Ethylene glycol, the active ingredient in most automotive antifreeze and coolant products, has a sweet taste that attracts dogs. Even a small amount, as little as a tablespoon per kilogram of body weight, can be lethal. The body metabolizes ethylene glycol into toxic acids and oxalate crystals that shred kidney tissue. Treatment is time-critical; once crystals form in the kidneys, damage is often irreversible.

How poisoning occurs

Spills in garages and driveways are the most common source. Puddles under parked cars, improperly stored containers, and radiator flushes all pose risks. Some dogs seek out the sweet liquid actively. Poisoning is most frequent in fall and winter when antifreeze use increases, but it can happen year-round.

Three stages of symptoms

In the first stage, one to four hours after ingestion, dogs appear drunk: stumbling, vomiting, excessive thirst, and frequent urination. The second stage, 12 to 24 hours later, may seem like improvement as neurological signs fade, but heart rate and breathing become abnormal. The third stage, 36 to 72 hours after ingestion, brings acute kidney failure with vomiting, lethargy, seizures, and drastically reduced urine output.

The treatment window

The antidote, fomepizole (4-MP), is most effective when administered within eight to twelve hours of ingestion. It works by blocking the enzyme that converts ethylene glycol into its toxic metabolites. Ethanol can serve as a backup antidote but carries more side effects. Beyond the early window, treatment shifts to aggressive fluid therapy and dialysis, with a much lower survival rate.

Veterinary care

Expect hospitalization with IV fluids, serial blood work, urine analysis for calcium oxalate crystals, and monitoring of kidney values over several days. Dogs that reach the oliguric or anuric stage of kidney failure face a guarded to poor prognosis even with intensive care.

Prevention

Switch to propylene glycol-based antifreeze, which is significantly less toxic. Clean up all spills immediately and thoroughly. Store containers in sealed cabinets. Check driveways and garage floors for puddles regularly. Prevent unsupervised access to areas where vehicles are serviced.

Veterinary disclaimer: This article is for general education only and does not replace an examination by a licensed veterinarian. If you suspect antifreeze ingestion, seek emergency veterinary care within hours; delay can be fatal.