I encountered my first case of antifreeze poisoning as a veterinarian when I was fresh out of college. This was a dog that just didn’t seem right to its owners. When I examined the dog the only thing I could find that was wrong was some sensitivity to touch in its high abdomen and an empty stomach. Unfortunately, the lab work showed that irreversible damage to the kidneys had already occurred. In my second case of antifreeze poisons I was much luckier. This was a Christmas gift Labrador puppy that was seen drinking antifreeze on Christmas morning. I sent my staff to the neighborhood liquor store and purchased a fifth of vodka. I administered intravenous fluids and bicarbonate to this pup and kept him drunk for 72 hours. He recovered completely.

Every year more than ten thousand dogs and cats are accidentally poisoned with automotive antifreeze. Although dogs and cats account for most cases, ethylene glycol is toxic to all creatures - including people. This is the most common cause of poisoning of dogs and cats in the United States. The toxic ingredient in the antifreeze is its major component, ethylene glycol. It makes up 95% of the product. It only takes a small sip of antifreeze to poison your pet. Cats are approximately four times as sensitive to the poison as dogs. One to two teaspoons full will poison a cat and three tablespoons-full is enough to kill a medium size dog.

Antifreeze poisoning occurs even in warm climates because radiator coolant in all climates contains ethylene glycol. In the North, the incidence increases substantially in the fall when automotive cooling systems and radiators are being flushed and refilled. Ethylene glycol is sweet and quite tasty to pets. Some cases occur when discarded coolant is left where a pet can get to it. In others the pets lick the empty gallon containers or the puddle that forms below a leaky radiator system. Because it is tasty - dogs and cats will actively seek it out. Antifreeze fluid is a translucent greenish color. If you change your coolant, discard the old coolant properly. If your car has a coolant leak wash off the concrete slab under your car until you get the vehicle fixed.

Ethylene glycol is also found in brake fluid, liquid rust inhibitors, hydraulic fluids and solar collectors. I know of one other source of antifreeze. I have read that it is or was an ingredient in the liquid placed inside of decorative “snow scene” glass globes which one inverts to see the flocculant snow fall.

How This Poison Affects Your Pet:

Ethylene glycol has an immediate and a long-term affect on the body. It is rapidly absorbed and metabolized once it has been consumed. Peak blood levels occur within three hours of ingestion. Within thirty minutes after drinking it, your pet will become ataxic or drunken in appearance. This phase continues for up to six hours. Eventually this tipsy behavior subsides and it appears that the problem is over. It is not however, because the ethylene glycol then enters the pet’s liver and kidneys where it is oxidized into toxic products that acidify the blood and destroy renal tubular cells in the pet's kidneys. When the kidneys are damaged, they loose their ability to cleanse the body of waste. The transformation of antifreeze leads from glycoaldehyde to glyoxcylic acid, formic acid, and oxalate. It is the glycolic acid and oxalate that is most responsible for kidney damage and resulting uremia. These compounds also seriously damage the central nervous system. There is no treatment that will reverse this damage. It can be so severe as to be fatal in a matter of a few days

Symptoms In Your Pet:
Clinical signs depend on how long it has been since the pet drank the antifreeze as well as the amount they drank. Early symptoms are much like alcohol intoxication. Dogs and cats may vomit due to the irritating effects of ethylene glycol on the stomach. They drink and urinate excessively and may be depressed and wobbly. The increased thirst is due to stimulation of the thirst centers of the brain. Pets may seem on the road to recovery twelve hours later as the ethylene glycol is metabolized by the liver and kidneys. However, a day later in cats and two days later in dogs the patients can suddenly become much worse. They may become depressed, weak, and dehydrated. They may develop diarrhea, mouth ulcers, rapid breathing and seizures. Their kidneys are often painful and swollen.

Diagnosis:
Dogs and cats can only be cured when the poisoning is detected before extensive kidney damage has occurred. Diagnosis is not difficult when an owner presents a pet that is staggering, and drunken in appearance and has seen the animal drink the poison. It is much more difficult when the ethylene glycol first reaches the liver because early in this stage the pet will appear healthy while later in this stage symptoms are multisystemic and nonspecific. We often confuse these signs with other diseases such as pancreatitis, acute gastroenteritis, diabetes or other forms of kidney disease. By the time ethylene glycol metabolites have attacked the kidneys it is too late for a cure. By this time the animal is very sick from uremia and acidic blood (acidosis). In unfortunate animals that die, it is the six-sided or Maltese-cross shaped crystals of calcium oxalate within kidney tubules that allow pathologists to make the diagnosis. Sometimes the urine of affected pets will glow when exposed to a woods or ultraviolet lamp.

How We Treat Pets That Drink Antifreeze:
The amount of ethylene glycol the animal consumed is very important in determining the success of treatment. Animals do not responding favorable to any treatment when they have ingested too much. Treatment is based on decreasing the absorption of ethylene glycol from the stomach and intestine and increasing its excretion through the kidneys. Preventing metabolism of ethylene glycol to glycolic acid and calcium oxalate and correcting acidosis of the blood is also very important.

The first step is to administer apomorphene or hydrogen peroxide solution to get the pet to vomit up any poison remaining in the stomach. I give the pet water between medications in order wash out the stomach thoroughly (gastric lavage). Then I administer activated charcoal to bind with any poison that is left.

While I am doing this I begin giving large amounts of intravenous fluids to increase urine production and excrete as much ethylene glycol as possible.

Some time ago, in Boston, a group of teenagers consumed antifreeze by accident during a garage party. It was found that the teenagers who were the most drunk suffered the least side effects from the poison. We use that information today in treating pets. We give them ordinary drinking alcohol. The recommended dose is 2.5ml of twenty- percent (forty proof) ethanol per pound of body weight diluted in IV fluids. We give this as a slow drip over six hours for five treatments and then over eight hours for four more treatments. At the same time we give them sodium bicarbonate to reduce the acidity (metabolic acidosis) of the blood. We judge the amount of bicarbonate to give by monitoring the acidity of the urine. In dogs, but not in cats, a drug, 40MP (4-methylpyraxole) is marketed specifically for this condition and replaces alcohol.