Our Guide To Allergic Reactions In Dogs

Estimated Reading Time: 6 min | Last Updated: May 29th, 2023

share this post!

Is it normal or is it an allergic reaction?

How do you know if your dog has an allergic reaction? Is your pet itching more than normal, skin appears swollen and reddened or has come up in lumps? It could be an allergic reaction. Just like us humans, our pets can suffer from allergic reactions too. In fact, allergic reactions are one of the most common reasons for a trip to the emergency vet.

This guide will take you through common causes of an allergic reaction, the signs and symptoms to be aware of, and the kind of treatment your dog would need should they ever have a reaction.

What you’ll learn

  • Can my pet have an allergic reaction?
  • What are allergic reactions?
  • What causes an allergic reaction?
  • What is the difference between allergic reactions and anaphylaxis?
  • What are the symptoms of an allergic reaction?
  • What should I do if my dog is having an allergic reaction?
  • What should I expect from a vet when treating my dog’s allergic reaction?
  • How can I prevent my dog from having an allergic reaction?

Can my pet have an allergic reaction?

Absolutely, our pets (all animals really) can develop allergies at any point in their lives, with most allergies appearing after six months of age. Some pooches can have spontaneous allergic reactions to something in their environment (known as an allergen), while others can have ongoing allergies to specific foods, plants, grasses, chemicals, etc.  Allergens can be found everywhere, so it’s best to know the common types so as you can lower your pooch’s risk of suffering from an allergic reaction.

While in most circumstances a pet’s first allergic reaction is mild some can have a severe reaction their first time. It has also been known that each reaction afterwards is likely to become progressively worse.

What are allergic reactions?

An allergy is an immune system reaction. An allergic reaction occurs when the body is exposed to a substance (allergen) that it perceives as a threat to the body. In a lot of cases the allergen that causes the allergic reaction may be harmless but the body has overreacted by seeing it as a threat.

The immune system is activated and special immune cells are released that produce inflammatory mediators and antibodies.  These inflammatory mediators cause the signs that we see in our pets which include puffy eyes, itching, reddened and swollen skin.

In order for an allergic reaction to develop, the body has to be exposed to the allergen either by being inhaled, ingested, injected or coming in contact with the skin to trigger the immune response.

What causes an allergic reaction?

Similar to us, our pooches can have an allergic reaction to just about anything! The most common allergies include:

  • Environmental allergies: Caused when an allergen is inhaled, ingested or is absorbed through the skin, including dust, pollens, grass, mould
  • Insect bites: The most common insect bites causing allergic reactions in dogs are bee stings and wasp stings
  • Chemicals: Household cleaners, air fresheners can also be a source of allergens for pets
  • Medications: Although rare some dogs can be allergic to certain antibiotics, tick and flea prevention products, vaccinations
  • Food allergies: While an uncommon allergy, it is caused by ingredients in food, commonly proteins or carbohydrates are the source
  • Flea allergy dermatitis (FAD): When fleas bite, their saliva is injected into your pet’s skin causing skin irritation

Unfortunately, most of the time the cause of your pet’s allergic reaction will be unknown. However, no matter the cause an allergic reaction can occur immediately or up to 48 hours later and needs immediate veterinary attention.

What is the difference between allergic reactions and anaphylaxis?

Allergic reactions can range from very mild to severe and life-threatening. These severe cases of allergic reaction are known as anaphylaxis.

Some allergic reactions are only mild to moderate. For example, your dog may develop itchy, swollen skin, hives or swollen eyes.

The most severe form of allergic reaction is anaphylaxis which can be life-threatening. This occurs when the immune system triggers the whole body to react to an allergen and goes into shock. Symptoms of anaphylaxis occur within minutes of being exposed to an allergen and these include collapse, vomiting, pale gums and loss of consciousness. It is rare for dogs to experience anaphylaxis, but should your dog ever experience this type of allergic reaction immediate veterinary treatment is needed.

What are the symptoms of an allergic reaction?

There are a number of signs and symptoms your dog can experience should they have an allergic reaction. Symptoms will also increase in severity depending on the type of reaction they are experiencing.

Signs and symptoms of mild allergic reactions include:

  • Sudden onset or increased itchiness, including scratching, licking, chewing or shaking of ears
  • Itchy or non-itchy hives, welts, bumps or rash
  • Generalised redness of the skin
  • Runny eyes
  • Sneezing or runny nose
  • Itchy ears and ear infections
  • Mild facial swelling (particular around the eyes, muzzle or near the ears
  • Feeling hot to the touch

Though rare, dogs can experience life-threatening reactions. Signs of severe allergic reactions include:

  • Vomiting
  • Diarrhoea
  • Pale gums
  • Severe facial swelling
  • Noisy or difficulty breathing (especially if inside mouth or throat is swollen or inflamed)
  • Abnormal heart rate
  • Sudden weakness and collapse
  • Tremors
  • Loss of consciousness
  • Cardiac arrest

What should I do if my dog is having an allergic reaction?

If your dog is showing signs of an allergic reaction or you suspect they are, contact your vet immediately. It is never recommended to wait and see if their symptoms improve. Even mild allergies such as hives and itchiness can sometimes progress to full anaphylaxis, especially with repeated exposure to allergens.

It is important to note that human medications like antihistamines, should never be given to pets without the guidance of a veterinarian. Medication doses are different for animals and side effects can be unpredictable.

If your pet experiences an allergic reaction it is best to consider it a medical emergency and see your veterinarian as soon as possible.

What should I expect from a vet when treating my dog’s allergic reaction?

pOn your arrival at your local vet or closest animal emergency hospital, the vet will assess your pet in order to develop a treatment plan. Your pet’s treatment will depend on how severe their allergic reaction is. For pets with mild allergic reactions, treatment can include:p

  • Administering of an antihistamine
  • Anti-inflammatories
  • Pain relief if necessary, particularly for patients with bee stings or other painful insect bites

For pets experiencing more severe allergic reactions, treatment can involve:

  • Intravenous fluid therapy to treat shock, improve blood flow to organ
  • Administering of antihistamines and anti-inflammatories
  • Adrenaline to quickly constrict blood vessels, relax muscles in the lungs to improve breathing, stimulate the heartbeat, and to reduce swelling
  • Medications to stop vomiting
  • Medications to improve blood pressure
  • Blood tests to assess the severity of your pet’s condition and to assess how they are responding to treatment
  • Oxygen therapy if they are having difficulty breathing
  • Depending on the severity of your pet’s condition, it may be recommended they are monitored in hospital until it is safe for them to go home

It is important to note that even after treatment there is a possibility of repeat episodes of allergic reactions 12 to 24 hours after the initial reaction has subsided.

How can I prevent my pet from having an allergic reaction

Here are our top tips for helping pets prone to allergic reactions:

  • If your dog has persistent allergies your vet or a veterinary dermatologist can perform an intra-dermal allergy test or blood tests to identify the allergens they are reacting to
  • Remove the allergen that is causing your pet’s reaction from their environment
  • If your pet has environmental allergies, help them by keeping the areas they spend most of their time inside free from allergens by regularly cleaning and vacuuming the floor and their bedding using non-toxic cleaning agents
  • Regular bathing may help relieve itchiness and remove allergens on their coat and skin. It is best to discuss with your vet which pet shampoo is best as too frequent bathing with a harsh shampoo can cause their skin to dry out
  • If your pet has or is suspected to have a food allergy, a prescription hypoallergenic diet may be needed which can be recommended by your vet

If your dog has severe allergies your vet may recommend treatment to help prevent and manage symptoms. Some of these treatments include:

  • Anti-inflammatory therapy: This treatment is often used for dogs with environmental allergies, the kind of allergens that are near impossible to avoid. Drugs like antihistamines are prescribed to help reduce the severity of the allergic reaction.
  • Shampoo therapy: Medicated shampoo can help treat secondary sores and infections caused by allergic reactions and can be prescribed by your vet.
  • Desensitisation therapy or allergy injections: After undergoing allergy testing, based on the results a series of injections can be developed to help desensitise your dog’s immune system.

For further advice on preventative methods for your pet, speak with your local vet.

If you suspect your pet is ill or injured, visit your nearest Animal Emergency Service hospital or your local vet immediately.

Related Posts