Non-infectious disorders of the nervous system

what lesions are found in granulomatous meningoencephalomyelitis (GME)?

histologically, it is marked by perivascular inflammation with lymphocytes, plasma cells macrophages, and granulomatous white matter lesions

what lesions are associated with necrotizing meningoencephalitis (NME)?

necrosis and inflammation in the cerebral cortex and subcortical regions

what lesions are associated with necrotizing leukoencephalitis (NLE)?

malacic lesions restricted to the cerebral white matter

what is acute polyradiculoneuritis (Coonhound paralysis)?

most common peripheral nerve disorder of dogs, manifesting as an ascending flaccid paralysis, starting in the hind limbs and advancing cranially

where are the primary lesions of acute polyradiculoneuritis?

in the ventral roots of spinal nerves and peripheral nerves, where nerve degeneration is evident, along with muscle atrophy secondary to nerve dysfunction 

what is neuritis of the cauda equina of horses?

a chronic and progressive neurological disorder of horses that primarily affects the lower spinal nerves

how does neuritis of the cauda equina (polyneuritis equi) present clinically?

tail paralysis, urinary incontinence, fecal retention, and pelvic limb weakness. In advanced stages, muscle atrophy becomes prominent, particularly in the coccygeal and hind limb regions.

what is the pathogenesis of polyneuritis equi?

precise cause remains uncertain, but an autoimmune origin is suspected, potentially following a viral infection

what are the gross lesions of polyneuritis equi?

the extradural segments of the sacral and coccygeal nerves may appear thickened and darkened due to chronic hemorrhage and inflammation

what are the defining histological lesions of polyneuritis equi?

granulomatous inflammation and extensive fibrosis (emphasizing the disease’s chronic nature and progressive degeneration)

what can cause polieoencephalomalacia of ruminants (PEM)?

thiamine (vitamin B1 deficiency) or excessive dietary intake

what is the most notable diagnostic clue in PM of animals with PEM?

autofluorescence of necrotic cortical material under UV light (seen in both fresh and formalin-fixed specimens)

which animals are most prone to salt poisioning?

pigs — due to higher dietary sodium intake but can also be seen in sheep and cattle

what is the most notable finding in histological examination of brain tissue of pigs with salt poisoning?

laminar cortical necrosis, neuronal malacia, and eosinophilic infiltration of the meninges and Virchow-Robin spaces

which animals are most prone to lead poisoning and why?

cattle due to their inquisitive feeding behavior

A group of calves that were recently moved to lush pastures suddenly developed blindness, head pressing, and seizures. Necropsy revealed auto fluorescent cortical necrosis under UV light. What is the most likely cause?

thiamine deficiency resulting in PEM

A group of pigs are found seizing after a period of water deprivation followed by sudden rehydration. Histology reveals laminar cortical necrosis and eosinophilic infiltration of the meninges. What is the most likely diagnosis?

salt poisoning 

what is focal symmetrical encephalomalacia (FSE)?

a toxin-induced neurologic disease seen in lambs and calves, typically triggered by high-starch diets that promote proliferation of Clostridium perfringens type D in the gut, resulting in systemic absorption of epsilon toxin

what lesions are associated with focal symmetrical encephaloamalcia (FSE)?

brain edema, causing hypoxia and symmetrical areas of malacia and hemorrhage, especially in the internal capsule, midbrain and cerebellar peduncles

what is mycotoxic leukoencephalomalacia of horses?

a fatal neurologic disease in horses caused by ingesting corn contaminated with fumonisin B1, a toxin produced by Fusarium fungi in warm, humid conditions

what lesions are caused by mycotoxic leukoencephalomalacia of horses?

toxic damage to blood vessels in the brain’s white matter, leading to localized areas of malacia, especially in the cerebral hemispheres

disease progresses quickly and prognosis is poor!

what is hepatic encephalopathy?

a complex neurological syndrome that arises in animals as a result of impaired liver function urea cycle enzyme deficiency, or conditions that allow portal blood to bypass the liver such as congenital or acquired portosystemic shunts, allowing substances normally metabolized by the liver to reach the brain in unaltered form 

what histological changes are seen in brains of animals with hepatic encephalopathy?

status spongiosus, or microcavitation within the myelin (particularly prominent in the cerebral cortex), ischemic neuronal degeneration and the presence of Alzheimer type II astrocytes

what are storage diseases?

a group of disorders defined by accumulation of intracellular materials that disrupt normal cellular function, leading to cell death 

what are lysozomal storage diseases?

buildup happens within lysosomes due to enzyme deficiencies that impair normal metabolic pathways, disproportionately affecting the CNS

what is the classic histological feature of storage diseases?

the appearance of distended cells swollen with vacuoles containing the undegraded or partially degraded substances

these vacuolated neurons and glia give the brain a distinctive spongy or foamy appearance on microscopic examination

what animals are most affected by copper deficiency?

young ruminants, particularly lambs and kids

what is swayback?

the congenital form of copper deficiency that develops in utero, typically when pregnant ewes are fed copper-deficient or molybdenum-rich diets

how do lambs born with swayback appear?

blind and severely uncoordinated

what gross findings are associated with swayback?

notable bilaterally symmetrical cavitation of the periventricular white matter in the cerebrum, often with associated enlargement of the ventricles

what is enzootic ataxia?

cooper toxicity that develops postnatally in kids and lambs that were clinically normal at birth

what histological features are found in both swayback and enzootic ataxia?

features of axonal degeneration and demyelination, especially in the dorsolateral and ventromedial columns of the spinal cord

what is perennial rye-grass staggers?

A mycotoxicosis affecting grazing livestock particularly sheep, cattle, and horses in regions like Australia, New Zealand, and parts of Europe, common during late summer and autumn

arising from ingestion of lolitrems, neurotoxic compounds produced by the endophytic fungus Neotyphodium lolii that naturally infects the rye grass

what is the primary microscopic lesion associated with perennial rye-grass staggers?

subtle fusiform enlargement of the proximal axons in cerebellar Purkinje cells, reflecting the toxin’s specific action on cerebellar motor coordination pathways

what is equine laryngeal hemiplagia (recurrent laryngeal neuropathy)?

idiopathic degeneration of the left recurrent laryngeal nerve, resulting in denervation atrophy of the intrinsic laryngeal muscles on that side, most notably the cricoarytenoideus dorsalis

muscle failure impairs the ability to adduct the arytenoid cartilage and vocal fold, leading to partial airway collapse during inspiration

what is the characteristic inspiratory noise of equine laryngeal hemiplagia?

“roaring”, especially evident during exercise

what is equine suprascapular neuropathy (sweeny)?

trauma to the suprascapular nerve leading to axonal degeneration, demyelination, and fibrosis, disrupting signal transmission

what gross lesions are associated with equine suprascapular neuropathy?

infraspinatus and supraspinatus muscles atrophy, producing noticeable shoulder depression and an abnormal gait or chronic lameness

what is equine stringhalt?

a neuromuscular disorder marked by an abrupt, exaggerated flexion of one or both hind limbs during movement, particularly as the leg swings forward. This gait abnormality is often sudden in onset and severity may vary between individuals

what are the two recognized forms of stringhalt?

sporadic (occurs without an identifiable environmental cause) and an epizootic form (seen in outbreaks associated with ingestion of certain pasture weeds like dandelion, flat weed and cheese weed)

how does stringhalt present pathologically?

distal axonopathy, with Wallerian degeneration primarily affecting heavily myelinated peripheral nerves. This suggests a toxin-induced or metabolic disruption targeting axonal integrity and motor control.