Blakley #2 Flashcards
(307 cards)
what is metaldehyde
a molluscide used to control snails and slugs
absorption of metaldehyde
well absorbed in intestine; can become addicting to dogs
metabolism of metaldehyde
rapidly metabolized to acetaldehyde
distribution and excretion of metaldehyde
readily crosses BBB, metaldehyde is responsible for toxicity, acetaldehyde causes vomiting/tremors and is excreted in urine
mechanism of action of metaldehyde
reduces GABA and serotonin levels in brain causing CNS excitation (occasionally depression); depression of medullary respiratory center leads to death
minor mechanisms of metaldehyde
gastroenteritis (chemical irritation), brain damage, mild liver damage
clinical manifestations of excitatory syndrome of metaldehyde toxicity
salivation, tremors, ataxia, continuous convulsions, opisthotonus, nystagmus (cats), elevated BT
clinical manifestations of depressive syndrome of metaldehyde toxicity
emesis, depression, incoordincation, increased RR and HR, cyanosis and coma
PM findings of metaldehyde toxicity
non-specific lesions; congestion and mild hemorrhage of liver, kidney and GIT; stomach smells like apple cider, large amount of content
what does the stomach contents of metaldehyde toxicity smell like
apple cider from acetaldehyde
diagnosis of metaldehyde toxicity
sudden onset of neuro signs, large quantities of pleasant smelling stomach contents, analysis of stomach contents
treatment of metaldehyde toxicity
sedation, anesthesia, emetics, fluids (shock/acidosis) +/- activated charcoal (crisis usually over in 24 hours due to rapid elimination)
species susceptibility with strychnine toxicity
all mammals are highly susceptible (dogs are the most); secondary poisoning/relay toxicity is common
absorption of strychnine
rapidly absorbed; clinical manifestations within 15 minutes to 1 hour
distribution of strychnine
can be detected in liver, kidney, brain, blood or stomach contents (stomach contents are best)
metabolism and excretion of strychnine
metabolized rapidly by liver with half life of 10 days; excreted in urine and saliva
mechanism of action of strychnine
strychnine competitively antagonizes glycine resulting in loss of inhibitory processes and neurological excitation (glycine in the predominant inhibitory neurotransmitter at level of spinal cord and medulla); interferes with post-synaptic inhibitory control at level of spinal cord; also alters K ion gates postsynaptically leading to motor neuron excitability
why does strychnine not interfere with post-synaptic inhibitory control in the brain
because it is regulated by GABA, not glycine
clinical manifestations of strychnine toxicity
sudden onset, apprehension, nervousness, tenesmus, rigid muscle (especially face), tetanic seizures begin in 15 minutes-2hours (extensor rigidity of all 4 limbs), as more strychnine is absorbed relaxation periods between seizures becomes shorter, seizures can be triggered by external stimuli, apnea (anoxia, coma and death within 1-2 hours)
PM findings of strychnine toxicity
no specific lesions because it is a neuro/biochem disturbance; agonal congestion and hemorrhage due to nature of death
diagnosis of strychnine toxicity
sudden death in normal healthy dog; analysis of stomach contents, vomitus or liver
treatment of strychnine toxicity
emergency treatment, apomorphine (emetic; prior to seizures), gastric lavage with activated charcoal or tannic acid (bind/precipitate strychnine), potassium permanganate, sedation, muscle relaxants
most important treatment for strychnine toxicity
sedation
which are the coumarin derivative anticoagulant rodenticides
warfarin, brodifacoum, difencoum