Cats should have approximately 8 fluid ounces or 240 ml of water per day. This is will come from your cat's diet as well as drinking water. The kind of food your cat eats will determine how much additional water he will need to drink.
For example, a cat raw and canned foods contain approximately 70% water, dry food is only 10% water. Therefore a cat fed canned food will obtain more water from his diet than a cat on dry food. The cat eating dry food will need to drink more water. Grams and ml are the same. So 200 grams of food would be the equivalent of 200 ml.
||Daily food requirements||Water content||Additional water required|
|Canned or raw food||200 g (100 g x two meals)||140 ml||100 ml|
|Dry food||75 g||7.5 ml||233 ml|
As you can see from the chart above, the cat on a canned or raw diet is getting more than half of his daily water requirements via his food, but the cat fed a dry diet needs to obtain almost all of his water by drinking. Not many cats will make up this shortfall by actually drinking water, and a common problem is that cats try to make up for this shortfall by conserving water, they do this by concentrating the urine. A knock on effect is that concentrated urine is the perfect environment for the formation of urinary crystals.
Water is absolutely essential for life. The cat's body is approximately 60% water, once that level drops by 5%, your cat will show signs of dehydration. Fluid is lost via the urine, feces respiration, and sweat (yes cats sweat, not as much as other mammals, but they do sweat via their paw pads).
Other factors also come into play, including:
- The size of your cat (obviously a 1kg kitten would drink less than a 5kg adult cat).
- The health of your cat. Cats with kidney disease or hyperthyroidism drink more water.
- If the cat is a pregnant or lactating queen.
- The current season, a cat will drink more water when it is warm.
- How much exercise your cat gets.
- Is the cat young and still nursing from his mother? Unweaned kittens get all the fluid (including water) they need via their mother's milk, they do not need additional water until the weaning process begins around 4-5 weeks of age. Even then, kittens will continue to nurse from their mother, however, water should be offered in addition to their mother's milk.
How do I know if my cat is getting enough water?
An easy way to check the hydration of your cat is to pull the skin behind your cat's neck, in a young and well-hydrated cat it will spring back immediately. If it is slow to go back it could be a sign your cat is dehydrated. Other indicators are dry, sticky gums, sunken eyes and slow capillary refill time. To check this, pull your cat's lip back, press firmly on the gum and remove your finger. The gum will be pale from the pressure you applied, see how quickly it takes for the gum to pink-up. The slower this takes, the more dehydrated your cat is.
How to I encourage my cat to drink more water?
This is often difficult, you can't force your cat to drink obviously. Increasing the amount of wet food will obviously result in him consuming more water overall. Other ways you can encourage water consumption include:
- Make sure water bowls are clean and water should be emptied out and refilled with clean, fresh drinking water daily.
- Try different types of water bowl. Plastic bowls can leech into the water, giving it an unpleasant taste to cats. Glass or ceramic bowls are better for your cat.
- If this doesn't work, try getting your cat a drinking fountain, some cats prefer to drink from running water.
My kitten won't drink water:
This is a question that used to come up on my forums quite a lot. As has already been said, young kittens should only consume milk until they wean, and then they should begin to consume small amounts of water, as well as still drinking from mum.
Once they are old enough to leave their mother and go to their new home, they should be drinking water. A kitten in a new home may initially refuse water, it can take a few days for some kittens to settle in. Try to give him wet food to ensure he's getting some water into him and keep an eye on him. If he appears to be lethargic, and you suspect he is dehydrated, please take him to a veterinarian. Kittens can dehydrate very quickly and this is life threatening. Your veterinarian can give him some fluids to correct his dehydration.
My cat is drinking too much water:
I have always said it is important to get to know your cat's own habits. Some cats naturally do drink more than others, but if you notice a change in behaviour and your cat is suddenly drinking more than usual (medically known as polydipsia) it could be a sign of the following:
- Diabetes mellitus - Either caused by insufficient insulin secretion or an insulin resistance.
- Chronic or acute renal failure.
- Hyperthyroidism - Benign tumour of the thyroid gland which leads to the excess secretion of thyroid hormones.
- Pyometra - Infection of the uterus.
- Liver disease.
- Cushings disease (hyperadrenocorticism)
- Hypercalcemia (high blood calcium concentration)
- Acromegaly - Excess of growth hormone in an adult cat, most often caused by a growth hormone secreting pituitary tumour.
- Hypokalemia - Abnormally low potassium concentration in the blood.
- Psychogenic polydipsia - Compulsive water drinking.
- Certain medications.
All the above conditions are life threatening and need to be treated by a veterinarian.
Image courtesy Dave Dugdale.