Assigning a Grade Level to your Horse after the Neurologic Exam
After the neurological exam is complete, the degree of ataxia your horse showed is assigned a grade. This grade uses the Mayhew system and assigns a number 0 to 5. This grade will usually be expressed as “2 out of 5”, which means grade 2 or “<3/5” which means less than a grade 3. The characteristics of each grade are as follows;
- Grade 0 – normal
- Grade 1 – minimal neurological deficits noted with normal gaits and requires manipulative tests (crossing legs, tail sways, tight circles, walking up and down hills, blind folding, backing, response to a dull object)
- Grade 2 – mild abnormal gaits seen at a walk (walks like a patient that has been sedated) and more obvious response to the manipulative tests. Patients can be performing successfully but when asked, they have trouble with lead changes, going down hills at a trot or gallop, stumble, are heavy on the fore hand, require a lot of leg to maintain propulsion, knuckle over when stopping, bunny hop behind when cantering, and drag hind toes a lot at a trot.
- Grade 3 – Easy to see at a walk, look like a drunken camel at a trot, very obvious at a canter but they do not fall.
- Grade 4 – Very ataxic – will fall especially in tight circles or backing. Usually will refuse to go any faster than a walk.
- Grade 5 – Recumbent – may not even be able to become sternal even with encouragement.
Below is a Journal article about Ataxia in horses- symptoms, causes, and treatment options.