When Sudden Hind Leg Weakness Strikes Your Dog, What’s Going On?

You’ve been playing with your dog in the park or watching it trot up the stairs when you see her hind legs suddenly weaken and give way. Could this hind leg weakness be the normal toll of old age? Or does your pet have a serious medical condition?

Sudden onset of collapse can be secondary to a variety of disorders including spinal cord injury, orthopedic disease, or systemic illness. This sudden hind-leg weakness may be a sign of a disease that requires prompt attention from your regular veterinarian. Or even a trip to the emergency room.

When dogs come to CARE with sudden hind-leg weakness, they receive a thorough evaluation to help determine the appropriate diagnostics and treatment. If the vet suspects neurologic disease, a complete neurologic examination will be performed. This is a specialized exam that evaluates their gait, reflexes, and their awareness. The results allow us to localize the affected region of the nervous system – what we call neurolocalization. Their neurolocalization, breed, age, and onset of clinical signs help prioritize the most likely cause of their neurologic decompensation.

Three Major Types of Acute Spinal Cord Injury

The most common causes of acute spinal cord are intervertebral disc extrusion (IVDE), acute non-compressive nucleus pulposus extrusion (ANNPE), and fibrocartilaginous embolism (FCE).

Think of the intervertebral discs as shock absorbers for the vertebrae (spine), consisting of the protective outer layer (annulus fibrosis) and a spongy inside (nucleus pulposus). With age the intervertebral discs can degenerate which can predispose them to herniation and subsequent spinal cord injury.

In IVDE the intervertebral disc’s fibrous outside breaks, and the nucleus herniates and causes spinal cord compression. The severity of herniation will dictate the level of spinal cord injury and subsequent neurologic dysfunction. Certain breeds’ intervertebral discs will degenerate at an earlier age and therefore predispose them to this condition. These include including the Dachshund and the French Bulldog. However, any breed can suffer a disc herniation.

In an ANNPE, a non-degenerated intervertebral disc will herniate and concuss the spinal cord causing a bruise or even bleeding.

With an FCE, a piece of the intervertebral disc breaks off and occludes the blood supply to the spinal cord, causing a stroke that can range from minor to severe.. Both ANNPE and FCE are commonly diagnosed in large breed dogs and typically occur during high impact activity.

Non-disc Causes of Sudden Hind-leg Weakness

Any disease that attacks the spinal cord, nerve, nerve muscle junction, or muscle can cause weakness. Certain cancers or meningitis can also affect the spinal cord. An MRI or electrodiagnostic (electrical testing of the nerve and muscles) can help diagnose these other conditions.

Detecting the Problem

Vets at CARE begin with a complete neurologic exam that identifies the affected region of the nervous system. If indicated, an MRI or CT would be recommended to diagnose the cause of this weakness. Treatment depends on the underlying condition. If your pet is diagnosed with intervertebral disc extrusion (IVDE), decompressive surgery will likely be recommended. Prognosis with surgery is dictated by a variety of factors, including neurologic status at time of surgery (i.e., if they can move their legs or feel their limbs).

Vets use this rule of thumb: If your pet cannot walk or appears to be in pain, seek emergency veterinary care immediately.

CARE performs the same services for animals as a medical center does for humans, providing all forms of treatment. It offers emergency care 24 hours a day, 365 days a year, and board-certified specialty care. You can take a visual tour of the practice at
carecharlotte.com/tour.