Hot Spots (Acute Moist Dermatitis)

Filed Under: Dogs, Cats, Parasites

Have you ever had an itch that was driving you insane? You just could not leave it alone even though the skin was becoming irritated? You may even scratch at the area so bad that you caused it to bleed. Everyone was trying to advise you not to scratch and yet you somehow just could not leave it alone. Sounds like a pet with a hot spot, or “acute moist dermatitis.”

Hot spots result from repeated self-induced trauma. The affected pet will bite or scratch repeatedly at a part of the body to relieve some perceived itch or pain. There are many possible underlying causes that may ensure the development of this scratch-itch cycle including allergic reactions, ectoparasites such as fleas and ticks, ear infections, impacted anal glands, soap residue following a bath, irritating chemicals such as the insecticide in a flea collar, or a matted coat that results in the retention of moisture underneath.

The typical hot spot is red, moist, and will be exudative (secrete fluid). The pet effectively removes all the hair from the affected area, irritates the skin, and causes a secondary bacterial infection. The lesion can be very painful and is usually located near the offending cause. The affected area typically gives off a foul, sweet, and yet necrotic odor. For example, if an ear infection is the source of the hot spot development, the area of affected skin will usually be behind or below the infected ear.

The skin 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 necessary to break the scratch-itch cycle and relieve the inflammation. Oral antibiotics are often necessary to control secondary skin infections.

There are many products available for topical use that incorporate corticosteroids, antibiotics, and topical anesthetics. Some of my favorite topical products include Neo-Predef Powder® available from Pfizer, Genesis Spray™ by Virbac, and Schering-Plough’s Gentocin Topical Spray®. A common sense rule in dermatology is: when the lesion is moist, then dry it up. The hot spot is moist, so in treatment we want to dry up the lesion. Neo-Predef powder does a superb job of drying the lesion out. It contains three essential components; a corticosteroid to relieve inflammation, an antibiotic to help control the superficial bacterial infection, and a topical anesthetic to relieve the pain associated with the lesion. Genesis spray is an inexpensive corticosteroid spray that may be used on ventral areas upon which a powder would not be practical. Gentocin topical spray is a similar product to Genesis Topical Spray® that incorporates an antibiotic in conjunction with a topical corticosteroid.

It is imperative to find and eliminate the causative agent resulting in the original hot spot formation or the pet may be subjected to repeated occurrence of the skin lesions. When ectoparasites are to blame, strict flea control is a must, or when due to an ear infection the ear infection requires treatment in addition to the hot spot.

Topics: ear infections, skin conditions

Symptoms: hair loss, itching, scratching

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