The human body is made up of 60% water, on average. A similarly large percentage of animal bodies are made up of water. It is obvious that water is essential component of every body, just as it is essential for life in general. But how much water is essential and what is excessive? Is excessive water intake by an individual a problem or have a potential for harmful effects? Does the required water intake vary from species to species?
It is estimated that for good health, an adult human being should drink approximately 8 glasses of water a day. Unlike humans, it would not be an easy task to make a pet drink the exact recommended amount of water per day. But a very important aspect of pet ownership and their dietary management is to be aware of the importance of water intake by your pet. A healthy dog should drink 60-80 ml of water per kg of body weight. This would amount to 1 to 1.5 cups of water (250-400 ml) for a 5 kg dog over a 24-hour period. This requirement varies based on many factors and is not the same for each dog. Similarly, a cat should have a daily water intake of about 40-60 ml per kg per day. This is roughly 3-quarters to 1 measuring cup per 24 hours. Some individuals will drink far lesser amounts per day, especially if a big proportion of their diet is moist food and if they have a more sedentary lifestyle (think indoor only pets and senior pets).
One of the wonders of the body’s physiology is to maintain hydration at all times unless if water is withheld or if stressful factors are involved. Thus, generally speaking we need not worry about inadequate water intake in our pets unless if they are obviously ill. From a monitoring standpoint, what is more significant is whether a pet is drinking (and urinating) in excessive amounts, also called polydipsia/polyuria (PU/PD). There is a long list of diseases attributed to PU/PD signs, including diabetes, kidney insufficiency, bladder infections, and hormonal disorders to name a few. Signs of PU/PD in pets indicate towards a need for immediate veterinary attention in order to rapidly diagnose and treat the cause of these symptoms. Withholding water to mask such symptoms will result in dehydration, weakness, and undue stress on the pet. Timely diagnosis and treatment may help achieve remission in a cat suffering from diabetes, or may help prevent bladder stones from developing in a dog with a UTI (urinary tract infection). Thus, having a good understanding of your pets’ water intake needs and frequency of urination during good health can help identify signs of PU/PD without delay, if they were to develop.
If you feel that your pets’ fluid intake is inadequate, it may help to add some water to their dry food, or to introduce a water fountain instead of the traditional water bowl. Providing fresh water by frequently refilling the water bowl is also helpful. Pets eating mostly canned food will often appear to have inadequate water intake. This should not be a concern in healthy cats and dogs. Keep in mind that some pets may have mild to moderate increases in water intake without excessive urination, during warmer summer days. While this should be a normal physiologic need, call you family veterinarian if the daily fluid volume intake appears abnormally high.
Jangi Bajwa, DVM
Veterinarian at Hastings Veterinary Hospital, Burnaby BC.