Dogs, and other pets, love the taste of anti-freeze because of the sweet taste. The chemical forms crystal deposits on the brain and kidneys. Even a small amount can cause very serious kidney damage and failure.
Symptoms include depression, convulsions and coma. Once a dog has ingested anti-freeze there is only a couple of hours to get help from your veterinarian before the damage is irreversible. If left untreated, the dog will die. If there is any suspicion that your dog has ingested anti-freeze, contact your vet immediately.
Always store antifreeze in a place that is inaccessible to pets.