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Feline Emergency :: Ethylene Glycol Toxicosis (Antifreeze Poisoning)
Ethylene glycol is a common ingredient in antifreeze, but is also found in photographic developing fluid, some cosmetics, and some plants. It is used as an industrial solvent for laquers and paints. Ethylene glycol has a sweet taste that appeals to many cats. Several toxic metabolites are produced including glycolate, glycoaldehyde, glyoxylate, and oxalate. The first three cause renal tubular damage, resulting in severe metabolic acidosis. The last one combines with calcium to form calcium oxalate crystals, which lead to renal tubular blockage, renal epithelial necrosis, and hypocalcemia. Hypocalcemia results in seizures. The toxic dose is 1-1.5 ml/kg or as little as one and a half teaspoons for an adult cat of average size. Vomiting, depression, seizures, and coma develop in one-half to 12 hours after ingestion. Tachypnea and tachycardia develop within the next 12 hours, and renal failure occurs within 24-72 hours after ingestion. Therefore, early diagnosis and therapy are essential in reversing this potentially fatal toxicity.
Diagnosis
History: Often, there is a history of exposure to a puddle of antifreeze. This is especially true in the fall as people winterize their cars.
Clinical signs: Ethylene glycol toxicity should be suspected when acute renal failure and neurologic signs are present.
Blood test: A test is commercially available for rapid identification of ethylene glycol in whole blood (Ethylene glycol Test Kit, PRN Pharmacol Inc., Pensacola, FL)
Ultrasound: Within a few hours, the renal medulla will be hyperechoic due to the presence of calcium oxalate crystals. This echo pattern may extend into the cortex. Later, the medullary rim sign and halo sign may develop. At this point, therapy is unlikely to be successful.
Urinalysis: When renal failure occurs, the urine specific gravity will be low or in the fixed range. Calcium oxalate crystals are usually present.
Primary Therapeutics
Induce vomition and lavage stomach - This should only be done within the first 4 hours after ingestion and only if the cat is conscious.
Ethanol 20% - This drug should be administered as soon as the diagnosis is made. Five intraperitoneal injections are made at 6-hour intervals at the rate of 5.5 ml/kg. Four more treatments at 8-hour intervals. To be effective, this must begin within 6 hours after ingestion.
Sodium bicarbonate - This is given primarily to counter metabolic acidosis. Administer according to serial plasma bicarbonate and base deficit determinations with monitoring every 4-6 hours. If this is not possible, administer at approximately 5 mEq/kg/h.
Fluid therapy - Agressive fluid therapy is important to maintain tissue perfusion and renal function and to correct metabolic acidosis.
Secondary Therapeutics
Peritoneal dialysis - When this is feasible, it can be important in maintaining the cat until renal function can be reestablished. This should be done only by those persons experienced with this technique.
Osmotic diuresis - Dextrose 20% (20 ml/kg q 6-8h IV) or mannitol 20% (1.25-2.5 ml/kg q 6-8h IV) can be helpful in reestablishing renal output.
It is unusual for a cat to recover if treatment does not begin within 6 hours of ingestion.
Electrolytes and acid-base balance should be monitored as frequently as possible.
Prognosis
The prognosis for ethylene glycol toxicity is always gaurded. However, if treatment is not begun within 6 hours of ingestion, the prognosis is grave.
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Reference:
The Feline Patient - Essentials of Diagnosis and Treatment
Gary D. Norsworthy
Mitchell A. Crystal
Sharon K. Fooshee
Larry P. Tilley
Copyright © 1998 Williams & Wilkins
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Additional Links On Antifreeze Toxicity:
From Pressenter.Com Antifreeze Poisoning
From Columbia Animal Hospital Antifreeze Poisoning - Columbia
From Washington State University Antifreeze Poisoning - WSU
From University of Illinois Antifreeze - U of I
From Toronto Humane Society Antifreeze - Toronto HS
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National Animal Poison Control Center: (888) 426-4435
$50 Fee (V, MC, DC, AmEx) : 24 hrs / 7 days a week
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