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69 Cards in this Set

  • Front
  • Back
13 toxins affecting the Nervous system
- strychnine
- metaldehyde
- penitrem A = requefortine
- bromethalin
- sodium fluoroacetate / - fluroacetamide
- 4-methylimidazole
- methylxanthine
- lead
- urea & non protein nitrogen intoxication
- organophosphorus - carbamate
- pyrethrum, pyrethrin, pyrethroids
- chlorinated hydrocarbon pesticides (organochlorides)
- blue-green algae
strychnine source
rodenticide - seed baits - often dyed to indicate toxicity
strychnine spp affected
all spp affected - dogs most common
strychnine mech of action
binds inhibitory glycine receptors causing huge overtransmission of signal so tiniest stimulus creates powerful muscle contraction
strychnine signs
powerful & painful convulsions with no cognitive or sensory impairment.
extensor rigidity
anoxia, hypoxia, hypercarbia, hyperthermia, rhabodmyolysis, metaboic acidosis
metaldyhyde source
mulluscide - snail / slug bait
metaldehyde spp affected
all spp affected - dogs most common
metaldehyde signs
"shake & bake syndrome"
msucle tremors & hyperthermia
Penitrem A - Roquefortine source
tremorgenic mycotoxin produced by penicillium in moldy foods (bread / garbage) & decaying organic material (compost)
Penitrem A - Roquefortine spp affected
all - dogs most common
Penitrem A - Roquefortine signs
rapid onset of muscle tremors & hyperthermia
Bromethalin source
bromethalin mech of action
uncouples oxidative phosphorylation --> fluid vacuoles b/w myelin sheaths which creates pressure on nerve --> reduced conduction & paralysis
Bromethalin signs
paralysis, muscle tremors & seizures
sodium fluoroacetate & Fluoroacetamide source
compound 1080 used for coyote & rodent control
sodium fluoroacetate & fluoroacetamide spp affected
ALL SPP affected
sodium fluoroacetate & fluoroacetamide mech of action
"lethal synthesis" w/in krebs cycle creates fluorocitrate which inhibits acontinase & shuts down the energy generating pathway. Acculation of citric & lactic acid results
sodium fluoroacetate & fluoroacetamide signs
multisystemic - dog primarily GI & nervous system.
Cats show vocalization
ruminants show mostly cardiac signs
4-methylimidazole source
ammoniated feeds
4-methylimadazole spp affected
adult cattle & nursing calves (secreted in milk)
4-methylimadazole signs
Bovine Bonkers syndrome
hyperexcitable - circling / wild running
methylxanthine source
theobromine (chocolate)
caffeine (coffee)
theophylline (tea)
methylxanthine spp affected
all spp affected
methylxanthine signs
death from arrhythmias & respiratory failure
lead source
SA - paint
LA - batteries
waterfowl - lead shot
lead spp affected
all - young more susceptible
cattle, young dog, waterfowl commonly
lead mech of action
carried by RBC - redistriubtes to tissues / bone.
Segmental demyelination of pharyngeal & recurrent laryngeal nerves
lead signs
SA - GI / neuro
LA - NERUO / gi, hyperthermia, depression
basophilic stippling, nRBC w/o significant anemia
lead tx
chelators (exchange Ca for Lb & enhance excretion)
Urea & Nonprotein Nitrogen Intoxication source
Improper supplement mixing or mismanagement - important to allow slow adaption to NPN sources
Urea & nonprotein Nitrogen source intoxication spp affected
cattle & sheep
urea & nonprotein nitrogen source intoxication mech of action
excess ammonia released via hydrolysis of urea by rumen microorganism. Ammonia inhibits krebs cycle and leads to lactic acid acidosis. metabolic acidosis --> hyperkalemia --> cardiac failure
urea & non protein nitrogen source intoxication signs
colic, abd pain, bloat
tremors, ataxia
blue green algae source
cyanobacteria in stagnant eutrophic ponds
(anaboaena flus aquae, aphanizomenon flos aquae, oscillatonia spp)
blue green algae toxins
(saxitoxin & neosaxitoxin)
blue green algae signs
muscle rigidity, tremors & paralysis
Chlorinated hydrocarbon pesticides (organochlorines) mech of action
diffuse nervous stimulation. Biologic magnification (increase effect as you move up food chain) with environmental contamination
chlorinated hydrocarbon pesticide (organochlorines)signs
muscle tremors & seizures. Diffuse CNS stimulation
pyrethrum, pyrethrin, pyrethroid source
insecticides - flea / tick repellants
(pyrethrum / pyrethrin from chrysanthemum flower -- pyrethroid is synthetic)
pyrethrum, pyrethrin, pyrethroid signs
increased salivation, tremors & seizures
pyrethrum, pyrethrin, pyrethroid treatment
lack of response to atropine

use muscle relaxant - diazepam, phenobarbital, methocarbamol
organophosphorus carbamate insecticides mech of action
acetylcholinesterase inhibitor --> increased acetylcholine
organophosphorus carbamate insecticide signs
muscarinic - SLUD
nicotinic - twitching / paralysis

colic, abd ain, diarrhea. Looks like pancreatitis in dogs. Death from respiratory failure
delayed neuropathy
organophosphorus carbamate insecticide treatment
atropine (tx SLUD)
oximes (mimics binding site on cholinesterase enzyme & so binds Ach & increases elimination.
4 toxins affecting the skin
- Chronic Selenium Poisoning
- Molybdenum Toxicity / Cu Deficiency
- fescue toxicosis
- ergot
Chronic selenium poisoning source
forages, feed additives
obligate indicator plants (require Se for growth) - astragalus
facultative indicator plants - aster
chronic selenium poisoning spp affected
all spp susceptible
horses appear sensitive
chronic selenium poisoning signs
bobtailed disease - rough hair coat, hair loss
hoof deformities
One way to reduce selenium poisoning in cattle
addition of arsenic salt at 0.00375% to enhance biliary excretion - or use high-protein diet to bind
Molybdenum toxicity - copper deficiency - source
dietary imbalance
Molybdenum toxicity / Cu deficiency spp affected
cattle most commonly
molybdenum toxicity / Cu deficiency signs
calves - depressed growth rate, spontaneous fractures
adults - diarrha, depigmentation, rough hair coat
ossification of tendons of insertion
fescue toxicosis clinical syndromes
summer syndrome in cattle - rough hair coat, tachypnea, hyperthermia

reproductive problem in mares, cattle, sheep - prolonged gestation, retained placenta, weak young, abortions

fescue foot - lameness, dry gangrene necrosis of tail, ears & digits
fescue toxicosis source
tall fescue containing endophyte

Toxin = ioline alkaloids & ergot-like alkaloids
fescue toxicosis mechanism of action
peripheral vasocontriction

suppress prolactin secretion
fescue toxicosis treatment
metoclopramide, doperidone - resolve agalactia & prolonged gestation

perphenazine prevents agalactia in horses (stimulates prolactin release)
ergot - source
fungus in rye, barley, seeds
ergot mech of action
ergotamine - peripheral vasocontriction
ergot signs
dry gangrene
gastrointestinal disorders
abortions (cattle & sheep)
1 toxin affecting the Oropharyngeal Cavity (& GIT)
slaframine source
fungus of red clover = mycotoxin
slaframine mech of action
mimics Ach action (parasympathomimetic)
slaframine spp affected
cattle, horse, sheep, goat
slaframine signs
profuse salivation

uriation, diarrhea, bloat,
toxicant affecting reporduction
zearlenone source
fusarium mycotoxin - corn, wheat, barley oats
zearlenone mech of act
functions as weak estrogen
zearlenone clinical signs
anestrus / pseudopregnancy
prolonged estrus
males - enlarged prepuce, impaired testicular development
zearlenone spp affected
cattle, swine