Large Animal Cranial Nerve and Focal Brain Disease Flashcards
what are the routes of infection for otitis media interna?
otitis externa
via eustachian tube
what are the risk factors for otitis media interna?
respiratory tract infections
streptococcus equi in horses
wet and cold weather
what are the diagnostics for otitis media interna?
ear swab
otoscopic examination and visualization of tympanic membrane
radiographs
CT scan
what are the peripheral vestibular disease signs with otitis media interna?
head tilt, vestibular ataxia
facial nerve paresis or paralysis
horizontal nystagmus, fast away from head tilt
purulent discharge
head shaking
what is the prognosis of otitis media interna?
better outcome in calves than older animals
chronic disease requires longer treatment and more often relapses
can be challenging
what is the guttural pouch?
diverticulum attached to eustachian tube which is running from the pharynx to the middle ear of horses
what are the most common signs of guttural pouch disease?
nasal discharge
epistaxis
dysphagia
laryngeal paralysis
what diagnostics are useful for guttural pouch disease?
radiographs
ultrasound
endoscopy (very helpful)
sampling of infection
serology or PCR for Strep equi
CT scan
what is temporohyoid osteoarthropathy?
progressive disease involving: stylohyoid bone, temporohyoid joint, temporal bone of skull, middle ear
what facial nerve signs are associated with temporohyoid osteoarthropathy?
ear drop
dropped upper eye lid
dropped lips
deviated muzzle
corneal ulceration
what is the prognosis of temporohyoid osteoarthropathy?
only about 50-60% return to athletic use
many have residual neurological deficits
where is the trunk of the facial nerve?
stylomastoid foramen
how does a lesion in the buccal branches of the facial nerve manifest?
paralyzed lips
deviated muzzle
difficulty in food prehension
what is neuropraxia?
interruption of nerve function without definitive structural damagee
function returns in 3-4 weeks, very rarely does not return
which branches of the facial nerve are most susceptible to trauma?
superficial buccal and auriculopalpebral branches
what is Listeria monocytogenes?
small, motile, gram positive, non-spore forming, extremely resistant, diphtheroid coccobacillus
where is listeriosis more frequently seen?
lower temperatures and colder climates
how does animal-to-animal transmission of Listeria monocytogenes occur?
fecal-oral route
what is most plausible for brain infection of listeriosis?
ascending infection along cranial nerve V
what is the histopathology of listeriosis?
micro abscessation mainly in brainstem
what are some infectious agents of otitis media interna?
Hemophilus somni
Mannheimia haemolytica
Mycoplasma bovis
Pasteurella multocida
Corynebacterium
Streptococcus
Staphylococcus
Pseudomonas aeruginosa
what signs are associated with otitis media interna extending into the brain?
depression
ataxia
proprioceptive deficits
opisthotonos
seizures
how does each guttural pouch communicate with the pharynx?
2-3cm funnel shaped orifice
what is in the guttural pouch?
carotid artery
vago-sympathetic trunk
cervical ganglion
accessory nerve
vagus nerve
glossopharyngeal nerve
facial nerve
mandibular nerve
temporohyoid apparatus
what are some common causes of guttural pouch disease?
empyema, Streptococcus equi
mycosis (Aspergillus)
tympani (air entrapment)
bleeding (infection, trauma)
how can Streptococcus equi infection be treated in the guttural pouch?
systemic penicillin G
gelatin/penicillin composite in pouch
phenylbutazone or flunixin meglumine
vaccines
what facial nerve branches are involved in ear movement?
caudal and internal auriculopalpebral
what are thee buccal branches of the facial nerve involved in?
muzzle, food prehension
what can Listeria monocytogenes infection cause?
keratoconjunctivitis
sepsis
mastitis
abortion
diarrhea
what is the most frequently recognized form of Listeria monocytogenes?
encephalitis or meningoencephalitis in adult ruminants
who is most at risk for listeriosis?
young ruminants
what can cause listeriosis?
changing teeth, infection via tooth defects
contaminated silage
what is a common clinical finding of listeriosis?
compulsive walking, head pressing, circling
how can listeriosis be diagnosed?
CSF: mononuclear pleocytosis, elevated protein
histopathology: microabscessation mainly brainstem
what is polioencephalomalacia associated with in ruminants?
thiamine deficiency
high sulfur diet
low-roughage diet
high doses of amprolium
cobalt deficiency diet
toxic plants
why is thiamine important?
krebs cycle: glucose energy metabolism
how can polioencephalomalacia be diagnosed?
difficult
CSF not diagnostic
plasma thiamine levels helpful
autopsy most helpful
