Allergic reactions, including reactions to vaccines, can happen at any veterinary hospital and anywhere – not just the Las Vegas / North Las Vegas area. In this blog post, Craig Road Animal Hospital’s own Dr. Tampira explains the various types of allergic reactions that your cat or dog may experience, and how to spot a minor versus a major life threatening emergency. Of course, if your pet experiences any allergic reaction please call Craig Road Animal Hospital, or your local veterinary clinic, or bring them straight in.

Dr. Tampira

By Orlena Tampira, DVM

Allergic reactions are an individual inflammatory response against a specific protein entering the body.  These proteins can be anything from pollens, foods, medications, or even vaccines.

These are the different types of reactions that your pet may have.

  • Facial swelling or Hives

Swelling of the face usually occurs around the muzzle and the eyes.  It can be so severe that the pet cannot open his eyes.  Hives are small bumps that can be located anywhere along the body.   In both cases, your pet is often very itchy.

  • Vasculitis and Hair loss

Vasculitis is the inflammation of the blood vessels that occur as part of an immune response.  The evidence of vasculitis is often manifested as flakey skin along the ear margins and hair loss at the site of where a vaccine was administered.  This is often seen several months later and near the right hip, where the rabies vaccine was administered.

  • Lump and/or Pain at the Vaccination Injection Site

Initially when a vaccine is administered, there is a raised lesion at the site of injection that may be painful but the discomfort should subside in a few days.  A lump may persist as the vaccine causes local inflammation and will resolve in few weeks.  If the lump persists longer then 3 months, it should be removed as they have the potential to develop into tumors.

  • Anaphylactic reaction

This is the most serious and life threatening of all reactions.  Anaphylaxis is an immediate response that when untreated, results in shock, respiratory and cardiac failure, and may progress to death.  This occurs within minutes to hours of the vaccination.  The most common symptoms are the sudden onset of diarrhea, vomiting, shock, seizures, coma, and pale gums.  If you witness any of these signs, please bring your pet in immediately as life saving measures need to be taken.


The treatment depends on the severity and type of the reaction.  If your pet has hives or a swollen face, antihistamines and steroids are administered to help decrease inflammation.  Hair loss and vasculitis may be treated with a medication to help improve blood flow.  Non-steroidal anti-inflammatories may be prescribed for any pain associated with vaccination.  Because each symptom is managed differently, please contact us to best tailor the most appropriate treatment for your pet.


In general, there is no way to predict which animals may develop a vaccine reaction. If your pet has a history of an allergic reaction, to a substance, medication, or vaccine then please inform your veterinarian at each visit prior to any medications or vaccinations are administered. Most often, however the inciting cause is never identified.

If your pet has had an allergic reaction to a vaccine, it is often advised to administer an antihistamine one hour prior to being vaccinated.  In some cases, certain vaccines may be excluded from your pet’s vaccination regimen, or a different type of vaccine will be used.

“For every 10,000 vaccines administered, there are 13 reactions”

Although your pet may have had the same vaccinations yearly without adverse reaction, you should always take precaution and not assume that this year will be the same.  Always monitor your pets for the next few days to ensure that they do not have a reaction.  As with any medical procedure, there is always a risk of adverse side effects.  When comparing the risk to benefit ratio, the diseases against which we vaccinate can be serious and lethal.  The risks associated with vaccinations are small compared to the risk of the developing disease.