Healthy cats do not drool. However, it
is common for cats to drool when they know they are going to be given an
unpleasant-tasting medicine or receive an injection. This is psychological. A
few cats will also drool when they are purring and very relaxed. It is
important to know what is normal for your individual cat.
Keep in mind that an animal who drools excessively and acts irrationally
could have rabies. Exercise great caution in handling such an animal.
Most housecats—although they’re much safer inside from disease and danger—tend to be overweight and underactive. Cats, like people and dogs, benefit from keeping fit and active, both mentally and physically. Exercise is essential for your cat’s mental and physical health because it relieves stress and boredom, improves circulation, builds muscle tone and can prevent or reduce behavioral problems.
So, we need to get our cats up and moving, and there’s no better way to coax out their natural instincts...
Drooling accompanied by signs of ill health, such as watering of the eyes,
is quite likely due to a feline viral respiratory infection. Young cats with liver shunts
will drool excessively. Mouth infections and foreign bodies in the mouth are
accompanied by drooling. Heat stroke can cause excess salivation, as can
certain poisons (such as insecticides and arsenic).
Treatment: This is contingent on identifying the cause of the drooling.
WebMD Veterinary Reference from "Cat Owner's Home Veterinary Handbook"