Equine Top 15 Neurologic Diseases - Part 1 Flashcards
what horses are most often affected by EPM?
more common in horses <4 years
what is the classic clinical presentation of a horse with EPM?
usually multifocal lesions of brainstem and/or spinal cord - asymmetric ataxia, asymmetric muscle atrophy, random well-demarcated focal areas of swelling, & teraparesis/paraparesis
what is mayhew’s grading scale for ataxia in regards to EPM?
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
what is the etiology of EPM?
sarcocytis neurona - rare but neospora hughesi
how is EPM diagnosed?
based on combo of clinical signs, history, geography/prevalence, labwork, & elimination of other diseases
what is the antemortem gold standard for diagnosing EPM?
serum CSF ratio of titers
how are serum titers used for diagnosing a horse with EPM?
positive titers mean nothing because many horses are exposed, but negative titers imply absces of disease except in acute cases (< 2 weeks)
what is seen on CSF fluid from a horse with EPM?
mononuclear pleocytosis & increased protein
what prevention is used for EPM?
keep possums off property, minimize stress
what treatment is used for EPM?
long term antiprotozoal therapy of ponazuril or diclazuril (very safe), short term anti-inflammatory drugs, & supportive care
what animal is the definitive host for EPM?
possum
what is the prognosis of EPM?
guarded to fair - horses with less severe signs tend to do better
what does SAG stand for?
surface antigens - SAG2, 4/3 titers
what is the life cycle of sarcocystis neurona?
opposum is definitive host, horse is the aberrant dead end host which ingests sporocysts, & merozoites are found in CNS lesions
what is another name for cervical vertebral malformation & malarticulation in horses?
equine wobbler’s
what signalment of horses are often affected by CVM type I?
developmental - thoroughbreds, warmbloods, & light breeds usually a few months to 4 years old, more often males
what signalment of horses are often affected by CVM type II?
acquired - usually seen in middle-aged horses
what is the classic case presentation of CVM?
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
what is the etiology of type I CVM?
developmental dynamic - mid-cervical region
what is the etiology of type II CVM?
acquired due to OA or trauma - caudal cervical region
what is seen on radiographs that supports a diagnosis of CVM?
vertebral canal stenosis, abnormal articular processes, & angular deformities
what horses with CVM have a good prognosis? what horses with CVM have a guarded prognosis?
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
T/F: horses with multiple sites of CVM have a very poor prognosis
TRUE
what treatment is used for equine wobb;er’s?
basket surgery (decompression & fusion), young horses can do significant caloric/exercise restriction, older horses can use NSAIDS +/- vertebral facet injections
what are signs of spinal trauma in a horse?
ataxia, paraparesis/tetraparesis, paraplegia (dog sitting), & urinary/fecal incontinence
what are signs of forebrain trauma in a horse?
coma, dementia, wandering in circles, seizures, & cortical blindness
what are signs of brainstem trauma in a horse?
strabismus, nystagmus, ataxia, & facial nerve deficits
what is the common signalment & history of a horse with a CNS injury?
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)
what are signs of fractures involving the middle/inner ear in a horse with a CNS injury?
cranial nerve VII deficits (ipsilateral face drooping), cranial nerve VIII deficits (ipsilateral vestibular deficits), dog sitting, & urinary/fecal incontinence
how are CNS injuries in horses diagnosed?
skull/spinal rads, MRI/CT, +/- CSF tap if unsure that an injury occurred
what treatments are used in horses with CNS injuries?
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
what is the prognosis for a horse with a brain injury? spinal injury?
brain - guarded, 40-60% survival depending on type/location, spinal - guarded, depends on location & severity for return to function
most spinal injuries in horses occur at what site?
between C1 & T2
what is the prognosis for a horse with a CNS injury that has bilateral pupil dilation & a coma?
very poor
what is the classic case presentation of botulism in a horse?
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
what is the classic case presentation of tetanus in a horse?
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
what is the etiology of botulism? what is the mechanism of its disease?
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
what is the etiology of tetanus? what is the mechanism of its disease?
clostridium tetani toxin - blocks neurotransmitter release from inhibitory interneurons in the spinal cord & brainstem
what testing is done for a horse with suspected botulism?
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
what testing is done for a horse with suspected tetanus?
history & classical clinical findings - +/- CSF tap to rule out meningitis
what treatment is done for a horse with botulism?
antibiotics (not in toxicoinfectious botulism as it may cause release of more toxins), nursing/supportive care, & antiserum if a known/suspected type (expensive)
what treatment is done for a horse with tetanus?
dark/quiet environment, sedation (phenothiazine, a2 agonist, benzo, or barbiturate), clean/debridement of wounds, penicillin or metronidazole
what is it called when a foal has botulism?
shaker foal syndrome - usually botulism type b toxin
what is the prognosis for a horse with botulism?
can range from poor to excellent but adults that are recumbent for more than 24 hours usually have a poor prognosis
giving the tetanus antitoxin to a horse vaccinated against tetanus puts it at risk for what?
theiler’s disease
what is the prognosis for a horse with tetanus?
good if the animal can drink, fair to good if not recumbent, & poor if recumbent
how is botulism prevented? how is tetanus prevented?
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
what does EDM/EMND stand for?
EMD - equine degenerative myelopathy & EMND - equine motor neuron disease
what is the classic case presentation of a horse with EDM?
insidious onset of signs - slowly progressive ataxia, hypometria, weakness, poor thoracolaryngeal (slap) test, & poor cutaneous trunci reflex
what is the common signalment of a horse with EDM?
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
what is the common signalment of a horse with EMND?
adult onset with a peak of 16 years - quarter horses, thoroughbreds, & similar breeds
what is the classic case presentation of a horse with EMND?
elephant ball stance, progressive weakness, increased recumbency, NO ataxia, muscle/weight loss, trembling, low head carriage, unable to lock stifles, weight shifting, & hypometria
how is EDM diagnosed?
based on clinical signs, history, serum vitamin e, & response to therapy
how is EMND diagnosed?
sacrocaudalis dorsalis medialis & spinal accessory nerve biopsies, EMG, & necropsy
how are EDM/EMND treated?
vitamin E supplementation
T/F: EMND horses move better than they stand
TRUE
T/F: for EDM, there is strong evidence that suggests a familial predisposing component
TRUE
what is the suspected etiology of EDM/EMND?
ikely a result of vitamin E deficiency - low serum vitamin E concentration is suggestive but not specific
how is EDM/EMND prevented?
adequate access to vitamin e-rich forage
