Neuro Flashcards
Where are circling and head tilt lesions usually located?
Vestibular
Propulsive movement originates form?
Frontal lobe
If you have an animal that is blind or has seizures, where is the lesion localized
Brainstem
Blindness — occipital lobe
What is the purpose of the basal ganglia?
Processing link, initiates and directs voluntary movement
Spastic ataxia, dysmetria, and tremors are associated with lesions in the _________
Cerebellum
If you have normal mentation and facial nerves but bilateral gait abnormalities, where would the lesion be?
Spinal cord
UMN/LMN?
Spasticity and hypertonic
Loss of inhibition of myotatic reflexes
Spinal reflexes intact
Paresis
UMN
UMN/LMN??
Hypotonia and hyporeflexia
Muscle weakness
Loss of spinal reflexes
Muscle atrophy
LMN
What two viruses cause hydrocephalus in ruminants?
Bluetongue and akabane
What neurological signs can be caused by a vitamin A deficiency?
Interferes with the absorption of CSF at the arachnoid villi
CSF pressure elevates
— results in blindness first followed by seizures
— papillidema at the optic chiasm
What is cerebellar abiotrophy?
Autosomal recessive traits of Herefords and short horns
BVD between 100-200 days gestation
— folial degeneration, cavitation of cerebellum
What ocular lesions can be assoicated with BVD?
Retinal atrophy and micro-ophthalmia
Hereditary disorder of the vertebral canal in Jerseys?
Hypomyelinogenesis
-spastic dysmetric gait if they can walk
Neuraxial edema is an autosomal recessive traits of what breeds?
Herefords
Charolais get what disorder of the vertebral canal?
Myelin disorders
Pathogenesis of tetanus?
Tatanospasim toxin
Necrotizing effect
— decreased tissue oxygenation
— facilitates Bacteria prolifertion
TeNT binds to nerve cell and is taken up by endocytosis
Moves retrograde up the axon
Internalized into interneurosn
Prevent release of glycine and GABA, binding irreversibly
Recovery only with growth of new nerve terminals
Clinical signs of tetanus?
Wound
Stiff gait Mild bloat, no ruminations Difficulty rising Pump-handle tail Hyperesthesia
Erect ears pulled back to poll, “sardonic grin”
Prolapsed third eyelid- spasm of retractor oculi m.
Spasm of masseter m- lock jaw
Loss of swallowing
Treatment for tetanus?
Wound debridement and antibiotics (PPG)
Tetanus antitoxin
Acepromazine and diazepam for relief of muscle spasm
Good nursing care
Prevention of tetanus?
Vaccinate with tetanus toxoid
Start at 6 weeks then every 2-4weeks
Clostridium bacterins C and D
Booster pregnant ewes/does in late gestationto protect lambs and kids
Tetanus antitoxin with docking/castratting
Where do cattle usually get botulism?
Decaying vegetation, carrion
How do ticks cause paralysis?
Tick saliva contains neurotoxin
Rx: remove tick, prog is good if dx quickly
What two types of ticks can cause paralysis?
Ixodes holcyclus
Dermacentor spp
How can you prevent rabies?
Vaccination of all livestock is NOT recommended
Imrab 3
T/F listeria is zoonotic
True
How is listeria spread?
In feces of many mammals, birds and fish
Survive in environment for months to years
What are sources of exposure of listeriosis?
Silage: pH <5.5 inhibits growth
Fecal contamination
Chronic intramammary infection
Poultry litter used as bedding
When does listeria infection usually occur?
Commonly associated with environmental and nutritional stress
Requires wound for entry
Rough browse/hay
Erupting teeth
What are the clinical signs of listeriosis?
Multiple unilateral cranial nerve defects
Circling, head tilt, facial paralysis
Fever-early
Silage eye: uveitis, conjunctivitis, keratitis (secondary to not blinking)
Anorexia, dysphagia
Recumbent- opisthotonos, paddling
What is the pathogenesis of listeria?
Rootlet trigeminal —> intra-axonal migration —> brainstem
Bacteria bind to cell via surface proteins
Enter cytoplasm via hemolysis
Multiply, press on internal surface cell membrane, form listeriopods that invaginate into adjacent cell
Cell to cell movement evades phagocytosis
PH must be above ____ for proliferation of listeria to occur?
5
Treatment for listeria?
Penicillin
OTC **
NSIAD, fluids, vitamins
Mortality approaches 100% if recumbent
How can you diagnose listeriosis antemortem ?
Clinical signs — doesnt usually cause limb paralysis
Chemistry: stress leukogram, evidence of dehydration
CSF: increased protein (>20mg/dl) and high mononuclear cells (>10 cells.ul)
What is the definitive diagnosis for listeriosis
PM
Mutifocal-to-coalescing areas of necrosis and severe infiltration of macrophages/neutrophils
Axonal swelling and degeneration
Lesions most severe in pons and medulla
Conditions causes by histophilus somni?
Thromboembolic meningoenchepalitis Pneumonia Arthritis UTI Abortion Myocarditis Neurological disease
Pathogenesis of TME?
Obligate of mucosal surface
Compromised host
Migrates through unprotected epithelial cells
Meets brain epithelial cells, causes cytoskeletal rearrangement
Increased paracellular permeability of vascular endothelial cells— neuro signs
Influx
Inreased CSF in Brian
Clinical signs of TEME>
Somnolence is the first clinical signs
Ataxia and weakness
Lateral recumbency, profound depression, opisthotonos, convulsions
Closes or partially closed eyelids
How can you confirm TEME diagnosis?
History and PE
CBC- non specific changes
CSF - cellular changes reflective of bacterial infection + evidence of hemorrhage
Treatment for TEME>
Only attempt early in dz
Ab with gram - spectrum
Down animals euthanize
Can be prevented with vaccination
Brain and pituitary abscesses are most often caused by what bacteria?
Trueperella pyogenes
Signs of brain/pituitary abscess?
Vision loss in contralateral eye, depression, mania, head pressing, circling with head tilt toward the side of lesion
How do pituitary abscesses arise?
Hematogenous origin — rete mirabile —> mesh of capillaries converging pituitary
— cavernous sinus —> valveless venous system bathing pituitary
Dehorning complication
Head butting
Clinical signs of pituitary abscess?
Blindness, pupillary dysfunction, nystagmus, dysphagia, facial paralysis, circling, head tilt
What is polioencephalomalacia?
Swelling and softening of gray matter
Dysfunction of Na-K ATP pump
- intracellular Na- promotes water into cell
Thiamine - cofactor in neuronal ATP production
Rumen microbes needed-thiamine production
Non-ruminants rely on diet
What type of diets promotes H2S gas formation which interferes with oxidative processes in mitochondria and deplete ATP
Grain
Where is H2S found?
Drinking water Molasses Forage Urine acidifiers mineral supplements Brassica grass
Clinical signs of polioencephalomalacia?
Central blindness, ataxia, proprioceptive deficits, head pressing, hyperexcitability
Leads to recumbency, opisthotonus, seizure, coma, and death
Also strabismus and convulsions
How an you diagnose polio/?
Test food/water for H2S
>1000ppm in water
>4000ppm in diet
> 1000ppm in rumen gas indicates toxic levels
Treatment of polio?
Thiamine
Increase forage adding gluogenic precursors
Dexamethasone
What can cause a nervous ketosis?
Negative energy balance
Most common CS of nervous ketosis
Anorexia
Drop in milk production
What is the pathology in nervous ketosis?
Diffused cerebrocortical neuronal necrosis
— bilateral blindness with intact PLR
Cerebellar purkinje cell necrosis
Rx for nervous ketosis?
Glucose
Propylene glycol
Main isolate from otitis media/interna in ruminants?
Mycoplasma bovis
What are sources of lead toxicity?
Grease, oil, old paint, lead-headed nails, batteries, linoleum, smelter discharges
What type of lead is readily absorbed?
Lead salts (eg acetate, phosphate, carbonate, hydroxide)
Sudden death, central blindness, tremors, chewing fits, seizures, bellowing
DDX?
Polio
Lead toxicity
How can you confirm diangosis of lead toxicity?
Basophilic stippling and normocytic, normochronic anemia
Blood lead measurement
Treatment for lead toxicity?
Usually die before/in spite of treatment
Remove from source immediately
Intermittent CaEDTA to chelate from bone
Early in disease — thiamine
A copper deficiency during prenatal/perinatal period can lead to what condition?
Sway back AKA enzootic ataxia
Copper deficiency prenatally results in bilateral symmetrical ____ in the dorsolateral spinal cord
Myelin degradation
Clinical signs of sway back?
Rear limb ataxia
Muscle atrophy and paresis
Tetraparesis seen at birth
Signs are static in neonates but progressive in older animals
What is the diagnosis for swayback?
Definitive dx on necropsy
Measure body tissue Cu
Plasma copper status (blood Cu increase with stress) and assess dietary Cu
Treatment of swayback
Hypomyelinogenesis and demyelination is irreversible
Supplement Cu to prevent more cases
Cu to molybdenum ratio 6:1
Progressive ataxia is a recessive defect in purebred/ mixed breed _________ calves at 6-36 months
Charolais
What is the major lesion in progressive ataxia?
Eosinophilic plaques on white matter in the brain/spinal cord
What are clinical signs of progressive ataxia?
Stiff neck
Dragging rear toes
Stumbling
Proprioceptive deficits worsening with exercise
Difficulty in maintain posture during urination and pulsatile micturition
What is another name for progressive degenerative myeloencophalopathy?
“Weaver syndrome”
Weaver syndrome is an inherited disorder in purebred ___________
Brown Swiss and Angler cattle
Clinical signs of progressive degenerative myeloencephalopathy?
Paraparesis Ataxia Dysmetria of pelvic limbs Insidious progression Muscle wasting over hindquarters
What is the MOA of organophosphate toxicity?
Bind with acetylcholinesterase —> increases ACh
Clinical signs of organophosphate toxicity?
Muscarinic: Dyspnea, hypersalivation, diarrhea, bradycardia, pupillary contrition
Nicotinic: muscle tremors, tetany, recumbency, and opisthotonos
What is the treatment for organophosphate toxicity?
Atropine
Oral activated charcoal
Oximes — break bone of OP and AChase within first 24hours
2-PAM
What bacteria are often the cause of veterbral osteomyelitis and spinal abscess?
Trueperella pyogenes
Fusobacterium necrophorum
How can you confirm vertebral osteomyelitis/spinal abscess?
Acute signs after fracture, veterbral collapse, or spinal cord compression
Malaise, fever, stiffness, lack of proprioceptive, paresis, and/or recumbency
Rads — proliferation, lysis, sclerosis and soft tissue swelling
Treatment for spinal abscess ?
Surgical curettage, lavage,and drainage
Long term antibiotics
Subsequent meningitis is often associated with poor prognosis
