SlimDoggy Health Check: Muscular Disorders
Last time, in our Muscular Disorders section of our Health Check Series, we focused on muscle & ligament issues including sprains and strains. Today we are going to take a closer look at other muscular disorders that may affect your dog.
There are two main types of muscular disorders:
- Myopathy which is a muscular disease in which the muscle fibers do not function for any one of many reasons, resulting in muscular weakness.
- Myositis which is an inflammation of the muscles used to move the body caused by an injury, infection, or autoimmune disease.
Degenerative Myelopathy is a progressive, degenerative disease that affects the spinal cord of the dog and eventually may lead to paralysis. Onset of the disease may be as early as eight years of age and is caused by a breakdown of the myelin, the sheathing that protects the nerves that control the communication between muscles and the brain. As this breaks down, so does muscle control. While this is not typically painful to the dog, it eventually leads to loss of mobility, bladder & bowel control and eventually may impact the front legs as well. It is thought to be an auto-immune disorder similar to MS in humans. Symptoms at first are just a wobbling when they walk, or they may have difficulty standing. It gradually increases to the point where they can no longer use their back legs. Diagnosis is made through elimination of other causes of the symptoms. Your vet will likely run xrays and an MRI to rule out degenerative disk disease or other spinal issues. There are no known cures for DM, so treatment revolves around maintaining quality of life by managing the disease and subsequent issues that may arise including incontinence and lack of mobility.
UPDATE: Thanks to our friends at 2 Brown Dogs who called our attention to more recent research from the AKC Canine foundation on Degenerative Myelopathy. They report on a number of tests involving DM, including research into causation, testing and treatments. One of their hypothesis is that it resembles ALS disease found in humans. You can read more about it at the AKC site.
Myositis is inflammation of the muscle and may affect just one muscle, or a group of muscles. It can be caused by any number of factors including auto-immune disorder, injury or even a parasite. There are several different types of myositis including Polymositis and Dermatomyositis. Symptoms include a stiff gait, swelling, and muscle wasting. Some Myositis may even cause lesions on the skin of the dog. If the muscles of the jaw are affected, your dog may have trouble chewing and may avoid eating. Diagnosis is made through a tissue sample of the muscle. Depending on the location of the myositis, treatment may be on an outpatient basis. The goal is to reduce the inflammation of the immune system and is typically accomplished through high dosages of steroids (prednisone). Your dog will always be susceptible to a recurrence, so prevention includes a monitored exercise program to keep your dog’s muscles strong and healthy.
Myasthenia Gravis is a serious disorder that affects the transmission of signals between the nerves and muscles. This breakdown prevents the muscles from contracting and leads to weakness and fatigue. The disease is genetic and typically found in Jack Russells, English Spaniels and Dachshunds. It can also be found in older dogs with weakened immune systems. Symptoms may vary but include extreme weakness and fatigue. Since it may affect the esophagus, it may impact your dog vocalizations, ability to eat and he may regurgitate. It may also lead to aspiration which can cause pneumonia. Since there are many things that may cause weakness and fatigue, your vet will likely prescribe a series of tests before being able to confirm this diagnosis. These may include: thorough blood panels, urinalysis & fecal tests, thyroid test, xrays and even MRIs. If diagnosed, the treatment plan will be tailored to your dog’s needs. If he has developed pneumonia, then proper antibiotics and possibly steroids may be prescribed. Your dog may also be given anticholinesterase which helps improve muscle strength by decreasing the disease’s attack on the muscles. There is no prevention for Myasthenia Gravis, but your dog will need regular monitoring and care to prevent a recurrence.
Generalized Inflammatory Muscle Diseases in Dogs
Inflammation of the Skin, Muscle, and Blood Vessels in Dogs
Degenerative Myelopathy – Disease Basics
Why Early Diagnosis of Canine Degenerative Myelopathy (DM) Is Important
Myasthenia Gravis in Dogs
Nerve/Muscle Disorder in Dogs