The Reasons & Problems of Low Water Intake in Cats


Have you ever wondered about the reasons behind low water intake in cats? Reasons date back centuries. That little fur-ball purring contentedly on your couch originates to some of the first carnivores to evolve 35 million years ago. The African wild cat (Felis Sylvestris Lybica) is generally accepted as the ancestor of most of today’s domestic cats.

The Felis Silvestris Lybica

The Felis Sylvestris Lybica is the ancestor of most modern cats


Felis Sylvestris Lybica lived in Northern Africa, the Near East and around the periphery of the Arabian Peninsula. Their descendants still roam the deserts of Israel, Saudi Arabia and other countries in the Middle East today. Living in a desert environment where water sources are scarce, their body physiology adapted to the demands of their environment. This allowed low water intake in cats in these regions enabling them to survive.

They have developed kidneys that are very efficient in conserving water and they are able to obtain most of the water they need from the food that they eat. They did not need a lot of water to survive. African wild cats are hunters with their main prey being rodents. Their natural diet also consisted of hares, rabbits, insects, birds, fish, and occasionally poultry and small livestock. The fresh meat of these animals is made of around 75% water and this is where wild cats get most of their water requirement from.

Low water intake in cats aided by wild hunting

Wildcats and feral cats get most of their daily water requirement from the prey that they catch and eat.

From their origins in the desert, our domestic feline companions have retained some of the physiology characteristics of their ancestors. Their kidneys still concentrate urine to conserve body water. Today’s cats still have a low thirst drive making them bad drinkers even when there is ample water in their bowls and their bodies are still adapted to getting most of the water they need from their food.



These characteristics inherited by our cats should pose no problem at all if they were allowed to go out and hunt for their natural food. But majority of cats being kept as pets today live purely indoors for safety reasons and are being fed with commercial food. In recent years, the growth of the pet food industry has skyrocketed and we have seen a deluge of commercial cat food, both wet canned and dry, in the market. Wet canned food is approximately 78% water and is closer in approximating fresh meat in terms of amounts of protein and water content. Dry food is at most only 10% water while having more carbohydrates than protein.

too much dry food leads to low water intake in cats

Modern dry cat food has at most 10% water

Perks of Dry food

Dry cat food has been called “unnatural” due to its very low water content, yet it is widely popular among pet owners because of its inherent advantages: (1) it can be kept longer after opened as long as it is placed in airtight containers, (2) it is easy and not messy to feed, (3) there is minimal waste, (4) it can be left longer in the bowl so the cat can have access to food even when the owner is away during the day, an advantage for busy cat parents, and (5) it is cheaper than canned wet food for pet parents on a tight budget.

How to Maintain a Healthy Dry Food Diet

Many believe that dry food of superior quality, grain-free and having a specific meat in the ingredient, not just animal by-products, is not really bad for cats but they would need to drink more water to make up for the very low water content of these dry food. Therefore cats on dry food should have access to fresh water at all times and drink a sufficient amount of it. But even cats who are on a canned wet food diet need and greatly benefit from drinking extra water.


cat lazy water


Water makes up about 80% of a cat’s body. It is essential for good health and vital to almost all body processes that maintain life. Cats need to drink more water, especially those who are on a dry food diet. Just keep kitty’s water bowl filled with water at all times and he will drink from it. Sounds fairly simple, right? But in reality pet parents know that seriously low water intake in cats can lead to complications.

As mentioned earlier, our domestic cats today have inherited the low thirst drive of their desert-dwelling ancestors so they are by nature not inclined to drink much water even when it is available. A compounding factor is the cat’s instinctive dislike for stagnant water making a still water bowl not good enough to provide for their daily water requirement.

Cat watching flowing water

Cats instinctively know that running water is cooler, fresher and cleaner. Their good peripheral vision also allows them to see running water better.

Theorists have proposed a number of reasons as to why this is so. Foremost factor is the evolutionary process. In the wild, the moving water of rivers is generally less polluted than the stagnant water of ponds and puddles. Therefore, cats that instinctively preferred to drink only from running water got sick less and had better odds at surviving and passing on their genes.

Cats have also learned that running water is fresher, cooler and taste better than standing water. Being predators, cats have more superior peripheral than forward vision so they can detect movement better. They cannot see still water very well so they will have difficulty determining the water level and be hesitant to drink from still water sources.


When your cat does not care for the water in his bowl, it is difficult to force it to drink from it. This will result to your cat having long-term low-level dehydration especially when he is on dry food. Dehydration, a condition wherein there is a harmful reduction in the amount of water in the body, increases the risk for developing a host of problems primarily related to the urinary system and affecting other body systems as well.

Cat's urinary system

Simplified diagram of a cat’s urinary system. Water flowing through this system is essential for keeping it healthy.

Kidneys, ureters, urinary bladder and urethra make up a cat’s urinary system. The kidneys filter waste products and toxins from the blood; they regulate the volume of body fluids; and they control the blood levels of certain chemicals and hormones. The other organs, collectively called the “lower urinary tract”, act as the passageway for urine carrying the body’s waste products to be excreted from the body. According to Dr. Lisa Pierson, a veterinarian and expert on feline health and nutrition, “Water flowing through the urinary tract system is the most important factor in keeping it healthy.”

The following is a simplified picture of what happens in the cat’s body, particularly the urinary system, when there is persistent low water intake and dehydration:

Urine Becomes More Concentrated

When the body senses that the amount of water in the bloodstream is lacking, it compensates for this by reabsorbing water from the urine resulting to a urine that has increased specific gravity. This means that because water was reabsorbed, the urine becomes more concentrated. The risk for the formation and growth of urinary crystals and stones increases with concentrated urine.

Urine specific gravity

The measurement of urine specific gravity. It will tell how dilute or concentrated the cat’s urine is. Crystals are less likely to form in dilute urine of adequately hydrated cats.

Elevation of the BUN and Kidney Damage

BUN stands for Blood Urea Nitrogen. Urea is a chemical waste product from the breakdown of protein in the body. Normally bloodstream carries urea to the kidneys. The kidney filters the urea and other waste products from the blood and the waste leaves the body through the urine.

A dehydrated cat’s blood volume will decrease and the blood will become thicker, resulting in slower blood flow from it’s organs back to the heart. When this happens, the heart reduces the amount of blood it can pump per minute and this affects the efficiency of the heart in sending blood to the other organs of the body. This reduces blood flow to the kidneys decreasing the effectiveness of blood filtration. The result is an increase in the amount of urea waste products remaining in the blood, hence elevation of the BUN.


Blood Urea Nitrogen Test

Blood Urea Nitrogen (BUN) are toxic waste products in the blood. When a cat is not drinking enough water the toxins stay in the blood and can damage organs.

Persistently increased levels of BUN can make the cat feel tired and sluggish. It can also result in vomiting and ulcers on the lining of the stomach and gums. Accumulated toxins in the blood and low blood flow can damage the organs including the kidneys. When kidney function declines they become unable to properly filter the toxic substances in the blood hence increasing the BUN even more. When waste products remain in the blood, it recirculates back to the different organs where it may cause organ damage that can be lethal to the cat.

Increased Risk of Formation and Growth of Urinary Crystals and Stones

Dr. Richard Goldstein, a veterinarian at the Animal Medical Center in New York, USA observed that crystal and stone formation tends to occur in domesticated cats who don’t take enough fluids and don’t urinate enough. Urine is made up of water with suspended minerals, cells, proteins and other debris. Chronically dehydrated cats produce urine with higher concentrates of struvites or calcium oxalate. When they reach concentration threshold, the minerals precipitate out as microscopic crystals. Later these crystals combine to form sand like material which may accumulate more minerals forming urinary stones.

Crystals made from dehydrated cat

Examples of crystals that may form in the urine of a dehydrated cat. They may block the urethra and cause painful urination.

Proof of the Theory

A study in the Veterinary Clinics of North America: Small Animal Practice demonstrated interesting results. Their examination of obstructed cats found that 60.4% presented with urethral plug made of crystals, proteins and other debris in the urine, and 11.3% with uroliths. Also, a study showed the prevalence of urolithiasis has undergone considerable change over the last 20 years. The 2016 World Small Animal Veterinary Association Congress associated this change with the use of commercial dry diets.

Negative Effects of Urinary Crystals and Stones

Urinary crystals are sand-like and they irritate the bladder causing inflammation. They may plug the urethra causing an obstruction to the flow of urine. This condition presents a bigger problem in male cats whose urethra are narrower than the female’s.

Urinary stones

Urinary stones inside the bladder. They cause bladder irritation and block the flow of urine which may lead to kidney damage.

Urinary stones irritate the bladder wall and block the passageway of urine flow from the bladder to the urethra. Urine becomes trapped in the bladder and backs up into the kidneys resulting to scarring and kidney damage. Impaired kidney function leads to increased BUN and Creatinine (another waste product from the muscles). Therefore when the obstruction to urination goes unchecked, it could ultimately become life threatening and many cats die from this.

Feline Lower Urinary Tract Disease (FLUTD) and Cystitis

FLUTD is a term which groups disorders affecting the lower urinary tract (bladder or urethra) in cats. These disorders arise due to various predisposing factors. According to claims data published by the Veterinary Pet Insurance Company in Veterinary Economics, FLUTD is the most common reason owners took their cat to the veterinary office.

In the article “Epidemiologic Study of the Risk Factors for Lower Urinary Tract Disease in Cats” published in the Journal of the American Veterinary Medical Association, uroliths account for 15-23% of FLUTD cases and bacterial urinary tract infections up to 22%. Other factors include stress, decreased moisture content of food and not consuming enough water to flush out/clean the bladder

Cats changing posture due to urination

Diagram of the posture a cat assumes during normal urination compared to difficult or painful urination.

The most common disorder under the FLUTD group is Cystitis which is the inflammation of the urinary bladder. Stress is a significant risk factor in the development of cystitis but according to Walker, in a study titled “Epidemiological Survey of Feline Urological Syndrome” published in the Journal of Small Animal Practice, the risk is increased with decreased moisture content of food and decreased water intake. The concentrated urine irritates the lining of the bladder wall predisposing the cat to cystitis. An inflammed urinary bladder makes it difficult and painful for a cat to urinate. Urine retained in the bladder backs up to the kidneys and cause damage.

Other Problems Caused By Chronic Low Water Intake in Cats and Dehydration
Low water intake in cats causes exhaustion

Cat dehydration can lead to several health issues for cats

Dehydration can cause a chronic imbalance of water and electrolytes in the body which can be detrimental. Lack of water effects blood circulation and compromises the effective delivery of oxygen and other nutrients to the different organs. It affects the collection of waste products and digestion too. When the body senses that it lacks water, the large intestines reabsorb water from food instead, resulting in chronic constipation.


I cannot overemphasise the importance of water to the overall well-being of your. Almost all body processes essential to life need water to function. Increased water intake results in dilution of urine which is beneficial for the prevention of kidney and lower urinary track diseases.

It helps reduce the risk for the formation of crystals in the urine, urethral plugs and urinary stones. Stress reduction is key in the prevention of FLUTD and cystitis but increasing water intake is also vital. Water makes the urine more dilute and it increases the frequency of urination which is nature’s way of “flushing”/cleaning the urinary system. For this reason Dr. Richard Goldstein of the New York Animal Medical Center recommends that you ensure your cat always has access to fresh water. Additionally he highlights that it is also important to check that it is drinking it frequently.

Drinking water can not only prevent disease but also help manage existing ones. Adequate hydration helps cats with Chronic Kidney Disease (CKD) and those struggling with loss of kidney function. This is due to minimising the accumulation of toxic body waste products in the blood. Additionally it prevents recurrence of issues such as urinary crystals, urethral plugs and urinary stones.


Having highlighted the importance of water, we now have the problem of how to get cats to drink more water. Cats are typically discriminating creatures and for most of them a still water bowl is just not good enough. You can discourage low water intake in cats is by providing a source of clean, fresh moving water for them. Your cat will benefit greatly from the extra water, regardless of if is on a wet or dry food diet. One of the best things you can do for your cat is to get him a water fountain to entice him to drink more. It is a worthy investment toward your cat’s well-being.

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