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Water is an essential nutrient for life, health and vitality. Water
- is the main constituent of cells, tissues and organs
- acts as a lubricant and shock absorber
- is the medium in which all transport systems of the body function
- maintains the vascular volume and enables blood circulation
- performs the critical function of transporting nutrients and removing wastes.
The cardiovascular and respiratory systems, the digestive tract, the kidneys and liver, the brain and peripheral nervous system – every aspect of the body depends on adequate hydration to function effectively. Yet 80% of cats in the U.S. are fed dry food, which has so little moisture, it literally robs the body of moisture to metabolize what nutrients kitty is able to derive from it. Given the importance of water, how can a food that provides almost no moisture be labeled “Complete and Balanced?”
Chronic kidney disease is the number one cause of death in cats over 5 years of age, and was the number one reason for visits to the vet by cats in 2015. Although the role of hydration in the development of chronic kidney disease (CKD) has been downplayed or misunderstood, current research indicates that even mild dehydration is a risk factor in the progression of all types of chronic kidney diseases. In fact, there is also evidence that increasing hydration may actually have a role in preventing CKD. Importantly, water consumption also has been shown to have an impact on bladder and urinary stone diseases, mitral valve prolapse, and cancers of the breast, colon and urinary tract.
The need for cats to consume plenty of water cannot be emphasized enough, and their need for water is often overlooked – or understated. Because there is no industry emphasis on the importance of water as a vital nutrient, there is often a lack of understanding of just how much water our cats need – and why.
It is well known that our pet cats were originally desert animals. They rarely drank water and historically ate a fresh food diet of prey that had a 70% – 80% moisture content. Our cats did not evolve a “thirst drive” similar to that of humans or dogs: from an evolutionary standpoint they derived almost all they water they needed from their diet. In a dehydrated state, dogs will consume enough water to replace 6% of their body weight in an hour vs. the 24 hours it takes for dehydrated cats.
Studies show that
- cats fed solely dry food have a lower water intake and lower urine volume than cats on a wet food diet, even if the cats have constant access to fresh water, (also see this reference)
- higher moisture intake and thus more frequent urination reduces the risk of developing Feline Lower Urinary Tract Diseases (FLUTD).
- Switching from dry to wet food decreased the incidence of FLUTD recurrence in cats (even on the prescription dry and canned foods!).
“But my cat drinks plenty of water!” Are you sure your cat drinks enough water? If eating kibble, almost definitely not, and it is worth taking the steps necessary to measure how much your kitty(ies) are drinking daily for a few days to see if you need to take steps to encourage more water intake. Most people are very surprised by the amount of water needed for proper hydration of our cats.
How Much Water Is Enough?
According to the Nutrition Research Council's "Nutrient Requirements of Dogs and Cats", (on which AAFCO nutrient requirements are based), a cat can maintain a hydrated state as long as the moisture level of the food meets or exceeds 63%, as fed (as they’re dehydrated at 61%).
The moisture content of cat foods varies dramatically:
According to this data from the NRC, if you are feeding canned or raw food with no dry food, your healthy cat is consuming plenty of water. Please note, however, that hyperthyroidism, diabetes and kidney disease greatly increase a cat’s daily water requirements.
As you can see, kibble-only diets create a state of chronic dehydration unless your cat consumes a LOT of additional of water. Generally speaking, to equal the amount of water a cat eating a canned-food or raw-only diet consumes, the average cat eating dry food needs to consume about one cup (240ml / 8 ounces / 15 tablespoons) of water a day. To obtain the ideal amount of moisture, illustrated below, a 12 pound cat eating one-half cup of dry food (weighing 2.5 ounces) needs to drink up to 318ml (10.5 ounces / 21.5 tablespoons) of water every day - that is almost 1.5 cups of water. Why does this seem so excessive? Because it takes water to metabolize the nutrients in food. While moist foods provide that water, kibble – dry food – literally robs the body of water just to process the food eaten by kitty. Cats eating dry food start at a deficit of moisture.
Clearly the typical pet food industry information that cats eating dry food need to drink “a few ounces” of water a day is quite misleading.
How much moisture does the diet you feed your cat provide?
When made as directed, homemade raw food using the EZcomplete fur Cats supplement is 77% moist (and you’re not paying for the water as you do with canned foods).
If a raw or canned food diet provides 77% moisture, that is 77 grams of water for every 100 grams of food.
A dry diet providing 10% moisture means there is 10 grams of water for every 100 grams of food.
Thus
- If your canned food provides 77% moisture, one 5.5 ounce can of food (156 grams) provides 120ml (4 ounces / 8 tablespoons) of water.
- 4.5 ounces of raw food (128 grams) at 77% moisture provides about 100ml (3.3 ounces / 6.7 tablespoons) of water.
- 6 ounces of raw food (170 grams) at 77% moisture provides 130ml (4.5 ounces / 9 tablespoons) of water.
A typical serving of kibble for an average adult cat provides one-half tablespoon of water. While weights and recommended amounts of kibble vary, a typical serving for an adult cat of 10-12 pounds (4.5kg – 5.4kg) is one half cup, weighing about 2.5 ounces. This is 71 grams, and at 10% moisture, provides just 7 ml ( ¼ ounce / one-half tablespoon) of water.
Is “hydrated” the same as “ideal?”
According to Merck Veterinary Manual’s “Nutritional Requirements and Related Diseases of Small Animals,” in the section on water, proper feline hydration requires a total of 44 - 66 milliliters of water per kilogram of body weight (or 0.7 to 1 ounce per pound) each day. These charts indicate how much water that is – though remember, some or much of this may be provided by food if feeding canned or homemade.
Using this method of measurement, even cats eating wet or raw food may need more water than diet alone provides. But this analysis clearly identifies a very important reason why chronic kidney disease is the number one cause of death in cats over 5 years of age: 80% of cats in the U.S. are fed dry food. Of course there are other reasons and other contributing factors. But given the current trends in research in humans on CKD indicate proper hydration *alone* may prevent development of chronic kidney disease, the importance of water as a critical nutrient in our cats’ diet cannot be overstated.
Water is life. Water is health. Please ensure your kitty has a moisture-rich diet and provide and encourage the drinking of additional water!
Please note: the contaminants in your tap water may surprise you. For more information, please see "Clean Water" by Lisa Provost at IBDkitties.