The Causes of Muscular Atrophy in Dogs

Muscular atrophy in dogs refers to the weakening or wear of their muscle mass. It's caused by both, lack of activity and secondary disease.
The Causes of Muscular Atrophy in Dogs

Last update: 23 October, 2019

Muscular atrophy in dogs (the loss of muscle tissue) is quite common. This muscle wear is usually the result of an injury or illness. You might not notice it at first, especially if your dog has long hair.

Limping will be more obvious if your dog recently underwent surgery. Therefore, atrophy will accelerate and be more noticeable. Actually, it’ll worsen before it gets any better. Today we’re going to tell you the most common causes.

Why isn’t muscle atrophy in dogs detected early?

Because dogs move using their four limbs, their balance is quite delicate. When one limb hurts, they just transfer their body weight to the other three legs to relieve it.

It’s for this reason that, in the early stages, you may not even notice it. However, if you feel their legs, you’ll notice that there’s a difference in muscle density. This is precisely how you’ll know that the muscle is atrophied. This is quite common when the dog isn’t using their legs so much due to pain.

Muscular atrophy mainly shows itself by thinning and becoming weak. It could also be a sign of a wide variety of conditions and diseases, so, if you notice that your animal is losing muscle mass in some areas, then run it by your veterinarian.

The normal canine aging process

A sad looking dog on a couch.

It’s natural for moderate, but progressive, muscular atrophy to appear as a dog ages. This results from the lack of growth hormones and a decrease in their metabolism.

As dogs become older, their nutritional needs change and they can’t process proteins the same way they did when they were younger. Thus, older dogs will eventually need a much more specialized diet, with protein that’s easier to process and other nutrition sources that will help them maintain their muscle mass.

In addition, a dog becomes less active as it gets older due to its lower energy levels; it can also lead to muscle loss. Note that this is part of the normal aging process and it usually happens in the hips, where the muscles are more evident.

Muscular atrophy in dogs and arthritis

This decrease in muscle mass also happens for many other reasons. It turns out that atrophy is a typical symptom of those with a chronic painful condition.

Even though arthritis mainly affects the joints and not muscle tissue, it’s common for it to lead to muscular atrophy. Arthritis is an inflammatory process that leads to osteoarthritis, often in the hips and knees. It causes intense pain and discomfort.

Constant pain reduces an animal’s mobility. In the long term, the decrease in activity will end in muscular atrophy.

Physiotherapy and pain control medication can minimize the effects of arthritis and improve a sick dog’s activity. Consult your veterinarian for them to prescribe the most appropriate treatment.

Genetic predisposition to associated diseases

An older dog lying on the floor.

You must be attentive to the conditions that certain breeds are predisposed to. For example, Labrador retrievers are prone to type II muscle fiber deficiency. In general, they’ll suffer muscle loss before their first year of age.

Likewise, German Shepherds are more likely to develop fibrotic myopathy, which usually shows itself in an animal’s thigh muscles. Other breeds, such as Greyhounds, will develop stress myopathy if forced to overexert their muscles.

Degenerative myelopathy is another disease that affects a dog’s spinal cord and then their limbs. This condition is common in German Shepherds, but also afflicts other breeds.

Muscular atrophy in dogs and inflammatory diseases

Muscular atrophy may occur at the same time as other types of inflammatory diseases, be they infectious or autoimmune types. This involvement can happen to only one muscle, or to a group of muscles. Usually, these diseases show themselves together with other symptoms that’ll help a veterinarian diagnose them accurately.

What you should know is that myositis – the inflammation of the muscle – could lead to muscle atrophy at times. Myositis is the result of an abnormal reaction of your dog’s immune system against their own muscle tissue.

There’s also myositis of the chewing muscles, also called eosinophilic myositis. It’s an autoimmune inflammatory disease and a pernicious condition. The dog develops antibodies that recognize and attack the M2 fibers of the masticatory muscles, which leads to their atrophy.

Symptoms of muscular atrophy in dogs

Watch for the following signs and symptoms so you can help your pet in time:

  • Lethargy and apathy. The dog barely feels like moving.
  • Flaccid state. Look for flabby muscles in your dog that aren’t as hard as they used to be. You may also notice that your dog feels softer and also thinner.

Sometimes, this type of muscle loss will only affect certain parts of the dog’s body. For example, if your dog has arthritis or an injury in their hind legs, you may notice that these are getting thinner, while the front legs are enlarging to compensate. If you suspect that your dog is losing muscle mass in one leg, then compare it to the other side.

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  • Prandi Chevalier, D., Eros Roncone, R., García Guasch, L., & García Arnas, F. (1997). Miopatía del complejo muscular Gracilis-Semitendinoso. Clínica veterinaria de pequeños animales, 17(3), 0143-150.
  • Santelices Iglesias, O. A., & Del Amo, A. Miopatía inflamatoria generalizada asociada a hepatozoonosis en un canino: reporte de un caso.
  • Amieva Garza, D. (2016). Manual de rehabilitación y fisioterapia del miembro pelviano en perros (con pérdida de masa muscular).
  • San Román Ascaso, F., Llorens Pena, M. P., Prandi Chevalier, D., Peña Giménez, M., García Arnas, F., & Franch Serracanta, J. (1988). Miositis eosinofílica en el perro: caso clínico. Clínica veterinaria de pequeños animales, 8(1), 0042-48.