Muscle problems may be in muscle itself but are more likely to be at the junction where muscle fibres and nerve fibres meet or in the nerve supplying the muscle. Strains, bruising and tearing are overwhelmingly the most common muscle problems.
Bruising And Tearing
Bruising, stretching or tearing of muscle fibres is difficult to see, especially in pets with full coats of hair. These forms of damage occur not only after injuries from falling, car accidents or abuse. They also occur after excessive work or exercise in dogs. Racing greyhounds are particularly prone to muscle tears. The signs vary with the degree of injury. Minor injuries produce local sensitivity and tenderness while major damage causes more swelling and greater pain.
Diagnosis And Treatment
Parting the hair may reveal reddening caused by bruised muscle damage below. Blood tests for muscle enzyme level indicate the degree of damage. X-rays differentiate between muscle conditions and those affecting bones and joints. Treatment is the same as for joint sprains - cold packs and rest. The most vital treatment is rest, for at least three weeks when damage is severe.
Polymyositis is, as its name says, an inflammation of many muscles. For unknown reasons it occurs most frequently in large, adult dogs. While parasitic diseases such as Toxoplasma, Neospora and Ehrlichia "cause" polymyositis, the clinical disease is really caused by overreaction of the immune system, inducing widespread muscle inflammation varying from mild to excruciatingly painful. There are other triggers for this immune-mediated disease in dogs including drugs such as trimethoprin-sulfa. The underlying cause is eliminated or treated. In addition, corticosteroids control both pain and the overactive immune system.
Immune-Mediated Jaw Muscle Disease In Dogs - Masticatory Muscle Myositis
This rare condition begins with dribbling saliva and swelling of the chewing (masseter) muscles. We have seen it most recently in a Hungarian Viszla pup. As the condition progresses the muscles shrink and it becomes painful for the pup to open its mouth. A muscle biopsy confirms diagnosis. Early treatment with corticosteroids is very beneficial.