Ethylene Glycol Flashcards
What is the best treatment for ethylene glycol toxicosis?
Fomepazole (4-MP)
**it will NOT created a false positive when testing for ethylene glycol
What is the most common route of exposure of ethylene glycol?
Ingestion
- *has a sweet taste
- low molecular weight - activated charcoal does not work well
What is the mortality rate reported for ethylene glycol toxicosis in dogs and cats?
59-70%
What is the minimal lethal does of antifreeze in dogs and cats?
Dogs: 4.2 - 6.6 ml/kg
Cats: 1.4 ml/kg
How is antifreeze absorbed?
Readily absorbed in the GIT
absorption will be delayed by food
What is the half life of antifreeze?
3-4 hours in dogs
shorter in cats
Dog - peak plasma level at 2 hours
What synthesis does antifreeze undergo in the liver?
Lethal synthesis
E.G. is oxidized to glycoaldehyde
Glycoaldehyde is oxidized to glycolic acid
Glycolid acid is oxidized GyloXylic acid—> TONS of other acids are made after this
What crystals are created from Oxalic acid and calcium binding due to the ingestion and absorption of antifreeze?
Insoluble calcium oxalate monohydrate crystals
form in the tissues - causing damage and passed in the uring
How long are the metabolites of ethylene glycol present for?
Several days
a small amount of ethylene glycol will be excreted in the urine unchanged (within 24 hrs)
What side effect do calcium oxalate monohydrate crystals have?
Hypocalcemia
What are the main toxic effects of the metabolites of ethylene glycol?
Metabolic acidosis and acute renal failure
What toxic effects does ethylene glycol itself, have on the body?
Direct GI irritation
increased serum osmolality = osmotic diuresis
CNS depression
What CNS effects does ethylene glycol have?
CNS dysfunction resulting in inhibition of respiration, dysfunction of: glucose and serotonin metabolism, alteration of amine concentration
marked cerebral edema in later stages
What are the early clinical signs noted in patients with ethylene glycol toxicosis ? (30min to 12 hours post ingestion)
DOG: nausea, vomiting, anorexia, CNS depression, ataxia, incoordination, hypothermia, PUPU, dehydration, tachycardia/pnea… death
*CATS: are markedly depressed and usually do not show polydipsia
**these signs are associated with EG and systemic acidosis
What are the late clinical signs noted in patients with ethylene glycol toxicosis ? (12 - 24 hours post ingestion)
Animals that survive early stage will develop oliguric renal failure
vomiting, anorexia, depression, severe lethargy, coma, seizures, oliguria, and renal pain
Anuria (72-96 hours post ingestion)
Clinical stages of EG toxicosis are shorter or longer in the cat when compared to the dog?
Stages are shorter in duration in cats
*early signs might not be noticed by owners
At what point in EG toxicosis does the prognosis really drop off?
Once renal signs develop.. they are not reversible
best prognosis is for patients who present and start treatment prior to development of renal failure
What lesions are characteristic of EG toxicosis?
HGE, pulmonary edema, pale and swollen kidneys with grey or yellow streaks
Where might calcium oxalate monohydrate crystals be found in a patient with EG poisoning?
in the kidney, urine. perivascular spaces in the brain
Anion gaps of more than ______ mEq/L are typical of EG
40-50
normal is 10-27 mEq/L
How soon after EG ingestion may you see an increased anion gap?
3-6 hours post ingestion
this will stay increased for about 48 hours
What laboratory changes will be noted in patients with EG poisoning?
Metabolic acidosis LOW urine specific gravity (w/in 3hr PI) hypocalcemia (~50% of p) hyperglycemia (~50% of p) Acute renal failure changes: elevated Creat/BUN, Hyperphosphatemia (this may rise very early 3-6hr PI), hyperkalemia
increased PCV/TP
What is the goal or MOA of EG antidotes?
To stop and prevent the lethal synthesis of ethylene glycol - so it will just be slowly excreted unchanged in the urine (since the acid metabolites will cause the most severe and irreversible damage)
What is the time frame of peak EG concentration in blood?
1-6 hours post ingestion
best time to test blood, urine, renal tissue
What are the 2 antidote treatment options for ethylene glycol toxicosis?
Fomepizole and Ethanol 20%
What are the advantages to Fomepizole treatment over using 20% Ethanol?
- NO CNS depression, diuresis, or hyperosmolality
- Will not create any false positives with EG tests
- Faster recover time
What is the downside to Fomepizole treatment?
SUPER EXPENSIVE
Ideally, at what time after formepizole treatment would you check EG blood levels?
36 hour mark
Tx is admin asap at dx, 12 hr, 24 hr, and 36 hr post ingestion
What are the negative side effects of Ethanol treatment? What is the MOA?
Ethanol is used as a competitive inhibitor for alcohol dehydrogenase (so no lethal synthesis will occur)
Causes CNS depression (animals are getting drunk) and increased blood osmolality - leads to diuresis. Patients need to be on IVF at the same time
T/F: Activated charcoal is recommended as a detox protocol for EG poisoning
FALSE
EG particles are too small to be effectively adsorbed by activated charcoal
What is the prognosis for EG poisoning in patients that are azotemic at diagnosis?
GRAVE
What is the prognosis for EG poisoning in patients that start early treatment?
Good prognosis if tx is started within 5-6 hours for dogs and within 3 hours for cats
Will fomepazole cause a false positive result on the Kacey EG test?
NO
will not cause any false positives on any EG test
Will ethanol cause a false positive result on the Catachem EG test?
NO
but propalyene glycol can on the qualitative portion - NOT the quantitative
Will ethanol cause a false positive result on the Kacey EG test?
YES
What is the window of opportunity for EG testing using the Kacey EG test?
30 mins - 14 hours post ingestion
Run on plasma only
T/F: A negative EG test result will always rule out EG poisoning
FALSE
EG may be in the secondary phase where EG presence is low and toxic metabolites are high
