Antifreeze (Ethylene Glycol) Poisoning

Laurie Anne Walden, DVM

Antifreeze is toxic to animals and people. Even a small amount of antifreeze licked from a paw or lapped from a puddle could kill a cat or dog. If you think your pet has been exposed to antifreeze, contact a veterinarian immediately.
 
The main ingredient of most types of antifreeze is ethylene glycol, a type of alcohol. Ethylene glycol has a naturally sweet taste.
 
Protect your pets by keeping them away from fluids that have leaked out of cars. Store antifreeze in sealed containers out of the reach of animals and children. Consider using antifreeze made of propylene glycol instead of ethylene glycol; it’s safer for pets.
 
Sources of ethylene glycol
Antifreeze (radiator coolant) is used in the engines of cars and other motor vehicles. The risk of exposure might be higher when seasons change and people change the antifreeze in their cars. Dogs have also been poisoned by drinking toilet water that has had antifreeze added to keep it from freezing.[1]
 
Although antifreeze is the most common source of ethylene glycol poisoning in dogs and cats, ethylene glycol can be present in other products:

• Brake fluid
• Windshield deicing solution
• Motor oil
• Solvents
• Rust removers
• Paint
• Snow globes
• Ink in stamp pads and ballpoint pens[1-3]

 
Signs of poisoning
The earliest symptoms are caused by the ethylene glycol itself. Symptoms that appear later are caused by toxic substances produced when ethylene glycol is broken down in the liver. The symptoms of poisoning occur in 3 stages.[4]
 
Stage 1: During the first 12 hours, symptoms are similar to those of alcohol intoxication:

• Vomiting
• Depression
• Stumbling and loss of balance
• Weakness
• Excessive thirst and urination

 
Stage 2: From about 12 to 24 hours after ingestion, the animal may seem to improve as “drunken” symptoms go away. But toxic products of ethylene glycol begin to alter the body’s acid-base balance and damage the kidneys. Signs include the following:

• Rapid heart rate
• Rapid or labored breathing

 
Stage 3: Between 12 and 24 hours after exposure (cats) or 36 and 72 hours (dogs), the kidneys stop working. The patient shows symptoms of acute kidney failure and other problems:

• Loss of appetite
• Vomiting and diarrhea
• Little or no urine produced
• Seizures
• Coma
• Death

 
Diagnosis and treatment
A blood test can detect ethylene glycol in the first few hours after ingestion. After a few hours, blood and urine tests begin to show evidence of acid-base disturbances and kidney damage. Diagnosing ethylene glycol poisoning can be tricky if no one saw the pet swallow antifreeze and the pet doesn’t arrive at the veterinary clinic until it is showing signs of kidney failure.
 
The sooner treatment begins, the better the prognosis. An antidote to ethylene glycol is available and should be given soon after exposure. This drug stops ethylene glycol from being converted to toxic substances. After most of the ethylene glycol has been metabolized by the liver, the antidote is less likely to be effective.
 
Other treatment is given to correct the body’s acid-base balance and support kidney function. Pets with ethylene glycol poisoning will probably need to stay in the hospital for a few days, even if the poisoning is caught early.
 
Prognosis
The prognosis is good for animals that begin treatment soon after ingesting antifreeze. For those that develop kidney failure, the prognosis is guarded to poor.
 
References
1. Antifreeze poisoning in dogs & cats (ethylene glycol poisoning). Pet Poison Helpline website. https://www.petpoisonhelpline.com/pet-safety-tips/antifreeze-poisoning-in-dogs-cats-ethylene-glycol-poisoning/. Accessed March 11, 2019.
2. Grauer GF. Overview of ethylene glycol toxicity. Merck Veterinary Manual website. https://www.merckvetmanual.com/toxicology/ethylene-glycol-toxicity/overview-of-ethylene-glycol-toxicity. Accessed March 11, 2019.
3. ToxFAQs for ethylene glycol. Agency for Toxic Substances and Disease Registry website. https://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=85&tid=21. Published November 2010. Accessed March 11, 2019.
4. Brownie CF. Managing ethylene glycol toxicity (proceedings). DVM360 website. http://veterinarycalendar.dvm360.com/managing-ethylene-glycol-toxicity-proceedings. Published August 1, 2010. Accessed March 11, 2019.
 
Photo by Ana Silva on Unsplash

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