Pet Allergies – Signs & Treatments

Cat Allergy
Allergies in this Cat caused Watery Eyes

If you type “pet allergies” into your search engine, you will find a lot of information about the allergies people have to pets and very little information about the allergies pets experience.  Despite this fact, dogs, cats and other mammals can have allergies, just as people do, and those allergies can cause discomfort and health problems if they are not diagnosed and treated.

Animal allergies result from the same mechanism as human allergies, an abnormal overreaction of the immune system to some substance.  The substance causing the reaction is called an allergen and when the immune system responds to an exposure, it can be harmful to the animal’s body.   Animal allergies are also caused by the same types of allergens humans react to including insect bites, plant substances, and even other animals.   Some of the most common examples of allergens that can affect dogs include:


  • Pollen from trees, grass and weeds
  • Spores from mold
  • Dander, dust and dust mites
  • Feathers
  • Prescription drugs
  • Cleaning products
  • Fabrics
  • Food ingredients


As with humans, the overreaction of the immune system in most animals triggers a release of histamine which is responsible for the inflammatory response seen in allergic reactions.  The inflammation is what causes the most common symptoms of an allergen exposure such as redness, swelling, and itching.   Animal exposure can happen through ingestion, inhalation, or through skin contact.

It is important to note, that animals can develop an allergy to a common substance over time.  This means that they may have been exposed to the allergen for years with no effect before the immune system decides the substance is an invader and decides to attack this.  Essentially, allergies can develop at any time and being exposed to something previously is not a guarantee that the animal will never have an allergic response at some point in the future.


The most common symptom is itching.  Allergic itching can be localized, meaning that it seems to be only occurring in one location, or it can happen all over.   Animals may also experience symptoms related to breathing or that involve the upper respiratory system such as coughing, wheezing, sneezing, or difficulty breathing.   Less commonly, allergic reactions can also cause diarrhea, vomiting, and runny discharge from the eyes, nose, or both.

The itchy skin commonly experienced with allergies in animals can cause additional problems if the animal scratches too much or too hard and breaks the skin.  When this happens there is a risk of infection and you need to take your pet to see the vet.


Dog Allergy
Allergies in Dogs can cause Itchy Skin

According to Dr. Paul Sedlacek of Animal Clinic of Morris Plains, understanding where and when the animal is itching can help determine what is causing the allergic reaction.  Animals can experience seasonal allergies, just like people, which generally occur more often in the spring or fall.  Flea allergies and food allergies can occur at any time based on exposure.

The most common ways to treat allergies in animals are also similar to the way they are treated in humans.  Antihistamines can be prescribed to help mitigate signs, but aren’t effective in some cases.  Cortisone orally or topically may be used to help alleviate itching.  Hypoallergenic medicated shampoos can also help to deal with skin irritation and itching.  If a secondary infection develops on the skin, the vet may prescribe antibiotics to handle the infection.  The use of specific medications like Apoquel (oclacitinib) can make a significant difference in your pet’s quality of life.   Your pet may also be able to go through a series of allergy injections that help eliminate the allergic reaction by inducing hypo-sensitization through gradually increasing exposure to the allergen.

If you suspect your pet has allergies, talk to your Veterinarian.  They can diagnose the problem and recommend the best treatment for your pet.