Is Propylene Glycol Harmful to Cats?

The e-liquid used in smokeless cigarettes is mainly composed of propylene glycol (PG), or vegetable glycerin (VG), which is often considered safer. But e-juice is just as often sold using a mixture of both. This substance, propylene glycol, is the vehicle for the vapor in your e-juice, and the heating of it by the atomizer creates the illusion of smoke. In itself, it is generally known to be safe for humans and and second-hand vapor does not present any real or concerning risks. However, cats may react differently to this chemical. This may be a problem for cat-loving vapers, and a reason to consider VG or vegetable-glycerin juices or vaping far away from your feline friends.

Propylene Glycol and Cats

PG can be harmful to cats due to the chemical’s particular effect on the feline animal’s red blood cells. Specifically, propylene glycol boosts the number of “Heinz bodies” in the red blood cells of cats.  Heinz bodies are essentially “denatured” hemoglobin lumps. This means that the hemoglobin has deteriorated structurally and has lost some of its ability to carry oxygen. Free radicals or oxygen-containing reactive chemicals cause this. Note that this phenomenon is not exclusive to cats exposed to PG.

The spleen of an animal usually reduces the damage caused by free radicals. The organ may also eliminate the damaged blood cell altogether. However, a large number of Heinz bodies in the blood can lead to anemia. While not directly responsible for said damage, the molecules present in the structure of PG can be.

Cats are particularly prone to this damage if exposed to high amounts of PG because of the relative ineffectiveness of the feline spleen in fighting against the generation of Heinz bodies. A relatively healthy cat has an average percentage of about two percent Heinz bodies in its bloodstream, so exposure to the chemical should be minimized if possible.

Surprisingly, propylene glycol was heavily used as a source of carbs and a preservative for and in cat food up to the early 90s. PG is still a part of consumer food products for people and dogs, but the FDA nonetheless reported it as unsafe for feline consumption in the mid-90s. An old study conducted back in 1989, showed an increase of 28% of Heinz bodies tested on cats after 5 week of high concentration doses.

Is the danger real? Not very much, but there are some simple principles to follow beyond keeping your e-liquid away from pets and children, which by the way, would be lethal in small doses due to nicotine content, much beyond the small danger that PG relatively presents. So rule #1 is responsible owners and users, whom put away ‘all’ drugs and pharmaceuticals, including PG liquid containing nicotine.

Some quick things to remember for cat owning vapers is to vape in a well-ventilated area if possible, and never exhale vapor right into the face of, or around your cat. Also, do not vape near your cat’s food and water to you minimize their exposure considerably. Second-hand vapor from your e-cigarette is unlikely to harm your cat, unless there’s a large amount of vapor accumulating in a confined room. A very strong precautionary measure would be to completely switch to vegetable glycerin juice, although not absolutely necessary, it  is very effective.

Just as important, and we have said this many times before, e-liquid containing cartridges and bottles need to be stored properly. Kept away from both pets and children. If you spot any symptoms in your cat and the possibility of ingestion is present, make sure to consult your vet.