Dog Behavior Change After Vaccination Explained

Zack Keithy, our author, is a certified veterinarian technician (UC Blue Ash) for over 6 years (contact him here). The articles written here are based on his expertise and experience, combined with a review by our expert vet reviewers including Dr M. Tarantino. Learn more about us here.

Have you noticed any particular changes in your furry friend’s behavior after getting them vaccinated?

Look, vaccinations are an essential part of keeping our four-legged companions healthy, but sometimes they can leave our pups feeling a bit under the weather.

It can be worrying to see your energetic pup suddenly becoming lethargic or experiencing a loss of appetite, but let’s not hit the panic button first.

And how do you explain dog behavior change after vaccination?

In this blog post, I’ll shed light on why these behavior changes occur, offer some tips to ease your worries, and help you navigate this common post-vaccination phase with confidence.

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Dear Dog Owner

What Are the Most Common Behavioral Changes in Dogs After Vaccination?

Common Behavioral Changes in Dogs After Vaccination

Vaccination can sometimes be a controversial topic among fur parents, with some claiming that vaccines can trigger behavioral changes in pets, including aggression. 

Are changes in behavior something that you should expect when you get your dog vaccinated? 

Well, yes, you can expect some, but it’s really quite normal since injections are painful.

The site where the needle entered can be a little sore, and to protect that painful area, your pet may become a little distant and extra sensitive for a few days. 

Don’t be surprised if your pet acts a little disinterested and irritable. 

Good news! These changes are usually temporary. 

Why Did My Dog’s Behavior Change After Vaccination?

Your pet’s immune system is the main reason why it may act differently. 

As their body activates to build its defense against illness, your pet may experience some mild discomfort, tiredness, and a general feeling of being “off.”

When we feel a little under the weather, we tend to be withdrawn or easily annoyed. The same is true for your four-legged companion. 

It’s not uncommon for pets to want to stay away from everyone and be a little snappy if anyone tries to come closer. That’s their natural reaction to anything that might cause them more pain.

The other extreme can also be true, where your dog may become a little clingy, trying to get some form of comfort from you.

Receiving gentle touches and calming words may very well soothe their stress from feeling unwell.

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Doggy says, consider reading this too: Lepto vaccine for toy breeds

What to Do if My Dog’s Behavior Changes After Vaccination?

The best you can do is be vigilant and let your pet heal in peace. 

While you may want to give your furry pal some quiet space as they recuperate from the effects of the vaccine, it is also important to be on the lookout for signs if they are reacting negatively to the shot.

Provide them with what they need during this uncomfortable period. Be ready with lots of water, some food, and lots of gentle reassurance. 

The good this is that your pet should bounce back quickly and return to normal in no time.

Doggy says, you might be keen to read this too: Pros and cons of Lyme vaccine for dogs

How to Tell if Your Dog Has an Allergic Reaction to a Vaccine?

Years of research and testing are dedicated to ensuring the safety of vaccines for pets. However, it’s crucial to recognize the rare possibility of allergic reactions. 

If your furry companion happens to be among the few allergic to a vaccine, there are specific signs to be aware of. 

  • Swelling is a common symptom, occurring not only at the injection site but also on other parts of the body. Keep an eye out for rashes or hives, as these could indicate an allergic reaction. 
  • Additionally, difficulty breathing, such as coughing, rapid breaths, or wheezing, is a concerning sign that you should be wary of. 
  • Pay attention to any vomiting or diarrhea that occurs shortly after vaccination. If your pet suddenly becomes excessively tired or weak, it may also be a potential reaction.

What Are the Most Common Reactions to Vaccines in Dogs?

Soreness at the injection site almost always happens, and some of our furry pals may also experience sleepiness, a slight dip in appetite, and mild fever.

There are also some cases when the dog goes on a sneezing spree or sniffles.

These are all common reactions since your pet’s body is trying to adjust to the shot.

Doggy says, you might be interested to read this too: Dog shaking after vaccine

Is It Possible to Prevent My Dog From Reacting?

While it’s not always possible to completely prevent a dog from reacting to vaccines, there are a few measures you can take to minimize the likelihood or severity of reactions. 

  • First, ensure that your dog is healthy and in good condition before getting vaccinated. This includes addressing any pre-existing health issues or allergies. 
  • Additionally, work with your veterinarian to develop a suitable vaccine schedule that aligns with your dog’s specific needs. 
  • Talk about spacing out vaccinations or adjusting the dosage if your dog has previously shown sensitivity. 

Is It Normal for a Dog’s Behavior to Change After Vaccination?

It is quite normal for your pet to show some temporary behavioral changes after vaccination.

Getting a shot can cause mild side effects that may leave your pet in pain or feeling under the weather.

To prevent feeling further pain, your pet may suddenly be a little withdrawn and refuse to engage in their usual activities.

You should just let them be for a day or two before taking any next steps.

Will My Dog’s Behavior Return to Normal After Vaccination?

Yes! Any changes in your pet’s behavior after receiving a shot should go away after a few days.

Most symptoms resolve on their own as your pet’s body adjusts to the vaccine.

Is your pet lethargic? Are they refusing to eat? Give them a few days to get over these symptoms.

If the worrying change persists or worsens, do not hesitate to give your vet a call.

What Are Some Problems That Arise After Rabies Vaccination?

What Are Some Problems That Arise After Rabies Vaccination

One of the most common problems that dogs experience is soreness and swelling where the shot was administered.

The tenderness is often mild and goes away after a couple of days.

Some dogs may also suffer from a slight fever, and it’s also quite common for pets to lose their appetite and feel a little tired after vaccination.

In rare cases, dogs may experience allergic reactions and vaccine-related complications.

Signs of these are breathing difficulty, facial swelling, seizures, diarrhea, and persistent vomiting.

Quick note: I don’t mean to scare you nor do I have sufficient expertise, but in the last few years, there seems to be a rise in rabies vaccinosis. This refers to the long-term effects on a dog that are not only physical but also mental and emotional. I recommend you do your own research to find out more. Here’s a good place to start.

How to Care for Your Dog After Vaccination?

Is your dog feeling a little under the weather after getting vaccinated? Here are some ways that you can make this uncomfortable time a little easier for your furry friend.

  1. Set up a cozy area with their favorite bed or blanket where they can relax undisturbed. 
  2. Keep the environment quiet and avoid any rough play or activities that may strain the injection site. 
  3. Provide them with some quiet toys or chew treats to keep them occupied and content. You can also offer gentle pets and words of reassurance.
  4. Keep your pet’s water bowl filled so they can take a sip whenever they need to.  You can also offer a small meal for them to enjoy. 
  5. Watch out for adverse reactions or unusual symptoms that could develop in the days following vaccination. Keep the vet apprised of your pet’s condition. 

What Are Some Common Myths About Dog Vaccinations?

With so much information regarding doggy vaccinations out there, it can be a challenge to separate the truth from the myths. 

  • One such misconception that deserves clarification is that vaccines can cause permanent behavioral changes in dogs. There is no scientific evidence linking the two. Understand that vaccines are tested meticulously for safety and have undergone thorough research before they get rolled out. 
  • Some people also believe that the dog’s natural immunity is enough to fight off any disease. Unfortunately, this is not the case. The truth is that there are illnesses that are too strong for your pet’s natural immunity to ward off.
  • Another common myth is that boosters are not needed. Some pet owners wrongly believe that vaccines provide life-long immunity. 

Yes, some vaccines do have lasting effects. Others require boosters so your pet can continue to be protected.


How long does it take for a dog to feel better after a vaccination?

The time it would take for a dog to feel better after getting their shot varies. In general, your pet should recover within a day or two after vaccination. If the symptoms last longer than a couple of days, consider calling your pet’s vet.

Why is my dog aggressive after getting shots?

Your pet may show some signs of aggression after getting their shots due to pain, discomfort, or stress.  It could be their way of protecting themselves from experiencing more pain. This behavior usually lasts for just a short time. 

How do you comfort a dog after a vaccination?

You can make sure that your dog’s home is calm and quiet. Provide additional comfort by gently patting, praising, or giving treats to your pet. You should also check for any signs of reactions and discomfort.

Why should I get my dog vaccinated?

Vaccinations protect dogs from contagious and potentially life-threatening diseases. Vaccines help prevent the spread of diseases among dogs. This is especially important if your pet frequents places where they interact with other animals.

Does my dog need all the available vaccines?

It is recommended that your dog receive all the core vaccinations. At the very least, ensure that your pet gets their shots against rabies, distemper, parvovirus, adenovirus, and other severe diseases. The necessity of getting the other vaccinations will depend on your pet’s age, lifestyle, and environment.

What breeds are more prone to vaccine reactions?

While all breeds can potentially have reactions to vaccines, some breeds may have a higher risk. Weimaraners, Chihuahuas, and Daschunds are examples of such breeds. Your pet’s vet may be able to tell you if your furry pal has a higher predisposition to a vaccine reaction.

In Conclusion: Dog Behavior Change After Vaccination

It’s really important to remember that some changes in dog behavior after vaccination are normal and temporary, so don’t start worrying too much too soon.

By understanding the potential problems, such as lethargy, soreness, and mild fever, you can be in a much better position to provide extra care, love, and a watchful eye

I’m sure your furry friend will bounce back to their happy, playful self in no time!

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Zack Keithy
Zack Keithy

Hey, I'm Zack, the Chief Editor here. I was formerly a Certified Veterinary Technician (CVT) for a good 6 years before moving on to greener pastures. Right now, I am still heavily involved in dog parenting duties, and it is my desire to share all our knowledge with fellow dog owners out there! Connect with me on LinkedIn, or read more about Canine Care Central!

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