Hair follicle tumors are not pretty to have to deal with, but are typically not malignant or an indicator of cancer in dogs. There are several different types of hair follicle tumors, one that can be serious, so it is important to have any skin growths or tumors checked through a biopsy to ensure they are benign.
Some breeds are more prone to hair follicle tumors than others. Poodles of all sizes are somewhat predisposed to this condition as are Cocker Spaniels and Basset Hounds. There is no indication that either males or females will be more prone to having the condition and it can occur at any age and with any type of diet. It has also not been linked to any particular grooming procedure and it seems from the research it may be an inherited condition but conclusive research has not been completed to be able state this as a fact.
The hair follicle tumor can involve or be part of any one of the eight specific layers of skin that are found in and around the hair follicle. The two basic types are trichoepitheliomas tumors or those that include the hair itself and the sheath or root of the hair, or the far less common pilomatricomas that involve only the hair shaft and the inner sheath of the root of the hair. The latter, the pilomatricomas tumors, are typically only seen in Kerry Blue and Wheaten Terriers, Standard Poodles, Bichon Frise and Bouvier des Flanders.
Either type of hair follicle tumor can be benign or, extremely rarely, malignant. In the case of both types of tumors a small wart like growth will be noticed on the skin, usually on the head or neck. The tumors may also be found on the trunk or body of the dog, especially in the case of adult and senior dogs of predisposed breeds. The tumors are typically flat to the naked eye or touch and are slightly raised from the skin. There is usually no hair on the tumor itself and it may be up to 5-7 cm in diameter. When it first develops it will feel like an unconnected cyst that will move slightly under the skin with gentle pressure. It is not usually painful for the dog. As the tumor enlarges it may discharge a thick, curded looking yellowish substance that will be very grainy in appearance with a pilomatricomas type of tumor. Usually the vet can easily distinguish between the two with a biopsy and examination of the tumor itself.
Treatment for both types of hair follicle tumors involves surgery to remove the tumor and affected hair follicle. This surgery may require the dog be completely anesthetized and the tumor removed, often stitches are not required if it is small. In the rare case where the tumor is malignant the vet will need more aggressive surgery to remove surrounding tissue. Usually dogs that have one hair follicle tumor will get more as they become older. Early detection and removal will help to decrease the chances of any type of bacterial infection and will also make the procedure much easier for both the dog and the vet.