By Matthew Kearns, DVM
When I hear the term “hot spots,” I usually think of free Wi-Fi. However, in veterinary medicine this term refers to a painful skin condition that is common this time of year (hot and humid weather).
“Hot spots” is a layman’s term. Pyotraumatic dermatitis or acute moist dermatitis are medical terms for hot spots and refer to rashes that pop up suddenly on the top layers of the skin (by suddenly, I mean within hours). The rashes resemble a human eczema type condition as the rash begins to weep. Patients appear to have been burned, are very warm to the touch, and have this condition more commonly in the warmer months. Therefore, the term “hot spot” is very appropriate.
What causes hot spots? They are usually the result of some allergy or irritation. Triggers included bug bites (including fleas and ticks), matted hair, contact irritations, seasonal allergies/food allergies, etc. The patient develops a focal rash that may be further irritated by self-trauma (chewing, licking, or scratching at the area). The most common sites are the neck and ears, followed closely by the thigh and tail region.
These rashes are commonly complicated by a Staphylococcus bacteria. This Staphylococcus species is considered normal flora, or bacteria that lives on the body at all times. Normally, they do not cause a problem because they are kept in check by the immune system. However, it can be a bit naughty if the conditions are right. When this bacterium proliferates it also releases an exfoliative toxin. An exfoliative toxin refers to a toxin produced by the bacteria that causes the cells of the skin to exfoliate, or fall off (like foliage falling off a tree). The dead skin cells, bacteria, and fluid from inflammation/self-trauma make a gooey mess.
How do we treat hot spots? If they are not too severe, they can be treated topically. Shaving and cleaning the area with antiseptic rinse or shampoo and topical medications (sprays, ointments, or powders) may be enough. However, many times these rashes are too painful (or at least initially too painful) to treat just topically. I will try to shave these areas but, if the patient is in too much pain, systemic medications like anti-inflammatories (corticosteroids, or cortisone derivatives) and antibiotics are needed to resolve these rashes.
If the rash is not resolving, your veterinarian may consider other causes that resemble hot spots and recommend additional testing (a culture or biopsy) to find the cause.
I hope this sheds some light on a condition with a weird name. Stay cool!!
Dr. Kearns practices veterinary medicine from his Port Jefferson office and is pictured with his son Matthew and his dog Jasmine.