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Causes of Hind Leg Weakness in Canines

Updated: Aug 5



If your dog's hind legs are weak, you might be wondering whether Cushing’s is to blame. The short answer is maybe. Cushing’s disease is one of many conditions, including neurological disorders and arthritis, that can be responsible for hind leg weakness. This article provides an overview of potential causes, some of which are related to Cushing’s and others unrelated. We strongly recommend consulting your veterinarian to determine which one applies to your pet.


Too much cortisol (Cushing’s disease)


Cushing’s disease often causes hind leg weakness because cortisol is a catabolic steroid that breaks down muscle tissue and converts it to glucose. The end result of excessive cortisol is that muscles become smaller and weaker. Cortisol has a major impact on muscles in the hind legs because they are more sensitive to its effects than muscles in other areas.


Treating Cushing’s disease and getting cortisol levels under control will usually slow down muscle wasting, but it can take time for dogs to regain strength in their hind legs. The earlier that a dog is started on treatment, the better the chance of recovery.


In addition to treating Cushing’s with medication, many pet owners use over-the-counter supplements to help with the process of rebuilding muscle. A list of supplements can be found in our article, Supplements for Muscle Health.


Not enough cortisol (Addison’s disease)


Excessive cortisol is not the only thing that causes hind leg weakness; it can also be caused by a lack of cortisol. If your dog is being medically treated for Cushing’s disease and develops symptoms such as hind leg weakness, trembling, shaking, or collapse, it’s possible that their cortisol levels have fallen too low. This is an adverse reaction that can happen when dogs are on an incorrect dose of Vetoryl (trilostane) that is higher than needed.


Pause medication and seek veterinary care as soon as possible if your dog exhibits any signs of cortisol insufficiency, including weakness, lack of appetite, vomiting, diarrhea, collapse, or shaking. Your veterinarian will conduct an ACTH stim test or Pre-Vetoryl Cortisol test to check cortisol levels.


Arthritis (can worsen with Cushing’s treatment)


Arthritis is another condition that often causes pain or weakness in the hind limbs. For many dogs, arthritis becomes more noticeable when Cushing’s disease is treated. Excess cortisol has a powerful anti-inflammatory effect that can hide joint pain, and lowering cortisol when treating Cushing’s unmasks this pain. If your dog shows signs of arthritis, your veterinarian will recommend treatment based on his or her specific needs.


Blood clot (saddle thrombus)


Sometimes, hind leg weakness is a sign of a dangerous blood clot, which dogs with Cushing’s have an increased risk of developing. When a clot forms in the aorta, the largest artery that carries blood from the heart, it can cut off blood supply to the hind legs and cause symptoms such as hind leg weakness, paralysis, and severe pain. Additionally, the rear paws may be blue or cold to the touch, due to lack of blood flow. This is a rare, but potentially fatal, condition requiring emergency medical attention. More details about saddle thrombus can be found in the article, Signs of Saddle Thrombus: A Time Sensitive Pet Emergency, by Garden State Veterinary Services.


Neurological disorders


There are several neurological disorders that can affect the hind legs. These include degenerative myelopathy, intervertebral disc disease, and lumbosacral stenosis. Treatment of neurological conditions depends on the cause. For more information, see 8 Neurological Disorders in Dogs That Affect Back Legs, by Glenn Parkes.


Other potential causes of hind leg weakness


Other potential causes of hind leg weakness in dogs include Lyme disease, congestive heart failure, traumatic injury, and exposure to toxins. Because there are so many health issues that can cause this condition, it’s important to have your dog examined and treated by a veterinarian when showing signs of weakness or muscle loss.


References


Cushing’s Disease in Dogs, by Long Beach Animal Hospital







Hypercoagulability and ACTH-Dependent Hyperadrenocorticism in Dogs (Journal of Veterinary Internal Medicine, Volume 27, Issue 5, September-October 2013)


 
 
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