Most Common Spinal Surgery in Dogs
The most frequently performed spinal surgery in dogs is for intervertebral disc disease (IVDD). Intervertebral discs are fibrous cartilage cushions located between the vertebrae (except for the first two cervical vertebrae). These discs function as structures that enable movement, provide support, and absorb shock. They consist of an outer fibrous ring (annulus fibrosis) and a gel-like center (nucleus pulposus). Degeneration of the intervertebral discs can lead to decreased shock absorption capacity and ultimately result in disc herniation and spinal cord compression.
Intervertebral Disc Disease (IVDD)
Intervertebral disc disease (IVDD) is a degenerative condition often associated with age. However, some "at-risk" dogs (such as chondrodystrophic breeds and their mixes) may experience disc problems at a young age. The early result of disc herniation is typically pain. In more severe cases, dogs may experience difficulty walking, coordination issues in the hind legs, or even complete paralysis.
Diagnosis and Surgical Intervention
Advanced imaging techniques, such as MRI, are essential for diagnosing intervertebral disc disease. MRI helps determine the location of the affected disc material and allows for surgical planning. During surgical intervention, the compressed disc material is completely removed from the spinal canal using techniques like dorsal laminectomy or hemilaminectomy.
The recovery process and degree of improvement depend on the dog’s clinical condition, the extent of spinal cord damage, and the duration of the disease. It is important to remember that time is critical in cases of disc disease. Immediate intervention is often necessary within the first 24 hours after symptoms appear.
Chondrodystrophic Dogs
Breeds such as Basset Hounds, Dachshunds, Lucas Terriers, Sealyhams, and Shih Tzus, which typically have disproportionately short limbs, are examples of chondrodystrophic dogs that are prone to early degenerative changes in their discs and carry a risk of herniation.
Types of Disc Herniation
Disc degeneration leads to reduced shock absorption capacity, ultimately resulting in disc herniation and spinal cord compression. The types of disc herniation are generally classified as Hansen Type I (nucleus pulposus degeneration and extrusion) and Hansen Type II (annulus fibrosis degeneration).
- Hansen Type I disc disease is the most commonly seen type in small breed dogs aged 2 years and older (though larger breeds can also be affected). Clinical signs typically appear suddenly.
- Hansen Type II disc disease resembles the disc disease seen in humans and occurs in non-chondrodystrophic dogs and cats (those without disproportionately short limbs). In this case, there is protrusion of the annulus fibrosis instead of extrusion of the nucleus pulposus.
- Hansen Type III disc disease, also known as ‘acute non-compressive’ disc disease, occurs suddenly, usually due to intense exercise or trauma, leading to severe displacement of normal nucleus material into the spinal canal.
Clinical Signs
Most dogs typically present with acute symptoms, but rarely, signs can develop subclinically and progressively. In these dogs, you may notice reluctance to exercise, get up, jump, or climb stairs, and they may adopt a hunched posture due to pain.
