As the exquisite carnivore, our cats are designed to be the prefect predator. Think of the lion, living in sub Saharan Africa, running down it's meal. This is your cat.
Like the lion, your cat gets its nutrition and water primarily from meals. For a free roaming cat, this means that its water requirements are met almost entirely from the mouse or bird that it captures. For our domestic cats, it means that most of its water intake should be coming from the food that they ingest. Obviously, this is difficult if they are eating dry food.
Another important fact is that our cats are adapted to arid climates, and are insensitive to their need for water. This is not an issue if their diet is includes moisture rich meals like a mouse or canned food. The problem arises if their diet consists mostly of dry kibble. A study many years ago illustrated that cats on dry food will appear to be drinking adequate water, but compared to cats ingesting canned food (who may seem to be drinking very little or no water) they are actually taking in less water.
Of course, it is not always easy to tell a cat what is "good" for them. But we can encourage them to have healthy habits. Placing multiple sources of water can induce more water intake. An interesting tip is to make sure that the water is not near their feeding area. Cats will drink more water if the the water is not near their food (this may herald back to the habit of "big cats" not bringing their "kill" to the neutral area of the watering hole). Other ways to encourage water intake are water fountains, offering bottled water (some cats are very sensitive to the "off odors" of our municipal water), and mixing water into their food.
Why Changes in Water Intake in our Cats Matters
Water is essential to every living process in our bodies and in our cats. Without water, a living organism cannot thrive or eliminate necessary wastes. An important question I ask the caretakers of cats: has the cat's water intake changed? Subtle changes in water intake can signal significant changes in organ function (even before other changes in the cat's behavior), and are clues of common diseases in the cat like kidney disease, diabetes, and hyperthyroidism. The changes in water intake can be easily confirmed by collecting a urine sample and testing the concentration of the urine. Cats that are truly drinking excessive amounts of water will have a lower urine concentration, indicating a possible serious disease. Comparing these values with certain blood work changes, we can often easily verify the pathological cause of the cat's increase thirst, and help me suggest important changes, treatment for my cat patients.
Dr Sue Lee, DVM