What to know about canine intervertebral disc disease

Intervertebral disc disease (IVDD) is the most common spinal cord disease in dogs.¹ Although this diagnosis is an umbrella term, it typically encompasses 3 distinct disease types, as follows:

• Hansen type 1 IVD extrusion (IVDE)
• Hansen type 2 IVD protrusion (IVDP)
• Acute noncompressive nucleus pulposus extrusion (ANNPE), which was historically referred to as type 3 IVDE, traumatic IVDE, or high-velocity, low-volume IVDE²

Other types of IVDD can include hydrated nucleus pulposus extrusion and intradural/intramedullary IVDE.

Each type of IVDD has a different pathophysiology, resulting in differences in clinical sign onset and breed predisposition (Table 1).

Regardless of the type of IVDD, when a dog presents with evidence of neurologic dysfunction, a complete neurologic examination should be performed. An orthopedic examination may also be beneficial to rule out orthopedic disease as the cause of the dog’s clinical signs or to identify any concurrent orthopedic disease that may impact assessment, treatment, or recovery from a neurologic disease process.

Neurologic assessment

A complete neurologic examination should include an assessment of mentation, gait analysis, cranial nerves, spinal reflexes, proprioception, cervical range of motion and direct palpation, thoracolumbar spinal palpation, and lumbosacral assessment. For IVDD, the neurologic examination will provide 2 distinct pieces of information: localization to a specific spinal cord segment and severity of the disease state. These details can guide diagnostic recommendations and aid in prognostication (Table 2).

Once a lesion has been neurolocalized, this can help to develop a prioritized differential diagnosis list and determine the site of interest if advanced imaging is performed. The most common spinal cord segment affected by type I IVDE and ANNPE is T3-L3,³ whereas type 2 IVDP more often affects the L4-S2 spinal cord segment. When IVDD is considered a top differential, other details of the neurologic assessment can help to determine the severity of the disease state, as a compressive myelopathy often progresses in the same manner each time (Table 3).

Spinal pain is often the first neurologic abnormality to be noted, followed by reduced-to-absent proprioception in the affected limbs. This can result in evidence of a proprioceptive ataxia. The affected limbs then become weak, as evidenced by a reduced ability to support the body weight while maintaining voluntary motor function of the affected limbs. This will begin in an ambulatory state and will subsequently progress to a nonambulatory state. Nonambulatory paresis is often confused with paralysis/plegia; however, it is important to note that a nonambulatory paretic dog retains voluntary motor function, whereas a paralyzed/plegic dog has no voluntary motor function in the affected limbs. Following the loss of voluntary motor function in the affected limbs, voluntary bladder function may be lost, and, finally, the dog will lose the ability to perceive pain in the affected limbs. The further a dog progresses through these stages of neurologic function loss, the more severe the neurologic dysfunction.

Treatment options

Treatment options for IVDD will vary depending on the type and severity of the neurologic dysfunction. Type 1 IVDE will result in a local concussive/contusive injury to the spinal cord with varying degrees of spinal cord compression. Type 2 IVDP will result in varying degrees of spinal cord compression, with secondary local inflammation and/or edema of the spinal cord. ANNPE will result in a local concussive/contusive injury to the spinal cord with no spinal cord compression.

Medical management is typically aimed at reducing local inflammation and allowing the spinal cord time to heal from concussive/contusive injuries. This can include anti-inflammatory medications, analgesics, and/or muscle relaxants, in conjunction with strict rest. As all 3 types of IVDD are affected by local inflammation and/or concussive/contusive injuries, medical management can be considered as a treatment option for all 3 types of IVDD.

Surgical management is typically aimed at relieving spinal cord compression. As ANNPE is a noncompressive spinal cord disease, surgical intervention is not warranted as part of its treatment. However, surgical intervention may be considered in both type 1 IVDE and type 2 IVDP when spinal cord compression is present, in conjunction with neurologic dysfunction. Medical management is often recommended as described above during both the pre- and postoperative periods for animals undergoing surgical interventions.

Although any dog diagnosed with type 1 IVDE or type 2 IVDP may be a candidate for surgical intervention when spinal cord compression is identified, not all dogs require surgery for successful clinical recovery. Dogs with persistent spinal pain despite medical management and dogs with progressive and severe neurologic dysfunction may benefit from surgical intervention. Particularly, dogs with nonambulatory paresis, paralysis, and/or loss of pain perception will see improved clinical recoveries following surgical intervention compared with medical management alone. Dogs with less severe neurologic dysfunction, such as spinal pain alone, proprioceptive ataxia, and/or ambulatory paresis, can see similar clinical recovery rates with medical or surgical interventions.

A definitive diagnosis is required prior to considering surgical intervention, as it will determine if spinal cord decompression is recommended, and it can identify the specific site that is affected, thus aiding in surgical planning. Alternatively, dogs with less severe neurologic dysfunction that may be treated with medical management alone may do so based on a presumptive diagnosis.⁴ If the neurologic dysfunction continues to progress or if the dog remains in pain despite medical management, advanced imaging for a definitive diagnosis could be considered at that time.

Diagnostic imaging¹

A definitive diagnosis of IVDD and its type requires imaging of the spine. Although radiographs may aid in ruling out some differential diagnoses, such as discospondylitis, vertebral fractures/luxations, and some neoplastic lesions, this modality often lacks sufficient detail to guide decision-making. As such, CT (+/- contrast) or MRI are more commonly employed imaging modalities, as they provide a 3D assessment of the local spinal structures. CT provides superior assessment of the bony structures, whereas MRI provides superior assessment of soft tissue structures such as the spinal cord itself. Both imaging modalities can provide details on the affected site, presence or absence of spinal cord compression, degree of spinal cord compression if present, and the location of extruded disc material. MRI, however, can further characterize the associated changes within the spinal cord itself, which can aid in the determination of the chronicity of the lesion. Further, ANNPE cannot be definitively diagnosed on CT due to its noncompressive nature, thus requiring more detailed information about the local effects on the spinal cord itself.

Prognosis⁵

The severity of neurologic dysfunction and the associated treatment will aid in prognostication for dogs diagnosed with IVDD (Table 4). Medical management can result in good to excellent outcomes in dogs with less severe dysfunction, including spinal pain alone, proprioceptive ataxia, and ambulatory paresis. However, the outcomes of medical management decline significantly for dogs with more severe neurologic dysfunction. Surgical interventions can result in good to excellent outcomes in dogs with neurologic dysfunction up to and including paralysis; however, the prognosis is fair to poor once there is a loss of pain perception.

Client expectations

Client communication is key to setting the expectations for recovery from IVDD. Medical management will be recommended for all dogs as a part of their treatment, either alone or in conjunction with surgical interventions. Strict rest and time are essential for spinal cord healing. Progression of neurologic function recovery will follow neurologic function loss in the reverse order. This can take weeks to months to reach the final neurologic functional recovery. Not all animals will regain complete neurologic function; however, most animals will regain sufficient function to be a pet when the prognosis is considered good to excellent. Recurrence of IVDD is possible at the same site or other sites in the future, and close monitoring of the dog’s neurologic function is recommended.

Katie Hoddinott, DVM, DVSc, BSc, DACVS (Small Animal), is an assistant professor in small animal surgery at the Atlantic Veterinary College, University of Prince Edward Island, in Canada. Her professional interests lie mainly in surgical oncology and minimally invasive soft tissue surgery. Her current research focuses on advances in clinical teaching for surgery residents and surgical site infections.

References

1. da Costa RC, De Decker S, Lewis MJ, Volk H; Canine Spinal Cord Injury Consortium (CANSORT-SCI). Diagnostic imaging in intervertebral disc disease. Front Vet Sci. 2020;7:588338. doi:10.3389/fvets.2020.588338
2. Fenn J, Olby NJ; Canine Spinal Cord Injury Consortium (CANSORT-SCI). Classification of intervertebral disc disease. Front Vet Sci. 2020;7:579025. doi:10.3389/fvets.2020.579025
3. Kurtscheidt A, Rupp S, Müller U, Forterre F. A comparative analysis of clinical presentation, prognosis and outcomes in paralytic dogs with a compressive and a contusive intervertebral disc disease. Vet Sci. 2025;12(3):287. doi:10.3390/vetsci12030287
4. Scalia B, Freeman P. Outcome of the use of clinical reasoning alone in dogs with acute thoracolumbar myelopathy and/or pain. Animals. 2024;14(7):1017. doi:10.3390/ani14071017
5. Olby NJ, da Costa RC, Levine JM, Stein VM; Canine Spinal Cord Injury Consortium (CANSORT SCI). Prognostic factors in canine acute intervertebral disc disease. Front Vet Sci. 2020;7:596059. doi:10.3389/fvets.2020.596059