Ethylene Glycol Toxicity or Antifreeze Toxicity

Source
Ethylene glycol is a toxin found in antifreeze, brake fluid, windshield de-icing agent, color film developing fluids and other commercial fluids. Because of its sweet taste, most pets find this liquid irresistible. The amount of antifreeze necessary to kill your pet is very small! In a 20 pound dog, the minimum amount needed to kill is 4.5 ounces. In the cat it is even more toxic – 1 tablespoon diluted with 1 tablespoon of water is enough to cause death to a 10 pound cat!

Clinical Signs
There are 3 stages of clinical signs in the dog and cat:
Stage 1: 30 minutes to 12 hours after ingestion with signs being nausea, vomiting, depression, inability to walk a straight line, seizures, coma and even death. This toxin mimics alcohol intoxication in your pet, so he/she will look “drunk.”
Stage 2: 12 to 24 hours after ingestion with signs being a fast heart rate and fast breathing rate.
Stage 3: 24 to 72 hours after ingestion in dogs and 12 to 24 hours after ingestion in the cat. This stage is when the toxin affects the kidneys, causing irreversible failure which leads to death. Some other signs in this stage are: severe depression, vomiting, diarrhea and death.

Diagnosis
Blood Test for Ethylene Glycol – Tests for ethylene glycol and its breakdown products. The highest test results will occur 1-6 hours after ingestion, although the test may remain positive 48-72 hours after depending on the amount ingested. A negative test does not mean that your pet has ingested the toxin – the toxin may have already been broken down or the dose may be too small for the test to detect. The test is not a good test for cats and if does come up positive, it means that your cat ate a large quantity of antifreeze.
Urine Analysis – This test is looking for signs of kidney failure and also a crystal that is specific to ethylene glycol toxicity (calcium oxalate, monohydrate crystals.)
Complete Blood Count – Often will only show signs of dehydration and stress and is not specific to this toxin.
Chemistry Panel – Elevation of kidney values indicating kidney disease/failure is the most predominate sign. Other changes: high blood proteins (dehydration), decreased serum bicarbonate (acidosis), highly elevated anion gap (due to the electrolyte disturbances caused by the toxin), decreased calcium levels (due to formation of calcium oxalate crystals), elevated glucose levels (stress, kidney disease, release of epinephrine.)
Black Light Test – Some antifreeze products contain a dye that will react with a black light. Your pet may show positive for 6 hours after ingestion. This is a crude test and a negative result does not mean that he/she has not ingested antifreeze.
Ultrasound of the Kidneys – Will help to diagnose dogs and cats in later stages of the disease. There is a specific pattern seen in the kidneys due to the deposition of calcium in the kidney.

Treatment
Less than 60 minutes – Your pet may be given medication to vomit up antifreeze IF the ingestion was within the last hour and not showing signs of the toxin. After that the toxin will be out of the stomach.

Less than 2-4 hours – Your veterinarian may sedate your pet to clean out its stomach and give activated charcoal to bind to the toxin.

4-MP (4-methylpyrazole) – This is a very effective, but expensive antidote for antifreeze poisoning in dogs only. It must be given soon after toxicity when tests show that the antifreeze is still in your dog’s bloodstream. This medication is VERY expensive and must be given over a 3 days period. The advantage is that this medicine works the best to stop the antifreeze from converting to bad breakdown products and damaging your dog’s kidneys. This medication must be started within 4 hours of poisoning for best results.

Ethanol – Pure ethanol given through an IV catheter will also work to stop the toxin, but it has more side effects in the dog and cat. This treatment must be started by at least 3 hours past toxicity in the cats and at least by 4 hours past toxicity in the dog.

IV Catheter and Aggressive Fluids – These will help to flush the kidneys.

Sodium Bicarbonate – This chemical will be given in bases when the blood becomes too acidic. This treatment helps to prevent damage to the major body organs.

Prognosis
If the pet is caught early and treated aggressively, the prognosis is fairly good. The cut-off time is 3 hours in the cat and 5 hours in the dog. Also, if kidney function is good in either species, then the prognosis is good for return to normal function.

Prevention
Always clean up antifreeze spills immediately. Check your car regularly for leaks. Always store your containers with antifreeze in marked containers and away from pets and children. Never allow your pets access to the area when you are changing antifreeze.

Utilize products with propylene glycol containing products, such as Prestone Low Tox ™ brand antifreeze, which contain a less toxic form of antifreeze that tastes bad to your pet.

Take Home Message
Antifreeze is a very toxic product to your pets and only with early detection and aggressive therapy will your pet survive intoxication. Article by Laura Meaux, DVM