IVG Newsletter – February 2016 Edition
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Advancing the Standards of Veterinary Care
This service is available at:
Massachusetts Veterinary Referral Hospital
Before a diagnosis can be made your pet’s neurologist will need to gather some information. The three key aspects of this exam will include:
The purpose of the neurological exam is to determine whether your pet has neurological disease and the most likely location (neurolocalization) of the disease within the nervous system.
It is important to note that the neurological exam only suggests the location of the disease, and does not tell us which disease is present.
Neurology is like real estate…it’s all about location, location, location. For example, if you lined up 3 dogs, one with a brain tumor, one that had a stroke and one that had a focal area of inflammation in the same area of the brain, their clinical signs would be similar, to identical.
Thus, the neurological exam tells us the location of disease and allows us to focus our diagnostic testing to a specific area of the nervous system.
Your pet will be observed in the exam room while the neurologist obtains the medical history. This will provide an idea of the level of consciousness your pet is displaying. Your pet should be fully alert and interact normally with you, the doctor, and his/her environment. Altered levels of consciousness (dullness, disorientation, stupor, and coma) can indicate disease in the front part of the brain (forebrain) or in the brainstem.
It is important to note that your pet may be displaying an altered mental status as a result of being systemically ill (similar to how a person with a cold would behave), so this does not necessarily mean he or she has a neurological disease.
As part of the neurological exam, the neurologist will observe your pet’s gait and body posture. Often the doctor will have you walk your pet in the hallway or outdoors where there is good traction. While watching your pet walk, the neurologist is trying to determine whether there are any abnormalities which suggest neurological disease, such as weakness or ataxia (incoordination).
The neurologist is also looking for lameness which can be attributed to either orthopedic disease (e.g., arthritis, cruciate ligament injury) or neurological disease. By analyzing the gait, we often can narrow the location of disease to the spinal cord, brain, or peripheral nerves.
There are 12 pairs of cranial nerves which leave the brain and supply various structures of the head. Your pet’s neurologist will perform a series of tests that will examine each of these nerves individually. These nerves originate and exit from specific areas of the brain. By testing these nerves individually, we can often narrow the location of the disease to a specific area of the brain.
“Postural reaction testing” is a series of tests which analyze your pet’s conscious and unconscious recognition of the location of limbs in space. If any limbs show abnormalities, the location of the disease can be narrowed down. For example, an abnormal response to postural reaction testing in the right legs could indicate disease on the right side of the cervical (neck) spinal cord or brainstem, or the left side of the forebrain.
The neurologist will test your pet’s reflexes. You might be familiar with some of these as they are similar to tests for people. The patellar reflex (knee jerk reflex), for example, is the same in pets, as it is in people; the doctor strikes the patellar tendon on the knee and looks for a knee jerk. This reflex tests the femoral nerve.
By testing this and other reflexes, the neurologist will be able to determine if there is spinal cord disease or disease of the nerve as it travels through the leg.