Note that a withdrawal reflex (the dog pulling back the leg) is still intact, which is common, but does NOT mean that deep pain is present.ĭiseases such as trauma, fibrocartilaginous emboli (FCE), meningitis, inflammatory disease, infection, and cancer can mimic the symptoms of disc herniation. Video demonstration of the absence of deep pain, negative sensory status, Stage 5. Note that the patient demonstrates a mental response to being pinched, proving that the painful stimulus is in fact felt.įigure 5 (above). Video demonstration of the presence of deep pain, positive sensory, Stage 4. Simply pulling the leg back in response to a pinch is simply a withdrawal reflex, Figure 5 (video).įigure 4 (above). If the dog pulls its leg back, but it doesn’t act like it is being hurt, deep pain is NOT present. Pain perception is present or positive in a pet only if there is a conscious mental response to the toe being pinched, like turning the head toward the pinch, crying out, trying to bite the pincher, or trying to get away, Figure 4 (video). Like reflexes, pain perception is commonly misinterpreted during a neurological exam. It is not necessary to pinch the toes of dogs with Stage 1, 2, or 3 IVDD. Pain perception is tested in animals by pinching the bone of a toe with hemostats. Pain sensation (commonly called “deep pain”) is used to assess stage 4 and 5 (as listed above) because stage is closely correlated with prognosis. Therefore, withdrawal of the limb is NOT an accurate assessment of neurologic stage as defined above, or prognosis. Reflexes do not indicate the degree of cord damage or prognosis.ĭogs can have complete disruption of spinal cord function and still have reflexes, particularly withdrawal from a toe pinch. The presence or absence of spinal reflexes only helps the veterinarian to localize the lesion to a specific region of the spinal cord. Reflexes are commonly misinterpreted during a neurological exam. Patellar, sciatic, panniculus, and withdrawal (pulling back the foot when pinched) are all examples of reflexes, controlled by a lower motor neuron arc in the spinal cord. A dog that can walk has to have pain sensation to the feet, and a dog that cannot feel its toes cannot possibly be walking. These signs always worsen in the order listed above, and they always return in the reverse order in the recovering patient. Stage 5: Paralysis with no feeling of a deep pinch to the toes Stage 4: Paralysis, which is the complete inability to move the legs but maintaining the ability to feel a deep pinch of the toes Stage 3: The ability to move the legs, but inability to stand and walk under their own power Stage 2: The ability to walk but with proprioception deficits (knuckling of paws, figure 3), and incoordination (ataxia or paresis) Stage 1: Neck or back pain without neurological deficits Progression of symptoms of IVDD occur in an orderly fashion: Photograph of a dachshund that has lost the ability to correct the position of the back foot, called loss of proprioception. In more severe cases, complete paralysis (loss of ability to move the legs) and even loss of pain sensation to the feet may occur.įigure 3. More significant pressure on the spinal cord will cause loss of the placing reflex or inability to right the toes if they are curled under when standing (called conscious proprioception), Figure 3. With mild disease, back pain and ataxia (walking wobbly or unsteadily in the rear limbs) can be seen. When a dog experiences acute Type 1 disc disease (extrusion of the center of the disk) a range of symptoms may be seen. If a disk ruptures fast and forcefully, the pressure on the spinal cord will cause pain and varying degrees of paralysis. A small disk rupture, or one that happens slowly and gradually over several weeks, may only cause back or neck pain with minimal paralysis. The severity of the symptoms a dog has is directly related to how much spinal cord damage has occurred. If a dog ruptures a disk in the back, the front limbs will have normal function, but the back legs will be affected. If a dog ruptures a disk in the neck, all four legs are affected. When a disk ruptures and puts pressure on the spinal cord, the signals from the brain to the legs are not transmitted normally. Herniated discs occur in the cervical (neck) and thoracolumbar spine (lower back). Without a doubt, IVDD is the most common neurosurgical condition presented to veterinarians. Common terms for IVDD include “disk rupture” or “slipped disk.” Some dogs have a combination of both types. This disk rupture can happen acutely, causing signs of pain and paralysis within a matter of hours (a Type 1 rupture), or it can happen slowly over time, causing chronic low grade back pain and nerve damage (a Type 2 rupture). From Hill’s Pet Nutrition, from the Atlas of Veterinary Clinical Anatomy, Illustration of intervertebral disk herniation.
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