Photos courtesy of Long Beach Animal Hospital (LBAH)

Come spring, you may change the antifreeze in your car’s radiator. A small amount of radiator fluid accidentally left in the gutter or in an open recycling container can be toxic to cats and dogs.

Automobile antifreeze is composed of 95 percent ethylene glycol. This is broken down in the liver to a compound that is toxic to the kidneys and will change the pH of the blood to dangerous levels.

If an average size cat drinks a little over one tablespoon, or a small dog drinks a quarter cup of undiluted antifreeze, it can be lethal. Within 12 hours of ingestion, the animal may appear intoxicated and start vomiting, and will drink and urinate more than usual. Your pet may only appear depressed—symptoms vary by species and amount ingested.

The second stage occurs 12 to 24 hours after ingestion. In this stage, there is a seeming improvement in the symptoms seen within 24 hours. Unfortunately, this apparent recovery does not last long.

The symptoms return in stage 3, which is one to three days after ingestion. There will be severe depression and a lack of appetite. Death will occur from kidney failure, a change in the pH of the blood and severe electrolyte imbalances.

If you think your pet may have consumed any amount of radiator fluid (antifreeze or ethylene glycol), time is of the essence, and you must get your pet to a vet immediately. This problem is difficult to diagnose without prior knowledge of ingestion, but there is a test that measures the level of ethylene glycol in the blood. This test can be used within the first few hours after ingestion to confirm the diagnosis of ethylene glycol toxicity.

When your pet is suspected of having ethylene glycol toxicity, we run a blood panel in-house to give us immediate information about the kidneys and electrolytes.

 

Blood sample typical of a pet with ethylene glycol toxicity.  The two circled tests are kidney tests.

If your pet is seen immediately after ingesting antifreeze, vomiting will be induced to remove as much of the toxin as possible. Activated charcoal will be introduced into the stomach to help absorb and bind up any antifreeze that remains. Ethylene glycol is rapidly absorbed in the stomach, so this treatment must be performed soon after ingestion to be of any benefit.

Intravenous (IV) fluids will also be administered to help the kidneys flush out the poison. For dogs, there is an antidote called Antizol-Vet that will block the conversion in the liver. It needs to be given within three hours of ingestion. In cats, this product is not as effective, so ethanol may be used. If all of these treatments are not given within four to six hours of ingestion, the prognosis is poor. Pets undergoing this treatment regimen need to be closely monitored for pH, respiratory problems, and electrolyte imbalances.

Note that many of the newer antifreeze compounds contain propylene glycol. These products are the ones we recommend for radiator fluid since they are less toxic if ingested.

Our website has a very detailed page on kidney disease.