Fluoroacetate / Metaldehyde

Question 1

Where is fluoracetate most commonly used?

Answer 1

New Zealand and Australia

as a rodenticide and in livestock protection collars

Question 2

What is the LD50 of fluoracetate in dogs?

Answer 2

0.06 - 0.2 mg/kg

EXTREMELY TOXIC

rodents is only 5-8 mg/kg –> relay toxicosis is a big concern

Question 3

Where is fluoracetate absorbed?

Answer 3

readily in the GIT, lungs, open wounds

but not through intact skin

Question 4

Is there tissue accumulation of fluoracetate ?

Answer 4

No.

wide distribution throughout the body - no particular tissues or accumulation

Question 5

How is fluoracetate metabolized and excreted?

Answer 5

Metabolized to a toxic metabolite - monofluoroacetic via hydrolysis

parent and metabolite are excreted in the urine

Question 6

What is the MOA of fluoracetate ?

Answer 6

Disrupts the TCA cycle = decreased cellular energy production

Question 7

What tissues will be the most affected from fluoracetate cell injury?

Answer 7

high energy demand organs: heart, brain etc

Question 8

What secondary toxic effect can be seen with fluoracetate toxicosis?

Answer 8

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

Question 9

What clinical signs are noted in dogs with fluoracetate poisoning?

Answer 9

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

Question 10

What is the main cause of death due to fluoracetate toxicosis?

Answer 10

Respiratory failure and anoxia

Question 11

What clinical signs are associated with fluoracetate poisoing in horses/cattle/goats?

Answer 11

Cardiac signs predominate in horses
Heart failure, staggering, arrhythmias, colic, convulsions

Sheep - disoriented running, blindness, weakness, ataxia, coma, death

Question 12

What signs are associated with fluoracetate toxicosis in cats and pigs?

Answer 12

Cats: both CNS and Cardiac signs - bradycardia and other arrhythmias

CNS Depression or excitement, vocalization, hyperesthesia, hypothermia

Question 13

What lesions are associated with fluoracetate toxicosis?

Answer 13

Rapid onset of rigor mortis

no specific lesions

Question 14

Elevated citrate levels in the kidney, heart, and blood would be considered diagnostic or supportive of fluoracetate poisoning?

Answer 14

supportive

Question 15

What abnormalities may be seen on the blood work of a patient with fluoracetate poisoning?

Answer 15

Hyperglycemia
metabolic acidosis
Low ionized calcium (total Ca may be normal)

Question 16

What is the treatment protocol for fluoracetate poisoning?

Answer 16

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

Question 17

What is the prognosis for fluoracetate poisoning?

Answer 17

Guarded to poor

Question 18

What is Metaldehyde used for?

Answer 18

Molluscicide that targets slugs/snails

Restricted use

may also be used for camping stove fuel

Question 19

How are animals most commonly exposed to Metaldehyde ?

Answer 19

ingestion of baits or malicious poisoning

Question 20

Products can release Metaldehyde for ____ days under moderately moist conditions

Answer 20

10-14 days

Question 21

What species are the most sensitive and most susceptible to Metaldehyde poisoning?

Answer 21

cats are most sensitive
dogs are most susceptible

livestock and horses are susceptible as well

Question 22

Through which route is Metaldehyde most toxic?

Answer 22

Inhalation

but ingestion is the most common route of exposure

Question 23

How is Metaldehyde metabolized?

Answer 23

in the liver by microsomal enzymes (suspected to be p450)

*enzyme inducers may decrease toxicity (phenobarb)

may undergo enterohepatic recirculation

Question 24

What happens to some of the Metaldehyde in the gastric environment?

Answer 24

Undergoes acid hydrolysis to acetaldehyde

Question 25

Does Metaldehyde cross the BBB?

Answer 25

YES

so does acetaldehyde

these are both absorbed through the GI as well

Question 26

What is the MOA of Metaldehyde ?

Answer 26

Decreases brain GABA (can lead to seizures and CNS excitation)

Causes direct GI irritation, metabolic acidosis, hyperthermia from excitation

Question 27

What is the usual cause of death from Metaldehyde toxicosis?

Answer 27

Respiratory failure

*if they survive they may develop liver failure - check ALT 2-3 days post hospital discharge

Question 28

What clinical signs are associated with Metaldehyde toxicosis?

Answer 28

“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

Question 29

What lesions are associated with Metaldehyde poisoning?

Answer 29

nothing specific

may note a formaldehyde odor in the stomach contents

Petechia in GI mucosa, congestion, edema. etc

Question 30

What is the decontamination protocol for Metaldehyde?

Answer 30

Emetics if patient is not showing CNS signs (within 1-2hrs)
Gastric lavage
*activated charcoal - unclear is beneficial
Enemas

Question 31

What treatment recommended for Metaldehyde toxicosis?

Answer 31

Supportive and symptomatic

Treat sz, hyperthermia, metabolic acidosis etc etc

Question 32

What is the prognosis for Metaldehyde toxicosis?

Answer 32

Good if they survive first 24 hrs

Full recovery may take 2-3 weeks