by: Hilary Levitin, DVM, DACVIM (Neurology)
Intervertebral disc disease (IVDD) is a common condition that we see on a referral basis. Conservative and surgical treatment options are available and assigned based on the severity of the dog’s condition. Recently the American College of Veterinary Internal Medicine (ACVIM) has provided a consensus report on the treatment of dogs with IVDD, for which we would like to share a summary with our referral community.
For dogs that remain ambulatory (paretic, ataxic, and possibly painful), conservative management (medications and rest) is recommended first, with a 70-80% success rate. We recommend treating with an anti-inflammatory for a minimum of 5-7 days, and dogs treated with a non-steroidal anti-inflammatory drug (NSAID) may experience fewer adverse effects from their medication as opposed to dogs on corticosteroids. That being said, there is no consensus as to which type of anti-inflammatory is preferred (NSAID or corticosteroid). The period of strict kennel rest should be a minimum of 4 weeks. If this is challenging due to the dog’s temperament or anxiety level, anxiolytic support should be provided. Beyond this, additional analgesia should be utilized as needed. For example, gabapentin and amantadine can be excellent pain relievers for these patients. While methocarbamol can be considered for muscle relaxation in dogs with cervical myelopathy (having active muscle fasciculations), we do not routinely use this medication for dogs with thoracolumbar myelopathies. If analgesic support remains required after 1-2 weeks, or, if they are declining neurologically (worsening paresis, ataxia, or progression to being nonambulatory), a referral is strongly recommended for advanced imaging to determine if decompressive spinal surgery is warranted.
The gold standard for diagnosis of IVDD with herniation is MRI. That being said, in young to middle-aged chondrodystrophic dogs, a CT scan is highly sensitive for the diagnosis of disc herniation. In this population of dogs, a CT scan can be considered as an alternative to MRI if they have never had another episode of myelopathic signs. If a young to middle age chondrodystrophic dog has been treated for IVDD in the past, MRI is indicated to help differentiate which disc herniation is causing problems now acutely.
Once imaging has been performed, the decision to move forward with surgery depends upon their clinical status. Indications for decompressive spinal surgery include (1) nonambulatory presentation, (2) paraplegic presentation, and (3) declining in spite of appropriate conservative management. The prognosis with surgery for nonambulatory and paraplegic dogs with intact nociception is favorable (90-95%), but when nociception is absent, the prognosis falls significantly, being 50-60% with surgical management and only 10% with conservative management. Additionally, dogs with absent nociception carry a 10% risk of developing myelomalacia, which is ultimately fatal.
Performing a full neurological exam is paramount for assessment of dogs with IVDD and suspected disc herniation. This information helps us to determine anatomical neurolocalization, appropriate first-line treatment, provide recommendations for the most appropriate diagnostic tool (CT vs. MRI), and most importantly, helps to elucidate their prognosis.