Neurotoxicities and Neurodegenerative Dz of the CNS

Question 1

Malacia

Answer 1

Softening (necrosis of tissue in the CNS)
Encephalomalacia/ myelomalacia/ encephalomyelomalacia

Question 2

Poliomalacia

Answer 2

Softening of gray matter

Question 3

Leukomalacia

Answer 3

Softening of white matter

Question 4

Primary causes of laminar neuronal cortical necrosis (Polioencephalomalacia)

Answer 4

Thiamine deficiency (bracken fern)
Sulfur excess
Lead/heavy metal toxicosis
Salt toxicity

Question 5

Polioencephalomalacia

Answer 5

Multifocal/ diffuse yellow areas of malacia(necrosis) in the cerebral cortex

Question 6

Lead toxicity

Answer 6

Acute poisoning = death in 12-24 hrs
Polioencephalomalacia
Seen in cattle

Question 7

Lead toxicity CS

Answer 7

Calves: stagger, muscle tremor, recombinant
Adult: Head pressing, blindness with death and convulsions

Question 8

Salt poisoning (NaCl)

Answer 8

Swine most susceptible, sheep resistant
Prevented by free access to water of low saline

Question 9

CS of salt poisoning in swine

Answer 9

Swine: convulsions start with tremors of snout → clonic spasms of neck → jerky opisthotonus that causes the pig to walk backward to sit

Question 10

CS of salt poisoning in cattle

Answer 10

Drag hindfeet or knuckle at the level of their fetlocks

Question 11

Microscopic lesions of salt poisoning

Answer 11

Esosinophilic meningoencephalitis and encephalomalacia
Laminar necrosis of cerebral cortex

Question 12

Bracken fern (thiamine deficiency)

Answer 12

↑ thiaminase
Causes polioencephalomalacia in horses (bracken staggers)

Question 13

T/F: cattle are resistant to thiamine deficiency

Answer 13

TRUE
due to production of thiamine in ruminal flora

Question 14

Yellow star thistle

Answer 14

Centaurea solstitialis, Rhaponticum repens (russian knapweed)
Causes Chewing dz in horses

Question 15

CS of yellow star thistle toxicosis

Answer 15

Difficult in prehension of food and water
Death from starvation

Question 16

Lesions of yellow star thistle

Answer 16

Malacic lesions in the globus pallidus and substantia nigra (nigropallidal encephalomalacia)

Question 17

Moldy corn toxicosis

Answer 17

Corn contaminated with Fusarium moniliforme fungus
Fumonisin B1 toxin produced
Equine and rabbits most susceptible

Question 18

__________________ is associated with moldy corn and is the cause of _______________

Answer 18

Leukoencephalomalacia
Porcine pulmonary edema

Question 19

CS of moldy corn toxicosis

Answer 19

Drowsiness, impaired vision, pharyngeal paralysis, weakness, circling, staggering

Question 20

Perennial ryegrass toxicity (ryegrass staggers) pathogenesis

Answer 20

Ryegrass infected with epichloe festucae
Ca-acting K+ channel inhibitor → prolonged depolar. and sustained motor end plate impulses

Question 21

Botulism

Answer 21

From C. bolulinum that produces toxins → release of ACh At NT junctions
In decaying carcasses and vegetation

Question 21

Perennial ryegrass toxicity

Answer 21

In horses, cattle, sheep and camelids
In pacific NW

Question 21

Perennial ryegrass toxicity CS

Answer 21

Muscle tremors starting @ face
Hypermetric gait, ataxia
Recumbency
Signs from loud noises, being frightened or exercise

Question 21

Tetanus (lockjaw) pathogenesis

Answer 21

C. tetani that produces toxin → internalized by presyn. termininays @ NJ and transported retrograde to the SC → blocks NT release from spinal inhibitory neurons

Question 22

CS of Botulism

Answer 22

Flaccid muscle paralysis, resp. distress then death

Question 23

Tetanus (Lockjaw)

Answer 23

Wound contamination with contaminated soil

Question 24

CS of Tetanus

Answer 24

Spastic paralysis, hypertonicity, hyperstimulatory Saw horse stance

Question 25

Degenerative diseases

Answer 25

Progressive loss of destruction of neurons Cerebellar abiotrophy of foals, equine myeloencephalopathy, equine motor dz

Question 26

Cerebellar abiotrophy of foals

Answer 26

Progressive neurodegenerative dz of cerebellar neurons Autosomal recessive Arabians and their cross breeds affected

Question 27

CS of Cerebellar abiotrophy of foals

Answer 27

Normal @ birth, starts 6w-18m Head tremor, ataxia, falling, wide-based stance, difficult rising, exaggerated gait

Question 28

Equine Degenerative Myeloencephalopathy (equine neuroaxonal dystrophy)

Answer 28

Progressive degeneration of spinal neurons, axons and myelin → ataxia and weakness Developed in the first year of life Associated with Vit. E deficiency and genetic predisposition

Question 29

Prevention of Equine Degenerative Myeloencephalopathy

Answer 29

Dam and foals have access to green pasture Measure serum from alpha-tocopherol (Vt. E supplementation need)

Question 30

Equine motor dz

Answer 30

Progressive degeneration of LMN in horses >2yr Quarter horses Prolonged Vit. E deficiency

Question 31

CS of equine motor dz

Answer 31

Weakness, trembling, shifting pelvic limbs, muscle atrophy Hindlimb under body with head lowered

Question 32

Lesions of equine motor dz

Answer 32

Degenerative lesions in the sarcodorsalis cadualis muscle or spinal accessory nerve