Antifreeze products contain ethylene glycol, propylene glycol, methanol or a combination of those products. Most automotive antifreeze liquids contain ethylene glycol and pose the greatest risk to pets. Relatively safe antifreeze products contain propylene glycol. Those products are considered GRAS (generally recognized as safe). Propylene glycol is also commonly used in toothpaste and cosmetics. Methanol is present in many windshield washer fluids.
All those compounds can depress the brain and cause “drunken” behavior. Of the three compounds, ethylene glycol is the most serious. It has a sweet taste that is attractive to dogs and cats. When ethylene glycol is ingested, it forms oxalate crystals in the kidneys that cause acute kidney failure and subsequent death without immediate treatment.
Clinical signs can occur within one hour after ingestion. Animals appear drunk and uncoordinated. Anywhere from 12 to 36 hours after ingestion, kidney failure develops with decreased urine production. The kidney damage is often irreversible and fatal. Diagnosis is based on a history of exposure to antifreeze and the clinical signs. Because many ethylene glycol formulations contain a fluorescent dye, the muzzle, paws, urine and vomitus may fluoresce or glow under an ultraviolet light! There are special test kits that can measure ethylene glycol in the blood. A few days later, blood and urine tests can show the typical oxalate crystals in the urine and kidney failure in the blood.
All ethylene glycol exposures are considered medical emergencies. Animals are hospitalized for administration of IV fluids to protect the kidneys. There is an antidote that binds ethylene glycol so it can be excreted without harming the kidneys. This antidote is called fomepizole. This is often needed along with IV fluids and supportive care for three to five days. In severe cases, dialysis may be needed.
Intensive monitoring of urine production and laboratory tests are usually needed for several days. Animals that survive may have residual chronic kidney damage that requires regular monitoring and special diets and drugs.
The best treatment is prevention. If you spill ethylene glycol, keep your pets away from it. Kitty litter works well to absorb the spilled antifreeze. If antifreeze is ingested, contact your vet immediately, as time is of the essence.
Dr. Karsten Fostvedt is a veterinarian at St. Francis Pet Clinic in Ketchum.