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.
Gastritis is an irritation of the lining of the stomach that comes on suddenly. The principal sign is severe and continuous vomiting.
Acute gastritis is severe and continuous vomiting that comes on suddenly. It is most likely caused by swallowing an irritant or a poison. Common stomach irritants include grass and other plants, hair, bones, spoiled food, and garbage. Certain drugs, notably aspirin, but also cortisone, butazolidin, and some antibiotics, produce gastric irritation...
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"