In colder months many people need antifreeze for their cars. But does every driver know about the danger? Antifreeze contains ethylene glycol - a dangerous poison and its consumption remains one of the most common toxicosis in dogs and cats. The ingestion of small quantities can cause heart and kidney failure and even death. Ethylene glycol is an odorless, colourless, sweetish tasting liquid, mixable with water. It has a strong freezing point-degrading effect (a mixture 1:1 with water only freezes at minus 40 degrees Celsius) . The name glycol (Greek glykos = sweetly) refers to the sweetish taste. Ethylene glycol is also present in de-icers for door locks and flight runways, in brake fluids, in lacquers and colors for the improvement of the spreadableness and also in cold/warm packs, which are frequently offered for warming and cooling therapy nowadays. Ethylene glycol was also used illegally to sweeten wines.
Ingestion of the poison:
The ingestion occurs orally. Spilling of antifreeze is dangerous, for example on the garage floor, as dogs and cats like the sweetish taste and lick it off. Only a few ml can start a deadly process. For children only one sip can be extremely dangerous, two sips for adults. This terrible mistake sometimes happens after refilling antifreeze in empty beverage bottles. The lethal (deadly) dose is indicated for humans as approx. 400 mg/ kg, for a dog as approx. 4 ml/kg. Usually young animals are affected most commonly. Ethylene glycol itself is not particularly lethal but its different metabolites which are excreted via the kidneys, cause serious toxicity. Glycol aldehyde affects heart and lung, glycol acid causes metabolic acidosis (acidifying of the blood) and calcium oxalate crystals damage the kidneys. Acidosis and kidney damage lead to heart and kidney failure
Ethylene glycol toxicosis can be divided in different clinical phases:
Approximately 30 mins after ingestion distinctive features begins, first exciting, then anesthesia-similarly, “drunken behavior”, similar to alcohol intoxication, ataxia, staggering course, tachycardia (increased heart rate), tachypnoea (increased breathing rate), doziness, up to shock, coma and by affecting the stomach intestine – and mucous membranes provoking vomiting and nausea.
Sometimes even after a temporary improvement the next step begins: dogs approx. 36 – 72 h, cats approx. 12 – 24 h after poison ingestion. Ethylene glycol is broken down to different metabolic products. The symptoms are Indication of the damage of the nervous system with convulsions, hypothermia and the indications of the increasing kidney failure with thirst, first polyuria (increased urine production), then oliguria (removing urine production) up to anuria (missing urine production), uremia.
Diagnosis of ethylene glycol toxicosis can be difficult. Fluorescent substances are added to some antifreeze products which can then be detected in oral cavity, feces, urine or vomit with the Wood’s lamp. Chromatographic proof in serum and urine. blood profile: raised creatinine, urea, potassium, blood sugar, hematocrit, metabolic acidosis, low calcium, among other things. Urine sediment: hematuria, proteinuria (blood and protein proof in the urine sediment causes by loss of blood and protein via the kidneys), calcium oxalate crystals
Poisoning with methanol, ethanol, amino glycoside poisoning, but also diabetes, leptospirosis, acute and chronic kidney disease.
The treatment should be initiated very quickly to optimise the chances for survival of the pet.
Vomiting: making the dog vomit is not useful unless the dog is presented immediately following ingestion, since ethylene glycol is very rapidly absorbed from the gastrointestinal tract. . Activated charcoal does not bind glycols.
Infusions of specific antidotes need to be given as soon as possible after poison ingestion, in order to prevent the metabolic change of ethylene glycol to toxic metabolites: intravenously ethanol (alcohol), or better fomepizol, with fewer side effects.
Further supportive treatment: Stabilization of cardiovascular system, respiration, symptomatic treatment of metabolic acidosis, vomiting and convulsions, pain, aggressive fluid therapy, forcing the urine elimination