Acute Moist Dermatitis (Hot Spots) in Dogs


Overview of Canine Hot Spots

Acute moist dermatitis, also known commonly as “hot spots”, are localized, moist, reddened bacterial infections of the skin in dogs. A hot spot starts because something irritates the skin. The body’s response is either to itch or become inflamed. The itching then causes the dog to lick or chew the area, which further damages the skin, and creates a cycle of itching, scratching and chewing.

Hot spots can be caused by anything that irritates the skin and initiates an itch-scratch cycle, but the most common irritants are fleas. Other causes are allergies (flea, inhalant, food), parasitic disease (sarcoptic and demodectic mange), anal gland disease, poor grooming, tick and mosquito bites, burrs, and summer heat. They are most common in long-haired and heavy-coated breeds, and are more prevalent during the summer months.

Typical locations for “hot spots” are the side of the face and the flank areas. Golden retrievers, Saint Bernards and young dogs seem to be predisposed to acute moist dermatitis.

What to Watch For

Typically, your dog will exhibit the following:

  • Areas of hair loss with very red skin that is moist and oozing
  • In some cases, the skin becomes crusty or scabbed
  • Intense scratching. Hot spots are extremely itchy and your dog will scratch without letup
  • Diagnosis of Hot Spots in Dogs

    Diagnostic tests are needed to recognize acute moist dermatitis and exclude other diseases. However, your veterinarian can usually make a preliminary diagnosis based on a history of rapid onset and the clinical appearance of the lesions.

    Treatment of Hot Spots in Dogs

    Treatment for acute moist dermatitis in dogs may include one or more of the following:

  • Clipping and cleaning of the affected areas. Lesions often are more extensive than they initially appear. Clipping the hair in the area is important to allow proper cleaning of the affected skin. Antibacterial solutions (chlorhexidine) or drying solutions (Burrow’s solution) combat infection and decrease pruritus (itchiness).
  • Interruption of the pruritic cycle. This is crucial to successful treatment. Once the cycle has been triggered, it is important to stop it so as to prevent self-mutilation. Orally-administered cortisone-like drugs often are used for a short period of time to make the dog more comfortable. Your dog may be more hungry and thirsty while receiving corticosteroids – this is a common side effect of this medication. As a consequence, the dog may need to urinate more frequently than normal. Some dogs may also pant as a consequence of corticosteroid therapy.
  • Secondary bacterial infection must be treated when present. In some cases, damage is so extensive that bacteria proliferate, resulting in secondary infection. In such instances, an antibiotic may be prescribed for 2 to 3 weeks.
  • Identification and treatment of the underlying cause is important to prevent recurrent episodes of acute moist dermatitis. Most cases are secondary to flea allergy and aggressive flea control usually is necessary.
  • Home Care and Prevention

    Clean the affected areas with antibacterial and astringent products daily until healing is complete. Make sure that your dog has sufficient water while receiving corticosteroids. House soiling incidents may occur during corticosteroid therapy if the dog is not allowed outdoors frequently enough.

    If your dog has flea allergy and is prone to develop hot spots, you should be aggressive with your flea control program. In addition to treating the environment, you also should apply an appropriate insecticide or repellent to your dog to prevent flea bites.        

    In-depth Information on Canine Acute Moist Dermatitis (Hot Spots)

    Hot spots (also called acute moist dermatitis or pyotraumatic dermatitis) are localized, moist, reddened areas on the skin caused by self-mutilation. Acute moist dermatitis is a very common skin disease of dogs. hot spots are frequently seen in long-haired and heavy-coated breeds, and are more prevalent during the summer months.

    The precise sequence of events leading to acute moist dermatitis is not known but anything that can initiate an itch-scratch cycle can lead to acute moist dermatitis. Common underlying causes of hot spots include allergies (flea allergy, atopy, food allergy), parasitic diseases (sarcoptic and demodectic mange), anal gland disease, clipping and grooming. Less common causes of hot spots include ringworm (dermatophytosis), drug reactions, autoimmune disease in which the body fails to identify self-components and reacts against normal tissues, and vasculitis (inflammation of blood vessels).

    Clinically, the lesions of acute moist dermatitis are secondary to self-inflicted trauma. Strangely, even severe self-trauma in some dogs will not create a hot spot while in others minimal self trauma may do so.

    The role of bacteria in the development of hot spots also is not clear. Some cases of acute moist dermatitis seem to be initiated by folliculitis (i.e. inflammation and infection of hair follicles), and this seems to be common in Saint Bernards and Golden retrievers. Other affected dogs do not seem to have an important bacterial component and respond to clipping of the hair, cleansing of the skin and corticosteroid therapy.


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