1.9 Equine Neurological Exam

Question 1

How do you assess the equine forebrain on exam?

Answer 1

The forebrain is involved in behavior, judgement, mentation, and personality

1. mentation: bright or depressed; responsive?
2. behavior: circling, hyperesthesia, head turn, odd posture, head pressing/excessive yawning, seizures

Question 2

How do you assess the equine cerebellum on exam?

Answer 2

cerebellar disease is very uncommon in horses; it is the cotrol center for ascending propreoceptive pathways and decending motor apthways

• spastic or exaggerated movements
• absent or diminished menace response
• intention tremor
• ataxia without weakness

Question 3

How do you assess the equine brainstem on exam?

Answer 3

includes the pons and medulla, reticular formation (consciousness), ascending propreoceptive pathways, decending motor pathways, and cranial nerve nuclei (10/12)

dysfunction in the brainstem leads to ataxia AND weakness

• PLR
• menace
• vision
• eye position (III, IV, VI - strabismus)
• horner’s syndrome (facial sweating)
• pharyngeal/laryngeal function

Question 4

How do you assess the equine spinal cord on exam?

Answer 4

unlike in small animals, you cannot easily assess spinal reflexes; instead you perform a gait analysis to assess for ataxia and proprioceptive deficits

• in a standing horse you assume the spinal reflexes are intact
• limb weakness cn help to localize spinal cord damage
• the cutaneous trunci reflex is good for identifying lesions between T1-T2 (check?)

Question 5

What is ataxia?

Answer 5

ataxia is a functional deficit associated with defective proprioception

Question 6

List the types of ataxia.

Answer 6

• hypermetria: over-reaching / high-stepping gait
• hypometria: under-shooting gait
• dysmetria: cannot judge the rate, force, or range of movements
• truncal sway

Question 7

How do you differentiate UMN from LMN deficits?

Answer 7

LMN: contract muscles

UMN: regulate the electrical signal to the LMN

• UMN deficit: inability to control the muscles, normal or increased tone, no atrophy, can easily pull horse over with tail while walking
• LMN deficit: inability to contract muscles (flacid), mucle atropy if chronic, can easily pull horse over with tail while standing

Question 8

How do you differentiate pelvic limb lameness from ataxia in the horse

Answer 8

• ataxia is generally irregularly irregular
• lameness is generally regularly irregular

(exemption is that sacroiliac pain and pelvic limb suspensory ligament desmitis tend to mimic irregular ataxia)

also: ataxia can be associated with hypermetria while lamness generally is not

Question 9

List some examples of equine lamness caused by muscle disease.

Answer 9

• post-exercise lameness
• exertional rhabdomyolysis
• polysaccharide storage myopathy
• ischemic myopathy (aorto-iliac thrombosis)

measure CK and AST to evaluate the imoprtance of muscle in lameness cases

Question 10

What are some signs of equine sacral nerve abnormalities?

Answer 10

• loss of perianal reflex
• loss of sensation around the perinea
• tail flaccidity
• rectal exam (fecal impations)
• urinary and fecal incontinance