"Polymyositis in Dogs

"Polymyositis in Dogs

Health & Safety

Polymyositis is a disorder that seriously and negatively impacts a dog's muscles. It is much like dermatomyositis only polymyositis affects the skeletal muscles causing all the damage through inflammation. Polymyositis does not involve any sort of lesions or pus forming in affected areas, but the condition can still cause a tremendous amount of pain and damage with some breeds being more predisposed to suffering from it than others.

Breeds Most at Risk

As previously mentioned, research has shown that some breeds are more at risk of developing polymyositis than others although why this is so remains a bit of a mystery. The breeds that are more predisposed to suffering from the condition are as follows:

  • Newfoundland
  • Boxer

Symptoms Associated with the Condition

When dogs develop the disorder, there are certain signs to watch out for which are a good indication of there being something seriously wrong with them. The symptoms most commonly associated with the disorder typically includes the following:

  • A stilted gait
  • Swollen muscles
  • Weakness in muscles
  • Muscle pain more especially when touched
  • Intolerance to exercise
  • An enlarged oesophagus
  • Regurgitating food

The Causes

Studies have shown that some dogs develop the condition when they suffer other health issues which includes the following disorders:

  • Immune mediated infections
  • A reaction to medication and drugs
  • Cancer

Diagnosing the Problem

A vet would ideally need to have a dog's full medical history and know their ancestry too. The more information a vet can be given the better, and this includes knowing how the onset of any symptoms first presented themselves. The vet would thoroughly examine a dog suspected of suffering from polymyositis and would usually recommend carrying out the following tests which would help confirm a diagnosis:

  • A complete blood count
  • A full biochemistry blood profile
  • A urinalysis
  • Tests to evaluate the levels of creatine kinase enzymes in a dog's brain, muscles and other tissues of the body which would help establish the degree of muscle damage that has taken place

Vets normally refer dogs with the condition to a veterinary pathologist who would be more qualified to evaluate the severity of the disorders and therefore be in a better position to recommend treatment options.

Treatment Options

A vet would prescribe a specific treatment for dogs suffering from polymyositis which would involve giving them medication to help suppress their immune systems if they prove to be overactive. Dogs would also need to be put on a course of antibiotics and it's essential they be given the full course for the treatment to be effective. In many cases, longer term medication is needed more especially if a dog's condition is diagnosed as being a severe immune mediated disease.

Living with a Dog with Polymyositis

Once a dog has been successfully treated for polymyositis, an improvement in the condition of their muscles would be apparent quite quickly. As such, it is essential for dogs to be exercised with an end goal being to improve muscle strength. However, should a dog have an enlarged oesophagus because they have suffered from the condition, they would need to be carefully hand fed small meals several times a day rather than one or two larger meals. Supportive care is crucial for dogs that have suffered from polymyositis more especially during their recovery period.


The prognosis for dogs suffering from polymyositis is generally very good with most dogs making a recovery once they have been successfully treated. However, if it is found that cancer is the underlying cause of a dog's condition, then the prognosis for dogs suffering from polymyositis tends to be very poor.

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