Acute Moist Dermatitis (also called Hot Spots) is caused by self-induced trauma. The pet will bite or scratch repeatedly at a part of the body in order to relieve some perceived itch or pain. There are numerous underlying causes for the scratch-itch cycle, including allergic reactions, ectoparasites such as fleas and ticks, ear infections, impacted anal glands, irritating substances such as the insecticide in a flea collar, or matted coats. The itching may be so intense that severe trauma results within a few hours. Hot spots occur more commonly in hot, humid weather.

A typical hot spot is red, moist and exudative (secretes fluid). The pet will have effectively removed all the hair from the area. The lesion is typically very painful and is usually located close to the offending cause. The area tends to give off a foul, sweet, necrotic odor. For example, if an ear infection is responsible for the hot spot development, the site of the hot spot is usually behind or below the infected ear.

The area should be clipped clear of hair and cleaned with an antiseptic or antiseptic shampoo. Sedation is sometimes necessary to clean a hot spot due to the pain associated with the lesion. In most cases a systemic corticosteroid is used to break the scratch-itch cycle. Oral antibiotics may be necessary to control secondary skin infections. There are many products available for topical treatment and include: corticosteroids, antibiotics, and topical anesthetics.

It is imperative to find and eliminate the causative agent or the pet may be subjected to repeat occurrence of the problem.