Wintertime is approaching and we all want to make sure that our automobiles are functioning properly. This means changing our radiator fluids and adding new antifreeze. Antifreeze products can contain ethylene glycol, propylene glycol, methanol, or a combination of these agents. Most automotive antifreeze liquids contain ethylene glycol and pose the greatest hazard to pets; they are often dyed fluorescent green. Propylene glycol is generally recognized as safe, but can also be dyed a green or blue color. Methanol is present in the windshield washer fluids as well as gasoline antifreezes.

All three compounds can develop a serious metabolic condition known as acidosis after pets drink these fluids. They can depress the brain and cause drunken behavior, mental depression, and coma. Of the three compounds, ethylene glycol is of the most serious concern for pets. It is said to have a sweet taste that is attractive to dogs and cats. When it is metabolized by the body, crystals form that are deposited in the kidneys. These crystals can cause permanent kidney failure.

Signs can occur within one hour after ingestion. Anywhere from 12-36 hours after ingestion, kidney failure may develop with decreased urine production. The kidney damage is often irreversible and fatal. Diagnosis is based on a history of exposure and appropriate clinical signs. Test kits are available that measures the concentration of ethylene glycol in the blood. Later in the course of toxicity, laboratories tests will show severe abnormalities in kidney function.

Animals exhibits signs of inebriation or have a positive ethylene glycol test are hospitalized and placed on dialysis. Because every moment that passes means further metabolism of ethylene glycol, all ethylene glycol exposures are considered to be medical emergencies. Animals are hospitalized for administration of intravenous fluids to protect the kidneys. Medications to prevent further metabolism of ethylene glycol may be given, such as fomepizole. Fomepizole is approved for use only in dogs but has shown some success in cats as well.

Intensive monitoring of urine output and laboratories tests are usually needed for several days. Animals that survive may have residual, chronic kidney damage that requires periodic monitoring. Prognosis is good for animal’s ingesting methanol or propylene glycol. If the animal ingested a large amount of ethylene glycol or if treatment was delayed, the prognosis is grave and death is likely. Please be careful when applying antifreeze products to your automobiles this fall.


Dr. Karsten Fostvedt is a veterinarian at St. Francis Pet Clinic in Ketchum.

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