Well, waking up to frost and reports of snow across Western Canada can mean only one thing – its time to start preparing for winter.  One of the annual rituals is to ensure our vehicles don’t freeze up as the temperatures drop, often by changing the coolant or adding antifreeze.  Unfortunately, at the same time, many pets are killed with the changing season because of antifreeze – ethylene glycol containing antifreeze to be exact. To make matters worse, ethylene glycol is sweet and our pets often develop a taste for it, quickly drinking more than the toxic dose.

When our pets drink fluids containing antifreeze, they metabolize the ethylene glycol into oxalate crystals in high numbers.  It doesn’t take much antifreeze to be fatal – less than 5 millilitres per pound of pet. That’s only 150 mls for a 60 pound dog!  Even at lower doses, your pet’s kidneys can be irreversibly damaged.  Antifreeze toxicity is unlike many other toxins in that regard.  For many other toxins, once your pet is over the initial crisis there are no other concerns.  Unfortunately, antifreeze is often fatal because of the damage it does to the kidneys after the initial signs have passed.  The course of antifreeze toxicity has three stages: early, transitional and late. Early signs of ethylene glycol toxicity occur up to 12 hours after ingestion and include:

• Vomiting
• Incoordination
• Depression
• Twitching

Catching antifreeze toxicity early is the key to successful treatment, as oxalate crystals start to form in the urine, irreversibly damaging the kidneys, before the initial stage of toxicity is over.  The crystals will continue to be formed for many hours after the initial signs have passed. The crystals, along with another acidic metabolic byproduct of the antifreeze, destroy the structure of the kidneys so that they are no longer able to produce urine and extract toxins from the blood.   Such changes are, of course, incompatible with life. As soon as you suspect your pet may have ingested antifreeze, or is already showing the early signs, contact your veterinarian. Once they begin to show signs of toxicity, your pet’s kidneys are being damaged. If caught within the first couple of hours, we can sometimes prevent absorption of the antifreeze.  After that, treatment consists of preventing metabolism into the toxic byproducts and stabilizing your pet. Unfortunately, kidney damage can still occur even if the levels are below those required for the early signs of toxicity.

The next two stages of antifreeze toxicity are the transition stage (12-24 hours after ingestion) and the late stage (24-72 hours after ingestion).  At this point, our pets are beginning to show signs of kidney failure. These include:

• Severe depression to Coma
• Seizures
• Salivation from the pain of oral ulcers
• Changes in urination 

Better yet, proper handling and storage of antifreeze, so your pet can’t drink it, will save you a trip to the vet.  So clean up any drips and spills quickly and store closed containers in a secure location where your pet can’t reach them.   

Dr Ryan Ridgway & Dr. Lynn Smart-Ridgway