Intervertebral Disc Disease
Intervertebral disc disease is a very common pathology in dogs. The intervertebral discs are fibrocartilaginous structures with a ring shape interpose in every intervertebral space (between the vertebrae). The disc has a donut shape with the center made by a lattice-like structure called nucleus pulposus. The disc`s function is to support the spine during movements and act as a shock absorber cushion.
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Degeneration of the disc results in loss of the normal disc function and may lead to dislocation of part of the disc within the spinal canal, which may ultimately cause spinal cord compression. Based on the amount of compression, the clinical signs range from back pain to complete paralysis. intervertebral disc disease is a very common pathology in dogs.
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Causes
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Intervertebral disc disease is often a hereditary condition (age-related). Chondrodystrophic breeds (dogs with a long body and short legs), such as Dachshunds, Shih Tzus, Pekingese and Basset Hounds suffer from early degenerative changes. However, any breed could be affected.
Clinical Signs
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The symptoms may vary from mild to severe pain or from partial to complete paralysis depending on the degree of compression. Mild signs are lameness or drunken gait (ataxia), whereas sever signs are partial or complete paralysis (drugging one or more limbs), muscle wastage and inability to urinate and defecate. Patients with chronic and severe clinical signs have less chances to recover even after surgery.
Diagnosis
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Typical clinical signs in predisposed breeds are very indicative of interverbal disc disease, however, diagnostic imaging is required to confirm the diagnosis. Radiographs may be useful to diagnose herniation of a calcified disc within the vertebral canal, narrowing of the intervertebral disc space or rule out other pathologies such as fracture or bone tumours. However, they rarely provide a final diagnosis.
Advanced diagnostic imaging, such as MRI, CT scan or Myelography, is essential for definitive diagnosis.
Treatment
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Medical
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Medical management with painkillers and rest is recommended on for patients with mild clinical signs. Overall, ambulatory patients have a better outcome when compared to not ambulatory patients. However, patients treated medically may have a recurrent flare-up of clinical signs.
Surgical
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Surgical treatment is performed on patients with moderate to severe clinical signs. Patients treated surgically have a faster recovery and a higher chance to return to a normal limb’ function. However, dogs with no pain sensation may have a poor prognosis even after surgery.
Surgery (Hemilaminectomy)
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The aim of the surgery (hemilaminectomy) is to reduce the compression on the spinal cord, removing the herniated material disc from the vertebral canal. An electric drill is used to drill the pedicles and lamina on one side of the vertebrae (roof of the vertebral canal) and have access to the vertebral canal directly above the discal space. Once the spinal cord is exposed, the extruded disc material is remover, achieving decompression of the exposed spinal cord.
Recovery Time
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Ideally, the patients should stay in the hospital for pain management for a few days and till are able to urinate independently.
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Several weeks may be required to have a normal leg function, with same patients recovering faster than others. Pets treated with physiotherapy and hydrotherapy post-surgery have a faster recovery time. Occasionally, some patients do not improve after the surgery. In these unlucky cases, mobility carts may be used to support their legs.
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Patients affected by severe compressions, may have no control of the bladder function. These patients require a manual expression of the bladder. This procedure may be performed by the owners at home. We can offer some training at our practices.
Clinical Case
The video shows a partial paralysis of both pelvic limbs in a French Bulldog. The patient was not able to stand on both legs. Back muscle wastage and reaction to pain (reaction to toe pinching) were detected on clinical examination.
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A spinal cord decompression was achieved by right hemilaminectomy. A significant improvement was detected 3 weeks after surgery.
