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Vaccine Reactions in Dogs: Everything You Should Know

Typically, the benefits of getting your dog vaccinated far outweigh the risk of reactions to vaccines. However, some dogs do react to getting their shots. Our McAllen vets list the most common reactions to vaccines in dogs in this post, and explain what to do if your dog has a reaction.

Why should I get my dog vaccinated?

By having your dog vaccinated early in life, and bringing them in regularly for booster shots as an adult, you'll provide them with their best opportunity to live a long, healthy life. Diseases such as hepatitis, rabies and parvovirus can be very serious and even fatal, especially in puppies. Vaccines keep these preventable diseases from developing in the first place, which is always preferable to treating them once they exist in your pet. 

Does my dog need all the available vaccines?

Your vet will identify the risk factors your dog faces based on their breed, lifestyle and age before advising you on which immunizations are appropriate for your dog. 

What are the most common reactions to vaccines in dogs?

All medical procedures have an inherent risk of adverse reactions, and vaccines are no different. While seeing your pet have a reaction to vaccines can be upsetting, it's essential to remember that most reactions are short-lived and mild. Understanding the signs of a reaction and what to do if your dog has a reaction can help to make vaccination time less stressful for both you and your dog. 


By far, general feelings of lethargy and discomfort are by far the most common reactions dogs have when getting their shots. These may be accompanied by a mild fever. When we experience the same sensations in our bodies, many of us would describe this as feeling 'off'. For your dog, this reaction means the immune system is working well and responding to the vaccine appropriately. These mild symptoms are normal and will likely only last a day or two. If your dog is still feeling lethargic after their shots or isn't feeling and acting back to normal within a couple of days, contact your vet. 

Lumps & Bumps

As with feeling 'off', lumps and bumps can be a common reaction to vaccinations in dogs. Following the vaccination, a small, firm bump may develop at the spot where the needle was injected into the skin or muscle, leaving the area somewhat tender. These bumps develop due to your dog's immune system rushing to resolve the localized irritation at the site. 

That said, any time the skin is punctured there is a chance of infection. Be sure to keep an eye on the site where the injection was given. Look for signs of swelling, redness, discharge and pain. If left untreated, infected areas may lead to more serious conditions. If you notice the area becoming increasingly red or showing any of the symptoms listed above, contact your vet.

Sneezing & Cold Like Symptoms

While most vaccines are given by injection, the Bordetella Bronchiseptica and parainfluenza virus vaccines are administered by drops or sprays into the dog's nose. Reactions to these vaccines can look much like a cold, and include coughing, sneezing and a runny nose. Most dogs recover from these symptoms within a day or two. If your dog is showing more severe symptoms or does not recover within a couple of days, it's time to call the vet.

Trouble Walking

Your dog's injection site may be painful or swollen after they receive their shots. Therefore, you may notice some limping and paralysis. Rear (posterior) end paralysis - a condition most common in dogs that have had a Rabies shot - means that a dog's hind or back legs cease functioning as a result of a reaction. 

As unnerving as this sounds, the paralysis is not permanent and will probably improve on the tenth day after symptoms first appear. If your dog is having trouble walking after getting his shots, monitor any paralysis or limping symptoms closely and ask your vet for advice. 

Yelping or Crying

If your puppy is yelping when you pick him or her up after their vaccination, it's understandable to feel some concern. Your instinct may be to ask your vet, "Why is my puppy crying when I pick him up after his shots?"

That said, this is also a natural reaction and not something to get too worried about. Yelping will usually stop in a few hours, or a day or two at the most. If your puppy is still yelping beyond the 48-hour timeframe, contact your vet. 

Serious Reactions to Vaccinations

Most reactions associated with vaccines are short-lived and mild. Nonetheless, in a few rare cases, more severe reactions can occur and require immediate medical attention. Anaphylaxis is a severe allergic reaction characterized by facial swelling, vomiting, hives, itchiness, diarrhea, and breathing difficulties. Anaphylaxis typically occurs very soon after the dog receives the injection but may occur up to 48 hours after the vaccine has been administered. If your dog shows any of the symptoms listed above, call your vet immediately or contact your emergency veterinary clinic.

Can I prevent my dog from having a reaction? 

Vaccines help to protect the long-term health of your dog, and the risk of your dog having a serious reaction to a vaccine is very low. 

That said, if your dog has had a previous reaction to a vaccine, it is important to inform your veterinarian. Your vet may advise you to skip particular dog vaccinations due to anticipated side effects in the future.

The risk of side effects from dog vaccinations increases somewhat when multiple vaccinations are given at one time. This can be particularly true in smaller dogs. To help reduce the risk of reactions, your vet may suggest getting your dog's shots over the course of several days rather than all at once.

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

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Looking for a vet in McAllen? Nolana Animal Hospital is now accepting new patients! Our welcoming vets are passionate about pets and will provide your cat or dog with the care they need. Contact us today to schedule your pet's first appointment.

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