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Dog Behavior Changes After Vaccination

Vaccinating your dog offers significant benefits and shields against various illnesses. However, some dogs may experience adverse reactions to vaccines. Our veterinarians in Exeter provided insights into the most common vaccine reactions in dogs and the necessary steps to take if your dog experiences any.

Why should I get my dog vaccinated?

Ensuring proper vaccinations for your dog from an early age throughout adulthood is crucial for their long-term health and well-being. Diseases like rabies, hepatitis, and parvovirus can incur substantial costs and, in severe cases, result in the loss of your beloved pet. Puppies are especially susceptible to these fatal diseases, making vaccination a preferable option over treatment post-symptoms. Generally, the risk of severe vaccine reactions in dogs is minimal, with the benefits typically outweighing any potential risks.

Does my dog need all the available vaccines?

Your veterinarian will evaluate your dog's breed, age, and lifestyle to determine the appropriate immunizations.

What are the most common reactions to vaccines in dogs?

Changes in behavior post-vaccination, particularly after critical vaccines like rabies, are common. While these changes may seem alarming, they're generally temporary and vary among dogs. You might observe the following responses after your dog's vaccinations:


After vaccination, dogs may experience fatigue and unease, possibly accompanied by a mild fever. Such reactions constitute a normal immune response that typically resolves within a day or two. If symptoms persist beyond a few days, it's advisable to contact your veterinarian.

Lumps & Bumps

Some dogs develop small, firm bumps at the injection site, causing tenderness. These are normal responses as the immune system reacts to the vaccine.

Sneezing & Cold-Like Symptoms

Certain vaccines, such as those for Bordetella bronchiseptica and parainfluenza virus, can cause cold-like symptoms like coughing, sneezing, and a runny nose. These typically resolve within a day or two. Seek veterinary assistance if symptoms worsen or persist.

Serious Reactions To Vaccinations

Although rare, dogs may experience severe reactions to vaccines, necessitating immediate medical attention:

Anaphylaxis -  Severe allergic reactions characterized by facial swelling, diarrhea, itchiness, hives, vomiting, and breathing difficulties, usually occurring shortly after vaccination.

Shock - Various factors contribute to behavioral changes post-vaccination, including individual sensitivity, vaccine components, and stress and anxiety during veterinary visits.

Factors Influencing Behavioral Changes

So why is your dog acting or your puppy acting weird after their rabies shot or other vaccinations? Various factors can contribute to the behavioral changes you might observe in your dog following their vaccinations. It is essential to consider these factors when evaluating your dog's response to the vaccines they recently received:

  • Individual Sensitivity -  Similar to humans, dogs possess varying sensitivities and reactions to vaccines. Some dogs may be more prone to experiencing behavioral changes, while others may exhibit no discernible difference.
  • Vaccine Components -  Vaccines consist of diverse components, including adjuvants and preservatives, designed to enhance potency and prolong shelf life. However, in rare instances, some dogs may develop allergic reactions to these components, resulting in significant alterations in behavior. If you have any concerns about your dog's reaction to vaccines, it is advisable to discuss them with your veterinarian. This ensures that only the appropriate vaccines are administered to your dog.
  • Stress and Anxiety-  Dogs may experience stress and anxiety during veterinary visits, particularly vaccinations. This stress and anxiety can stem from various sources, such as the anticipation of discomfort, unfamiliar surroundings, or encounters with unfamiliar individuals, resulting in transient changes in behavior. Offering gentle reassurance and positive reinforcement during these visits is vital to alleviate your dog's stress.

Can I prevent my dog from reacting? 

While severe reactions to vaccines are uncommon, informing your veterinarian about any previous reactions is essential. Consider spreading out vaccinations over several days to minimize the risk of adverse reactions, particularly for smaller dogs.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

To learn more about vaccinations and preventive healthcare for your dog, contact our Exeter vets today to book an appointment.

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