The next most common cause of itching in dogs is atopic dermatitis. These dogs have a defective skin barrier and are allergic to pollen, dust mites, and house spores (the things that cause asthma in people). These dogs are frustrating to deal with.

As the pollen and spores are difficult to keep away from the dog, the problems are recurrent. To reduce the severity of the outbreaks, the itching should be treated as soon as possible.

The itching and rash in these dogs develop on fine-haired regions of the body that are not well protected. These dogs often have itchy feet, muzzle, ventral abdomen (tummy) and axilla (armpits), and the concave surface of the auricle (pointed part of the ear).

These dogs bite and scratch constantly and frequently develop secondary dermatitis and skin and ear infections due to chronic inflammation and colonization of the deeper layers of the skin by bacteria that penetrate the defective skin barrier.

It has recently been discovered that atopic dogs lack ceramides in the outer layer of the skin.

As with humans suffering from eczema, the skin loses moisture and becomes very dry. Atopic dogs have dry and often scaly or red skin.

This defective skin barrier lets water and pollen and other allergens out, triggering allergic skin reactions. The release of histamine in the skin causes redness and maddening itching. Dogs will constantly lick and mutilate themselves when scratching.

Atopic dermatitis rarely begins in the dog’s first year of life and commonly begins around 18 to 24 months of age.

If your dog didn’t have problems until about two years of age, he’s probably atopic.