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Ask a Vet: How Much Water Should a Cat Drink?

Cats should always have access to fresh water, and most vets agree that cats should be encouraged to drink more.

 |  Apr 29th 2014  |   12 Contributions


It is common sense that water should be available for pet cats at all times. Cats, like all earthbound life forms, need water to survive. But it also is widely known that cats have a somewhat complicated relationship with water. Most cats avoid getting wet to the greatest extent possible, and legend has it that cats can't swim (the legend is completely false -- cats instinctively are excellent swimmers).

It turns out that a dislike of being wet isn't the only way in which cats' relationships with water are imperfect. Cats, in general, don't drink as much water as most veterinarians feel would be healthy. This renders them chronically on the verge of dehydration.

The cause for cats' generally low water intake is anyone's guess. One prevalent theory is that as descendants of desert creatures their powerful kidneys conserve so much water that they don't need to partake heavily when water is readily available.

Regardless of the reason, it is generally agreed that most pet cats would be healthier if they drank more water. Greater water consumption generally is good for cats' urinary tracts.

Photo of Dr. Eric Barchas by Liz Acosta

The matter starts with the kidneys. In the course of normal metabolism the various tissues and organs of the body consume nutrients and produce waste products. The waste products are released into the blood stream, and it is the job of the kidneys to move the waste products from the blood to the urine.

Young healthy feline kidneys are remarkably strong. They can concentrate large quantities of waste into very small quantities of urine. But such effort is taxing upon the kidneys, and is believed to contribute to the development of chronic kidney disease, which in turn is the most common major illness (and No. 1 cause of death) in mature cats.

Strong, concentrated urine also appears to be linked to feline idiopathic cystitis (FIC), also known as feline lower urinary tract disease (FLUTD). This diabolical syndrome causes recurrent episodes of bladder pain and can predispose male cats to urinary obstruction.

Cats who can be coaxed to drink more water will by nature proceed to excrete it. This means they will produce more urine. Although it seems counterintuitive at first, producing more urine is actually less work for the kidneys. Furthermore, weaker urine is less likely to predispose cats to FIC/FLUTD.

So, let's get down to the question in the title of this article. How much water should cats drink? The answer in most cases is as much as they want, and then some.

I recommend that all cats have ready access to multiple fresh water sources. Several bowls of water should be available and easily accessible at all times. Owners should keep track of general trends in cats' water consumption because changes in consumption can signal medical problems. Although formulas exist to calculate so-called "maintenance" fluid needs, I don't recommend measuring how much water your cat drinks each day. It's simply not practical and it will be a waste of your time.

Many cats seem to enjoy extremely fresh water. The suspected reason (or perhaps confabulation would be a better word) for this again goes back to cats' desert origins. As desert creatures they are predisposed to drinking from very fresh sources. It is for this reason that so many cats like to lick up water from the shower floor, and why many cats will jump onto the counter to drink directly from the sink (sometimes demanding that the owner turn on the faucet for the cat's benefit).

Purpose-built recirculating water bowls, often referred to as cat fountains, capitalize on the common proclivity of cats for fresh, circulating water. I encourage their use because a great deal of cats seem to prefer them.

Another way to facilitate water consumption is to feed wet food. Water content is the significant difference between wet food and dry food, so cats that eat wet simultaneously consume extra water. Owners of cats with specific conditions such as cats with FIC/FLUTD, who would benefit from increased water intake, often add water to wet food. Cats that eat such "soup" consume substantially more water than those who eat straight cat food.

I mentioned above that it is wise to monitor trends in water consumption. This is because changes in water consumption can indicate medical problems. Cats with kidney disease, diabetes, or a host of other issues may drink more water. Cats with inflammatory bowel disease or other causes of nausea may drink less.

Many cats are sneaky water drinkers. This, along with evaporation, can complicate monitoring of water consumption. Fortunately, there is an easy proxy for water consumption: urine production. Urine production and water consumption are two sides of the same coin. If your cat is producing dramatically more or less urine then you should seek veterinary care.

Finally, if your cat is producing more urine, resist the urge to limit his access to water in order to make the litter box easier to clean. Increased urine output precedes increased thirst in diseases such as kidney failure or diabetes. Cats with such conditions produce more urine regardless of how much water is available, and restricting access to water simply leads to dehydration.

In short, watering your cat is quite simple. Encourage him to drink as much as he desires, and talk to the vet if his needs suddenly change.

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