Hot Spot …or Not?

   One of the most often used terms to describe an area of irritation on pets is “hot spot”. When pet owners describe their dog’s lesions as “hot spots”, they might be asked what that actually means to them and to explain what they are describing as a “hot spot”. Many times, what is initially referred to as a “hot spot” is simply a bacterial infection and the approach and the diagnostic implications of these two things can be completely different.

What exactly is a “hot spot”?
     Hot spots are areas of irritation on the skin produced by self-trauma. Unless the patient has created the lesion on the skin due to scratching it is NOT a “hot spot” by definition. The initial source of the itch to the particular area may be caused by an allergy, ear disease or parasites.  To seek relief from the itch, the patient will scratch or chew creating a surface irritation and inflammation. 
     The result is a red, moist and raw area (see picture) that may be accompanied by matted hair that has accumulated fluid and blood and will develop adherent crusting to the skin. These lesions can develop rapidly, literally overnight. Most hot spots are located on the side of the face, neck, rump or tail. Surface infection or overgrowth of bacteria are generally present as well.
    

      Crusted lesions and pustules indicative of a bacterial pyoderma are often incorrectly called hot spots by pet owners. It is true that a hot spot often develops a degree of infection but infections that develop on the skin are NOT hot spots. An infection is the growth of bacteria in a break in the skin or hair follicle. The infection and a hot spot may present similarly but the approach to treatment is different.
     For a hot spot, identification of the underlying cause of itching is key. First the hot spot must be treated to bring comfort to the dog and then address the cause of the irritation. To treat a hot spot, topical or occasionally oral glucocorticoids may be needed to help break the itch cycle. In addition, topical or oral antibiotics are often needed to treat the surface infection. Once that is controlled, investigation into the cause of the itching that created the hot spot becomes important. While generally for bacterial pyodermas, topical and oral corticosteroids are contraindicated and may result in persistence or recurrence of the bacterial infection. Oral or topical antibiotics in these cases will resolve the infection. In cases where bacterial infections may be pruritic, antihistamines are a better choice. However as with hot spots, continued investigation as to the cause of the bacterial infection will be important to prevent and manage relapse.
Source: David Duclos, Canine & Feline Skin Diseases
Rusty Muse DVM, ACVD, Animal Dermatology Clinic


** Download the PDF print version of Derm Digest to see additional articles **