Dermatomyositis in Dogs
Dermatomyositis is a hereditary inflammatory condition affecting the skin, muscles, and blood vessels in dogs. It commonly manifests in young collies, Shetland sheepdogs, and their mixed-breed counterparts. While similar symptoms have been observed in breeds like the Beauceron Shepherd, Welsh Corgi, Lakeland terrier, Chow Chow, German Shepherd, and Kuvasz, as well as in individual dogs, these cases are currently classified as ischemic dermatopathy rather than dermatomyositis. Research indicates that dermatomyositis follows an autosomal dominant inheritance pattern, with varying degrees of symptom severity. Typically, skin lesions appear before six months of age, sometimes as early as seven weeks, and reach their full extent by one year. Although rare, dermatomyositis can also occur in adult dogs.
Symptoms and Types
Symptoms of dermatomyositis encompass a spectrum, ranging from subtle skin lesions and muscle inflammation to more severe manifestations such as significant skin lesions and a general decrease in muscle mass, also known as muscle atrophy, accompanied by an enlarged esophagus. The intensity of skin lesions around the eyes, lips, face, and inner surface of the ears can vary, sometimes affecting the entire face. Additionally, the tip of the tail and prominent bony areas may also be impacted.
These lesions may fluctuate in severity over time, characterized by varying degrees of crusted areas and loss of skin surface, known as erosions or ulcers depending on the depth. Other skin manifestations include redness (erythema), accumulation of surface skin cells (dandruff), or scaling. Initial skin lesions might leave behind scars. Severely affected dogs may experience difficulty in eating, drinking, and swallowing.
Typically, symptoms of dermatomyositis manifest in affected dogs before the age of six months. While multiple litter-mates may be affected, the severity of the disease can differ significantly among them. Additional symptoms may include foot-pad ulcers, mouth ulcers, nail abnormalities, or loss, along with muscle inflammation. Signs of the disease may vary, ranging from subtle muscle mass reduction around the head, behind the eyes, and lower jaw to more generalized muscle loss across the body. A stiff gait may also be observed. Dogs diagnosed with an enlarged esophagus are at risk of developing pneumonia, necessitating precautionary measures to prevent pneumonia-inducing conditions.
Causes
The causes of dermatomyositis typically stem from hereditary factors, although they can also be linked to immune-mediated disorders or infectious agents.
Treatment
The majority of dogs with dermatomyositis can receive treatment on an outpatient basis. However, dogs experiencing severe muscle inflammation and an enlarged esophagus might require hospitalization for supportive care. In cases where the condition is too severe for treatment to be effective, euthanasia may be advised and recommended by your veterinarian.
Living and Management
To safeguard your pet’s skin from further irritation or harm, it’s important to avoid activities that could traumatize the skin. Keeping your pet indoors during the day can help prevent exposure to intense sunlight, which may exacerbate skin lesions due to ultraviolet-light exposure. Adjustments to your pet’s diet might be necessary if it has an enlarged esophagus or struggles with eating and swallowing.
Your veterinarian might suggest using hypoallergenic shampoos and treatments for any secondary bacterial skin infections. Additionally, they may prescribe supplements such as Vitamin E and essential fatty acids, along with steroids to reduce inflammation and medications to improve blood flow. It’s advisable not to breed infected animals, and intact animals should undergo neutering as recommended.