Overview of Intervertebral Disk Disease (IVDD)
Intervertebral disk disease is degeneration and protrusion of the intervertebral disk that results in compression of the spinal cord, spinal nerve, and/or nerve root. It is a common cause of spinal cord disease in dogs. The intervertebral discs (the cushion that resides in the space between adjacent spinal vertebrae) are subject to a number of degenerative conditions and forces that predispose them to bulge or rupture over time. This rupture leads to two types of damage to the spinal cord, compression and concussion.
Compression is the physical pressure exerted over time against the spinal cord which leads to slow degeneration and loss of neurons (nerve cells). Intervertebral disc rupture that is purely compressive usually begins slowly and leads to gradual worsening of neurologic function. Concussion force is the physical damage caused by a rapidly extruded disc impacting the spinal cord causing profound swelling and degeneration and loss of neurons. Purely concussive forces are usually rapidly progressive and have an acute onset. Most intervertebral disc ruptures are a combination of compressive and concussive forces that lead to the rapid degeneration of nervous tissue in the spinal cord.
Breeds at risk
Chondrodystrophoid (dwarfed) breeds of dogs whose normal cartilage development has been altered genetically for the purpose of a short, stout appearance – i.e.: Dachshund, Beagle, Shih Tzu, Lhasa Apso, and Pekingese -- are most commonly affected. Other chondrodystrophic breeds that may be affected by IVDD include Corgis, Cocker Spaniel, Pekingese, Shih-Tzu and Poodle. Nonchondrodystrophic breeds that are commonly affected by IVDD include German Shepherd, Labrador Retriever and Doberman Pinscher. Obese dogs of predisposed breeds are especially likely to suffer from IVDD.
After researching a breed of dog to add to her family, Helen Tjader decided on Cardigan Corgis. Her greatest concern about possible genetic conditions that affect this breed was hip dysplasia. None of her research indicated that Cardigan Corgis were at high risk of developing IVDD. Ieuan was a happy dog, full of pep. He was never overweight and was always in excellent condition with good muscle tone, facts that were noted by every veterinarian Ieuan visited over the years.
Shortly after Ieuan’s 7th birthday, he suffered a ruptured disc in his back and was diagnosed with IVDD. Ieuan underwent successful surgery at Tufts University Hospital in North Grafton, MA and Ms. Tjader followed the post-op recovery plan set out by the veterinary surgeon. Ieuan improved and recovered nearly all function in his hind limbs with only a slight, occasional ‘knuckling’ in one back paw. In an effort to prevent injury, Ms. Tjader had always made sure Ieuan followed the advice of the breeder and veterinarians to avoid stairs. The only stairs Ieuan encountered regularly were the two leading into Ms. Tjader’s home – stairs that the veterinarian, after Ieuan was well recovered -- indicated would be ok for him to handle. Unfortunately, one evening Ieuan came up the two stairs into Ms. Tjader’s home and was suddenly in pain. After consultation with an emergency room veterinarian and Ieuan’s regular veterinarian, Ms. Tjader declined more surgery and opted instead to begin a slow and cautious recovery plan similar to what Ieuan had experienced a few months earlier. Sadly, Ieuan’s pain grew much worse over the weekend and after returning to the emergency veterinarian, it was agreed that there was no hope for recovery.
Symptoms
The observable signs of IVDD vary. And while the following list of symptoms associated with IVDD is not exhaustive, affected dogs may show one or more of the following signs which can be sudden, intermittent or gradual in onset:
- Neck and/or back pain and stiffness (reluctance to move the neck and head)
- Lowered head stance
- Abdominal tenderness or tenseness
- Arched back (hunched posture, called “thoracolumbar kyphosis”)
- Sensitivity to touch (possible aggression)
- Weakness, stiffness, and/or sensitivity to movement (yelping unexpectedly)
- Impaired, incomplete or inappropriate urination
- Lameness and/or paralysis in one or more limbs
- Dragging one or more legs when walking
- “Toeing over” or “knuckling over” when walking or standing
- Stilted gait; tentative gait
- Reluctance to rise and/or collapse
- Tremors, trembling, shaking
- Lack of coordination (“ataxia”)
- Abnormal reflexes
Acute traumatic injury is not the same as IVDD, although the symptoms can be very similar. IVDD involves a degenerative process and does not result merely from sudden trauma, although sudden trauma can cause rupture or herniation of an intervertebral disk in a dog whose disks already are weakened by IVDD.
Treatment
Definitive diagnosis of IVDD is made by a veterinarian through physical exam and x-rays. In less severe cases medication may be provided for pain relief with a combination of crate rest. If IVDD has progressed and the dog has ruptured a disc, surgery is the normal course of treatment, along with pain medication and crate rest. In any case, it is recommended that if your dog seems to be suffering from IVDD symptoms a veterinarian is consulted to determine the best course of treatment in order to help the dog live comfortably and free from pain.
Ms. Tjader hopes that by sharing Ieuan’s story, more dog owners will understand that while keeping your dog fit and healthy are important steps, awareness of genetic conditions like IVDD is critical in order to seek appropriate medical care and consultation. As Ms. Tjader discovered, IVDD can affect many different breeds of dogs and canine health alone is not always an accurate indicator of the presence of a degenerative, genetic disease. “Ieuan was a wonderful dog,” said Ms. Tjader, “above and beyond all our expectations as a pet and I will never forget him.
References:
The Merck Veterinary Manual
American College of Veterinarian Surgeons (ACVS) http://www.acvs.org/AnimalOwners/HealthConditions/SmallAnimalTopics/IntervertebralDiscDisease/
WiggleLess http://www.wiggleless.com/chondrodystrophic-dog-breeds/
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