Propylene Poisoning in Dogs

Propylene glycol is created like glycerol and is colorless, has no taste or odor, and is slightly thickened when stored at room temperature. In order to become a vapor it must be shaken or heated. Propylene glycol is used in a variety of substances within the home and in industries. In addition to its many uses, it is also found in antifreeze.

Propylene glycol is somewhat controversial; researchers and veterinarians claim that the substance is quite toxic when ingested, but on the other hand, other researchers and medical professionals claim that it is not as toxic as many professionals say. It is contained in cosmetics, dog food, human food, and in some medications primarily to maintain proper moisture levels, and the FDA approves the use of propylene glycol for uses such as these in addition to other uses. The controversy is also due in part to the fact that ethylene glycol, a main ingredient in antifreeze, is highly poisonous. Antifreeze that contains propylene glycol is proven to not be as toxic; however, many professionals warn against dogs coming into contact with this agent. Although it is not as toxic as other glycols, it is still quite poisonous when ingested by dogs.

Propylene glycol poisoning in dogs is caused by ingesting propylene glycol. Propylene glycol is a common ingredient in antifreeze, lubricants, and products of plasticity. Propylene glycol is not as toxic as another common antifreeze ingredient known as ethylene glycol; however, it is still poisonous and dogs require medical treatment if ingested.

When a dog ingests this compound, lactic acidosis can occur, as propylene glycol metabolizes to lactate rapidly. Symptoms can occur in as little as 30 minutes. It can also cause renal failure and damage to the liver. Other symptoms of propylene glycol poisoning are:

• Central nervous system depression
• Weakness
• Ataxia
• Seizures
• Vomiting
• Anemia
• Hypernatremia
• Increased thirst
• Increased urination

Types

There are several types of products that contain propylene glycol. It is important to keep these in a safe place and out of the reach of dogs. These products include:

• Artificial smoke
• Antifreeze
• Lubricants
• Resin
• Ink
• Liquid pharmaceutical medications
• PVC products
• Deicers

Causes of propylene glycol poisoning in dogs, in addition to the ingestion of propylene glycol, are rapid central nervous system injury. The ingestion of propylene glycol can be prevented by: 

• Cleaning any spills from antifreeze
• Disposal of any rags used for antifreeze
• Keeping rags contaminated by antifreeze in a sealed container
• Keeping antifreeze in a sealed container and out of the way of pets
• Prohibiting access to underneath vehicles
• Keeping dogs away from radiator fluid
• Monitor the outside water your dog drinks to avoid drinking any antifreeze run -off
• Keep your dog from roaming
• Watch your dog and prevent access to puddles, as the water may contain antifreeze

Even though propylene glycol is indeed less toxic than ethylene glycol, the ingestion, diagnosis, and treatment is quite similar to ethylene glycol poisoning. A lethal dose of propylene glycol is considered to be at an amount of 9 mL/kg. If you suspect your dog has ingested propylene glycol, it is important to take him to the veterinarian. The veterinarian will ask questions pertaining to the substance and the amount he consumed.

Your veterinarian will depend on the dog’s history, a complete physical examination, and laboratory testing to form a diagnosis. Your veterinarian will perform blood serum testing and urinalysis, as well as a biochemistry profile. It is important for the physician to  test the organ function and check for metabolic acidosis, which is the removal of acid from the body via the kidneys or if the body is producing too much acid.

There are differential diagnoses of this type of poisoning that affects the central nervous system, such as gastroenteritis, renal ischemia, pancreatitis, or other types of illnesses that have the same symptoms. It is very helpful to tell the veterinarian if you highly suspect or witnessed your dog consuming a product with propylene glycol.

The prognosis of the dog is dependent upon the amount of propylene glycol ingested and the time it takes to receive treatment. Treatment methods may include:

Removal of Stomach Contents

The veterinarian may induce vomiting in your dog; however, if he is showing any neurological distress, this will not be performed due to the risk of aspiration. Gastric lavage may be performed to flush out the contents of the stomach while following up with activated charcoal. In some cases, though, activated charcoal may not be effective in absorbing copious amounts of propylene glycol. This will be determined by your veterinarian.

Fluid Therapy

Fluid therapy will be given intravenously to help with urine production and to reverse or prevent dehydration.

Medications

Certain medications, such as methylpyrazole, are used to decrease the activity of alcohol dehydrogenase. Sodium bicarbonate may be used to correct metabolic acidosis. Other medications may utilized to correct any imbalances in acids and bases and electrolytes.

Recovery from propylene glycol poisoning solely depends on the severity of the toxicity and the dog’s response to treatment. While propylene glycol is one-third less toxic than ethylene glycol, prognosis may be guarded. If your dog received immediate treatment and responded positively, then prognosis is good.

If your dog is showing signs of recovery, the veterinarian will have you monitor him at home. He will want to see him again to check his vital signs and be sure that he has made a complete recovery. While at home, it is imperative that you keep an eye on him and take note of any behavioral changes or new symptoms. If any new symptoms occur, please contact your veterinarian with any questions.