Section: Information In-depth
Related Diseases
Many skin diseases can cause or can contribute to pruritus. Every dog has a threshold of pruritus. When the nerves of the skin are stimulated by mediators of inflammation to a level below that threshold, the dog will not scratch. Scratching begins when the stimulation exceeds that threshold. It is common to see dogs with two or more skin conditions that cause pruritus concurrently. For example, a dog with a mild allergy to house dust mites may be below the threshold but may begin to scratch severely when he becomes infested with fleas.
Allergic Skin Diseases
Flea allergy is the most common allergic skin disease in the United States. Dogs with flea allergy tend to scratch their back ends leading to lesions on the rump, hind legs, tail and belly. Since it takes just one flea to make the dog react, the presence of fleas on the dog may be minimal to absent.
Atopy is a reaction to airborne allergens such as pollens, house dust, house dust mites and molds. Dogs with atopy tend to scratch their ears and face and tend to chew and lick at their feet. The condition is often worse during summer months when pollen and mold levels are increased.
Food allergy is a reaction to one or more ingredients in their food. These dogs tend to scratch in the same places as those with atopy.
Insect allergies (insect bite hypersensitivity) are less common than other allergies. Lesions are evident in areas where insects such as mosquitoes are likely to bite (bridge of nose, ears).
Contact allergy is a reaction to an irritant that touches the skin, often the belly or chest. Allergies of this type are rare.
Parasitic Skin Diseases
Scabies is an intensely pruritic skin condition caused by the sarcoptic mange mite. Lesions are seen on the ears, elbows and hocks (ankles).
Demodectic mange is caused by the demodex mite. This is usually a disease of young dogs and causes dramatic hair loss and dermatitis. This disease is often not pruritic, but can lead to a secondary bacterial infection of the skin (pyoderma) which may be itchy.
Fleas can cause pruritus in dogs that are not flea allergic, although the degree of pruritus is less severe.
Cheyletiellosis is an itchy skin condition caused by the cheyletiella mite. Lesions are usually most dramatic along the top of the back. These mites are sometimes visible to the naked eye as small, moving, white specks, hence the name "walking dandruff mite".
Lice are small insects that are easily seen with the naked eye that can cause pruritus.
Ear mites cause itching of the ears in dogs and can sometimes cause itching elsewhere on the body.
There are many other causes of pruritus, including secondary bacterial skin infections (pyoderma) and secondary yeast infections.
Related Articles
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Atopy in Dogs
Atopic disease (atopy) is a pruritic (itchy) skin disease of animals that is caused by an allergy.
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Food Allergy in Dogs
Most pets develop allergies to food ingredients that they have been fed for a long time, usually more than two years. In fact, if your dog has an immediate adverse reaction to a new food, it is probably...
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Demodicosis (Red Mange) in Dogs
Demodicosis (red mange) is a common skin disease of dogs causes by a microscopic mite that are present in small numbers on all dogs. In predisposed individuals the mites increase in number causing disease....
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Acute Moist Dermatitis (Hot Spots)
A hot spot starts because something irritates the skin, and the body either itches or becomes inflamed. The itching then causes the dog to lick or chew the area, which further damages the skin, creating...
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Sarcoptic Mange in Dogs
Sarcoptic mange (also known as scabies) is a highly contagious disease caused by microscopic mites that invade the skin of healthy dogs and puppies and create a variety of skin problems.
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Flea Allergy Dermatitis in Dogs
Flea allergy dermatitis is the most common allergy in dogs and is caused by flea bites, specifically the saliva of the flea. It is a very itchy disease and predisposes to the development of secondary skin...
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