Clinical Neurology Approach to the Horse Flashcards
How is a Differential Diagnosis list made?
D: Degenerative/ Developmental A: Anomalous/ Autoimmune/ Anatomic M: Metabolic/ Mechanical N: Nutritional/ Neoplastic I: Inflammatory/ Infectious/ Inherited/ Immune-mediated/ Iatrogenic/ Idiopathic T: Trauma/ Toxic V: Vascular
What are the most common differentials from DAMNITV in the young and old horse?
- Young:
Developmental/ Inherited, Infection/ Infestation, Neoplastic (Lymphoma) - Old:
Degenerative, Neoplastic
What disease(s) are Thoroughbred horses predisposed to?
- Cervical vertebral stenotic myelopathy (CVM 1 = Dynamic form)
- Mainly in 6 months to 3 years in rapidly growing colts
- This form is more common in younger horses. Spinal cord compression is caused by excessive movement of the vertebrae during flexion and extension of the neck and is therefore dynamic in nature. Vertebrae C3-C5 are most commonly affected.
What disease(s) are Sport horses predisposed to?
- Cervical vertebral stenotic myelopathy (CVM 2 = Static Form)
- This form is more common in older horses, as a result of osseous change in the vertebrae. The spinal cord is constantly compressed. Vertebrae C5-C7 are most commonly affected.
What disease(s) are Arabian horses predisposed to?
- Epilepsy
- Atlanto-Occipital malformation
What disease(s) are Appaloosa horses predisposed to?
- Blindness
What disease(s) are Quarter horses predisposed to?
- Hyperkalemic Periodic Paralysis (HYPP)
What are the 2 main reasons to a change in behaviour and mentation in a horse?
1) Lesion in the brain/ spinal cord (Focal vs Diffuse)
2) Metabolic lesion that affects the brain/ spinal cord
What kind of lesion are the following clinical signs associated with?
Animal turns, leans, holds head and circles to the affected side, with a reluctance to turn to the other side
A Focal Lesion of the Brain
What kind of lesion are the following clinical signs associated with?
Excitement, restlessness, aggression, compulsive walking and circling, progressive depression, head pressing, apparent pruiritus (biting at itself), blindness
A Diffuse Lesion of the Brain
What kind of lesion are the following clinical signs associated with?
Mild to profound depression, cranial nerve deficits, apnea and non-responsive mydriasis
A Brainstem Lesion
What other body systems of the horse might be involved or exhibit similarly to a neurological disorder?
- Liver
- Kidney
- Musculo-skeletal
- Gastrointestinal
- Systemic disease
Which reflex and cranial nerves are we assessing by doing a Menance test?
- Palpebral reflex
- Cervico-facial reflex
CN’s 2, 5 (trigeminal), 7 (facial) and 11
Which cranial nerve are we assessing by doing a Tongue Tone test?
CN 12
Which cranial nerve are we assessing by looking for facial symmetry?
CN 7 (facial)
What CN deficit do the following signs suggest?
ear droop, ptosis, decreased menance, deviated muzzle
CN 7 deficit
Which cranial nerve are we assessing by testing to see if the horse can chew?
CN 5 (trigeminal)
What CN deficit do the following signs suggest?
head tilt
CN 8 (vestibular)
What CN deficit do the following signs suggest?
head tilt to side of lesion, horizontal nystagmus with quick phase away from lesion, loss of exterior tone ipsilaterally
CN 8 (vestibular) Specifically a Peripheral Vestibular Disease (as opposed to Central Vestibular Disease)
note: horses often have concurrent 7 & 8 damage
What CN deficit do the following signs suggest?
depression, deficits of other cranial nerves, ataxia/ paresis/ proprioceptive deficits, vertical/ positional nystagmus
CN 8 (vestibular) Specifically a Central Vestibular Disease (as opposed to Peripheral Vestibular Disease)
note: ataxia/ paresis/ proprioceptive deficits suggest injury to the tracts in the brainstem
Which cranial nerves are we assessing when we do an ophthalmologic exam?
CN 2, 3, 4, 5, 6, 7 & 8
Which cranial nerves are we assessing when we do a Pupillary Light Reflex on the eye?
CN 2 & 3
note: it does not test vision quality, just if the eye is receptive to light or not
note: tests ipsilateral 2 and 3, and contralateral 3 = when light shines in one eye, both should constrict, but the ipsilateral side should constrict MORE
Which cranial nerves are we assessing when we do a Dazzle reflex test?
CN 2 & 8
Define ‘Strabismus’
Strabismus is a condition in which the eyes do not properly align with each other when looking at an object