Unless you’re a brand-new dog owner, chances are you’re aware of the danger that antifreeze poses for your beloved canine companion. But people who don’t have pets may not be aware of the kidney-killing nature of antifreeze, or engine coolant, that contains ethylene glycol. We’ll review how your dog can be exposed to antifreeze, what the signs and symptoms of poisoning are, what steps you can take to prevent poisoning, and what you should do if your dog drinks antifreeze.
Not a winter-only hazard
Many people associate antifreeze with winterizing their car, truck or SUV. However, an analysis of calls to the ASPCA Animal Poison Control Center (APCC) showed the percentage of ethylene glycol antifreeze cases is fairly consistent from one month to the next, with a slight spike seen in December. Engine leaks, coolant spills and improper storage are common routes of exposure. Another common exposure in some areas is cabin toilets that have been winterized through the addition of antifreeze.
How dangerous is antifreeze?
Antifreeze can be very toxic if the active ingredient is ethylene glycol — one of the most common ingredients used in engine coolants. Ethylene glycol was first used as an automotive antifreeze during the 1920s and became the predominant ingredient in antifreeze after World War II. It also became one of the most common causes of serious accidental poisonings of dogs (and cats).
Veterinary toxicologists know the minimum lethal dose of undiluted ethylene glycol antifreeze (95 to 97 percent ethylene glycol) for a dog is 4.4 to 6.6 milliliters per kilogram of body weight (ml/kg). That’s roughly 2.5 tablespoons for a 20-pound dog. What toxicologists don’t know is the minimum dose to cause sudden kidney failure and severe nervous system disease, which can occur after small amounts of ethylene glycol are consumed.
Signs and symptoms vary with poisoning stage
Three stages of poisoning can be seen after a dog drinks ethylene glycol-containing antifreeze, and the symptoms and signs vary with each stage.
Stage 1 occurs 30 minutes to 12 hours after ingestion. Ethylene glycol is rapidly absorbed from the gastrointestinal tract, and peak blood concentrations typically occur within 3 hours of ingestion. Because ethylene glycol is an alcohol, antifreeze poisoning looks similar to alcohol poisoning initially. Dogs may stumble when walking, appear uncoordinated or disoriented, act sedated and have decreased reflexes. They may also drool, vomit, and drink and urinate more frequently.
Stage 1 may pass quickly and go unnoticed. But dogs that have consumed a large amount of ethylene glycol may either progress to stage 2 or pass away.
Stage 2 occurs from 6 to 24 hours after antifreeze consumption. The signs and symptoms appear to resolve and an affected dog seems to be improving. In reality, serious internal injury is happening as the liver and kidneys break down ethylene glycol into acidic compounds that upset the acid-base balance of the body. During this stage, dogs become dehydrated and develop faster heart and breathing rates, which you may or may not notice. Seizures and death can also occur at this stage if enough antifreeze has been ingested.
Stage 3 is when acute (sudden) kidney failure occurs. While this stage may occur as early as 12 hours after ingestion, it tends to affect dogs anywhere from 36 to 72 hours following antifreeze consumption. Oxalic acid, one of the breakdown products of ethylene glycol, combines with calcium in the blood to form calcium oxalate crystals that block and damage nephrons in the kidneys. These crystals can also form in the brain, according to APCC veterinary toxicologists.
Signs can include loss of appetite, decreased activity (lethargy), drooling, vomiting, abdominal pain, ulcers in the mouth, little to no urination, seizures and coma. Urinalysis may reveal dilute urine that contains glucose and/or calcium oxalate crystals.
What you should do if your dog has consumed antifreeze
If you suspect or witness your dog consuming antifreeze, the best thing to do is seek immediate veterinary care. If your usual veterinary clinic is closed for the evening or weekend, do not wait until they open again — take your dog to the nearest emergency veterinary hospital. You’ll also want to bring the antifreeze container with you, if it’s available, so the veterinarian can determine the best treatment protocol based on the amount ingested and the ingredients in the antifreeze.
At the hospital, the veterinarian will perform a physical examination and run blood and urine tests. If you’re not sure whether your dog consumed antifreeze, your veterinarian can have an ethylene glycol test performed. Since peak blood levels of ethylene glycol are seen within a few hours of ingestion, it’s important that testing is done early on in the evaluation of suspected poisoning cases.
An antidote is available for treating dogs that have ingested ethylene glycol antifreeze. However, it is extremely important to start treatment as soon as possible. That’s because the antidote is only effective if given with 8 to 12 hours of antifreeze ingestion. Prognosis is very poor once clinical signs have developed.
Take steps to prevent antifreeze poisoning
Preventing pet exposure to ethylene glycol-containing antifreeze is key to dealing with such toxic products. The College of Veterinary Medicine at Washington State University and Nationwide pet insurance offer these tips to help prevent accidental antifreeze poisoning:
- Keep new and used antifreeze in sealed, leak-proof containers out of your pet’s reach.
- Take used antifreeze to a service station or garage for disposal. Do not pour on the ground.
- Routinely check your garage floor and driveway for antifreeze leaks or spills. Clean up any spills immediately.
- Dispose of empty antifreeze containers and rags in a garbage can that pets can’t open or access.
- Consider using alternative antifreeze products that are less toxic to pets.
- If antifreeze is used to winterize toilets at the cabin or in recreational vehicles (RVs), make sure the toilet lid is down and the door to the room is closed.
- Be wary of puddles that have an unusual color or iridescent haze, and avoid letting your dog lick from them.
Most dogs that ingest ethylene glycol-containing antifreeze can recover if they are treated within 8 hours or less with the appropriate antidote. The kidneys of some dogs may recover fully; however, others may progress to chronic kidney disease, so routine monitoring of kidney function in recovered dogs will be important for the rest of their lives.