The itchy skin diseases in this table are characterized by constant scratching, biting at the skin, and rubbing up against objects to relieve the itch.
- Allergic contact dermatitis: Same as contact dermatitis, but rash may spread beyond the area of contact. Requires repeated or continuous exposure to allergen (such as wearing a flea collar).
- Canine atopy: Severe itching that occurs in young dogs and begins in late summer and fall. Caused by seasonal pollens. Occurs in mixed breeds as well as purebreds. Common. Tends to get worse each year. May start with face rubbing and foot chewing.
- Chiggers: Itching and severe skin irritation between the toes and around the ears and mouth. Look for barely visible red, yellow, or orange chiggers.
- Contact dermatitis: Red, itchy bumps and inflamed skin at the site of contact with a chemical, detergent, paint. or other irritant. Primarily affects feet and hairless parts of the body. Can also be caused by rubber or plastic food dishes, with hair loss on the nose.
- Damp hay itch (pelodera): Red pimplelike bumps on skin. Severe itching. Occurs in dogs bedded on damp hay and similar grass. Caused by a parasite.
- Flea allergy dermatitis: Red, itchy pimplelike bumps over the base of the tail, back of rear legs, and inner thighs. Scratching continues after fleas have been killed.
- Fleas: Itching and scratching along the back, and around the tail and hindquarters. Look for fleas, or black and white gritty specks in hair (flea feces and eggs).
- Fly-bite dermatitis: Painful bites at tips of erect ears and bent surfaces of floppy ears. Bites become scabbed and crusty black, and bleed easily.
- Food allergy dermatitis: Nonseasonal itching with reddened skin, papules, pustules, and wheals. Found over the ears, rump, back of the legs, and undersurface of the body. Sometimes confined just to the ears with moist, weeping redness.
- Grubs/Cuterebra: Inch-long fly larvae that form cystlike lumps beneath the skin with a hole in the center for the insect to breathe. Often found beneath the chin, by the ears, or along the abdomen.
- Lice: Two-millimeter-long insects, or white grains of “sand” (nits) attached to the hair. Not common. Found in dogs with matted coats. May have bare spots where hair has been rubbed off.
- Lick granuloma (acral pruritic dermatitis): Red, shiny skin ulcer caused by continuous licking at wrist or ankle. Mainly in large, short-coated breeds.
- Maggots: Soft-bodied, legless fly larvae found in damp matted fur or wounds that aren't kept clean.
- Scabies (sarcoptic mange): Intense itching. Small red spots that look like insect bites on the skin of the ears, elbows, and hocks. Typical crusty ear tips.
- Ticks: Large or very small insects attached to the skin. May swell up to the size of a pea. Found beneath the ear flaps and where hair is thin. May or may not induce itching.
- Walking dandruff (cheyletiella mange): Occurs in puppies 2 to 12 weeks of age. Large amounts of dry, scaly, flaky skin over the neck and back. Itching is variable.
This article is excerpted from “Dog Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.