Feline Hydration
The importance of hydration
Water is vital to life, and it is considered an essential nutrient for supporting a multitude of physiological functions including metabolic regulation and elimination of waste products through the kidneys. For that reason, correct hydration is necessary to maintain a proper equilibrium of electrolytes, minerals and fluids within the body¹.
Why don’t cats drink much?
There are several evolutionary, physiological and behavioural reasons that make cats more susceptible to dehydration. Cats have evolved as desert dwellers with very high urine concentrating ability enabling them to adapt to periods of scarce water. Domesticated cats tend to increase their urine concentration rather than drinking more when eating food with a low moisture content.
When cats become dehydrated, they can be slow to initiate drinking and have a low thirst stimulus. When they do start to drink, they are not very efficient as they cannot create a suction with their tongue. When they lap at a bowl of water, only 3/100ths of a teaspoon of water is consumed with each flick of the tongue, meaning a lot of lapping is required when they drink.
Behaviour also has an impact; cats can feel vulnerable when drinking from a bowl of water and can be sensitive to the presentation and taste of the water. Cats also have poor close-up vision, which can make it difficult for them to see the meniscus on the surface of their water bowl. All of these may impact the volume that they drink and should be taken into consideration when trying to increase water intake.
Credit: Lightspruch
Why might we want to encourage increased water intake?
Whilst a healthy cat with free access to water can maintain a good water balance, there are some situations, particularly with certain conditions, where increasing and promoting water intake may be beneficial.
In cats with Feline Lower Urinary Tract Disease (FLUTD), greater liquid intake and urine dilution is beneficial³. Causes of FLUTD include idiopathic cystitis, urolithiasis and urethral plugs. Dilute urine contains a lower concentration of bladder irritants, stone and crystal components and encourages more frequent urination.
Dehydration can be associated with several conditions including chronic kidney disease, constipation, diabetes mellitus, as well as something to watch out for in the senior life stage. It is also worth considering any cat that has polyuria (urinating more) or other increased water losses such as those with poor faecal quality or skin diseases, where they may be losing water via the skin or loss of saliva from over grooming.
Increasing a cat's liquid intake should be considered as a key factor to reach a correct level of hydration, together with a healthy diet and proper environmental management.
Encouraging increased fluid intake
There may be some trial and error when implementing these strategies, as all cats respond differently; this is something that owners should be prepared for. It is best to only change one thing initially, as cats can find changes stressful. Multiple strategies may be needed long-term.
Changing diet when appropriate
If wet food is available that meets the cat’s needs, a 100% wet diet can be an effective way to encourage moisture intake4. Cats on a dry diet drink more water than if on a wet diet but there is a net reduction in total water intake. Feeding a combination of wet and dry food does not tend to be a successful alternative. Unfortunately, not all cats will accept wet diets, although feeding a variety of both wet and dry food from a young age may minimise the risk of a cat developing a strong preference for one or the other.
Sodium enriched dry diets can also be effective5. Examples include veterinary urinary diets that are designed to promote dilute urine.
Encouraging intake of drinking water with environmental modifications
Whilst cats demonstrate clear individual drinking preferences there is still a lack of evidence to support that these adaptations increase overall water intake. That said, supporting the owner to understand their cat’s preferences may still play a part in encouraging drinking and water intake. Cats should always have free access to clean, fresh water but consider trying several types of water, such as tap, bottled, filtered or even rainwater. Most cats will prefer water at room temperature, not chilled.
Pet owners should be encouraged to experiment with several types of water bowl. Plastic bowls can taint the water, so materials such as ceramic, porcelain, metal or even glass may be preferred. The bowl should be shallow, and wide enough that the whiskers don’t touch the sides. Whichever bowl is used, ensure that it is full so that the cat can see the meniscus of the water. Some cats may prefer running water such as from water fountains or dripping taps. Take care to position bowls away from food and litter trays and in safe areas where the cat can drink undisturbed. Consider elevating bowls slightly for older, arthritic cats.
Flavouring water
For some cats, the above strategies still may not be appealing, so another option could be to flavour their water. This could be achieved by adding spring water from tinned unsalted tuna or the water used to poach plain chicken or fish.
Nutrient enriched water
Apart from feeding a 100% wet diet, only nutrient-enriched water has clinical studies to support a clear benefit in improving hydration status in cats. Nutrient-enriched water can be considered in all cats that require additional support to help increase water intake.
Credit: AAronAmat
The science behind ‘water supplements’
PURINA® PRO PLAN® Hydra Care™ is a new concept in hydration for cats. This revolutionary supplement has been created to help cats consume on average 50% more water every day than water alone and helps to increase urine dilution*. In a research study, cats offered PRO PLAN® Hydra Care™ had lower urine specific gravity and osmolality, than cats offered only tap water⁶.
PRO PLAN® Hydra Care™ is a complementary pet food, in the format of a tasty, soft-textured jelly which is served on its own, as an extra third bowl. It is poultry-flavoured for palatability and contains a low-calorie mix of specific amino acids and glycerol. These osmolytes help to retain fluid in the body, making PRO PLAN® Hydra Care™ a useful tool to encourage water intake in various situations where increased hydration is beneficial.
If you are interested in the PRO PLAN® Hydra Care™ supplement you can find the product here: PPVD® HC Hydra Care Wet Cat Food | Purina
*Compared to cats consuming only water in addition to dry feeding. Cats must consume at least 25mls/kg of body weight daily for benefit. Internal Purina Study, 2020
References
1. Stanton C.A, et al., (1992): Bioelectrical impedance and zoometry for body composition analysis in domestic cats. American Journal of veterinary Research, 251-57.
2. Buckley C.M.F, et al., (2011): Effect of dietary water intake on urinary output, specific gravity and relative supersaturation for calcium oxalate and struvite in the cat. British Journal of Nutrition, 106, S128-S130.
3. Brian M. Zanghi, (2017): Water need and hydration for cats and dogs. Nestle Purina Comp Anim Nutr summit. Proceedings, 15-23.
4. Markwell PJ, Buffington CA, Chew DJ, Kendall MS, Harte JG and DiBartola SP (1999). Clinical evaluation of commercially available urinary acidification diets in the management of idiopathic cystitis in cats. Journal of the American Veterinary Medical Association 214(3):361-365.
5. Hawthorne AJ and Markwell PJ (2004). Dietary sodium promotes increased water intake and urine volume in cats. The Journal of Nutrition 134(8 Suppl):2128S-2129S. DOI: 10.1093/jn/134.8.2128S
6. Zanghi BM, Gerheart BS and Gardner CL (2018). Effects of a nutrient-enriched water on water intake and indices of hydration in health domestic cats fed a dry kibble diet. American Journal of Veterinary Research 79(7):733-744. DOI: 10.2460/ajvr.79.7.733
*Reg. Trademark of Société des Produits Nestlé S.A.
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