Allergies in dogs explained

September 9, 2022

Allergies are the body reacting negatively to a substance which would usually be harmless. The body overreacts when it comes into contact with a certain substance and acts as if the substance is harmful, these substances are called allergens. Coming into contact with an allergen causes the immune system to start a chain of events which will manifest as an allergic reaction.

As the immune system becomes hypersensitive to an allergen, the body releases antibodies to try to remove the harmful substance, the chemicals released are known as histamines, and these are what cause the inflammation and symptoms of an allergic reaction.

Types of allergic reactions

Flea or insect bite allergy Caused by the bite or sting of an insect, most commonly flea saliva.
Symptoms	Treatment
Severe itching of the bite area, the dog may bite and scratch to the point of hair loss, (especially around the base of the tail) and/or wounds causing secondary infection	Antihistamines or corticosteroids Strict monthly flea preventatives are essential and thorough removal of fleas and their eggs from around the home
Food allergy (adverse food reaction) Caused by ingesting the allergen in their food, most commonly a certain protein, dairy, wheat, soy or artificial additives.
Symptoms	Treatment
Itchy skin which will cause the dog to scratch, lick or rub the area against things, red skin and fur loss/bald patches – ears may become itchy and infected – itchy paws which will cause the dog to excessively lick and/or chew them – gastrointestinal issues	Hypoallergenic elimination diet is the only fully effective way to determine the source of the allergen
Seasonal/environmental/inhalant/atopy allergy Caused by an allergen which is in the dog’s home or garden, or anywhere the dog may regularly spend time. These allergens can either be inhaled or direct contact through the skin. Common sources include pollen, dust mites, shed skin cells, mold, mildew and fibres from plants or animals.
Symptoms	Treatment
Itchy skin which will cause the dog to scratch, lick or rub the area against things, red skin and fur loss around the paws, lower legs, underarms, stomach, ears and face – ears may become itchy and infected – itchy paws which will cause the dog to excessively lick and/or chew them	Oral or injected medications, antihistamines, steroids, immunotherapy, medicated shampoo, frequent bathing, additional fatty acid supplements
Contact allergy Caused by direct contact to allergen, for example chemicals, pesticides, materials
Symptoms	Treatment
Itchy skin on the contact area, most commonly around the feet and stomach	Identify the allergen, avoid contact with it or remove the allergen
Immediate hypersensitivity (anaphylaxis) Caused by a severe reaction to an allergen which happens immediately, most commonly from insect bites and stings, medications, vaccines, chemicals, proteins, environmental allergens
Symptoms	Treatment
Either a localised reaction such as swelling, extreme salivating, vomiting and diarrhoea or it can cause a systemic reaction if severe resulting in difficulty breathing and a blue tinge to tongue and gums	A localised reaction may be treated with antihistamines or corticosteroids. A systemic reaction requires immediate emergency medical treatment from a Vet.