Dermatomyositis in Dogs

Dermatomyositis like another disorder known as polymositis is a condition that negatively impacts a dog's muscles. The real difference between the two conditions, is that dermatomyositis not only damages a dog's skeletal muscle, but it causes lesions on the skin too and studies have established that some breeds appear to be more predisposed to developing the condition than others although why this is so remains unclear.

Breeds Most at Risk

The breeds that appear to be more predisposed to suffering from dermatomyositis includes the following:

• Rough-coated Collies
• Shetland Sheepdogs
• Australian Cattle Dogs

Symptoms Associated with the Disorder

Affected dogs show definite signs of there being something wrong with them when they suffer from the condition. The symptoms most commonly associated with dermatomyositis typically include the following:

• A still, stilted gait
• Swollen muscles
• Painful muscles when touched
• Weakness
• An intolerance to exercise
• A swollen oesophagus which is referred to as megaesophagus
• Regurgitation
• Skin lesions

The Causes

When dogs develop dermatomyositis, it is usually because they are suffering from the following health issues:

• Immune-mediated infections
• Cancer

However, it is worth noting that a dog might develop the condition as a reaction to certain drugs and medication they have been given too.

Diagnosing the Condition

A vet would ideally need to have a dog's full medical history and be told how the onset of any symptoms first presented themselves. The more information a vet can be given, the better. A vet would thoroughly examine a dog suspected of suffering from dermatomyositis and would typically recommend carrying out the following test to confirm a diagnosis:

• A complete blood count
• A full biochemistry profile
• A urinalysis
• Test to assess creatine kinase enzyme levels which are found in muscles, the brain other tissues which would confirm the extent of muscle damage
• X-rays to establish if a dog's oesophagus has been damaged and which would also help identify any growths or tumours

Treatment Options

The first thing a vet would want to do is suppress a dog's immune system when they are suffering from dermatomyositis. They would also prescribe a course of antibiotics with the end goal being to fight off any infection and it's essential for the complete course to be finished for the treatment to be effective. Should it be found that the cause is a more severe immune-mediated disorder, a dog may need to be put on long-term treatment of corticosteroids.

Living with a Dog with Dermatomyositis

Providing a dog responds well to a treatment and the inflammation to their muscles decreases, they can be given more in the way of exercise which would help strengthen their muscles. However, if a dog's oesophagus has been negatively impacted, they would need to be hand fed a special diet that would be easier for them to swallow and which would reduce the risk of regurgitation. If the oesophagus is severely affected, it may be necessary to feed a dog via a tube to ensure they are receiving the correct level of nutrition which often means a dog may well have to remain hospitalised until they can eat on their own again.

Supportive care is all-important for dogs when they are recovering from dermatomyositis and this includes making sure any lesions and other skin issues like ulcers are treated correctly should they develop again.

Prognosis

The good news is the prognosis for dogs suffering from dermatomyositis where the underlying cause is an immune-mediated disorder tends to be positive. However, should the vet find the underlying cause to be cancer, the prognosis tends to be a lot poorer.