Dr. Jeff Grognet DVM & Dr. Louise Janes DVM September 2011
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Antifreeze Legislation
by Jeff Grognet, DVM, BSc (Agr) and Louise Janes, BSc (Agr), DVM
British Columbia was the first province to enact laws protecting dogs from toxic antifreeze. Legislation that took effect January 1, 2011 makes it mandatory to add an extremely bitter substance to antifreeze and engine coolant.
Ethylene glycol, the most common type of antifreeze commercially available, has an extremely sweet taste. This means that pets, wildlife, and even children are attracted to it.
Unfortunately, ethylene glycol (EG) is also very toxic. Once it is absorbed through the intestinal lining, it is metabolized in the body to a chemical called oxalate. In the blood, oxalate causes little harm, but when it concentrates in the kidney tubules, it forms microscopic crystals.
These crystals plug the tubules, block urine flow and shut down urine production. With nowhere to go, toxins build up in the bloodstream and poison the pet.
When EG is first consumed, the animal suffers from vomiting and delirium but, in many cases, owners do not notice these symptoms. Over the next few days as kidney function deteriorates, drinking increases significantly. Once toxins reach a toxic level, which is normally three to four days after EG consumption, appetite falls and the legs become weak.
Over time (a few more days), the toxins cause extreme lethargy and dullness. Pets can then slip into a coma or begin convulsing. Death soon follows.
Treatment, once signs are evident, is considered futile. The kidneys are already damaged beyond repair. The only ones that recover from EG toxicity are ones that are caught consuming EG and treated immediately. If therapy begins within an hour of consumption, the conversion of EG to oxalate can be inhibited and the poisoning averted.
The treatment for EG poisoning is administration of ethyl alcohol (the one you drink) intravenously. The high level of ethyl alcohol in the blood saturates the enzyme that converts EG to oxalate and stops oxalate from being created. The EG is eliminated from the body and causes no harm. Alcohol intoxication must be continued for 48 hours.
Because EG poisoning is so deadly, it’s not surprising it is the number one cause of fatalities in dogs and cats. It is also an issue with children who may find the bright, often yellow container attractive and consume it. This has led to pressure from both veterinarians and animal welfare groups against antifreeze manufacturers and government for change.
Years ago, and even now, groups promote the use of the non-toxic antifreeze propylene glycol instead of EG. Labeled as “pet-safe”, propylene glycol is slightly more expensive than EG, bit it is a great way to protect dogs. You can ask your mechanic to add this instead of the traditional antifreeze on the next radiator fill up.
The other way to protect pets is to make EG unpalatable. This is done by adding a bittering agent. In the BC legislation, it is mandatory to add denatonium benzoate to EG sold at the retail level in BC.
Denatonium benzoate is the bitterest chemical compound known to date. Sold as Bitrex or Aversion, it has been used for years in products such as nail biting remedies for people and anti-chewing products for dogs. It is regarded as safe for consumption. It also does not impair antifreeze performance or invalidate vehicle warranties.
Though the bittering agent will lessen the appeal of EG to pets, it does not eliminate its toxicity. You still need to be careful when handling or disposing of any antifreeze product.
Accidental Antifreeze Exposure
The most common way pets become poisoned with antifreeze is through a leaky radiator. A pipe may crack or the radiator itself may leak, with the end result that toxic antifreeze is on the ground. Inquisitive dogs and cats may start licking it and consume enough to become poisoned.
If you see a leak, get it attended to right away. If there is fluid on the ground, use cat litter to soak it up and dispose of it so that pets can’t find it. In gravel driveways, use water to wash it into the ground.
For more information contact Dr. Jeff Grognet or Dr. Louise Janes at
Mid-Isle Veterinary Hospital
5-161 Fern Road West
Qualicum Beach, BC
Tel (250) 752-8969