Water is the most important nutrient; a lack of water can lead to death in a matter of days. Clean, fresh water should be available at all times. Multiple water sources encourage consumption.
Several approaches have been used to estimate daily water needs. There are general guidelines for daily fluid requirements in dogs, but individual variations exist. The quantity of water required depends on a number of different factors, including the animal’s diet, environment, activity level, and health status. The moisture content of canned pet foods varies from 60% to >87%. Dry pet foods contain 3%–11% water, and semimoist foods contain 25%–35% water. As a result, dogs consuming predominantly canned food generally drink less water than those consuming predominantly dry diets.
In a thermoneutral environment, most mammalian species need ~44–66 mL/kg body wt. Another approach considers that water needs appear to be highly associated with the amount of food consumed. In this case, daily maintenance fluid requirements in mL should equal the animal’s MER in kcal of ME. A third technique sets daily water intake as 2–3 times the dietary dry matter intake. When provided ample amounts of water, healthy animals can effectively self-regulate their intake. Water deficiency can be seen as a result of poor husbandry or disease. Dehydration is a serious problem in many different disorders, including those of the GI, respiratory, and urinary systems.
Source: https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-and-related-diseases-of-small-animals
