As Victor says, its Ethylne Glycol that is toxic, and because there is a misconception around that we as vapers, are vaping Antifreeze, and yes, I have had people say that to me, the two have got mixed up.
PG is toxic to cats, but, the amount they would have to ingest would be very high, and trust me, a cat is not stupid, they will not lap a saucer of PG, as the taste is not attractive to them. EG on the other hand, has a sweet enticing taste, hence children are at risk from it.
Here in the UK we have tried petitioning the Government to follow the US example over Antifreeze, but until a child dies, they will do nothing.
Several of my cats like the smell of some of the juices I vape, especially the sweeter ones, like Coconut Ice or RY4, and if there are a few of us vaping, the cats go from person to person, sniffing the air, almost as through they are doing a comparison of smells.
We all changed to Vaping as we thought it would be healthier for us, and a safer environment for our families, with fresher air to breathe, PG and its antiseptic qualities, aids that, so lets just remind ourselves all the time of our health and safety. Keep our Nicotine safe and out of reach of children, wipe up spills immediately and our homes will be a safer place for our families and pets.