Lecture 36: Nervous 5 Flashcards
What are arboviruses
arthropod trasmitted viruses
List 3 arboviruses that target horses? What lesions do they cause?
Eastern/western/venezualan encephalitis virus
polioencephalomalacia
edema/necrosis/hemorrhage
histo = nueron necrosis and vascultitis
How are horse arbovirsues prevented?
3 and 4 way vaccines
What type of virus is west nile virus? How does it infect horses?
flavivirus
it comes from birds like robins or crows. Mosquitoes transmit it to horses
What are the lesions associated with west nile virus
polioencephalomalacia
brainstem and thoracolumber hemorrhage
causing systemic disease and viremia
What is the clinical presentaiton of a horse with EHV1?
abortion
perinatal foal death
upper resp infection
rarely = encephalomyelitis
Why does EHV1 sometimes cause encephalomyelitis in horses?
because it has an endotheliotropism which causes vasculitis/thrombosis and infarct
What are the gross lesions associated with EHV1
hemorrhage and necrosis in the brain and spinal cord
in both grey and white matter
What causes equine protozoal encephalomyelitis?
sarcocystis neurona
What are the gross lesions of sarcocystis neurona?
hemorrhage and necrosis
in the spinal cord mainly > brainstem > brain
in both grey and white matter
What causes leukoencephalomalacia in horses?
fusarium fungi found in moldy corn that produces the toxin fumonsin B
What is the pathogenesis of leukoencephalomalacia in horses?
The toxin causes lipid breakdown in the white matter mainly in the cerebral hemispheres (frontal and parietal)
it affects the brainstem/cerebellum less
it causes secondary cerebral edema
What diesase in horses is caused by mouldy corn?
leukoencephalomalacia
What is a cholesteatoma? What is the common signalment for an animal presenting with one?
cholesterol granuloma in the ventricles
found in old horses
What causes cholesteatomas?
recurrent edema and/or hemorrhage
What are the gross and histo signs of a cholesteatoma
gross: yellow nodular mass in the ventricle
histo: cholesterol crystals ( due to foreign body reaction)
rarely can cause hydrocephalus
What animals does listeria monocytogenes mainly affect? Where is it found?
ruminants
found in the environment
mainly in bad silage
What is the pathogenesis of listeria infection
trauma in the oral cavity allows infection
it enters the nerves and retrograde transports to the trigeminal ganglion and brainstem
it causes encephalomyelitis
What are the gross and histo signs of listeria infection in ruminants
grossly there are multifocal hemorrhage in the brain and brainstem + meningeal opacity
histo = microabscesses with meningoencephalitis in brainstem
it can also cause abortion and septicemia
What causes thrombotic meningoencephalitis? What animals does it affect?
histophilus somni
cattle
What are the clinical signs of thrombotic meningoencephalitis
septicemia causing polyarthritis, pneumonia, myocarditis, meningoencephalitis
What is the pathogenesis of thrombotic meningoencephalitis?
respiratory infection
hematogenous spread to the body including the cerebral cortex
causes vasculitis, thrombosis, infarct
What are the gross lesions of thrombotic meningoencephalitis
hemorrhage and necrosis in the cerebral cortex and sometimes the spinal cord
What animals does copper deficiency primarily affect?
lambs
baby goats
What are the 2 main disease complexes that copper deficiency causes? What is the difference?
swayback
- congenital (due to copper deficiency in the mom)
enzootic ataxia
- <6 mo
What are the main lesions of swayback?
neuronal necrosis and demyelination in the brainstem and spinal cord
symmetrical hydraencephaly in the cerebral cortex
What are the main lesions of enzootic ataxia
neuronal necrosis and demyelination in the brainstem and spinal cord
no impact on the brain (sometimes in the cerebral cortex)
What are clinical features of copper deficiency?
wool and hair pigmentation
altered MSK and connective tissue
abnormal molybdenum utilization
What is another name for pulpy kidney disease? What animals does it affect mainly?
Clostridium perfringens type D
non-neonatal sheep and feeder lambs
What are the gross lesions of C. perfringens type D infection
gross symmetrical foci of malacia
solf and pulpy kidneys
What is the pathogenesis for C. perfringens type D infection?
High carbohydrate/forage diet (overfeeding)
Allow proliferation of C. perfringens type D
Produces epsilon toxin
hematogenous spread to the CNS causing increased vascular permeability
edema and necrosis
What is the causative agent for pseudo rabies? What animal does it affect? What is another name for the disease?
suid herpes virus 1
pigs = severe disease
(non pigs = mad itch)
aujeszkys disease
What are the lesions associated with pseudorabies
lymphoplasmocytic meningoencephalitis
interstitial pneumonia
multifocal liver necrosis
What causes edema disease? What animal is affected?
STEC: shiga toxin producing e coli
growing feeder pigs
What are the lesions associated with edema disease in pigs?
vascular necrosis causing edema in organs and infarcts in the brain
focal symmetrical brainstem malacia
What type of virus causes canine distemper? How is it spread?
morbillivirus
aerosol
What is the pathogenesis for canine distemper virus?
primary viremia causes infection of lymphoid tissue
leads to immunosuppression
increases susceptibility to secondary bacterial infection
can have a secondary viremia that infects the CNS and epithelium
- infect oligodendrocytes causing demyelination
- recruit microglia after immune function is recovered = meningoencephalitis
it is a pan tropic virus
- targets the lymphoid tissue/epithelium/demyelination in the CNS
What are the 3 clinical disease manifestations of canine distemper virus
severe immunosuppression resulting in fatal encephalomyelitis
robust immune response resulting in recovery
delayed and weak immune response resulting in chronic demyeliination of the white matter and encephalomyelitis
What are the lesions of canine distemper virus
demyelination of the white matter
- targets the oligodendrocytes
secondary inflammation and meningoencephalitis
can affect the cerebellum (also the cerebrum/optic nerve/spinal cord)
What causes old dog encephalitis?
Persistant infection from canine distemper virus
What are the lesions associated with old dog encephalitis?
lymphoplasmocytic meningoencephalitis in the cerebrum and brainstem
What is the common signalment of granulomatous meningoencephalitis? What causes it?
young/mid aged small dogs
idiopathic
What are the gross and histo lesions of granulomatous meningoencephalitis?
gelatinous foci of white matter in the brain
perivascular cuffing with granulomatous inflammation (macrophages and lymphocytes)
Where in the body does intervertebral disc disease mainly target?
thoracolumbar spine because it is narrower
What are the 2 types of IVDD?
chondrodysplastic aka hansen type 1
age related degeneration aka hansen type 2
Explain the process of chondrodysplastic IVDD
nucleus propulsus undergoes metaplastic change - turns to cartilage
- more brittle
causes a full rupture of the disc
Explain the process of age related degenerative IVDD
the nucleus propulsus undergoes age related fibrosis
causes gradual compression of the spinal cord
- wallarian degeneration in axons and blood vessel compression
Which is worse hansen type 1 or 2? Why?
Hansen type 1 aka chondroplastic disease is worse
- acute and more severe because there is no collateral blood flow
Hansen type 2 is less severe because it is a chronic process and collateral blood flow can develop
What is canine cognitive dysfunction? What causes it?
it is a clinical syndrome caused by the accumulation of senile plaques and amyloidosis in old dogs
causing structural and functional impairment and cognitive dysfunction
analogous to human alzheimers
What causes FIP?
mutated enteric corona virus
What is the pathogenesis of FIP?
systemic spread in macrophages
forms immune complexes and causes cytokine release (due to perivascular macrophages)
resulting in vasculitis and fluid leakage
What are the lesions associated with FIP
pyogranulomatous vasculitis
meningitis
ependymitis
encephalomyelitis
Define neuropathy
non inflammatory disease of neurons
Define neuritis
nerve inflammation
Define dysautonomia
degeneration of GI nerves
Define polyradiculitis
disease of multiple cranial and spinal root nerves
Define polyradiculoneuritis
disease of multiple cranial and spinal root nerves along with their peripheral nerves
A brachial plexus avulsion due to a HBC can cause what kind of damage to the PNS?
traumatic
What is one example of traumatic injury to the PNS of a horse
facial nerve paralysis due to handling error, the halter in anesthesia, or a guttural pouch infection
What type of damage causes calving paralysis in cattle? Why?
traumatic
sciatic and obturator nerve damage due to improper feto-pelic proportions
What animals are affected most by laryngeal hemiplasia?
horses
thoroughbred/draft
What is the pathogenesis of laryngeal hemiplegia in horses
The left recurrent laryngeal nerve degenerates
innervation and atrophy of the left cricoarytenoideus muscle
Laryngeal paralysis aka roaring
- can cause aspiration pneumonia
What can cause dysautonomia? What is a consequence?
can be caused by hereditary factors or peritonitis
- increased inflammation and cytokines causing damage to the nerves (can resolve is peritonitis is treated)
causes reduced intestinal motility/ileus
What is colonic agangliosis? What is another name for it? What animals does it affect and why?
aka lethal white foal sydrome
american white paint horses
- autosomal dominant trait (from parents with overo markings)
due to mutation in endothelium B causing improper neural crest migration
What are the clinical signs of colonic agangliosis?
colic
no meconium passed
death within days of birth
functional obstruction in the GI but normal gross morphology
- no myenteric or submucosal ganglia
white foal
How is colonic agangliosis prevented
DNA testing to screen parents
What animals are commonly affected by vitamin A deficiency? What does it cause? What is the clinical outcome?
neonatal calves
peripheral neuropathy
- reduces osteoclast bone remodelling resulting in a narrow optic formina
- it compresses the optic nerve and causes wallarian degeneration
= blind
What causes equine motor neuron disease? What are the associated lesions?
selenium deficiency (due to old hay)
causes oxidative injury in lower motor neurons and axons
resulting in wallarian degeneration and muscle atrophy
What type of injury can neuromuscular junction injury cause?
severe muscle dysfunction
not associated with deinnervation atrophy
What is the pathogenesis of Clostridium botulinum
neurotoxin permanently prevents Ach release at the synapse
result in flaccid paralysis
- can result in respiratory paralysis and death
List 3 routes of infection of C. botulinum
ingestion
GI contamination (foals)
wound inf - rare
horses are very sensitive
What causes limberneck in ducks?
botulism
can be ingested from eating contaminated maggots
What is myesthenia gravis? What animals does it affect?
congenital disease that causes autoIg to block Ach receptors
dogs
What are 3 main clinical consequences of myesthenia gravis?
megaesophagus
thymoma
aspiration pneumonia
no specific lesions
What is coonhound paralysis? What causes it?
It is immune mediated demyelination of ventral spinal nerve roots and the associated peripheral nerves
it can occur 1-2 weeks after a bite or scratch from a raccoon
- does not require raccoon contact tho
similar to guillian barre syndrome in humans
What are the clinical signs of coonhound paralysis?
ascending flaccid paralysis
hyperesthesia (pain from a non-painful stimuli)
weakness
no gross lesions
What animals are most affected by tumors in the PNS?
dogs
cattle (can have a multicentric form = neurofibromatosis)
What are the features and types of PNS tumors?
nerve sheath tumors - benign or malignant
can be spinal (brachial plexus) or cranial (trigeminal) in origin
schwann cell = schwannoma
fibroblast = neurofibrone
perineural = perineuroma
What are the associated lesions for PNS tumors
wallarian degeneration due to nerve compression
muscle atrophy
