| Antifreeze or ethylene glycol (EG) is very toxic and lethal in small amounts to all animals. Because of their inherent nature to taste everything, dogs and cats are especially susceptible.
Antifreeze is readily absorbed by the gastrointestinal system and can produce direct toxic effects to the kidneys. In addition, the by-products of antifreeze can cause metabolic acidosis, respiratory depression, and upset glucose metabolism.
It is often too late to intervene by the time antifreeze poisoning is diagnosed. Unfortunately, the prognosis is dependent on the amount of time between ingestion and treatment. Most dogs treated within 8 hours of ingestion will recover and most cats treated within 4 hours of ingestion will recover. Consequently, prompt diagnosis and treatment is very important.
Early signs of antifreeze poisoning include vomiting and incoordination the first few hours after ingestion. Later signs include dehydration, increased urination, followed by incoordination, depression, coma, and death.
The effectiveness and mode of treatment depends on how soon the pet is diagnosed and treated after ingestion of the antifreeze. Within two hours of ingestion of the antifreeze, methods such as induced vomiting, stomach pumping, and stomach installation of charcoal adsorbents can be used to try to prevent absorption of the ethylene glycol (EG). After absorption of EG, treatment involves trying to stop it from being metabolized by preventing the action of the liver enzyme alcohol dehydrogenase (ADH). Traditional treatment to stop this enzyme involves taking a combination of 20% ethanol with bicarbonate and steroids intravenously. These doses have to be repeated every 4-6 hours for over 2 days in order to stop the liver enzyme from metabolizing the EG. However, the treatment can cause severe depression and result in difficulty in treating the patient.
A newer treatment is available. Unfortunately, it does not seem to be effective in cats. For dogs, this new drug, 4-methylprazole (4-MP), has been shown to be more effective at stopping the metabolism of EG without the side effects of the ethanol. If this drug is administered within the first 2 to 3 hours of ingestion, nearly all of the antifreeze can be removed by the dog's kidneys in its original unmetabolized form.
The amount of kidney damage depends on how long the antifreeze is in the pet's system before treatment. Additional treatments may include intravenous fluid therapy and a diet which requires the kidneys to do less work (e.g. low protein).
If you suspect your pet has ingested antifreeze, don't waste time. Contact your veterinarian immediately for diagnosis and treatment.
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