3 - Nervous System III Flashcards
What is the most common toxicosis in cattle?
- Lead
- *mostly from discarded card batteries
- *SEASONAL: April till September
What does lead toxicosis cause? What does it look like grossly?
- Poilioencephalomalacia
o Laminar cortical necrosis of the GREY MATTER
o THIN GYRI, WIDENED SULCI
o Maybe some cysts on cross section (from loss of parenchyma)
o *fluoresces under UV light
What fresh samples would you submit to confirm lead poisoning?
- Liver
- Stomach content (especially if acute)
What is salt toxicity also known as? What species are most commonly affected?
- Water deprivation syndrome
- *direct (too much salt in water) and indirect (not drinking water)
- *pigs most common
- Cattle and sheep
What is the pathogenesis of salt toxicity? What does it give you?
- Unable to remove excess Na from brain (energy dependent)
- *polioencephalomalacia AND
- *eosinophilic meningocephalitis
How would you determine if an animal has salt poisoning?
- Assess fresh brain sample for Na
o If high=salt poisoning - Give thiamine in live animal, if get better=salt poisoning
Sulphur poisoning
- Thalamic hemorrhage (in thalamus
- *nothing to test for in the animal, NEED to test the WATER
What is the cause of Tetanus?
- *clostridium tetani
- Secondary to penetrating wound: nails
What is the pathogenesis of tetanus toxin?
- Bacteria release tetanospasmin (toxin) transported by RETROGRADE axoplasmic flow
- *tetanospasmin blocks release of INHIBITORY NTs (ex. glycine, GABA)
How do you diagnosis tetanus?
- CLINICALLY
- **NO gross or histo lesions and NO confirmatory tests available
o Same with botulism
o (rabies gives you histo lesions, but not GROSS lesions)
What causes botulism?
- Neurotoxin of Clostridium botulinum
Botulism
- Mainly HORSES thorugh wounds OR ingestion of toxin
- *toxin inhibits release of ACh = flaccid paralysis
- *NO gross or histo lesions
Plant toxins (Locoweed poisoning): ‘steps’
- Astragalus, Oxytropis, Swainsona poisoning
- Chronic ingestion
- Enzyme inhibition causing lysosomal storage disease (mannosidosis)
- Abnormal accumulation of molecules in brain and elsewhere
- Neuronal swelling and death
What does prolonged ingestion of yellow star thistle cause?
- Nigropallidal encephalomalacia
- *HORSE DIESEASE
**Moldy corn disease (Leukoencephalomalacia)
- Ingestion of moldy feed
o Mainly corn or corn by-products contaminated with Fusarium moniliforme (fungus) - *white matter undergoes NECROSIS
*What is the primary toxin isolated from Fusarium moniliforme?
- Fumonisin B1
- *interferes with spingolipid biosynthesis
o Accumulate and then cells die
What are some incidental findings of the CNS?
- Congenital melanosis
- Dural ossification
Congenital melanosis
- Melanin pigement makes brain appear dark brown, BUT does NOT cause any abnormality
Dural ossification
- Osseous metaplasia
- *age related change
- DOGS and CATS
- Usually incidental but can cause compression
- *red, bony concretions in dura matter of SC due to hematopoiesis in bone marrow
What causes Ischemic myelopathy?
- DOGS
- Herniation of degenerative disk material into vasculature
o Herniated material BLOCKS blood supply and cause a large area of NECROSIS
o *due to a fibrocartilaginous emboli - Always acute, sudden onset of neurological deficit (hindlimb paresis)
- *ASSOCAITED WITH EXERCISE AND/OR TRAUMA
Hypomyelinogenesis
- Process in which there is UNDEVELOPMENT of myelin
Dysmyelination
- Formation of biochemically DEFECTIVE myelin
Hypomyelinogenesis and dysmyelination
- Both occur in early postnatal period
- Have similar clinical and pathologic features
o Young animal with neurological deficits - *viruses and hereditary conditions
o BREED specific abnormalities
Traumatic injury
- Skin then,
- Bone damage
- Grossly detectable HEMORRHAGE
- Tearing of CNS tissue
o Results in tissue NECROSIS and NEURONAL LOSS - *epidural, subdural, and subarachnoid space under the pia matter and in the brain
Compressive injuries in brain: examples and what does it cause
- *neoplasms
- Abscesses
- Granulomas
- *compress brain causing herniation
Compression injuries to SC: 2 types
- Intramedullary compression
- Extramedullary compression
Intramedullary compression: SC, causes
- Neoplasms
- Abscesses
- Granulomas
- *LESS COMMON
Extramedullary compression: SC, causes
- MORE common
- Intervertebral disk herniation (dog)
- Cervical stenotic myelopathy (wobbler syndrome) in HORSE and DOG
If tumor below the cerebellum in YOUNG animals, what tumor would it be?
- Medulloblastoma
Medulloblastoma: cell of origin and age category
- Primitive cells originating in neuroepithelial roof of 4th ventricle that gives rise to EXTERNAL GRANULAR CELL LAYER
- *young animals
Astrocytoma: cell or origin and location
- DOGS
- Astrocyte
- Often not very well demarcated
- *often pyriform lobe is involved
Choroid plexus papillomas and carcinomas
- Tumor within the ventricular system from choroid plexus
- *finger like projections
Oligodendrogliomas: cell of origin and demarcation
- Oligodendrocyte
- *usually well demarcated (looks like an “O”)
Meningiomas: location and species
- Most common intracranial tumor of CAT
- *tumor on TOP of brain (not in the brain=compresses the brain)
- **happens in ALL SPECIES
What are some metastatic tumors to the brain? Where are they normally located?
- Hematogenous
- Mammary carcinomas
- Hemangiosarcomas
- Melanomas
- *often found at WHITE GRAY MATTER JUCNTION: the vessels are smaller=tumor gets lodged
What do all viral infections in the horse cause?
- NON-SUPPURATIVE inflammation histologically
- NO specific gross lesions
Equine encephalomyelitis
- Alpha virus: togaviridae
- Mosquito transmitted
- Grey matter is MOSTLY affected in brain and SC
West Nile (horses)
- Flavivirus Flaviviridae
- Mosquito transmitted
- Grey matter is primary affected (lower brain stem and ventral horns of the thoracolumbar SC)
Equine herpesvirus-1: Myeloencephalopathy
- EHV1
o Also cause abortion, neonatal death and rhinopneumonitis (young animals) - Adults: mainly CNS
- Ganglia affected in addition to grey and white matter for brain and SC
o *either herpes or rabies - *vasculitis is common finding
Equine degenerative myeloencephalopathy
- Axonal degeneration in white matter of SC (mainly) and brain (less affected)
- YOUNG horses
- NO compression lesions
- Unknown cause: but could be related to Vit E deficiency
Cholesterol granuloma (horses)
- Seen mainly in HORSES
- Concretions within ventricular system
- Usually an incidental finding, but can cause hydrocephalus if obstruction occurs
Listeria monocytogenes (ruminants)
- Ruminant disease from silage
- Lesions may NOT be visible grossly
- **GROSS: medulla oblongata and pons
- Histo: microabscesses
What are the steps of Listeria moncytogenes in ruminants?
- Oral cavity
- Trigeminal nerve
- Retrograde axonal transport
- Medulla oblongata
Thrombotic meningoencephalitis (TME) (bovine)
- Bovine disease
- Cause: histophilus somni
- 4 main lesions
- Neutrophilic vasculitis
- Thrombosis
- INFARCTION in multiple organs including the brain
What are the 4 main lesions from histophilus somni in bovine?
- Pneumonia
- Polyarthritis
- Myocarditis
- Meningocephalitis
Bovine malignant catarrhal fever
- Cattle, bison, deer
- Cause is OVINE herpes-virus 2
- *sheep are CARRIERS
- Lymphocytic vasculitis in brain, SC and any organ
- Brain gross lesion NOT always present
- *may see erosions in GI (ORAL) with swollen lymph nodes and urinary bladder
- *corneal edema
Maedi-Visna
- ADULT sheep disease
- Cause: lentivirus
- NON-suppurative encephalitis with primary demyelination
What are the lesions/combo of lesions Maedi-Visna can cause?
- Interstitial pneumonia (maedi and ovine progressive pneumonia)
- Encephalomyelitis (visna of sheep)
- Arthritis
- Mastitis
Caprine arthritis encephalitis
- GOAT disease
- CAE virus: lentivirus
- *CNS lesions seen in YOUNGER ANIMALS (2-4 months of age)
- *arthritis seen in adults that SURVIVE
Polioencephalomalacia
- Pilio: grey matter
- Malacia: necrosis
- RUMINANT DISEASE
- *thin gyri (neuronal necrosis), widened sulci
- *gray matter will fluoresce under light
- Laminar cortical necrosis histologically
- *sometimes responds to thiamine treatment
What are the 4 causes of polioencephalomalacia in ruminants?
- Lead poisoning
- Salt toxicity or water deprivation
- High water sulfur
- Thiamin deficiency
Copper deficiency
- Sheep and goats affected (ruminants)
- 2 syndromes
What are the 2 syndromes from copper deficiency in sheep and goats?
- Swayback
- Enzootic ataxia
Swayback: copper deficiency in sheep and goats
- Congenital form
o Brain and SC affected
o Cavitation due to malacia
Enzootic ataxia: copper deficiency in sheep and goats
- Delayed form
- Seen 6 months after birth
- *only brains stem and SC affected
- Need histology to see lesions
Clostridium perfringens type D: species and lesions
- Enterotoxemia in multiple spp
- In sheep: neurological manifestations can be seen
- *brain: BILATERAL SYMMETRIC HEMORRHAGE AND MALACIA OF BASAL NUCLEI AND THALAMUS
Canine distemper
- Morbillivirus
- Multisystemic disease
- BRAIN: non-suppurative inflammation
- Eosinophilic intranuclear inclusion bodies in NS
- **PRIMARY DEMYELINATION (when oligodendrocytes are KILLED)
o (secondary: due to loss of axons)
Thiamin deficiency (dog and cats)
- Thiamin: absolute dietary requirement
- EAT FISH containing thiaminase or DIET DEFICIENT in thiamin
- *gross and microscopic lesions: BILATERALLY SYMETRIC and commonly INVOLVE BRAINSTEM NUCLEI
o Soft due to necrosis
Reticulosis/granulomatous meningoencephalitis (GME)
- Smally to breed DOG
o 1-6 years of age
o Higher prevalence in females - Inflammatory disease of UNKNOWN etiology
- BRAIN STEM is mainly affected
- Optic form: optic nerve and retina are affected
Feline infectious peritonitis
- Feline coronavirus
- Noneffusive form results in
o Leptomeningitis
o Chorioependymitis
o Focal encephalomyelitis - **LOVES THE VENTRICULAR SYSTEM
Edema disease in PIGS
- Growing, healthy feeder pigs (4-8 weeks)
- Cause: E. coli producing Shiga-like toxin
- *lesions are secondary to endothelial damage by toxin=EDEMA
- *affects WHITE MATTER in the brain
