Sciatic Nerve Injury in Dogs

Due to the nerve running over the greater sciatic notch, injuries may be common as a result of poor injecting of intramuscular injections (these are injections that are inserted into the muscle) or pelvic fractures. Tumor growth may also have an impact on the nerve.

The sciatic nerve is a sensory motor nerve with two divisions that innervate the muscles behind and below the knee. These divisions are the tibial and peroneal nerves.

The sciatic nerve is a sensory nerve that originates from the 7th lumbar vertebrae and sacrum of a dog’s spinal cord. 

• The dog will not be able to flex their hock and knee
• Flexion and extension of the paw will not occur
• Lameness
• Back pain in the lumbosacral region
• Inability to urinate or defecate properly
• Change in posture
• Muscle wastage due to lack of blood flow
• Abnormal gait movement; the dog will not put much pressure on the affected side
• Pain on affected side, however should a deep lesion on the sciatic nerve occur then pain may not be observable

Types

Sciatic neuropathies may be associated with compression of the sciatic nerve, this may be caused by lymphomas, which are benign tumors. Iatrogenic trauma occurs as a result of fracturing in the pelvic region. Lumbosacral disease associated with the compression of the sciatic nerves, like humans, would be associated with sciatica.

Sciatic nerve injury may further be classed into 3 levels of severity:

Neurapraxia refers to the least severe case of sciatic injury, where by the dog’s nerve may have mild damage and with appropriate treatment this damage is reversible.

Axonotmesis refers to the second class of damage of the sciatic nerve. Animals with Class 2 may have their axons partially destroyed while surrounding connective tissue may still be intact. As such, canines classed with axonotmesis may often experience lack of motor function by the nerve, pain, and an inability to stretch their hind limbs. Muscle waste (atrophy) may be a common clinical sign.

Neurotmesis refers to the most severe and often irreversible injury of the sciatic nerve. This occurs as a result of complete destruction of the axons and connective tissue of the sciatic nerve.

Injuries to the sciatic nerve are often quite common in dogs as they may have a range of causes. These include:

• Hip fractures
• Displacement of the lumbosacral joint
• Iatrogenic trauma - these may be seen as femoral fractures, diaphyseal fracture repair, triple stabilization of hip luxations, repairing any hernia in the perineal region and intramuscular injections directed to the hamstrings

Diagnosis is based on clinical signs, history of any traumatic injury, electrophysiology, spinal reflex testing and/or X-rays, should your dog have experienced a trauma (for example, a car accident).

In regards to spinal reflex testing, a withdrawal reflex may be done in order to determine the flexing of the hock.

If the cause of sciatic nerve damage was a result of neoplasm (such as a tumor growth) then a CT, MRI or ultrasound may be done in order to verify the presence of cancerous growths such as lymphosarcoma.

Treatment of sciatic injuries may vary depending on a multitude of factors such as severity and cause. Should the sciatic nerve be completely paralyzed then your vet may surgically reroute the digital extensor tendon to an area on the femur. This is referred to as muscle relocation which is a procedure that allows the knee joint to be supported by the quadriceps.

Should the sciatic nerve be damaged as a result of injury towards the lumbosacral plexus, then veterinarians may consider amputation of the affected hindlimb. Sciatic nerve injury as a result of neoplasia may be treated with either chemotherapy and/or through surgical removal of the growth.

Postoperative recovery and management may take anywhere from 2 to 6 months of recovery depending on the severity of the operation. Management often involves:

• Avoiding the recovering limb from sustaining any more secondary problems such as pressure exertion and lack of blood circulation
• Hydrotherapy and/or shockwave therapy

 If amputation was not the method of treatment, then postoperative care may involve reducing inflammation that may have occurred as a result of traumatic injury. Your veterinarian may administer NSAIDs (non-steroidal anti-inflammatory drugs) for approximately 5 to 7 days post op. The purpose of this is to promote blood circulation and regeneration of nerves by decreasing the risks of edemas.

Your veterinarian may suggest physiotherapy in order to prevent muscle wastage. Additionally, owners are encouraged to massage their dogs’ affected leg in order to stimulate recovery time.