That old saying of “Cats rule, dogs drool!” isn’t entirely correct. In fact, cats may be more discreet and cute about it but they drool as well. It is not as common as it is in dogs as they release heat from their mouth as well as get triggers from scents that make them drool. Cats, on the other hand, tend to drool from pure joy.
When it comes to kittens, it is very common for them to pick up the behavior from being taken from their mother too soon. This is the case when kittens lose their mother at a young age and have to be bottle fed. The drooling can be very minimal to quite severe. It is usually accompanied by purring. When a kitten or cat drools, little drops form below the nose and drip out. This happens from them relaxing their jaw which allows saliva to easily escape from their mouth without them being none the wiser. Some lose this as they grow into adults, but some never do.
When it comes to adult cats drooling, and being taken to soon from their mother is not the case, it is simply due to being over-joyed. This is very common in cats who have been starved for attention. Many stray cats who once had homes and ended up on the streets, then found new homes show this behavior quite often. They simply are happy and relieved to finally have the attention they have been longing for. Just as the kittens relax their jaws, adult cats do this as well. It is always accompanied by purring and usually kneading as well.
Other things can can trigger a cat to drool is catnip, recently being put under for surgery, or the scent of another cat while in heat. Catnip can cause a cat to become so mellow and relaxed they lose tension in their jaws and mouths. It is very common for cats to drool after coming out of sedation as the nerves are extremely relaxed. As for being in heat, it is simply due to hormones and is more commonly seen in females than males. The scent of a male’s spray can cause a young female in heat to become excited so much so that she drools.