Ch 6 Metabolic Flashcards
What are the three major lesion types in metabolic-toxic diseases?
Malacia +/- hemorrhage, selective necrosis or loss of neurons, axons, or myelin, spongy state
Malacia refers to the softening of tissue, which can indicate underlying metabolic or toxic issues.
What is polioencephalomalacia?
A type of malacia affecting the cerebral cortex +/- hippocampus, basal and thalamic nuclei, colliculi, and cerebellar cortex
It is characterized by swelling, flattening of gyri/sulci, and may show slight yellowish discoloration.
Which vitamin deficiency is associated with polioencephalomalacia in ruminants?
Thiamine deficiency
This can occur due to high carbohydrate diets leading to ruminal acidosis and overgrowth of thiaminase-producing bacteria.
What are common causes of polioencephalomalacia in pigs?
- Hypoglycemia
- Cyanide poisoning
- Carbamates
- Organic mercury poisoning
In pigs, eosinophilic perivascular and parenchymal infiltrate may be present with PE.
What are the characteristics of equine nigropalladial encephalomalacia?
Caused by yellow star thistle or Russian knapweed; lesions include gray matter necrosis in substantia nigra and globus pallidus
Symptoms include abnormal tongue and mouth movements, prehension, and swallowing difficulties.
What is the primary toxin associated with equine leukoencephalomalacia?
Moldy corn disease caused by Fusarium moniliforme, specifically mycotoxin fumonisin B1
This toxin selectively damages white matter.
What is the histological feature of leukoencephalomalacia?
- Necrotic vessels with fibrin thrombi
- White matter necrosis
- Infiltration by gitter cells and neutrophils
These features indicate significant vascular damage and inflammatory response.
What are the main lesions associated with dysautonomia?
- Ganglionic and enteric neurons
- Central autonomic neurons
- Neuronal degeneration with chromatolysis
This condition affects various species including horses and cats.
True or False: Cerebellar nuclei lesions in metronidazole toxicity are reversible.
True
What is the primary effect of ammonia in hepatic encephalopathy?
It enters the brain and is metabolized to noxious glutamine, causing astrocyte swelling
This process ultimately leads to astrocytic dysfunction and brain edema.
What are the signs of equine motor neuron disease? What is the cause?
- Chromatolysis
- Nuclear changes
- Loss of spinal cord and brainstem motor neurons
This condition is suspected to be related to selenium and vitamin E deficiency.
What type of poisoning is associated with a dying back polyneuropathy?
Delayed organophosphate poisoning
This condition affects long nerve fibers primarily in distal portions.
What are the lesions seen in Wallerian degeneration?
- Fragmentation and loss of axons
- Secondary demyelination
- Reactive phagocytosis
This degeneration can occur due to various toxicities and nutritional deficiencies.
What is the effect of bromethalin on the nervous system?
Causes spongy state characterized by vacuolation in white matter
Other substances like ammonia and hexachlorophene also cause similar effects.
What is the common symptom of hound ataxia? What is the cause?
Gradual onset of ataxia and spastic paresis
This condition is due to a deficiency of methionine and altered methionine synthetase activity.
What is the role of noxious glutamine in astrocyte swelling?
Acts as an osmolyte causing astrocyte swelling
Noxious glutamine can lead to astrocytic dysfunction and brain edema
What does noxious glutamine split into within mitochondria?
Glutamate and ammonium
This process generates free radicals and damages mitochondria
What are the histological features of astrocytic dysfunction?
Varying degrees of white matter vacuolation
Includes boundary areas between white and gray matter in a bilaterally symmetrical pattern
What are the effects of noxious glutamine on astrocytes in gray matter?
A2 astrocytes show marginalized chromatin and clear center
Associated with renal encephalopathy
What is a characteristic of renal encephalopathy?
Accumulation of neurotoxic metabolites
No specific neurotoxin has been identified yet
What is salinomycin poisoning primarily used for?
Coccidiostat in poultry and growth promoter in ruminants
It is toxic in cats, horses, and dogs
How does salinomycin affect the body?
Chelates monovalent cations, affecting electrical potential and energy metabolism
Causes structural damage in muscle and axons
What is the consequence of salinomycin poisoning in the peripheral nervous system?
Widespread primary axonal Wallerian degeneration
Affects sensory and motor nerves, and dorsal tracts of the spinal cord
What are the effects of vincristine poisoning in cats?
Focal and axonal swelling and demyelination in motor and sensory nerves
Leads to Wallerian degeneration in more distal portions of nerves
