What is a "hot spot" in a dog?

Category: Canine

My dog, a golden retriever, has a wound on her front right leg. It is about the size of a quarter and she keeps biting at it. She had been biting at this area before the wound appeared. My neighbor called the wound a "hot spot." What is this? What should I do to treat it?

An acute skin condition caused by self-inflicted injury.

A "hot spot," or acute moist dermatitis, is an acute, painful, erosive, inflammatory condition of the skin. It results when a dog repeatedly bites or scratches a specific area of its skin or ears. An underlying problem that produces itching or pain usually prompts this self-induced trauma. The hot spot will have a reddish border surrounding a central area of crusty, eroded or ulcerated skin. Hot spots are moist and tend to drain. They often are infected, usually with Staphylococcus intermedius, a bacterium similar to a type that causes boils in people. Small pockets of pus may appear to migrate out from the middle of the hot spot. Hair loss will occur in the affected area. Hot spots tend to occur in dogs living in hot, humid environments and in homes or facilities with poor ventilation. Large breeds are more likely to develop hot spots than smaller dog breeds.

There are many different conditions that may cause a dog to engage in this biting and scratching behavior. The most common cause is fleabite allergy. When a dog becomes sensitive to flea saliva, a fleabite will cause intense, persistent itching. Other allergies, including inhalation (atopy) and food allergies, may also cause scratching and biting that leads to the development of hot spots. Other conditions that may stimulate self trauma include inflammatory conditions of the skin, ears or anal sacs, bacterial, fungal or parasitic infections, and joint or muscle pain. Canine behavioral disorders may cause this as well.

Diagnosis of acute moist dermatitis is based on history, clinical signs of biting and scratching and the findings of a physical examination. Diagnosis of the underlying cause may require laboratory tests. These may include various skin tests for allergies, fleas and other parasites, fungal and yeast infections, or bacterial culture and susceptibility. Occasionally a skin biopsy may be necessary.

Treatment is directed both at the hot spot and the underlying cause of the biting or scratching.

An Elizabethan collar may be used to mechanically bar biting and scratching of the affected areas. Treatment for hot spots starts with clipping the moist hair to expose the lesion to the air. Clipping is a very important factor in treating these lesions, as they need to dry out in order to heal. Topical or oral medications, including corticosteroids (for their anti-inflammatory effect), antibiotics, and anti-pruritics (anti-itching drugs) may be given to help resolve the hot spot. Occasionally injectable forms of these medications are given. Drying agents may also be appropriate.

The underlying cause of the affected dog's biting and scratching is treated accordingly. If fleas or other parasites are involved, parasiticides are given and other control measures are taken. If allergies are causing the itching, antihistamines may be prescribed, as well as allergy shots if the allergen (the substance causing the allergic reaction) cannot be avoided. If pain due to arthritis or other conditions is involved, appropriate analgesics and anti-inflammatory medications may be prescribed.

You should take your dog to your veterinarian for a physical examination. First your veterinarian will make sure that the problem your dog has is a hot spot. Then he or she will determine the underlying cause of your dog's biting and scratching and recommend treatment. Your veterinarian may give you topical medications to help dry the lesion out and decrease the itch. Injections of steroids or oral steroid medications are often used for the acute flare-ups, but long-term control may be better achieved by successfully treating the underlying disorder.