Brachial Plexus Avulsion in Cats

Brachial plexus avulsion in cats is a condition that results from an injury to the brachial plexus. The brachial plexus is a large network of nerves located in the chest and armpit area of your cat. These nerves are responsible for controlling movement, feeling, and general function of your cat’s front legs. Avulsion is a medical term for tearing or pulling away. Brachial plexus avulsion, therefore, occurs when the nerves sustain damage, typically as a result of being pulled or torn.

Symptoms of brachial plexus avulsion will occur in the front legs of your cat. While the severity will depend on the extent of the injury, the signs of the condition will have common characteristics.

• Lameness of front limb
• Lack of feeling in pad, paw, or upper portion of limb
• Drooping elbow
• Drooping shoulder
• Inability to flex paw, sometimes causing cat to walk on top of paw
• Appearance of one leg longer than the other due to immobility
• Horner’s syndrome which includes one pupil different size than other, droopy lip and protrusion of third eyelid

Types 

Brachial plexus avulsion has three types, or classes, based on the severity and permanence of the condition.

Class I

Class I brachial plexus avulsion is also known as neuropraxia and involves a temporary dysfunction with little to no structural damage. Class I brachial plexus avulsion will often resolve within days or weeks.

Class II

Class II brachial plexus avulsion involves structural damage to some or all of the nerves with nerve sheaths remaining intact. This allows the possibility for the nerves to regrow, but healing may take many months.

Class III

Class III brachial plexus avulsion is the most severe form of injury. In Class III brachial plexus avulsion, the nerves and connective tissue have been completely severed which means the nerves will not be able to regrow.  In this case, there is often permanent paralysis of the leg.

Brachial plexus avulsion occurs when there is an injury to the brachial plexus nerves. This typically occurs as a result of trauma or injury. Brachial plexus injuries are seen in cats after car accidents, trauma involving a leg being pulled on, or injuries caused in wire cages or other instances when a cat’s paw or leg has become stuck and they’ve pulled on it, causing damage.

Diagnosis of brachial plexus avulsion will require a complete history of your cat’s symptoms including when they first appeared and whether there has been any change or worsening. You will need to inform your vet if your cat has been in an accident or has suffered any trauma. You should also let your veterinarian know if you cat is allowed outdoors where they may have been injured without your knowledge.

Symptoms of brachial plexus avulsion tend to be fairly distinctive. Since trauma or injury is a known cause, your vet may also want to run several other tests to confirm there are no additional injuries. X-rays can help check for fractures to the leg and ultrasounds may be helpful to confirm there is no damage to internal organs such as the lungs or bladder.

Treatment of brachial plexus avulsion will begin with your vet potentially administering pain medicine and anti-inflammatory drugs to reduce the swelling as a result of the underlying injury. The ongoing treatment of choice for brachial plexus avulsion is physical therapy. Careful massage therapy by a knowledgeable professional can promote blood flow to the injured area, decreasing healing time. Careful movement of the leg at your vet’s direction can also prevent muscle atrophy. In some cases, underwater treadmills, also known as hydrotherapy, can also be used to prevent loss of muscle tissue.

The only treatment for healing the actual nerve damage is time. Your cat should be kept as quiet as possible to prevent further damage to the brachial plexus or damage to the limb due to loss of feeling and motion.

Recovery from brachial plexus avulsion will depend on the severity of the injury. In minor to moderate cases, cats can recover most, if not all, of their range of motion over several months. Some cats may have varying degrees of loss of use of the leg for the entirety of their life. For some cats, the loss of mobility and use may be manageable and provide only a minor inconvenience.

In cases of severe and permanent nerve damage, your cat’s leg may need to be amputated in order to avoid additional damage to the affected limb which could create infection or systemic problems. Many cats manage well with only three legs. In these cases, you will need to carefully follow your veterinarian’s post-surgical and physical therapy instructions in order to give your cat the best chance at adapting.

With either amputation or full or partial recovery, damage to the brachial plexus does not affect your cat’s overall lifespan or general health.