Equine Top 15 Neurologic Diseases - Part 1

Question 1

what horses are most often affected by EPM?

Answer 1

more common in horses <4 years

Question 2

what is the classic clinical presentation of a horse with EPM?

Answer 2

usually multifocal lesions of brainstem and/or spinal cord - asymmetric ataxia, asymmetric muscle atrophy, random well-demarcated focal areas of swelling, & teraparesis/paraparesis

Question 3

what is mayhew’s grading scale for ataxia in regards to EPM?

Answer 3

grade 0 - normal strength/coordination, grade 1 - subtle to mild neuro deficits noted only under special circumstances (walking in a circle), grade 2 - mild neuro deficits but apparent at all times/gaits, grade 3 - moderate deficits at all times/gaits that are obvious to all observers regardless of expertise, grade 4 - severe deficits with tendency to buckle, stumble spontaneously, trip, or fall, & grade 5 - recumbency, unable to stand

Question 4

what is the etiology of EPM?

Answer 4

sarcocytis neurona - rare but neospora hughesi

Question 5

how is EPM diagnosed?

Answer 5

based on combo of clinical signs, history, geography/prevalence, labwork, & elimination of other diseases

Question 6

what is the antemortem gold standard for diagnosing EPM?

Answer 6

serum CSF ratio of titers

Question 7

how are serum titers used for diagnosing a horse with EPM?

Answer 7

positive titers mean nothing because many horses are exposed, but negative titers imply absces of disease except in acute cases (< 2 weeks)

Question 8

what is seen on CSF fluid from a horse with EPM?

Answer 8

mononuclear pleocytosis & increased protein

Question 9

what prevention is used for EPM?

Answer 9

keep possums off property, minimize stress

Question 10

what treatment is used for EPM?

Answer 10

long term antiprotozoal therapy of ponazuril or diclazuril (very safe), short term anti-inflammatory drugs, & supportive care

Question 11

what animal is the definitive host for EPM?

Answer 11

possum

Question 12

what is the prognosis of EPM?

Answer 12

guarded to fair - horses with less severe signs tend to do better

Question 13

what does SAG stand for?

Answer 13

surface antigens - SAG2, 4/3 titers

Question 14

what is the life cycle of sarcocystis neurona?

Answer 14

opposum is definitive host, horse is the aberrant dead end host which ingests sporocysts, & merozoites are found in CNS lesions

Question 15

what is another name for cervical vertebral malformation & malarticulation in horses?

Answer 15

equine wobbler’s

Question 16

what signalment of horses are often affected by CVM type I?

Answer 16

developmental - thoroughbreds, warmbloods, & light breeds usually a few months to 4 years old, more often males

Question 17

what signalment of horses are often affected by CVM type II?

Answer 17

acquired - usually seen in middle-aged horses

Question 18

what is the classic case presentation of CVM?

Answer 18

history of over-conditioning or rapid growth, progressive ataxia in pelvic limbs or all four limbs with toe dragging, thoracic limb hypometria, & absent slap test

Question 19

what is the etiology of type I CVM?

Answer 19

developmental dynamic - mid-cervical region

Question 20

what is the etiology of type II CVM?

Answer 20

acquired due to OA or trauma - caudal cervical region

Question 21

what is seen on radiographs that supports a diagnosis of CVM?

Answer 21

vertebral canal stenosis, abnormal articular processes, & angular deformities

Question 22

what horses with CVM have a good prognosis? what horses with CVM have a guarded prognosis?

Answer 22

good - young horses with mild clinical signs & a single site, guarded - young horses requiring surgery may not be able to return to athletic function, older horses, & chronic signs, & poor - multiple site involvement

Question 23

T/F: horses with multiple sites of CVM have a very poor prognosis

Answer 23

TRUE

Question 24

what treatment is used for equine wobb;er’s?

Answer 24

basket surgery (decompression & fusion), young horses can do significant caloric/exercise restriction, older horses can use NSAIDS +/- vertebral facet injections

Question 25

what are signs of spinal trauma in a horse?

Answer 25

ataxia, paraparesis/tetraparesis, paraplegia (dog sitting), & urinary/fecal incontinence

Question 26

what are signs of forebrain trauma in a horse?

Answer 26

coma, dementia, wandering in circles, seizures, & cortical blindness

Question 27

what are signs of brainstem trauma in a horse?

Answer 27

strabismus, nystagmus, ataxia, & facial nerve deficits

Question 28

what is the common signalment & history of a horse with a CNS injury?

Answer 28

young/fractious/athletic horse with a cute onset of signs with a history of a fall, thunderstorm, flipping over backwards (basilar bone fracture due to the pull from rectus capitus ventralis muscle)

Question 29

what are signs of fractures involving the middle/inner ear in a horse with a CNS injury?

Answer 29

cranial nerve VII deficits (ipsilateral face drooping), cranial nerve VIII deficits (ipsilateral vestibular deficits), dog sitting, & urinary/fecal incontinence

Question 30

how are CNS injuries in horses diagnosed?

Answer 30

skull/spinal rads, MRI/CT, +/- CSF tap if unsure that an injury occurred

Question 31

what treatments are used in horses with CNS injuries?

Answer 31

check airway, stop bleeding, treat shock, sedation if needed for thrashing, no steroids for head trauma, NSAIDS, serial neuro exams, but time is often the best treatment

Question 32

what is the prognosis for a horse with a brain injury? spinal injury?

Answer 32

brain - guarded, 40-60% survival depending on type/location, spinal - guarded, depends on location & severity for return to function

Question 33

most spinal injuries in horses occur at what site?

Answer 33

between C1 & T2

Question 34

what is the prognosis for a horse with a CNS injury that has bilateral pupil dilation & a coma?

Answer 34

very poor

Question 35

what is the classic case presentation of botulism in a horse?

Answer 35

any age affected, history of a food change especially in round hay bales - flaccid teraparesis to tetraplegia, dysphagia, hypersalivation, muscle tremors, tongue/tail/eyelids poor tone!!!! wet slippery flaccid tongue, flaccid tail, & lack of audible click of palpebral

Question 36

what is the classic case presentation of tetanus in a horse?

Answer 36

history of omphalitis/recent injury/recent surgery - stiff hypometric gait, elevated tailhead, bloat, dysphagia, erect/pulled back ears, prominent nictitatting membranes, flared nostrils, & hypersensitivity to touch/sound

Question 37

what is the etiology of botulism? what is the mechanism of its disease?

Answer 37

clostridium botulinum toxin - blocks exocytosis of Ach at presynaptic membrane, toxin is ingested in feed or in toxicoinfectious, organism can grow in a wound or abscess where the toxin is produced - most common neurotoxins in horses are types B, C, & D

Question 38

what is the etiology of tetanus? what is the mechanism of its disease?

Answer 38

clostridium tetani toxin - blocks neurotransmitter release from inhibitory interneurons in the spinal cord & brainstem

Question 39

what testing is done for a horse with suspected botulism?

Answer 39

PCR (best) or mouse bioassay, grain test is suspected botulism if the horse can't eat 1 cup of grain within 2 minutes, EMG, & isolation of c. botulinum from feed, feces, or wounds

Question 40

what testing is done for a horse with suspected tetanus?

Answer 40

history & classical clinical findings - +/- CSF tap to rule out meningitis

Question 41

what treatment is done for a horse with botulism?

Answer 41

antibiotics (not in toxicoinfectious botulism as it may cause release of more toxins), nursing/supportive care, & antiserum if a known/suspected type (expensive)

Question 42

what treatment is done for a horse with tetanus?

Answer 42

dark/quiet environment, sedation (phenothiazine, a2 agonist, benzo, or barbiturate), clean/debridement of wounds, penicillin or metronidazole

Question 43

what is it called when a foal has botulism?

Answer 43

shaker foal syndrome - usually botulism type b toxin

Question 44

what is the prognosis for a horse with botulism?

Answer 44

can range from poor to excellent but adults that are recumbent for more than 24 hours usually have a poor prognosis

Question 45

giving the tetanus antitoxin to a horse vaccinated against tetanus puts it at risk for what?

Answer 45

theiler's disease

Question 46

what is the prognosis for a horse with tetanus?

Answer 46

good if the animal can drink, fair to good if not recumbent, & poor if recumbent

Question 47

how is botulism prevented? how is tetanus prevented?

Answer 47

botulism - c. botulinum type b toxoid vaccine of mares twice in the last trimester in areas where common & keeping water/food sources clean from dead animals, tetanus - core annual vaccine guidelines followed from AAEP

Question 48

what does EDM/EMND stand for?

Answer 48

EMD - equine degenerative myelopathy & EMND - equine motor neuron disease

Question 49

what is the classic case presentation of a horse with EDM?

Answer 49

insidious onset of signs - slowly progressive ataxia, hypometria, weakness, poor thoracolaryngeal (slap) test, & poor cutaneous trunci reflex

Question 50

what is the common signalment of a horse with EDM?

Answer 50

northeast USA, horses with a lack of access to fresh green forage, 6-12 month old foals, familial in appaloosa, standardbred, & paso fino - possible familial in norwegian fjord, arabian, QH, welsh pony, & haflinger

Question 51

what is the common signalment of a horse with EMND?

Answer 51

adult onset with a peak of 16 years - quarter horses, thoroughbreds, & similar breeds

Question 52

what is the classic case presentation of a horse with EMND?

Answer 52

elephant ball stance, progressive weakness, increased recumbency, NO ataxia, muscle/weight loss, trembling, low head carriage, unable to lock stifles, weight shifting, & hypometria

Question 53

how is EDM diagnosed?

Answer 53

based on clinical signs, history, serum vitamin e, & response to therapy

Question 54

how is EMND diagnosed?

Answer 54

sacrocaudalis dorsalis medialis & spinal accessory nerve biopsies, EMG, & necropsy

Question 55

how are EDM/EMND treated?

Answer 55

vitamin E supplementation

Question 56

T/F: EMND horses move better than they stand

Answer 56

TRUE

Question 57

T/F: for EDM, there is strong evidence that suggests a familial predisposing component

Answer 57

TRUE

Question 58

what is the suspected etiology of EDM/EMND?

Answer 58

ikely a result of vitamin E deficiency - low serum vitamin E concentration is suggestive but not specific

Question 59

how is EDM/EMND prevented?

Answer 59

adequate access to vitamin e-rich forage