Neurology Flashcards
Control of PLRs
Oculomotor (III)
Localization of brain lesion, and midbrain
?
Most sensitive test for rabies
Immunofluorescent antibody test in brain Gold standard by public health department
Horse with 3 week history of hind limb ataxia, fecal retention, decreased tail tone, facial nerve paralysis, masseter muscle wasting
Polyneuritis equi
Cause of stringhalt
False dandelion (Hypochoeris radicata)
Clinical sign in horse with Horner’s syndrome
Unilateral sweating
Histology lesion in listeriosis
Micro-abscesses in brainstem
Polioencephalomalacia: treatment and prevention
• Thiamine: 10 mg/kg IV q6h for 3 days Chelation therapy for lead: CaEDTA, Zn supplement because it chelates too • Dietary management • Water source evaluation • Avoid high sulfur feedstuffs (Gyspum, molasses) • Remove or fence of junk piles • Early identification of cases
Types of botulism in adult horses
Mostly type B (A in western USA, B in eastern)
Sheep with alopecia on trunk and axilla, nibble when itched
Scrapie
Guttural pouch nerves
Accessory (XI) Hypoglossal (XII)
Most indicative lesion on radiographs for Wobbler’s
?
Most important cell to fight EHV-1
Cytotoxic T lymphocytes –> lyse virus-infected cells
Causative agent of dummy lambs
Blue tongue virus, related to MLV to pregnant ewes
Temporohyoid osteoarthropathy
?
Clinical signs of equine motor neuron disease
○ Trembling ○ Muscle fasciculations ○ Base-narrow stance (“horse-on-a-ball”) ○ Shifting weight rear limbs, better when walking, hypometric steps but no ataxia ○ Abnormal sweating ○ Excessive recumbency, low carriage head ○ Muscle atrophy (esp triceps, quadriceps, gluteal, neck → low head carriage) § Onset 1 month before acute signs ○ Tail elevated (Denervation atrophy and fibrotic contracture of the sacrococcygeous dorsalis) ○ Weight loss despite normal or ravenous appetite ○ No ataxia, move better than stand
Life cycle of Parelaphostrongylus tenuis in white tail deer
adult worms in subarachnoid space and venous sinuses–> eggs in venous blood–> lung–> embrionate –>larvae penetrate airways–> cough to pharynx –> swallow–> feces L1 –>penetrate snails and slugs(L1–>L3) –> ingestion snail –> GI wall –> abominal migration 90d–>migration nerve rootlets–>CNS
Cerebral Perfusion Pressure
MAP – ICP
Best Diagnostic test for CSF from a horse with suspected Neospora hughesi:
IFAT?
What is the Single Nucleotide Polymorphism that differentiates more neuropahtogenic EHV-1 strains?
SNP DNA polymerase D752 (neuropathogenic)
In a horse that falls on its back and is bleeding from its nose what is the best choice to perform IV fluid therapy:
Hypertonic saline.?
Horse with symmetric muscle atrophy and weakness, sweating one side a spot only, muscle atrophy in the epaxial muscles: what is the best to diagnostic test?
Biopsy muscle: sacrocaudalis dorsalis (Se 90%)
Guttural pouch lesion on left side, leading to Horner’s syndrome. Clinical signs?
?
Filly with scoliosis neck towards right side, weakness, ataxia in all limbs, analgesia of the right side of the neck. Where is the lesion?
Grey mater horns right side?
Neurological sx in steers at feedlot
H. somni
Calves in a dairy with signs of otitis media, central vestibular disease, what to prevent it?
Pasteurize milk for the calves (Mycoplasma)
What mycoplasma is associated with otitis media in dairies?
M. Alkalscesns,?
Ayrshire cow with head pressing and hx blindness. Treatment?
Edta treatment plan (lead toxicity)
Listeria relation with
winter months in cattle
Meningeal worm related with
majority of cases in fall (not all cases have Eosinophilia)
Listeria adhesion and supervivence in macrophages
Listeriolysin-O permits escape form phagosomes
Listeria ocular lesions, associated with
silage
PEM associated with
High levels of Sulfur in water
Tx for viral encephalitis with EHV-1
valacyclovir > oral availability
Lamb with posterior ataxia
Enzootic ataxia, Cu deficiency
Heifer with dorsomedial strabismus
PEM sulfur feed - water
EHV-1 CSF findings
Increased RBC, increased protein, increased leukocytes
Tetanus toxin
spinal nerves, spinal cord, interneurons, inhibition motor ventral neurons
Botulism toxin
Inhibit release of Ach at the neuromuscular junction
What most adequate concent for tx of hypernatremia 178 mmol/L
175 mmol/L
In botulism, which chain cleaves?
Light chain
7 week old Arabian foal, no menace, hypermetria, head tremors
Cerebellar abiotrophy
Lesion of NAD QH/EDM:
Axon necrosis and demyelination
PEM in feedlot cattle drinking well water
Sulfur toxicity
Tetanospasmin
Synaptobrevin
How is scrapie transmitted?
Colostrum
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Horse on sorghum, clinical signs?
Flaccid bladder, tail paralysis
Virulence factor of listeria
Listerolysin O
Clinical signs of Horner’s syndrome in horses
- Ptosis upper eyelid
- Miosis
- Enophtalmos –> Protrusion nictitating Mb
- Unilateral facial-C2 sweating
What is the origin of the clinical signs in Horner’s syndrome?
Dysfunct of sympat nerve supply to the neck and head
How can you determine if the lesion for Horner’s syndrome is pre- or postganglionar?
Epinephrine application to the eye:
- Post-ganglionar lesion –> midriasis in 20min
- Pre-ganglionar lesion –> midriasis retarded (30-50min)
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What type of propioception is altered in lesions to the cerebrum and midbrain?
Concious propiocention –> abnormal potural reactions
- If lesion rostral to medulla oblongata –> signs are contralateral
Signs of cerebellar disease
- Failure to blink to bright light
- Lack menace response
- Head tremor
- Intentional tremors
- Hypermetry
Which of the equine encephalitis has a high viremia, thus it is able to be transmitted from the horse
Venezuelan Equine Encephalitis (VEE)
Which proteins are important in the virulence of WNV?
M (Mb) and E (Envelope)
Which receptor is used by WNV to enter the cells?
Chemokine CCR5 receptor
Diagnosis of equine encephalitis
IgM capture ELISA
- Can distinguish between disease (IgM) and vaccination (IgG)
Cranial nerves affected in WNV
VII, IX, XII
Head tilt, flaccid muzzle and lips, inability to swallow
Pathogenesis of Borna disease
Nasal –> transaxonal transport to CNS –> replication neurons and glial cells –> migration to perif nerves and retina –> blindness
*Persistent infection
This plant corresponds to Yellow Star Thistle, Knapweed. To which condition in horses it is related?
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Equine Nigropallidal Encephalomalacia
- Toxic principle → repin → inhibits dopamine release
Cranial nerves affected in listeriosis
V to XII
Is listerioris a concern for human health?
Can infect mammary gland –> excreted in milk –> zoonosis
Bacteria implicated in otitis media-interna in calves
Mycoplasma bovis (Dairy)
Pasteurella multocida (feedlot)
Which is the single nucleotide polymorphism (SNP) related to EHM and why?
D752 leads to higher magnitude and duration of viremia (theory)
Why are older horses more susceptible to EHM?
Greater IFN-γ response to EHV-1
Gold standard for diagnosis of EHV-1
Virus isolation
- Nasal/nasopharyngeal swab or buffy coat
Test of choice for EHV-1
PCR (Glycoprot B)
- High sensitivity and specificity (Exceeds virus isolation)
- Nasal samples > nasopharyngeal samples –> Results indicate risk of shedding
- Uncoagulated blood –> Results indicate active viremia (Not latent infection)
Usefulness of serology for diagnosis of EHV-1
Screening in-contact horses exposed to virus in outbreak (Indirect evidence EHV-1)
For EPM horses ingest _______ from infected feces of opossum
Sporocyst
How do sporocyts from S. neurona reach the CNS?
Leukocyte associated parasitemia
Isn’t this so cool! This parasite is a badass!
What is the form of S. neurona that gt stablished in the CNS?
Schizonts
Merozoites
What does IFAT detect for diagnosis of S. neurona?
IgG against whole merozoite
What is one of the main downsides of IFAT for the diagnosis of EPM?
Unable to differentiate btw S. neurona and S. fayeri
Is the use of snSAG1 acceptable for the diagnois of EPM?
NO NO NO! The Se is unacceptable
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What does a C-value > 1 means when using snSAG2
CNS production of antibodies
Test with best Se and Sp for EPM
snSAG 4/3 serum-to-CSF ratio
Which test for EPM is ore accurate for CSF samples?
IFAT
Mechanism of action of ponazuril
Works at plastid body in merozoite → mitochondria and energy metabolism affected
Where do you have to pay more attention when interpreting a myelogram?
Compression of the DORSAL column
Compression of ventral column is normal
Lesion on EDM/NAD
Demyelinization of dorsal funiculi of spinal cord and brainstem (young horses)
- Caudal brainstem nuclei (medulla oblongata) and spinal cord (dorsal spinocerebellar tracts esp)
- Diffuse neuronal fiber degeneration (dystrophy) of white matter
- Astrocytosis, astrogliosis vacuolization, myelin loss, spheroid formation (axonal swelling) and lipofuscin-like pigment accumulation
Cause of EDM
Unknown, believed combination of dietary vitamin E deficiency and genetic predisposition
Breeds where NAD is more described
Morgans and Haflingers (familial tendencies) and QH
Mode of inheritance of EDM/NAD
Autosomal dominant
Parasite that causes cervical scoliosis in horses
Parelaphostrongylus tenuis
Effect of organophosphates in horses
Bilateral laryngeal paralysis
Enzootic ataxia in sheep (aka awayback) is caused by…
Deficient maternal diet in Cu
Inheritance of cerebellar abiotrophy
Autosomal recessive in Arabians
gene MUTYH
In tetanus, which toxin is internalized in axons, transpoted retrograde and after 1-14 days enters CNS, reaches neuronal cell body and binds irreversible to presynaptic inhibitory interneurons?
Tetanospasmin, LIGHT chain
Effects of light chain of tetanospasmin
Inhibits release of inhibitory neurotransmitters GLYCINE and GABA ==> muscle rigidity and spasms
Effects of Mg infusion in cases of tetanus
Blocks neuromuscular transmission, interfere with catecholamine release, reduces receptor responsivenes to catecholamines, antagonizes action of Ca, anticonvulsivant and vasodilator
Which antimicrobial is preferred to manage tetanus in horses and cattle
Horse: metronidazole
Cattle: penicillin
*penicillin has anti-GABA and proconvulsant properties*
tetanus immunization for foals from nonvaccinated mares
3 doses at 4 week intervals, beginning at 1-4 months old
most common route of infection of botulism in horses and cattle
Ingestion preformed toxin
Diagnosis for C. botulinum
- Demonstrate preformed toxin in serum, GI contents or wound
- Demonstrate C. botulinum spores in GI contents or feed, with compatible clinical signs
- Detec Ab response in recovering animals
Best test for C. botulinum
Mouse bioassay –> the most Se (before PCR available)
PCR
What is the effect of the botulinum toxin?
light chain is released into cytosol → inactivates the SNARE complex
→ Prevents fusion of synaptic vesicles → prevents exoxitosis and release of the Acetilcholine at NEUROMUSCULAR JUNCTION
In cases of botulism, why is it important to treat promptly with the antitoxin?
It binds only toxin that is not bound to neuromusc junction
Characteristics of EMND
Generalized neuromuscular weakness
Neurogenic muscle atrophy
In chronic form of EMND, what ocular abnormality can be found?
retinopathy (mosaic pattern→lipofuscin-like pigm deposition in fundus, no visual impair)
Where to do muscle or nerve biopsy for diagnosis of EMND?
- Sacrocaudalis dorsalis (Se 90%)
- Ventral branch of spinal accessory nerve (more sensitive in chronic cases): Bungner’s bands
Characteristics of polyneuritis equi (neuritis of cauda equina)
tail and anal sphincter paralysis, often accompanied by cranial and peripheral nerve damage
Cause of polyneuritis equi
unknown. Suggested primary immune reaction and viral inflammatory disease
Diagnosis of polyneuritis equi
- Definitive: post-mortem
- Inflammatory leukogram
- CSF: elevated prot + elevated WBC (mononuclear) / or normal
- P2 myelin Ab *in CSF (weak evidence because can be observed in adenovirus and EHV-1)
Diagnosis for equine grass sickness
Topical phenylaphine (0.5%) –> reversion ptosis within 30 mins is supportive for diagnosis
Hystopathology enteric ganglia and autonomic ganglia (gutt pouch: cranial cervical ganglia) –> Gold standard
What type of nerve damage correlates to the picture
(Stifle and hock extended, fetlock flexed)
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Sciatic nerve paralysis
- Can support weight if limb is placed under body
- Limb is held to the rear
Official test for rabies according to the CDC guidelines?
Fresh samples of the brain for detection of viral antigen by fluorescent antibody test (FAT)
Transverse section of the cerebellum and the underlying brainstem
Which muscle is used for biopsy when a case is suspected of EMND?
Sacrocaudalis dorsalis medialis
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Which alphaviruses are more neuroinvasive?
EEE and epizootic VEE
For which equine encephalitis the horse is an important vector? Yes… it is actually a risk for human outbreaks!
Epizootic Venezuelan Equine Encephalitis
- Subtypes IAB, IC
- High viremia
Which receptor does WNV uses to enter cells
Chemokine CCR5
Which proteins and cells are involved in neuronal apoptosis of WNV?
- Caspase 9
- CD8+ T cells
What is the fundamental lesion in PEM
Neuronal edema with necrosis
- ATP depletion –> decrease function of Na/K pump –> edema
- Edema leads to pressure necrosis