Propylene glycol is the active ingredient in "safe" antifreeze solutions for cars, heating systems and air conditioners. This clear, colorless, and almost odorless liquid is used in place of the highly toxic chemical ethylene glycol. Dogs administered 9 ml per kg of body weight had a 50 percent chance of survival if given immediate treatment, according to "Small Animal Toxicology." Signs and symptoms often go unnoticed until serious damage occurs, making the anecdotal toxicity of propylene glycol much higher.
Central Nervous System Depression
Central Nervous System (CNS) depression is one of the first signs of propylene glycol poisoning. This is marked by staggering, weakness, and uncoordinated movements, or ataxia. The poisoned dog may act as if it were drunk, which is not far from the truth since propylene glycol is an alcohol. Dogs show a slow reaction time to stimuli, and slowed reflexes. Dogs suffering from CNS depression as a result of propylene glycol toxicity often breathe slower than usual and have a slower pulse. Many dogs fall asleep when CNS depression sets in, making it difficult for owners to note whether their dog is suffering ill effects. They may sleep until the central nervous system effects of the toxin wear off.
During the absorption of the toxin by the body, dogs may vomit or become nauseated. Dogs who are poisoned with propylene glycol may be thirstier than usual, drinking more than their average intake of water at any given point. Dogs suffering from the ingestion of propylene glycol urinate more frequently than usual and may not be able to hold their urine long enough to eliminate in the appropriate area, or may have accidents without even attempting to signal the need to urinate.
Vocalizations and Rapid Vitals
Approximately 12 to 24 hours after ingestion, dogs display rapid breathing and pulse as the alcoholic effects of the poison wear off. At this point, dogs exposed to propylene glycol may vocalize in pain or due to the central nervous system effects on the dog's body. They may cry, whine, grunt, or moan frequently. The poisoning becomes more severe at this point, and emergency treatment is absolutely imperative.
The internal effects of propylene glycol ingestion are not immediately evident. Acidosis, or an abnormally high level of acids within the body, is present. Liver damage and kidney damage are likely if a large enough dose is given. These problems result in a buildup of toxins within the dog's body, which, if left untreated, can lead to seizure, coma, and death.
- "Clinical Textbook for Veterinary Technicians"; Joanna Bassert, Dennis McCurnin; 2009
- "Handbook of Poisoning in Dogs and Cats"; Alexander Campbell, Michael Chapman; 2000
- "Small Animal Toxicology"; Michael Peterson, Patricia A. Talcott; 2006
- "The American Red Cross and The United States Humane Society--Pet First Aid"; Barbara Mammato, DVM; 1997
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