Neurotoxicities and Neurodegenerative Dz of the CNS Flashcards
Malacia
Softening (necrosis of tissue in the CNS)
Encephalomalacia/ myelomalacia/ encephalomyelomalacia
Poliomalacia
Softening of gray matter
Leukomalacia
Softening of white matter
Primary causes of laminar neuronal cortical necrosis (Polioencephalomalacia)
Thiamine deficiency (bracken fern)
Sulfur excess
Lead/heavy metal toxicosis
Salt toxicity
Polioencephalomalacia
Multifocal/ diffuse yellow areas of malacia(necrosis) in the cerebral cortex
Lead toxicity
Acute poisoning = death in 12-24 hrs
Polioencephalomalacia
Seen in cattle
Lead toxicity CS
Calves: stagger, muscle tremor, recombinant
Adult: Head pressing, blindness with death and convulsions
Salt poisoning (NaCl)
Swine most susceptible, sheep resistant
Prevented by free access to water of low saline
CS of salt poisoning in swine
Swine: convulsions start with tremors of snout → clonic spasms of neck → jerky opisthotonus that causes the pig to walk backward to sit
CS of salt poisoning in cattle
Drag hindfeet or knuckle at the level of their fetlocks
Microscopic lesions of salt poisoning
Esosinophilic meningoencephalitis and encephalomalacia
Laminar necrosis of cerebral cortex
Bracken fern (thiamine deficiency)
↑ thiaminase
Causes polioencephalomalacia in horses (bracken staggers)
T/F: cattle are resistant to thiamine deficiency
TRUE
due to production of thiamine in ruminal flora
Yellow star thistle
Centaurea solstitialis, Rhaponticum repens (russian knapweed)
Causes Chewing dz in horses
CS of yellow star thistle toxicosis
Difficult in prehension of food and water
Death from starvation
Lesions of yellow star thistle
Malacic lesions in the globus pallidus and substantia nigra (nigropallidal encephalomalacia)
Moldy corn toxicosis
Corn contaminated with Fusarium moniliforme fungus
Fumonisin B1 toxin produced
Equine and rabbits most susceptible
__________________ is associated with moldy corn and is the cause of _______________
Leukoencephalomalacia
Porcine pulmonary edema
CS of moldy corn toxicosis
Drowsiness, impaired vision, pharyngeal paralysis, weakness, circling, staggering
Perennial ryegrass toxicity (ryegrass staggers) pathogenesis
Ryegrass infected with epichloe festucae
Ca-acting K+ channel inhibitor → prolonged depolar. and sustained motor end plate impulses
Botulism
From C. bolulinum that produces toxins → release of ACh At NT junctions
In decaying carcasses and vegetation
Perennial ryegrass toxicity
In horses, cattle, sheep and camelids
In pacific NW
Perennial ryegrass toxicity CS
Muscle tremors starting @ face
Hypermetric gait, ataxia
Recumbency
Signs from loud noises, being frightened or exercise
Tetanus (lockjaw) pathogenesis
C. tetani that produces toxin → internalized by presyn. termininays @ NJ and transported retrograde to the SC → blocks NT release from spinal inhibitory neurons
CS of Botulism
Flaccid muscle paralysis, resp. distress then death
Tetanus (Lockjaw)
Wound contamination with contaminated soil
CS of Tetanus
Spastic paralysis, hypertonicity, hyperstimulatory
Saw horse stance
Degenerative diseases
Progressive loss of destruction of neurons
Cerebellar abiotrophy of foals, equine myeloencephalopathy, equine motor dz
Cerebellar abiotrophy of foals
Progressive neurodegenerative dz of cerebellar neurons
Autosomal recessive
Arabians and their cross breeds affected
CS of Cerebellar abiotrophy of foals
Normal @ birth, starts 6w-18m
Head tremor, ataxia, falling, wide-based stance, difficult rising, exaggerated gait
Equine Degenerative Myeloencephalopathy (equine neuroaxonal dystrophy)
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
Prevention of Equine Degenerative Myeloencephalopathy
Dam and foals have access to green pasture
Measure serum from alpha-tocopherol (Vt. E supplementation need)
Equine motor dz
Progressive degeneration of LMN in horses >2yr
Quarter horses
Prolonged Vit. E deficiency
CS of equine motor dz
Weakness, trembling, shifting pelvic limbs, muscle atrophy
Hindlimb under body with head lowered
Lesions of equine motor dz
Degenerative lesions in the sarcodorsalis cadualis muscle or spinal accessory nerve
