Antifreeze poisoning is diagnosed based upon the dog’s history, presenting symptoms and specific blood testing. Sometimes, the owner will have seen his dog licking antifreeze from spills or puddles under leaking automobile radiators. Less commonly, the dog may have been observed licking antifreeze straight from an open or leaky container. These ingestions are usually witnessed in a driveway or garage, during the fall or winter months, especially in very cold climates. However, most of the time, the dog’s owner will not witness his dog eating or drinking antifreeze. Diagnosis then must be made based on swift assessment of the dog’s clinical signs and veterinary tests to identify circulating ethylene glycol (EG) levels in the dog’s blood.
Blood samples can be accurately assessed in both veterinary and human laboratories for levels of blood ethylene glycol concentrations and, more importantly, for the blood levels of circulating metabolites of EG. While the time turnover for these results is usually quite quick, it may not be fast enough to save the animal in question. Bedside blood tests have been developed to estimate blood EG concentrations, and at least one such test – the Ethylene Glycol Test Kit - is commercially available for use in dogs. Bedside tests assess the levels of EG, not its toxic metabolites. As a result, they must be used within a few hours of the dog’s ingestion of antifreeze to be considered reliable. Another common diagnostic test for antifreeze toxicity is called a blood gas analysis. Within 3 or 4 hours post-ingestion of antifreeze, and especially by 12 hours later, the levels of carbon dioxide and bicarbonate in the dog’s blood and the pH of its blood will be markedly decreased. Routine blood work, including a serum biochemistry profile, can also be very helpful in diagnosing antifreeze poisoning, as can the results of a urinalysis.
There are a number of more advanced diagnostic tests that can be performed to confirm antifreeze poisoning. Usually, these are not necessary.