This is one of the biggest concerns we hear from owners of senior dogs, “my older dog’s back legs are giving out! What can I do?” It is definitely distressing to watch your dog struggle to get up and to walk. We start to worry about that final trip to the vet.

Dog with general weakness.

Before we can figure out what to do about the legs giving out, we need to figure out why they are giving out, as it can happen for a number of reasons. While a through physical exam by either your vet or canine rehab therapist can help determine the cause, here’s a list of some of the more common reasons we see for back leg weakness.

1. Osteoarthritis

Osteoarthritis, or “arthritis,” is the loss of cartilage within a joint that results in pain and inflammation. Often what happens with dogs who develop arthritis is the pain can lead to decreased levels of activity. This can be on the part of the dog who no longer gets up and moves around as often because it’s painful, or on the part of the owner who doesn’t feel confident in taking their dog for as long of a walk because they are fearful of harming their dog.

Very quickly, this reduction in physical activity can lead to muscle loss. This weakness can cause a dogs hind legs to collapse when first getting up or when they are fatigued. Quick jolts of pain in the legs can also, for very short moments (like milliseconds) cause the leg muscle to turn off, causing a collapse.

So there are two problems with arthritis: 1. Pain 2. Weakness

2. Degenerative Myelopathy.

Degenerative Myelopathy, or “DM,” is similar to human ALS. It involves the degeneration of the nerves within the spinal cord, essentially disrupting the message between the brain and the muscle in the body. If the muscles don’t get the instructions from the brain on how to work, they don’t work well and eventually stop being able to work at all.

Unlike arthritis, DM is not painful. This is not to say that dogs with degenerative myelopathy can’t have pain, but rather the degenerative myelopathy itself doesn’t cause pain.

 

The problem with DM: the message to the muscles on how to work is not coming through clearly (or at all).

Dog with Degenerative Myelopathy
Farley

3. Muscle Loss Due to Aging

It is a fact that aging mammals, including dogs and humans, lose muscle mass with aging. Surprisingly, research hasn’t 100% identified why this happens. The theory is that as the body ages, it does not create new muscle as efficiently as it used to. This doesn’t mean that all hope is lost. We can help our dogs increase their muscle mass with healthy diets that contain enough protein and with exercises that target the specific muscles that need strengthening.

Dogs place 60% of their body weight on their front legs and 40% on their back legs. Is it any wonder then that we see weakness happening in the back legs sooner than the front legs? They are using them less to begin with.

It is common for dogs to lose strength in their back legs as they age but we shouldn’t accept this as normal. It is easily combatted with diet and exercise.

The problem with aging: loss of muscle mass

4. Intervertebral Disc Disease

Most people think of intervertebral disc disease, or “IVDD,” as a condition that happens in small dogs like Daschunds, French bulldogs and Beagles. With these breeds, the progression from walking, to pain to paraesis (weakness) to paralysis tends to happen generally quickly (hours to days). It happens because the disc pushes into the spinal cord and interrupts the message traveling from the brain to the legs. It is different than DM, in that there is pain involved along the spine.

Larger breeds can also be affected, such as Labradors, German Shepherd Dogs and Doberman Pinschers. The difference in larger dogs, is the onset of symptoms tends to be much more gradual happening over days, weeks or even months. Because the symptoms tend to happen more gradually, it can be easy to overlook a neurological cause to back leg weakness. However, because the message from the spinal cord is still being interrupted, the back legs can still be weak, drag or even collapse.

With either type of IVDD, if the pressure on the spinal cord is not relieved, eventually the muscles in the back legs will start to lose strength and size because they are no longer working. If you don’t use it you lose it. If the message can be restored, the muscle strength can be saved or rebuilt.

The problem with IVDD: disruption of the nerve messages to the back legs which can eventually lead to a real loss of strength in the muscles.

Dog with IVDD

5. A Combination of Reasons

For most dogs, especially senior ones, there can be a combination of things leading to weakness. The dog with IVDD may also have arthritis in their hips and knees or may have already started to lose strength in their back legs before a disc become problematic.

Now that you have an idea of some of the common reasons why your dog’s back legs might be weak or collapsing you can start to devise a plan. Otherwise treating the wrong thing is kind of like trying to put a band aid on a blister when you keep wearing the same shoes that cause the blister…the blister isn’t likely to heal and will keep coming back as long as you wear those shoes. Instead, getting a better fitting pair of shoes will allow the skin to heal and keep a new one from forming. If we can find the source of the problem we can treat it and improve strength, and keep your dog’s back legs from buckling.

Falco Exercises