and a reasonable one.
It feels intuitive to think that combining vaccines would put more stress on the immune system. In reality, the opposite is true.
Combo vaccines are designed to reduce risk, not increase it.
Here’s why.
A combo vaccine is one injection that protects against several diseases at the same time. Instead of giving multiple separate shots, we group compatible vaccines together.
This helps because:
- Fewer injections means less inflammation
- Fewer needle sticks means less stress
- Fewer visits mean fewer chances for minor reactions
From the immune system’s point of view, this isn’t “too much.” Every day, your puppy or kitten’s immune system responds to thousands of new bacteria and viruses just by eating, playing, and sniffing the world.
The amount of immune stimulation from a combo vaccine is tiny compared to normal life.
Importantly, combo vaccines are carefully tested to make sure:
- The vaccines don’t interfere with each other
- The immune response is effective
- The safety profile is equal to—or better than—giving vaccines separately
So when your veterinarian recommends a combo vaccine, it’s not about convenience alone. It’s about reducing risk while still giving full protection.
Using combo vaccines lets us protect your pet while doing the least amount of poking, stressing, and inflaming possible—and that’s always the goal.
Why Are There So Many Boosters?
This is one of the most confusing parts of puppy and kitten care—and one of the most important.
Here’s the key idea:
The core “distemper combo” vaccine is really one vaccine that needs multiple lessons.
Think of it like learning a skill:
- First dose: “Pay attention.”
- Second dose: “Remember this.”
- Third (sometimes fourth): “Respond fast when it matters.”
Those boosters aren’t separate vaccines.
They’re steps in the same immune training process.
This matters even more for puppies and kittens because antibodies from mom can block early responses. The vaccine series creates a window where the immune system can actually learn.
Skipping boosters doesn’t make vaccines gentler.
It often means the protection never fully develops.
As your veterinarian, my role isn’t to push shots—it’s to make sure your pet’s immune system actually learns the lesson before they’re tested by the real world.
When I worked at an emergency clinic, we saw a lot of parvovirus cases—sometimes dozens in a single week.
One of the most heartbreaking involved a new bulldog puppy. The puppy was kept indoors, and the owners felt they were doing everything right. There was another adult dog already in the home, but no outside exposure.
When the puppy became sick and was diagnosed with parvovirus, I asked about the vaccination history of the other dog in the household. That’s when we learned the older dog had received one or two vaccines as a puppy but never completed the series.
Those partial vaccines, along with being an adult, likely helped the older dog have very mild or no symptoms. But they didn’t prevent infection—and they didn’t prevent the virus from spreading.
Despite intensive care and doing everything else right, the owners had to watch their new puppy fight for days before ultimately passing away from the disease.
“But the Risk of Rabies Is So Low… Do We Really Need That Vaccine?”
You’re right—rabies exposure is uncommon.
But it’s uncommon because of vaccination.
Rabies is still present in the United States, especially in wildlife. Once symptoms begin, it is always fatal. There is no treatment. And it can spread to people.
That’s why rabies vaccination is required by law—not because rabies is common, but because the consequences are absolute.
Choosing not to vaccinate because rabies is rare is like arguing that rollercoasters don’t need safety restraints because very few people die on them.
Even people who don’t believe in seatbelts usually want to be strapped in on a rollercoaster.
Why?
Because those restraints are the only reason the ride is safe. When something goes wrong at high speed, you don’t get a second chance.
Rabies works the same way. The risk may be low—but the outcome is final.
Vaccination is the safety system that keeps a rare event from becoming a tragedy—and my job is to make sure it’s in place before it’s ever needed.
“Everyone Has an Opinion… Who Should I Trust?”
Most people giving advice about vaccines are trying to help. They’re speaking from personal experience, not bad intentions.
But not all experience is the same.
A helpful way to think about this is how many animals someone has worked with—and what kind of training they have.
- A pet parent may have cared for a few dogs or cats.
- A breeder or groomer may work around animals every day.
- A veterinarian has treated tens of thousands of pets and studied animal health for years.
- Large veterinary organizations base recommendations on millions of cases, not single stories.
Being around animals a lot does not automatically mean someone understands animal health.
Here’s a comparison most people recognize:
My kids’ hairdresser works around children all day. They see a lot of kids and hear a lot of stories. But I don’t take their medical advice more seriously than my pediatrician’s.
Why?
Because exposure is not the same as medical training.
The same is true for pets. Groomers, trainers, breeders, and boarding staff often have great practical knowledge—but diagnosing disease, weighing risk, and understanding immune response requires medical education and population-level data.
My role isn’t to replace your instincts—it’s to help you make decisions using experience and data that go far beyond any single story.
So… Does My Puppy or Kitten Really Need These Vaccines?
Short answer:
Your pet needs the vaccines that match their risk—not fewer, not more.
Longer answer:
- Vaccines are about prevention, not overkill
- Boosters are part of one learning process
- The diseases we vaccinate against still exist
- Your pet’s plan should be individualized—not crowdsourced
If something feels excessive, ask.
If something feels rushed, pause.
But don’t confuse thoughtful medicine with unnecessary medicine.
Because the pets we see suffer most from vaccine-preventable disease are almost never the ones who were “overvaccinated.” They’re the ones whose protection was delayed, skipped, or never completed.