Localized keratinization syndromes (Proceedings)
There are a variety of keratinization defects that affect specific body locations, some of which are breed or species specific. The current discussion will cover acne, nasodigital hyperkeratosis, acne, stud tail, ear margin dermatosis, linear keratosis, schnauzer comedo syndrome and idiopathic facial dermatitis
Dogs and cats may both develop a disease referred to as acne. There is little to no work suggesting canine or feline acne has similarities to human acne. In humans acne is a complex disease and there is a role played by hormones, diet, the bacteria Propionibacterium acnes , sebaceous glands, and possible keratinocyte activation.(Heymann 2004; Adebamowo, Spiegelman et al. 2005; Nagy, Pivarcsi et al. 2005; Placzek, Arnold et al. 2005) Not only has little been done to study the disease in cats and dogs compared to humans we do not even no if it is the same in cats and dogs.Canine
Canine acne is believed to relate to abnormal follicular keratinization resulting in comedones. It has been suggested that dogs are different because hairless breed comedones have fatty acid profiles suggesting epidermal derivation and not sebaceous. Work in dogs prone to acne has not been done. Some cases do have prominent sebaceous glands in dogs with acne. We do not know if canine acne relates to abnormalities in sebaceous secretions that cause a localized fatty acid deficiency. In humans the local fatty acid deficiency then causes the follicular hyperkeratosis. We do know in dogs that the abnormal follicles become infected, usually with staphylococcus intermedius. Follicular rupture (furunculosis) may also occur and contributes more to the inflammation by inducing a foreign body reaction. Trauma and ingrown impacted hairs may also play a pathologic role in some cases.
Acne is most common in short coated breeds with Boxers, Great Danes and Doberman pinschers being especially prone. Lesions include comedones, papules, pustules, nodules and furuncles on the chin, lips and muzzle. Cellulitis with larger plaques may be seen.
Treatment is not always needed in young or mildly affected dogs. Benzoyl peroxide shampoos and gels are often prescribed for milder cases or as adjunctive therapy in more severe cases. Topical mupirocin is also helpful. Recently the author has had success utilizing Douxo ® Seborrhea Spot-on with 1% phytosphingosine as a spot on application twice weekly. In severe cases systemic antibiotics are indicated. Doxycycline has been shown to be effective and whether this is due to antibiotic or other effects is still to be determined.(Bensignor and Guaguere 2004) Rarely topical or systemic glucocorticoids or retinoids may be needed. The author has also used tacrolimus in some cases with limited response. Pentoxifylline can also be of value in more scarring cases for help with tissue perfusion of systemic antibiotics.