There are many causes of dry mouth. Dry mouth most commonly occurs as a side effect of medications that cause decreased saliva production, including high blood pressure medications, antihistamines, antidepressants, diuretics, nonsteroidal anti-inflammatories, narcotics, and many others.
Liquid diet: The Liquid diet is the restriction of solid food intake, and replacement of solid food with liquids. In hospitals, liquid diets are prescribed by doctors for a number of reasons for patients who are unable to consume solid foods. Liquid diets may be prescribed following surgery or as a preparation for certain medical procedures.
You will probably have been given a liquid feed to administer. This is usually in the form of 'Science Recovery' or 'Critical Care'. These are complete foods in powder form, containing essential nutrients for poorly chins or chinchillas recovering from illness and/or operations etc.