Large Animal Neurologic Examination
What is a neurologic examination?
The neurologic system is comprised of the brain and spinal cord (central neurologic system). Problems in the brain tend to cause loss of alertness, seizures, changes in personality, vision loss, and hearing loss. The brainstem connects the brain to the spinal cord and is the origin of many cranial nerves in charge of many important things like swallowing, balance, and facial expressions. The spinal cord tells the limbs where they are in space and allows coordinated walking and running over uneven ground. Unlike people, animals cannot be asked if they have a headache, or feel nausea, so we must examine them to see if this system is functioning correctly.
Why would a neurologic examination be performed on a horse or farm animal?
A veterinarian will perform a neurologic examination for several reasons such as:
- Perhaps your horse, cow, or goat has been clumsy recently? They don’t seem to know where their legs are. They trip or even fall.
- Have they had a personality change? Did that have a collapsing episode, or are they bumping into objects? Are they circling, or is their head tilted in one direction? Are they having problems chewing their feed?
- Are you buying a new horse and getting a Prepurchase Examination?
How is a neurologic examination performed on a horse or farm animal?
Frequently, animals with suspected or diagnosed neurologic disease are referred to an internal medicine specialist for an assessment and additional diagnostics. Every veterinarian performs a neurologic examination slightly differently based on their training and personal experience. The neurologic system is often split into different areas and assessed by the signs the animal is displaying. It is common for a veterinarian to start by asking a few questions to help localize the disease to which part of the nervous system is affected and come up with a list of things that may cause the problem, followed by the examination itself
Is this animal well vaccinated?
- Diseases like Rabies, West Nile Virus, and Tetanus can be caused by a lack of vaccination resulting in neurologic disease.
What foods does the animal eat?
- Some toxins are present in certain feeds or plants that can cause neurologic signs.
Are any other animals affected?
- Some neurologic diseases happen in an outbreak situation with multiple animals affected at one time.
Following a thorough physical examination, a neurologic examination is conducted. Specific body systems and different nervous system components are assessed to determine the possible location, cause, and extent of the disease.
Is there a fever?
- Fevers can often indicate infection with viruses, bacteria, and sometimes even fungi and are important part of a physical examination.
Is the animal aware, alert, and responsive?
- If the animal is mentally normal, then this often means the brain is unaffected which will help the veterinary specialist narrow down the causes of the neurologic disease.
The cranial nerves that come from the brain and provide motor and sensation to the head and neck are evaluated by conducting several tests to determine if these nerves are working correctly.
- Examples include assessments to determine if the animal can chew and swallow and if they can see.
- They are put through an impromptu obstacle course to determine if the animal knows where its limbs and feet are.
What happens after a neurologic examination?
Once the examination is complete; the veterinarian has an idea of where the problem is in the body. This helps us decide which tests to do next. Examples of further testing that may be recommended based on the neurologic exam findings include radiographs of the neck or back, a spinal tap to collect some of the fluid surrounding the spinal cord for analysis, or a myelogram (injecting dye around the spinal column to see if the spinal cord is squished at a pressure point). Results from these tests will help the veterinary specialists work with the animal’s primary care veterinarian to determine the best course of treatment for that patient. Treatment for neurologic disease depends on the diagnosis and may include medications to treat a bacterial, viral, or fungal infection. Steroids may be used in some cases to decrease inflammation and other medication to support the nervous system may be prescribed. In some cases, surgery may be recommended. The prognosis for animals with neurologic disease varies and is dependent on the underlying cause.