Recent years have seen more and more dogs suffering from allergies. It is estimated that one out of seven dogs has some form of canine allergies.
Although some breeds of dogs may be more prone to allergies, almost all dogs, regardless of breed, gender, and age, can develop allergies.
What is Canine Allergy?
Allergy is a reaction caused by the dog being exposed to an “allergen”. An allergen can be any substance, ranging from food ingredients to something in the dog’s environment (e.g. house dust mites, molds, pollens, weeds, flea control medications, etc.).
An allergic (or hypersensitivity) reaction is basically how a dog’s immune system responds to the allergen in question.
Allergic reactions occur after the dog has breathed or ingested the allergen in question. Of course, an allergen can also be absorbed into the body through the skin.
How Allergies Develop
A dog has to be exposed to an allergen at least two times to have an allergic reaction.
The first time a dog is exposed, the dog’s immune system produces IgE antibodies specific to the allergen. Each IgE antibody attaches to a mast cell to form a “combined unit”.
When the dog is exposed to the same allergen for the second time, the allergen attaches itself to the combined unit of IgE antibody and mast cell.
Upon attachment, it triggers a reaction that results in the disintegration of the mast cell, causing it to release, among other chemicals, histamine, which is the chemical mediator that is responsible for the allergic reaction.
Symptoms of Dog Allergies
When an allergic reaction is triggered in dogs, the target organ is usually the skin, with itching being the most obvious sign.
Allergic reaction in dogs can be “immediate” or “delayed”.
An immediate reaction occurs shortly after a dog is exposed to the allergen and usually produces skin hives.
A delayed response occurs a few hours or even days later after the exposure and causes intense itching.
Because of the itch, an allergic dog scratches, chews, licks, and bites his skin incessantly, causing skin lesions and discoloring of the skin.
Skin lesions can further lead to other complications such as secondary bacterial infections, causing small red bumps to form on the skin. Skin lesions can also lead to yeast infections, causing greasy, smelly yellow scales to form.
Sometimes, dog with allergies may show other symptoms not related to the skin, such as runny nose, runny eyes, wheezing, sneezing, vomiting, and diarrhea.
Common Dog Allergies
Dog allergies fall into four types:
Canine Atopic Dermatitis
Canine atopic dermatitis, or canine atopy, is one of the most common dog allergies, affecting about 10% of all dogs. It is caused by inhaled airborne allergens (e.g. ragweeds, plant pollens, molds).
Just like in humans, dog allergies caused by airborne allergens like ragweed, and pollens are seasonal, but other types can occur all year round, such as allergies caused by molds and mildew.
Atopic dogs usually start showing symptoms when they are between one and three years of age, although symptoms may start showing up in older dogs as well.
Dog Flea Allergies
Also known as flea allergy dermatitis, this type of allergy is rather common as well.
It is caused by an allergic reaction to one or more substances found in the flea’s saliva. Dog flea allergies can cause immediate and delayed responses. The dog may suffer intense itching almost immediately after being bitten and the itching can last for a long time, long after the fleas have been killed and eliminated.
Dog Food Allergies
A dog is said to suffer from canine food allergies when he shows allergic reactions to his food.
The dog must have been exposed to the food ingredient one or more times to become allergic.
Food allergies are non-seasonal and can cause severe and intense itching in dogs. Also, anti-inflammatory and anti-itch drugs (e.g. corticosteroids) have no effect on dogs suffering from food allergies.
Feeding an elimination diet is the only way to accurately diagnose food allergies.
Contact Dermatitis
Contact dermatitis is caused by the direct effect of a chemical or irritant on the skin.
Usually it occurs in areas where the skin is not well protected by hair, such as the feet, nose, chin, the underbelly, etc.
This type of dog allergy can occur after a single exposure or repeated exposure. A dog with contact dermatitis will suddenly develop skin irritations such as itchy red bumps, rashes, rough scaly skin, and hair loss.
Many common household items can cause contact dermatitis in dogs, such as:
- Chemicals found in some soaps, disinfectants, carpet cleaner, weed killer, fertilizers, and insecticides
- Leather
- Plastic and rubber dishes
- Paint
- Carpet dyes
Flea collars can also cause contact dermatitis and the dog will develop a circular area of hair loss and inflammation or redness around the neck where the collar has been. Sometimes, lesions of the mouth can also occur if the dog licks the areas affected by the dermatitis.