Intervertebral disc disease

Canine Awareness

Intervertebral Disc Disease (IVDD) refers to a herniated disc within the dogs spine. Certain breeds are more at risk than others, chondrodystrophic breeds typically have short limbs and longer backs such as; Dachshund, Beagles, Basset Hounds, Lucas Terriers, Sealyhams and Shih Tzus. These dogs often have more strain on the spine and suffer early degenerative changes which makes the disc more likely to herniate although all breeds can be effected.

Most common sign of IVDD is pain. The area of paralysis usually determines which disc is effected. Nerves flow from the brain to the muscle along the spinal cord. Disease in disks of the neck can cause all four limbs to be paralysed, disks in the lower back usually effect the hindlimbs

Symptoms range from:

Mild: abnormal posture, panting, shivering, unwilling to move, difficulty going up and down stairs, shivering, lameness.

Severe: Poor control of the limbs, ataxia, incontinence complete paralysis, dragging one or both legs, unable to stand unable to feel painful sensations.

Often stages are referred to when talking about IVDD, here below are common ‘stages’.

Stage 1:  Neck or back pain without neurological deficits

Stage 2:  The ability to walk but with proprioception deficits (knuckling of paws, figure 3), and incoordination (ataxia or paresis)

Stage 3:  The ability to move the legs, but inability to stand and walk under their own power

Stage 4:  Paralysis, which is the complete inability to move the legs but maintaining the ability to feel a deep pinch of the toes

Stage 5:  Paralysis with no feeling of a deep pinch to the toes

Around 10% of dogs that present with no feeling in both back legs can unfortunately deteriorate further going on to develop myelomalacia. This is an irreversible softening of the spinal cord that ascends the spinal cord and can start to affect the front legs and the muscles used for breathing. You should check your dog by pinching the hind feet and causing the withdrawal reflex to test for deep pain.

How is IVDD diagnosed?

IVDD can be suspected based on clinical signs but to be sure can only be diagnosed via diagnostic imagery. For mild cases the veterinarian can give the dog anti-inflammatories, pain-killers, rest, rehabilitation and physiotherapy. For more extreme cases the veterinarian may need to perform an X-Ray, MRI or CT scan which requires general anaesthesia. This will then determine if the dog requires surgery (two types; Fenestration surgery and Decompressive surgery- see below)

How does my dog recover?

Recovery time is variable in each and every dog and unfortunately some dogs do not regain full control of their limbs or bladder. To ensure your dog has the best chance of rehabilitation, physiotherapy is necessary to help show you the correct exercises to perform with your dog.

More about anatomy and types of disease......

Intervertebral discs are cushions between the vertebrae which allows movement and act as shock absorbers with a fibrous outer rim (annulus fibrosis) and jelly-like substance (called the nucleus pulposus) in the centre. Degeneration of the disk reduces the shock absorption and can lead to herniation of the disc and spinal cord compression.

There are 3 types of disc disease:

Hansen Type 1 (Nucleus pulposus degeneration aka jelly!)

- In a normal disc the jelly is squidgy and able to move, in a diseased spinal cord the jelly becomes hard and eventually explodes or oozes out, which then compresses the spinal cord. The velocity of impact and volume of disc extrusion affects the severity of the case. Clinical signs can be from pain signs to paralysis.

Hansen Type 2 (annulus fibrosis aka outer rim degeneration and protrusion)

- This type of IVDD can occur in any breed of dog. In this condition the outer part of the disc starts to bulge and protrude. This can then potentially cause the outer rim to tear and extrude into the spinal canal which then compresses the spinal cord. Clinical signs range from pain to paralysis and can worsen if the dog exercises. The dog may be reluctant to rise, jump, climb stairs, have a hunched back or look stiff.

Hansen Type 3

- This disease is known as high velocity, low volume disc disease. There is usually a sudden cause of the disease usually associated with intense exercise or trauma, causing a normal nucleus to explode from a sudden tear in the outer rim. As long as the injury does not result in compression of the spinal cord then these cases can recover well with rest, physiotherapy and rehabilitation without surgery. Clinical signs are usually pain (in mild cases) to ataxia or complete paralysis (in more extreme cases. In severe cases there may be a development to myelomalacia (softening and dying of the spinal cord) which can be fatal.

Surgical procedures.

The two surgeries are available are used dependant on the type of disease and the location.

Fenstration: For a thoracolumbar disc extrusion the nuclei pulpous of the thoracic vertebrae T11/12 to Lumbar Vertebrae L3/L4 are removed through a window in the outer rim/annulus fibrosis. In the case of a cervical disc disease the cervical intervertebral spaces are removed. This then reduces the chances of further disc extrusions. This can be done alongside a decompressive technique, however should not be performed if the dog has a severe spinal compression as there will be a delayed recovery or permanent neurological deficits.

Decompressive surgery: Removes the disc from the vertebral canal. The most common procedure in the thoracolumbar spine is a Hemilaminectomy. This procedure creates a bony window using a spinal drill to open the space where the vertebrae is overlying.

Problems associated with surgery:

All surgeries have risks however if your dog is in the high-risk category for not recovering from IVDD without surgery, then this is a risk your veterinarian is highly likely to advise. The main two probelems to keep an eye out for are; Urinary Tract Infections and Myelomalacia.

If your dog shows any signs of IVDD, it is essential to get to the vet as soon as possible. Your vet will begin with a thorough medical history, and will ask about lifestyle, past health issues, and current symptoms. Next, your vet will conduct a complete physical examination.

A neurological exam will be part of this process. The vet will look at motor function, reflexes, response to manipulation of the feet and limbs, and ability to stand and place feet on the ground properly. The vet will also watch the dog walk (or attempt to walk, depending on the severity of the dog's signs).

How to try and prevent IVDD

IVDD is not entirely preventable. However, there are ways to minimize risk in predisposed dogs:

• Having a dog overweight can contribute to IVDD, so keep your dog's weight under control by reducing meals and regular weigh-ins at the vets. Most vets will offer this free of charge.

• Try to limit the ways your dog can potentially get injured, especially when they jump up and down off of furniture or run up and down stairs. You can use a ramp or stairs made for dogs.

• Use of a harness rather than a slip-lead or collar and lead can reduce the likelihood of IVDD in the neck.

• Most importantly, make sure your dog sees a veterinarian and a veterinary physiotherapist for at least an annual check-up. Your vet may be able to detect small changes that indicate IVDD before it gets serious. This can allow your dog to get early treatment, preventing the pain and immobility caused by IVDD later on. Your veterinary physiotherapist can provide you with exercises to help strengthen your dog and provide alternative treatment to muscles to keep them supporting your dogs musculoskeletal frame.