Nervous and Respiratory System Toxicity Flashcards
Fumonisin
Mycotoxin infecting corn kernel
Causes Equine leukoencephalomalacia
Degeneration of white matter
States with warm humid climates
Toxins associated with fumonisin
Fumonisin B1 and B2 stored in moldy corn, commercial and pelleted feeds
CS of fumonisin toxicity
Neurotoxic (first) and hepatotoxic
Compulsive walking, hypersensitivity, head pressing, muscle tremors and death
T/F: death within 4-24 hr after onset of CS with fumonisin toxicity
TRUE
Dx fumonisin
Feed analysis (fumonisin levels)
Clin path: ↑ liver enzymes, BR, and CSF protein
How does fumonisin look on necropsy?
Liquefactive necrosis and malacia of white matter
Pathophysiology of fumonisin toxicity
Disrupts endothelial cell walls and BM → vasc damage in brain → degeneration
Tx of fumonisin toxicity
Tx cerebral inflamm and edema
Corticos, NSAIDs and DMSO
Diuretics and mannitol (if not internal bleeding/ anemia)
Thiamine (B1)
Human euthanasia
Botulism
Decaying organic material (C. botulism)
Types A, B and C1* toxin
Normal mentation
CS of botulism
Progressive flaccid paralysis
Inability to eat/ swallow, ptyalism, nasal discharge, muscle tremors, difficulty rising, dyspnea and death
What causes botulism
Ingestion (moldy feed/ hay) or exposed wounds
Hay baled wet or stored in damp warm environment
Botulism toxin
B*, C and D from Clostridium botulism
Forage poising (adults) and shaker foal syndrome
Forage poisoning
Ingestion
Dyspnea, flaccid tail and muscle tremors
Severe paresis to rapid recumbency
Unable to retract tongue, drooling
Shaker foal
Toxicoinfectious botulism (type B and C)
1-12m old (early as 2 weeks)
Ingests soil with C. botulism
CS of Shaker Foal
Inability to swallow (drooling, nasal discharge while nursing, repeated cough)
Poor tone, abnorm gait, progressive weakness and CS then death
Tx of botulism
Fatal if not given antitoxin: botulism antitoxin and hyperimmune plasma
Supportive therapy
Prevention of botulism
Vaccinate adults with endemic (type B toxoid)
Nigropallidal encephalomalacia
Yellow star thistle and Russion Knapweed
Toxin: sesquiterpene lactone (parkinsonism, chewing dz and wooden expression)
How does a horse get Nigropallidal encephalomalacia
Eating large quantities of YST and RK
Green and dried plants toxic
neuro signs irreversible
CS of yellow star thistle and Russian knapweed
Involuntary chewing, muscle tremors
Difficulty prehending/ swallowing, grinning appearance, protruding and lolling tongue
Dx Russian knapweed
Repens causes lesion in the globus pallidus and sustantia nigra
Bracken fern
Inadequate forage, incorporation into hay
Causes equine bracken staggers
Thiaminase inhibitor
CS of bracken fern
Appear 30-60d after ingestion
Staggers, death, wide-base stance, arched back, m. tremors, progressive incoordination
Bracken fern MOA
Thiaminase → deactivated B1 → accumulation of pyruvate/lactate → thiamine deficiency
Tx of bracken fern
Untxable, administer thiamine initially
Avermectins
Acute progressive neurologic condition
Progressive, ataxia, drooping lips, muscle fasciculations, bilat mydriasis, neg menace response
Moxidectin
Macrocyclic lactone
Asc. paralysis, dyspnea, depression, tremors, ataxia, weakness and seizures
Swainsonine (loco weed) initial CS
Depression and incoordination
Then aberrant behavior, aggression, circling, WL and death
Swainsonine (loco weed) chr. CS
Created lysosomal dz
Alpha mannosidase inhibited
Swelling of axonal hillocks and growth of new dendrites and synapses (severe and irreversible)
Tobacco
Toxin: nicotine
Hyperexcitability then depression, incoordination, paralysis, colic and death possible
Marijuana
Toxin: delta-9 THC
Prolonged depression, incoordination, sleepiness/ excitation, hypersalivation, low BP, dilated pupils, seizure, etc
Eucalyptus acute CS
Salivation, resp. irritant, diarrhea, depression and weakness
Eucalyptus chr. CS
WL, lung damage (irreversible)
Chr. resp problems and death
Cyanogenic plants
Early growth and plant damage: most toxic
Sudan, sorghum and hyrid
Death usually 30-45 minutes during severe convulsion
CS of cyanogenic plants
Excitation with rapid breathing and HR
Drooling/ watery eyes, muscle spams
MM bright red then blue
Dx cyanogenic plant toxicity
Hydrocyanic acid (GI, blood, liver and muscle)
Confirm with necropsy within 4 hr
Tx cyanogenic plants
Tx immediately and oxygen therapy
Antidote: sodium nitrate, sodium thiosulfate and methylene blue
Sudan grass
Requires 1 week to 6m of ingestion
Loss of nerve function to hind legs and bladder, stumbling when forced to move, paralysis, fetal deformities or fetal death
Lemon grass
Oil grass, cyanogenic glycosides
Difficulty breathing, weakness, rarely death
Black cherry
With family Rosaceae: apricot, plum, peach
Brick red mm, dilated pupils, difficult breathing and shock
Cyanide reduces O2 carrying capacity of Hg in RBCs
