IVDD in DachshundsJune 4, 2013
Written by Gena Silver, DVM, MS, DACVIM (Neurology)
The name comes from the German word for badger dog. The German word for dog “Hund” sounding like “hound” might have led to the dog being mistakenly classified as a hound, when it actually may not be. Many believe that the breed should be considered a terrier given their personality and in the case of the wire haired Dachshund, their appearance.
Whether a hound or terrier, they were developed specifically for tracking and chasing badgers and other animals that live in burrows. Their long and narrow bodies are perfect for flushing animals out of holes in the ground so that hunters can better chase them.
There are different sized Dachshunds, including the standard (16 lbs), the miniature (about 11 lbs) and the kaninchen (8-10 lbs). The smallest size-the kaninchen, means rabbit-is actually only recognized by non-English speaking kennel clubs.
Dachshunds are pack animals that do not like to be left alone for long periods of time. They are very intelligent and stubborn. They need dominance training or they will try to be the leader of the house! They are natural born hunters, they love to dig and chase/catch wild rodents. They bark/howl to alert you to noises and are wary of people outside the pack. They enjoy children but are not tolerant to teasing/poking and will not hesitate to snap if provoked.
The Dachshund is considered a dwarf breed and like all dwarf breeds are prone to back injury which is what this discussion will focus on.
Anatomy of the Spine
Dogs have 7 cervical, 13 thoracic, 7 lumbar and 3 sacral vertebral bodies. There is a disk or “cushion” that sits in between every vertebral body in the spinal column with the exception of C1/C2 and S1/S2/S3. Thus the average dog and cat has 26 intervertebral disks! The disks act as shock absorbers to help dissipate the forces placed on the vertebral column.
There are two components to the disk, an outside fibrous covering (annulus fibrosis) and an inside, more gelatinous center (nucleus pulposus). With each movement of the spinal column, forces are placed on the disk. The center portion of the disk absorbs these forces and radiates the pressure to the rest of the disk in an equal centripetal manner.
As the disk ages, the water content and elasticity is reduced. This makes the overall disk less supple, more rigid, and less able to withstand forces placed upon them from every day activity. In chondrodystrophic (dwarf) breeds such as Dachshunds, French bulldogs, Pekingese, etc, the aging changes of the disk are seen as early as 8-24 months of age. As the nucleus pulposus undergoes these changes, it loses its elasticity and ability to act as an efficient shock absorber. In time the resulting disintegration will result in calcification of the disk. When a compressive load is passed through the affected nucleus pulposus, the pressure generated within in no longer radiates equally in all directions to the annulus. If too much force is placed on the disk, it can be squeezed and expand or rupture. When the disk ruptures the N.P. contents it is known as a Hansen Type I disk disease or a disk extrusion. Any breed of dog can have a type I disk herniation, especially when external trauma is involved. However, because of the unique metabolic difference of their disks, the dwarf breeds are far more likely to develop significant disk disease in their lifetimes.
Approximately one in every four dachshunds will have some degree of disk related problems in their lifetime. The age of incidence for dwarf breeds is highest between three and seven years as opposed to eight to ten years for non-dwarf breeds.
Intervertebral Disc Disease
The clinical signs of disk disease vary highly depending on which disk herniates, the amount and speed at which disk material actually extrudes and which nervous system structures become involved and to what extent. Type I disk herniation tends to occur explosively with large amounts of nucleus pulposus escaping into the spinal canal at one time. The spinal cord is damaged from the impact of the disk contacting the spinal cord and then by compressive forces where nuclear material compresses the spinal cord. The clinical signs can range from being painful to having trouble walking or not being able to walk at all. The more severe the spinal cord damage, the worse the clinical signs. Animals with severe spinal cord damage can lose the ability to move and to feel (conscious sensation: deep pain) their limbs. To know if an animal can consciously feel, we have to pinch the toes and see if the animal vocalizes or tries to bite us. While this test may seem harsh, it is very important. If an animal has lost the ability to feel in the legs, the chance of walking again is about 50% if spinal surgery is performed within 24-48 hours from the injury and less than 5% if the surgery is performed > 48 hours from the injury. If an animal can still feel the legs, even if it can’t move, there is an 85-95% chance that it will walk again if surgery is performed.
The diagnosis of disk disease is initially based on clinical signs. To prove that a disk is pressing on the spinal cord, a special diagnostic study to evaluate the spinal cord is necessary. Radiographs (x-rays) are helpful to evaluate the vertebral bodies but do not allow us to evaluate the actual spinal cord or possible herniated disks. Radiographs may be a part of the work up, but advanced imaging such as a CT, MRI or myelogram are required to evaluate for spinal cord compression. In our hospital, we use magnetic resonance (MRI) imaging for this purpose. The MRI is the safest, most non- invasive, and informative imaging procedure available for viewing the spinal cord in human and veterinary medicine. This study will show where the spinal cord is damaged, and helps the surgeon to know exactly where the surgery should be performed. A spinal tap may also be needed to test for signs of spinal inflammation or infection. Anesthesia is necessary to perform these procedures.
General guidelines have been established for therapy depending upon the severity of clinical signs. Mildly affected animals (animals with pain alone or mild weakness but able to walk) may be managed with cage confinement for at least two weeks. Strict confinement is very important to allow for healing of a partially damaged disk. If improvement is noted, continuation of cage confinement is indicated for up to two weeks after the animal is clinically normal. However, if after or two weeks signs are not improved, or during the two weeks the clinical signs deteriorate, further work up (MRI) and surgery are typically recommended. More severely affected animals (those who are unable to stand and walk) are considered for surgery. The surgery is performed to remove extruded disk material from around the spinal cord, relieving the compression and giving the spinal cord the best chance of healing.
The prognosis depends upon the severity & duration of clinical signs. In general, animals that still perceive pain when their toes are pinched have an 85-95% chance for recovery (average recovery time is 2-6 weeks). Animals that do not perceive pain have a 50- 60% chance for recovery if surgery is performed within 24 hours and a 5-20% chance for recovery if surgery is performed more than 24-48 hours after loss of pain sensation.
Studies indicate that the chance for recurrence is variable with recurrence rates ranging from 5-40% depending on the study and the breed. Dachshunds have the highest risk for disc herniation and the highest rate of recurrence. Here at Mass Vet, our recurrence rates are about 10-15% at some point in the future.