Neck pain in our dogs and cats can be caused by a myriad of underlying causes. Careful attention needs to be given to patient signalment, clinical signs, and onset of clinical signs. I often find myself guilty of prematurely diagnosing a patient prior to full diagnostic testing. Although we often are correct in our premature diagnosis and our clients feel better "knowing" what is going on with their pet, we can often be humbled after the full diagnostic work up is done and another etiology is identified.
The differential diagnostic pneumonic I typically use is V.I.N.D.I.C.A.T.E. (Vascular, infectious, neoplastic, drugs/degenerative, inflammatory, congenital, autoimmune, traumatic, endocrine/metabolic). The following is a brief overview of the most common neurologic cervical conditions seen in our busy neurology private practice. Of course, we cannot forget that non-neurologic disease (i.e., myositis, polyarthritis, otic or jaw disease, etc) can cause neck pain as well.
Vascular: Steroid responsive vasculitis arteritis can be seen in young, large breed dogs. Typically this disease affects the meninges but can affect the parenchyma as well. It is diagnosed with cerebrospinal fluid analysis. The cellular counts are primarily neutrophilic and the dogs are typically febrile. It is important to also test for infections that can cause vasculitis (i.e., RMSF, ehrlichia).
Infection: Spinal infections are rare but can involve the intervertebral discs. Discospondylitis can be found in animals that have had chronic infection, foreign body, prior surgical intervention, or septicemia. The most common bacterial cause of discospondylitis is Staphylococcus intermedius Other causative infectious agents have been found and these include Brucella canis, Escherichia coli, Streptococcus sp., and fungal pathogens. The diagnosis is made via radiographs or if the infection is in its early stages or located in a difficult area to assess radiographically (thoracic spine, lumbosacral space, etc), advanced spinal imaging is recommended. If there is any ataxia or paresis present a spinal MRI is the ideal diagnostic tool because it highlights changes within the parenchyma that radiographs and computed tomography are unable to identify. Ideally cultures of the blood, urine, and/or affected sites are performed to isolate source of infection.
Neoplasia of the spine, vertebrae, and/or the brain can all cause neck pain. Meningiomas are primary neurologic tumors that have a tendency to grow in the cervical spine. If a tumor is present in the brain, the stretching of the meninges can cause neck pain as the only presenting clinical sign. The most common vertebral tumors include multiple myeloma, osteosarcoma, chondrosarcoma. With brachial plexus tumors the clinical signs commonly start with a forelimb limp and profound muscle atrophy prior to the development of neck pain.
Immune mediated conditions such as non-infectious meningoencephalomyelitis can cause neck pain. With this condition a patient can have just neck pain or have multifocal central nervous system signs. An MRI will reveal focal or multifocal areas of parenchymal and/or meningeal enhancement. The cerebrospinal fluid tap typically reveals predominantly lymphocytic pleocytosis. This condition can affect any breed but small, purebred dogs are the most common breeds affected. Treatment involves immunosuppression and is typically life long.
Intervertebral disc disease is the most common neurologic condition seen at our practice. This is a degenerative condition that is heritable. There are two main categories of disc disease Hansen Type I and Hansen Type II. Hansen Type I discs are those where the dorsal annulus of the disc is compromised and the nucleus pulposus herniates into the vertebral canal. Hansen Type II causes protrusion of the dorsal annulus into the vertebral canal. Both types can cause spinal cord or nerve root compression but with Hansen type I disc extrusion the inflammation or parenchyma hemorrhage is typically more severe. Many different imaging modalities are available to diagnose intervertebral disc disease. Radiographs are often taken to identify arthritic change and intervertebral disc mineralization they are inadequate when determining spinal cord compression or damage. Computed tomography and myelography can identify compression but does not identify parenchymal damage. Spinal MRI can identify disc disease, parenchymal damage, and, if there are multiple sites of spinal cord compression, it can help to identify the area(s)most affected.
There are three congenital conditi
ons that are commonly seen in cervical disease. The first is caudal occipital malformation syndrome (COMS). It is a congenital neurologic syndrome found in dogs that involves malformation of the occipital bones of the skull. These malformations alter the shape of the foramen. Most dogs that are affected are small breed between the ages of 3-6 years of age. The typical presenting signs include neck pain, scratching at the neck, scoliosis, trouble walking, etc. Many breeds have been found to have the condition but the Cavalier King Charles Spaniels (CKCS) are the most represented breed. The bony and soft tissue malformations cause the skull and the foramen magnum to be markedly smaller in size and diameter. When this occurs there can be significant compression of the cerebellum and brainstem and commonly cerebellar herniation as well. Multifocal spinal cord damage is often seen and is suspected to be secondary to the altered cerebrospinal fluid (CSF) flow through the abnormal foramen magnum. Spinal cord damage is often seen and is suspected to be secondary to the altered cerebrospinal fluid (CSF) flow through the abnormal foramen magnum. The damage is due to both compression of the parenchyma and the formation of fluid filled structures within the spinal cord that are commonly termed syrinx, syringohydromyelia, and/or syringomyelia.
The second congenital condition seen is called atlantoaxial instability. Atlantoaxial instability is a neurologic condition involving the first two cervical vertebrae. In this condition the development of the dens of axis and/or ligamentous attachments between the atlas and axis is abnormal. These abnormalities lead to cervical spine instability. Animals presenting for atlantoaxial instability will often be of small breed, young (6 months to 2 years of age) with a relatively acute onset of clinical signs. This condition is diagnosed based on dynamic cervical radiographs and/or advanced imaging. Care needs to be used when an animal is sedated or anesthetized because it could make the instability markedly worse.
The third congenital condition is called cervical vertebral malformation malarticulation syndrome is a condition seen in both young and older dogs. It is commonly known as Wobbler syndrome. This is a complicated syndrome and each animal will be different. In young dogs it is caused by malformation of the cervical vertebrae and articulations. In older dogs it can involve the intervertebral discs, ligaments, and articulations. In both young and old we often see multiple areas of spinal cord compression and changes. Surgical planning depends on advanced imaging (CT or MRI) performed with both static and dynamic studies to identify the site(s) and structures causing the neck pain.
As mentioned earlier, the work up for cervical pain can be extensive and include everything from sedated radiographs to magnetic resonance imaging and cerebrospinal fluid analysis. Therefore it is important to think through every diagnosis and diagnostic test result appropriately before giving a definitive diagnosis to an owner.
