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Vaccine Reactions. Some Dogs Have Them And Some Dogs Don’t.

Just like people, dogs can suffer from allergic reactions from vaccines.

Allergic reactions from a vaccine can be a scary thing for any pet owner when they aren’t aware of what one is.

I see vaccines given several times a day every week and rarely do I see a pet have a reaction but we always make sure that clients know what to look for if their pet is getting a vaccine for the first time.

What is a vaccine reaction in pets?

“In many cases, a vaccine is simply a strain of the virus modified to allow the dog’s immune system to fight and destroy it.

The immune system builds antibodies that will fight off any future invasion of this virus, thus rendering the dog “immune” to the virus.

However, the dog can sometimes display side effects of the disease or virus itself, and some dogs appear to “get sick” for a day or two after being inoculated.” 

small dog getting a vaccine over right rear leg

Mild Vaccine Reactions Seen In Dogs

Many dogs will experience mild vaccine reactions that often subside after a few hours or a day. 

Most dog owners won’t even notice these symptoms because they are so mild but they can include:

  1. Pain or soreness where the vaccine was given
  2. Lethargy
  3. Mild fever. Read how to check your dog’s temperature.
  4. A small lump where the vaccine was given.

small dog getting vaccine over right shoulder

Moderate Vaccine Reactions Seen In Pets 

Moderate vaccine reactions can be seen in any dog and they can appear within minutes of the vaccine being given or they can take several hours to appear. 

These reactions may include:

  1. Hives. 
  2. Swelling of the face and/or muzzle
  3. Mild vomiting and/or diarrhea

dog at vet for vaccine reaction

Severe Vaccine Reactions In Pets

A severe dog reaction from a vaccine is also referred to as anaphylaxis. 

An anaphylaxis reaction requires immediate attention from a veterinarian.

Signs and symptoms of a server vaccine reaction in a dog may include the following:

  1. Pale gums
  2. Severe vomiting/drooling
  3. Weak pulses. Read how to check your dog’s pulse from home.
  4. Shallow/rapid breathing
  5. Seizures
  6. Collapse
  7. Coma, and in worst-case scenarios, death.

How Long After A Dog Vaccine Is Given Can A Reaction Occur?

Vaccine reactions can occur immediately following the administration of the vaccine or can take up to 48 hours to appear.

In most cases, a severe reaction will occur almost instantly.

I always explain to clients that a vaccine reaction is similar to a reaction your dog might have if they get stung by a bee and are allergic to them.

Some dogs have no reactions to a bee sting, some have mild reactions, some moderate reactions and a few have severe reactions.

The reason I bring this up is that the other day I saw my first case of a dog that went into anaphylactic shock after a vaccine was administered.

small dog being given a vaccine in the right rear leg

The dog had a history of vaccine reactions but not with this particular vaccine, of which it had been given before.

Within 10 minutes of giving the vaccine, the dog began to vomit white foam, had pale gums, went limp and had a fever of over 103, and was breathing rapidly.

In my seven years of being a vet assistant, I personally, had never had a patient have this severe of a reaction to a vaccine before and to say that it was scary would be an understatement.

Thankfully, we were able to stabilize the dog and within an hour the dog was basically back to normal and sitting up smiling at me which is when I came down off of my adrenaline rush, took and a deep breath, and almost vomited on the floor.

dog being checked for a vaccine reaction

How Long Do Dog Vaccine Reactions Last?

Some mild vaccine reactions such as a bump or nodule under the dog’s skin can take up to 14 days to go away.

If the bump seems to be getting bigger or is painful when touched you should contact your veterinarian. 

Mild lethargy symptoms after vaccines can last a few hours to a day.

If a dog is more sleepy than what is normal for them for more than a day you should contact your veterinarian. 

If your pet is showing any signs of distress or you suspect your pet is seriously ill, contact your veterinarian immediately.

This information is not meant to be a substitute for veterinary care.


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Saturday 21st of July 2018

wow! so scary! Our 6 yr.old Italian Greyhound baby had SEVERE reaction last summer-2017 to the COMBO-5 Vaccines given to him, so this year, we decided to only give (2) Rabies-Dist/Parvo.Vacc- thinking that the LEPTO that was added to the combo 5 Vet used year before was the issue! NOT poor BABY he got a PRE-benedryl shot, and STERIOD and still had life threatening reaction on just the 2-PArvo-Dist/Rabies!!!! SO back to the ER so scary for Benedryl& Steriod, while hes ALIVE thank you LORD! he still weak, has a new small lump under near his lower right lip jaw area :( Don't want to think what that might be, just popped up! all the hives, swelling, bumps- itchy spots have gone down, but this hard knot on outside mouth at crease opening has me worried about what 2 years of horrible VACC reactions might have caused in our tiny IGGY baby :( NEVER shots or VACC!!!! Again never! we are going to look for a NEW Vet that does NOT have the 1 for all every year Vacc! mentality! to a new local Dr. who deals with small delicate breeds and really takes time to know and care about the VACC. issue, or any other issues that deal with EACH dog that is precious!


Saturday 13th of June 2015

My shih tzu did when he received two shots, including bordatella, last month. Several hours later his face became very swollen and one of his eyes was virtually shut and he was very lethargic. My girl friend gave him a little benadryl and when I got home we took him to the pet hospital where they gave him a steroid and benadryl injection. Today he had his leptospirosis shot but his vet pre medicated him with benadryl and steroid shots prophylactically and later I am to give him one benadryl cap


Saturday 13th of June 2015

I wrote about a year ago regarding my dog Wendy. She passed soon after in my arms. Never experienced anything like that before, having a healthy, happy, living, breathing being die like that, in my arms. I was traumatized. I now have her ashes. I changed veterinarians. I do have a new dog now but, of course, he has not replaced Wendy. He has his own unique personality and is a clown. I was very adamant about spacing his shots. I can't go through something like that ever again.


Friday 21st of February 2014

My chihuahua went for her booster yesterday at about 11am, by 7pm I noticed she was rolling round in the floor scratching at her eyes and mouth then nibbling her whole body so I went over to see what was going on n her muzzle had swallen up inside her mouth was all swallen also aswell as her eyes! She had hives all over her body and was struggling to breath. I have to say this was the scariest thing I've ever seen, my poor baby :(( I callee the vets which was closed and it gave me an emergency line to ring, I then got through to the vet which drove out to see my dog. She had a moderate to extreme reaction! Vet injected her with steroids and anti hystamine. Withing a hour all the swelling had gone down a bit , she was drowsy so I snuggled in bed with her n kept a very close eye on her for the next 6-8hours. By far the scariest thing I've seen never cried so much in my life.


Monday 4th of August 2014

The key is to take immediate action. We had to take two of ours in for emergency life saving measures after immunizations. You are blessed that your vet came to the house. Our now former vet, didn't call us back for 2 days and we ended up in a local animal hospital.


Saturday 8th of February 2014

I have a 4 year old female Carin Terrier. She had her annual shots and the next day has these collapsing episodes. She'll breathe heavy then fall to her side legs stiff. Then she sits on her belly to weak to stand for a couple of minutes. She's had these shots before. Makes me cry. I'll be returning her to the vet Monday. No idea why she's having these reactions. Didn't have them until after the shot.


Tuesday 24th of December 2013

I just found your blog today, searching after my dog had an anaphylatic reaction today to his rabies vaccine. He is 1 yr old italian greyhound/rat terrier mix and got 3 vaxes today-kennel cough, distemper and rabies, with rabies being the only one he was getting for the first time. Within about 5-10 mins he started acting strange, walking funny. Immediately after his vaxes they clipped his nails, and he had to be held firmly for that. When the tech put him down, I thought maybe he had pulled a muscle in the wresting match we were having with him trying to clip his nails. Then he immediately got worse, was being very unsteady on his feet and I immediately got the vet's attention (she was in the room still, putting in a prescription for my other dog-both were there for simple annual visits) and she checked him for an injury to his legs then I told her I thought it was maybe a stroke or seizure and at that point, he was staring to collapse. The vet quickly said he's having a reaction to the vaccines. I grabbed my child (preteen son, he was very upset at this point) and went to the waiting room to get out of their way. So we waited while the vet clinic suddenly turned into managed chaos with other vets/techs rushing to my dog's room to assist. Within about 10 mins they brought him to me wrapped in a towel and told me to take him immediately to the ER vet (about 15 mins away.) They had quickly typed up a medical info paper to take (said what happened, what medications they gave,etc) called the ER vet for me, and off I rushed. We were at the ER vet about 4 hrs and very luckily, my dog is ok now, but it was horrible and I am so scared to get any more vaccines for him at all. :(

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