Basics of Equine Neurological Examinations
Updated April 18, 2023 | Featuring Andris J. Kaneps, DVM, PhD, DACVS, DACVSR
This video features Dr. Andy Kaneps who explains what horse owners can expect when a vet needs to do an equine neurological examination. He goes over the basic steps and tests that will happen, why they are done, and what to expect in terms of results.
When Your Vet May Perform a Neurological Exam
A neurologic examination is conducted when your equine vet is concerned that the central or peripheral nervous system may not be functioning correctly.
A dysfunction could be as subtle as a change in behavior. For example, a horse that's normally active and alert becoming depressed, or be as severe as stumbling and the horse having trouble standing. The most severe manifestation of a neurologic disorder would be with the horse laying down and unable to get up.
Components of Equine Neurologic Exams
A neurologic examination systematically evaluates different portions of the nervous system and assesses whether function is normal or abnormal. If abnormal, your vet will assess to what degree (whether severe or mild).
Your vet will first ask for a health history so they can understand if there may be anything new in the horse's diet or potential exposure to illnesses or diseases, such as EHV-1. Other questions your vet may ask to narrow down a diagnosis include:
- Did the horse go to a show recently?
- Has the horse been coughing?
- Did the horse have a fever?
The physical examination will usually start with observing the horse, either free in a paddock or in the stall. Does the horse move normally? What is their level of alertness? Is the horse head pressing? When the horse turns, does the horse stumble or seem unaware of the limb positions?
Cranial Nerve Exam
After observing, your vet will do a close-up exam. We will usually start with evaluation of the cranial nerves that originate in the brain and go to different parts of the body, particularly the head. Some evaluations that are part of a cranial nerve exam include checking:
- whether the horse can blink its eyes
- if the horse can feel a finger in a nostril
- whether or not the horse can use its tongue or swallow
The next step vets usually take would be to do mild pinpricks on the skin. Normally, the horse will respond just as it would with a fly on the skin by shivering the skin. They assess whether that's present to a normal or abnormal degree throughout the body.
Your vet will check to see whether the horse has normal strength of the tail. If the horse resists tail movement when we grasp it, that is usually quite normal. If it is completely flaccid, then that is abnormal.
The vet will check whether the anus has normal tone by a mild prick, such as just placing a thermometer in. They will assess if there's normal or abnormal muscle strength in that area. Also, seeing whether the horse can urinate by checking if the stall is wet to a normal degree or if the horse been observed peeing or not.
Your vet will then assess how the horse manages its self-carriage. The horse may be walked back and forth in a straight line to see if the horse tracks normally or abnormally.
They may introduce a log or a rail on the ground or a curb and have the horse walk over that. Can the horse tell that there is an obstruction on the ground? They may also weave the horse back and forth over objects. By doing that, the horse has to fully assess its location in relation to the obstacle. Does it trip over the obstacle, or does it stumble during the turns?
The next part of the exam is to pivot the horse on its hind legs to assess proprioception. Can the horse tell where its limbs are? Normally, a horse will mildly cross over its back legs as we pivot in a tight circle. The horse should do that without reaching out far with the outside limb. Reaching out far is called circumduction, and that's an abnormal finding.
The next thing to evaluate is limb strength. Your vet will evaluate this in the forelimbs by pushing on one shoulder to push the horse’s weight onto the opposite leg. The horse should normally resist and not collapse or act weak. The same can be done to the hind legs by pulling the tail and walking the horse forward. Can the horse support itself well as we shift its weight onto one limb?
Up and Down Slopes
Another item of the exam is to walk the horse up and down a slope. To properly manage a slope, the horse has to take in visual information and its limb’s sensations, then compile that information to keep it from stumbling.
Sometimes, your vet may do portions of the exam with a towel over the eyes to eliminate the visual input. That may show more subtle abnormalities in proprioception and strength and full use of the horse's body.
Diagnostic Imaging and Laboratory Tests
If the prior findings show abnormal neurologic function, blood samples may be taken to assess for various diseases. Your vet may also take spinal fluid to test for levels of inflammation and other diseases.
Once laboratory results are considered, diagnostic imaging may be indicated. X-rays of the neck may be taken if your vet suspects some type of pressure on the spinal cord. Your horse may require a myelogram which is a procedure under general anesthesia where contrast medium or dye is injected into the spinal canal.
For further information on neurologic conditions of the horse, check the SmartPak Horse Health Library.