Fortunately, hot spots - also known as lick granulomas, acral lick dermatitis or acute moist dermatitis - are not especially difficult to diagnose. The raised, thickened, red and often weeping wounds that are the classic signs of hot spots are usually quite easy for owners and veterinarians to see, even on long-haired breeds. However, it often is quite difficult to identify, treat and successfully resolve the underlying cause of the dog’s condition.
Most veterinarians are easily able to recognize hot spots based on a dog’s history of compulsive licking and chewing and on its clinical presentation. Unfortunately, detecting what is causing the chronic licking behavior is not so simple. The veterinarian can take skin impressions by pressing a glass slide directly onto the hot spot and then examining it under a microscope to look for the presence of cancer cells and to rule out abnormal overgrowth of Demodex canis mange mites. Deep skin scrapings can also be taken from the affected area and evaluated microscopically. Special laboratory growth media are available to culture and identify nonparasitic fungal infections. Biopsies can be taken from the affected area and should include both healthy and unhealthy tissue in the same sample. Biopsy specimens usually are sent to an outside diagnostic laboratory for microscopic assessment through a process called histopathology. Skin samples may also be cultured to identify infectious bacterial and/or viral organisms.
Many veterinarians will take blood and urine samples and run routine blood work (a complete blood count and serum biochemistry profile) and perform a standard urinalysis on dogs presenting with hot spots. This can be useful to get a snapshot of the dog’s overall health and to uncover evidence of any underlying disorders, such as kidney disease, hyperadrenocorticism (Cushing’s Disease) or hypoadrenocorticism (Addison’s Disease). Thyroid tests can be run on a blood sample to see whether hypothyroidism is a contributing factor. Food elimination diets may be recommended to identify any allergies to ingredients in the dog’s diet. If fleas, mites or other external parasites are visible, they need to be eradicated, and then the dog should be put on a regular parasite-preventative program as recommended by its doctor. Radiographs (X-rays) can help the veterinarian detect any bony abnormalities, foreign bodies or joint defects that may be contributing to the dog’s discomfort. Finally, the veterinarian may refer the owner to a veterinary behavioral specialist, especially if no primary organic abnormality is found.
The search for the primary cause of a dog’s excessive and self-destructive licking that leads to hot spots can be extremely frustrating, for the owner and no doubt for the animal as well. However, if the owner sticks with it, most hot spots can be successfully treated.