Propylene glycol

What is propylene glycol and how does it work?

Propylene glycol (1,2-propylene glycol) is an organic compound that is obtained from crude oil. It belongs to the alcohols and has the chemical formula C3H8O2. It is completely soluble in water and has a sweet taste.

Propylene glycol is used in the food industry as a humectant, i.e. it binds water in products and prevents them from drying out or going moldy. It is used in baked goods, sweets, ice cream and spices, for example. Propylene glycol is also used in pet food, especially in canned dog food. It ensures that the pieces of food remain soft and juicy and do not spoil.

Propylene glycol is broken down by enzymes in the human and animal body. Some of it is converted into lactic acid, which is further processed in the metabolism. Another part is excreted unchanged via urine or the air we breathe.

Is propylene glycol dangerous for dogs?

Propylene glycol should not be confused with ethylene glycol, which is also an antifreeze, but is highly toxic to dogs and cats. Propylene glycol has a different molecular structure and is therefore less toxic. The European Food Safety Authority (EFSA) has approved propylene glycol as a straight feeding stuff and classified it as safe. There are legal limits for the use of propylene glycol in dog food, which must be adhered to by manufacturers.

However, propylene glycol can cause side effects in sensitive dogs or if ingested in excess. These include:

• Dehydration: propylene glycol binds water in the food, which is then no longer available to the body. This can lead to a lack of fluids, which manifests itself in dry mucous membranes, reduced skin elasticity or increased thirst.
• Digestive problems: Propylene glycol can cause diarrhea, vomiting or flatulence in some dogs. This is because it increases the osmotic pressure in the intestine and thus attracts water. This can disrupt the intestinal flora and impair digestion.
• Nervous system: At high doses, propylene glycol can lead to a narcosis-like effect, which can manifest itself in ataxia (unsteady gait), depression or respiratory arrest. This is because it is deposited in the membranes of the nerve cells and thus impairs their function.
• Blood formation: Propylene glycol can lead to hemolytic anemia in cats, i.e. the breakdown of red blood cells. This is because it reacts with the sulphur groups of haemoglobin and forms so-called Heinz bodies. These can damage the erythrocytes and cause them to burst. This effect is less pronounced in dogs, but is still possible.

How do I recognize propylene glycol in dog food?

Propylene glycol must be declared on the list of ingredients in dog food. It can appear under various names, for example as E 1520, 1,2-propanediol or propane-1,2-diol. If you want to avoid propylene glycol in your dog's food, you should therefore always check the list of ingredients.