Central Nervous System

Question 1

in the brain, where is the grey matter and where is the white matter?

Answer 1

grey matter is on the outside and white matter is on the inside

Question 2

what are the two functions of astrocytes?

Answer 2

1. repair (glial scar)
2. support and important component of the BBB

Question 3

what is the function of oligodendroglia?

Answer 3

myelinating cells within the CNS

Question 4

what is the function of microglial cells?

Answer 4

phagocytic cells of the CNS

Question 5

how do neuronal cell bodies respond to degeneration within axons?

Answer 5

chromatolysis

Question 6

what do injured axons undergo?

Answer 6

Wallerian degernation

Question 7

what are the 2 astrocytes that he wanted us to know for the exam?

Answer 7

gemistocytic astrocytes and Alzheimer’s type II astrocytes

Question 8

what are the two types of demyelination?

Answer 8

1. primary - due to loss of oligodendrocytes
2. secondary - due to loss of axons (most common)

Question 9

what type of brain edema is the most common and is due ti extracellular fluid accumulation? what is the underlying mechanism?

Answer 9

vasogenic edema
underlying mechanism is a breakdown of the BBB

Question 10

what type of brain edema is due to the accumulation of intracellular fluid in the neurons, astrocytes, oligodendroglia, and endothelial cells?

Answer 10

cytotoxic edema

Question 11

what type of brain edema is elevated ventricular hydrostatic pressure?

Answer 11

hydrostatic edema

Question 12

when does hypo-osmotic edema occur?

Answer 12

after the over-consumption of water (water intoxication)

Question 13

what is it called when the brain has no gyri?

Answer 13

Lissencephaly

Question 14

what in-utero viruses an cause cerebellar hypoplasia in calves, kittens, puppies, and piglets?

Answer 14

calves - pestivirus (BVD)
kittens - panleukopenia virus
puppies - canine parvovirus
piglets - classic swine fever virus

Question 15

what are the two types of hydrocephalus? which is the most common?

Answer 15

communicating (more common) and non-communicating (due to obstruction)

Question 16

what it is called when there is an abnormal dilation of the central canal of the spinal cord that leads to the formation of a cavity in which CSF may accumulate?

Answer 16

hydromyelia

Question 17

what is it called when there is a fluid filled cyst within the spinal cord separate from the central canal and not lined by ependymal cells?

Answer 17

Syringomyelia

Question 18

what are the 3 portals of entry to the CNS?

Answer 18

• direct extension (from inner ear, nasal sinuses through the cribriform plate or bones)
• hematogenous
• retrograde axonal transport (rabies and listeria)

Question 19

what bacteria can cause brain abscesses?

Answer 19

streptococcus, E. coli, staphylococcus, Corynebacterium, Klebsiella

Question 20

if you have meningitis in a calf, what is the most likely cause?

Answer 20

most likely streptococcus or e. coli secondary to an umbilical infection, which goes septic

Question 21

what two viruses cause ganglioneuritis?

Answer 21

rabies or herpesvirus

Question 22

what virus has no gross lesions but non suppurative encephalitis is present histologically?

Answer 22

Rabies

Question 23

what fungi has a particular affinity for the CNS, and enters the leptomeninges and subarachnoid space by direct extension through the cribriform plate? How does it protect itself from host defenses?

Answer 23

Cryptococcus neoformans
has a thick mucinous capsule

Question 24

what parasite causes feline ischemic encephalopathy?

Answer 24

Cuterebra larva

Question 25

what is the most common toxicosis in cattle? what does it cause? what should be sampled?

Answer 25

Lead poisoning
causes polioencephalomalacia
sample fresh liver and stomach contents

Question 26

if you have polioencephalomalacia, but no lead toxicosis, what is your next suspected condition? What should you see?

Answer 26

Salt toxicity
histologically should see eosinophilic meningoencephalitis

Question 27

what is the pathogenesis of tetanus? what will you see upon necropsy?

Answer 27

Clostridium tetani releases tetanospasmin (toxin), which is transported by retrograde axoplasmic flow. The toxin blocks the release of inhibitory neurotransmitters like glycine and GABA
no gross or histology lesions

Question 28

what bacteria causes flaccid paralysis of muscles by blocking the release of ACh and causes no gross or histological lesions?

Answer 28

Clostridium botulinum (botulism)

Question 29

Leukoencephalomalacia (moldy corn disease) is caused by what fungus and causes what?

Answer 29

Fusarium moniliforme
necrosis of the white matter of the brain

Question 30

what is the tumour called of the young animal brain in the roof of the fourth ventricle? Why is it significant even if it is benign?

Answer 30

medulloblastoma
compresses the brain stem, any space occupying lesion of the brain is problematic (no room for fooling around)

Question 31

what tumour of dogs involves the pyriform lobe?

Answer 31

astrocytoma

Question 32

what type of brain tumours look like an “O” and are well demarcated?

Answer 32

Oligodendrogliomas

Question 33

what is the most common intracranial tumour of cats? Where is it located?

Answer 33

Meningioma
tumour on top of the brain

Question 34

what is the ruminant silage disease? Where do the lesions occur?

Answer 34

Listeria monocytogenes
medulla oblongata and pons

Question 35

what disease is seen in adult sheep, causing non-suppurative encephalitis with primary demyelination? What is the causative virus?

Answer 35

Maedi-Visna
Lentivirus

Question 36

what disease of young goats causes CNS signs and arthritis in older goats that survive? what is the causative virus?

Answer 36

Caprine Arthritis Encephalitis
Lentivirus

Question 37

what are the 4 causes of polioencephalomalacia?

Answer 37

1. lead poisoning
2. Salt toxicity
3. high water sulfur
4. thiamin deficiency

Question 38

if you have a case of polioencephalomalacia that isn’t lead or salt toxicity, what is your next guess? Where would you check?

Answer 38

High water sulfur, test the water source

Question 39

what are the two syndromes of sheep and goats that are associated with copper deficiency?

Answer 39

1. swayback - congenital form
2. enzootic ataxia - delayed form, seen at 6 months after birth