Fluoroacetate / Metaldehyde Flashcards
Where is fluoracetate most commonly used?
New Zealand and Australia
as a rodenticide and in livestock protection collars
What is the LD50 of fluoracetate in dogs?
0.06 - 0.2 mg/kg
EXTREMELY TOXIC
rodents is only 5-8 mg/kg –> relay toxicosis is a big concern
Where is fluoracetate absorbed?
readily in the GIT, lungs, open wounds
but not through intact skin
Is there tissue accumulation of fluoracetate ?
No.
wide distribution throughout the body - no particular tissues or accumulation
How is fluoracetate metabolized and excreted?
Metabolized to a toxic metabolite - monofluoroacetic via hydrolysis
parent and metabolite are excreted in the urine
What is the MOA of fluoracetate ?
Disrupts the TCA cycle = decreased cellular energy production
What tissues will be the most affected from fluoracetate cell injury?
high energy demand organs: heart, brain etc
What secondary toxic effect can be seen with fluoracetate toxicosis?
Citrate toxicity (there will be a build up since there is a disruption in the TCA cycle)
This will cause hypocalcemia and inhibition of various enzymes
What clinical signs are noted in dogs with fluoracetate poisoning?
Rapid onset (30mins - 2-4 hrs post ingestion)
CNS stimulation and GI signs:
Vomiting, dhr. hypermotility of the GIT, tenesmus, Hyperexcitablility, intermittent tonic clonic seizures, opisthotonos, hyperthermia, mydrasis
death within 1-12 hours
What is the main cause of death due to fluoracetate toxicosis?
Respiratory failure and anoxia
What clinical signs are associated with fluoracetate poisoing in horses/cattle/goats?
Cardiac signs predominate in horses
Heart failure, staggering, arrhythmias, colic, convulsions
Sheep - disoriented running, blindness, weakness, ataxia, coma, death
What signs are associated with fluoracetate toxicosis in cats and pigs?
Cats: both CNS and Cardiac signs - bradycardia and other arrhythmias
CNS Depression or excitement, vocalization, hyperesthesia, hypothermia
What lesions are associated with fluoracetate toxicosis?
Rapid onset of rigor mortis
no specific lesions
Elevated citrate levels in the kidney, heart, and blood would be considered diagnostic or supportive of fluoracetate poisoning?
supportive
What abnormalities may be seen on the blood work of a patient with fluoracetate poisoning?
Hyperglycemia
metabolic acidosis
Low ionized calcium (total Ca may be normal)
What is the treatment protocol for fluoracetate poisoning?
Due to the rapid onset - many animals will die before treatment
Inducing emesis is questionable due to CNS signs
activated charcoal can be given
Supportive care: IVF, O2, Ca, anti convulsants, etc etc
What is the prognosis for fluoracetate poisoning?
Guarded to poor
What is Metaldehyde used for?
Molluscicide that targets slugs/snails
Restricted use
may also be used for camping stove fuel
How are animals most commonly exposed to Metaldehyde ?
ingestion of baits or malicious poisoning
Products can release Metaldehyde for ____ days under moderately moist conditions
10-14 days
What species are the most sensitive and most susceptible to Metaldehyde poisoning?
cats are most sensitive
dogs are most susceptible
livestock and horses are susceptible as well
Through which route is Metaldehyde most toxic?
Inhalation
but ingestion is the most common route of exposure
How is Metaldehyde metabolized?
in the liver by microsomal enzymes (suspected to be p450)
*enzyme inducers may decrease toxicity (phenobarb)
may undergo enterohepatic recirculation
What happens to some of the Metaldehyde in the gastric environment?
Undergoes acid hydrolysis to acetaldehyde
Does Metaldehyde cross the BBB?
YES
so does acetaldehyde
these are both absorbed through the GI as well
What is the MOA of Metaldehyde ?
Decreases brain GABA (can lead to seizures and CNS excitation)
Causes direct GI irritation, metabolic acidosis, hyperthermia from excitation
What is the usual cause of death from Metaldehyde toxicosis?
Respiratory failure
*if they survive they may develop liver failure - check ALT 2-3 days post hospital discharge
What clinical signs are associated with Metaldehyde toxicosis?
“shake and bake”
Acute neurotoxicosis and hyperthermia
onset of signs in a few hours
hypersalvation, vomiting, dhr. incoordiation. muscle tremors. convulsions (elicitable by stimuli in cats, +/- in dogs)
eventually coma and death within 24 hrs with no treatment
What lesions are associated with Metaldehyde poisoning?
nothing specific
may note a formaldehyde odor in the stomach contents
Petechia in GI mucosa, congestion, edema. etc
What is the decontamination protocol for Metaldehyde?
Emetics if patient is not showing CNS signs (within 1-2hrs)
Gastric lavage
*activated charcoal - unclear is beneficial
Enemas
What treatment recommended for Metaldehyde toxicosis?
Supportive and symptomatic
Treat sz, hyperthermia, metabolic acidosis etc etc
What is the prognosis for Metaldehyde toxicosis?
Good if they survive first 24 hrs
Full recovery may take 2-3 weeks
