Dermatomyositis in dogs is a potentially severe, hereditary disease of the skin, muscles, and blood vessels that causes severe inflammation of these tissues in the body. An incurable condition with no known cause — but suspected to be an immune-mediated process, or caused by infectious agents — dermatomyositis can often be managed at home with lifestyle and dietary changes, hypoallergenic shampoos, and anti-inflammatory medications.
Dermatomyositis typically occurs early in the dog's life, before six months of age and as early as seven weeks. The full extent of lesions will be seen by one year of age. Adult onset of this disease is rare, but it does occur.
Some dog breeds suffer dermatomyositis more than others
Dog breeds with the genetic DNA trait for the disease are collies, Shetland sheepdogs, and their crossbreeds. Although symptoms of the disease have also been reported in German shepherd dogs, Beauceron shepherds, chow chows, Welsh corgis, Kuvasz, and Lakeland terriers, their condition is currently classified as low blood supply to the skin called ischemic dermatopathy — not dermatomyositis.
The signs and symptoms of dermatomyositis in dogs.
Characterized by variable symptoms, from subtle skin lesions to a dramatic loss of muscle mass (atrophy), some clinical signs of dermatomyositis are:
- Severe, crusty skin lesions
- Patches of hair loss (alopecia)
- Ulcers around the eyes, lips, and other areas of the face, the inner surface of prick ears, and the tip of the tail or any bony protuberances which erupt, then subside for a while, then erupt again.
- Reddened skin (erythema) with the accumulation of dandruff-like skin cells or scaling.
- Ulcers inside the mouth, on the foot pads and nail beds
- Stiff or "goose-step" gait in severely affected dogs.
Scarring can develop in the affected areas such as the chewing muscles, which makes eating, drinking, and swallowing difficult. If the esophagus — the tube that carries food from the mouth to the stomach — dilates, it may cause regurgitation, weight loss, and aspiration of food or liquid leading to pneumonia.
Diagnosing dermatomyositis in dogs.
Treatment and management of dogs with dermatomyositis and the prognosis.
Although the prognosis for dogs with dermatomyositis depends on the severity of the disease, a dog with a mild case has an excellent prognosis and may only need some lifestyle modifications. Often, the disease resolves on its own in mild cases with no scarring of tissues or muscles.
If a dog is moderately affected by dermatomyositis, symptoms may resolve spontaneously, but scarring is common.
Severe cases of dermatomyositis cause life-long muscle and skin inflammation. If the treatment protocol is ineffectual, euthanasia may be indicated due to the significant disintegration of the dog's quality of life. Supportive hospital care may be required in some serious cases. Only time will tell how an individual dog will ultimately be affected by the course of the disease.
If a dog's chewing muscles are affected by dermatomyositis, softened food rolled up in a ball and hand-fed makes meals more comfortable for him. Food consistency and feeding patterns can be customized for your dog by your veterinarian if the esophagus is enlarged.
To keep your dog's skin protected from further irritation and damage, avoid ultra-violet light exposure by limiting the time he spends outdoors — it's best to keep him indoors on intensely sunny days. Also, avoid any activities which may cause trauma to the skin or muscles. Skin erosions can be managed as they occur with veterinarian-prescribed anti-inflammatory creams to control any secondary bacterial infections. To control non-specific symptoms, some dogs will need vet-prescribed hypoallergenic shampoos for bathing.
Anti-inflammatory medications such as steroids and medications to improve blood flow may also be prescribed by your veterinarian along with Vitamin E and essential fatty acid supplements.