These nasty, rapidly spreading skin lesions are medically termed acute moist dermatitis, with the common name "hot spots".

These skin infections can flare up and spread within a matter of hours, making your dog extremely miserable. Cats get them on occasion, but dogs, especially those with thick coats, are most susceptible.

The skin has a built–in barrier to protect itself from bacteria, primarily "staph" bacteria, which live naturally on all skin. When the natural skin barrier is compromised due to flea bites, allergic reactions, or ear infections, your dog will itch and scratch causing more damage to the skin surface with bacteria invading.

This sets up a nasty infection, which grows rapidly along the surface of the skin because the environment is so conducive: thick fur, not much air circulation to dry it out, dark and warm, get the picture? Plus, as bacteria grow on the surface, itching increases, so your dog scratches more, abrades the skin more and we have a vicious cycle.

First, you will find a moist, pink skin area that your dog scratches or chews. The most common areas I see "hot spots" on dogs are on the side of the face, under the neck, on their outer flanks and sometimes the tail. Bacterial growth causes the lesions to turn yellowish to green on the surface as other bacteria join the mix. The worst one I´ve have seen was on a Labrador and his entire chest – from under his chin down to his legs –was one big oozing sore.

Don´t be angry at your vet for shaving his fur! Often, this is the only way to stop the infection from spreading, as it removes the "nice" environment. If the spot is small, you might be able to stop the spread by cleaning it with hydrogen peroxide (which may sting a little) and anti–bacterial soap. Then treat topically with antibiotic and steroid ointment. A little oral antihistamine helps take the allergic reaction away as well.

When the spot is large, your dog will often need to have the area shaved and cleaned. If warranted, I give a corticosteroid injection so the dog won´t be so miserable, and then put on an antibiotic.

If you find your dog chewing a little spot or digging at an ear canal when you leave for work, you can definitely find a "hotspot" when you come home. If you come home to your dog with this condition, inspect him for fleas, even one can be a problem. If you have allergy medications for your pet, treat before the chewing causes a more severe problem. Flea products, ear cleanser and a good cleansing bath and drying may help stop the problem from progressing as well.

Sharon E. Anderson, DVM

Sharon E. Anderson, DVM, answers medically-related questions, but will not attempt to diagnose or recommend specific treatments. Her advice is not meant to replace professional care. If your pet is ill, contact your veterinarian immediately.