Estimates of daily water requirements have been reported for cats.1,2 However, daily water needs for healthy cats are only marginally defined, and little is known regarding how incremental changes in water intake may affect urine measures associated with hydration. Daily TW drinking volume is relatively stable in healthy cats ingesting a dry food diet when portion size remains unchanged, resulting in the natural production of highly concentrated urine. Even in this situation, cats may be minimally and chronically in a dehydrated state, whether this is because cats are naturally evolved from arid climates or because they appear to have a generally lower thirst drive. Results of recent studies3–5 suggest cats that are chronically dehydrated or that consume an all-dry-food diet might be predisposed to chronic illnesses such as chronic kidney disease, obesity, LUTD, and diabetes. Therefore, cats eating exclusively dry food might benefit from greater water intake, and it is reasonable to consider that some potential health risks may be decreased if additional water intake and greater hydration could be achieved. However, means of supplementing water intake by encouraging increased drinking have not been fully explored as a strategy to address feline hydration.
Nutrition studies of cats have been conducted to investigate health concerns related to LUTDs with a focus on evaluating increased water ingestion that could be beneficial to such patients. These investigations have provided some evidence that increased water intake can be achieved by modification of dietary moisture content to increase water intake through food6,7,a or provision of food with higher sodium content to stimulate drinking.8,9,b When changing from dry to wet food, the daily water intake measured as water-to-calorie intake ratio (mL/kcal of ME) typically increases from approximately 0.6 to 0.7 with dry food intake1,10,11 to 0.9 with wet food intake.12
More recently, our group performed a study11 in which healthy cats fed dry food with free access to TW were switched to a regimen of free access to an NW, followed by free choice of TW or NW, without changing the diet. Results of that study11 revealed that cats had greater mean free liquid intake (through drinking) and mean total water intake from all sources when only the NW was provided with food, compared with their own baseline values (when only TW was given with food). Consequently, those cats had a mean water-to-calorie intake ratio > 1.0 when drinking the NW, a value that was significantly greater than the baseline ratio for the same cats. Cats with access to NW throughout that study11 also had greater free liquid intake, more dilute urine, and greater urine output than did a cohort of cats that received the same dry diet with TW and no NW option over the 8-week treatment period. These findings revealed that an alternative strategy can encourage cats to increase water intake by greater amounts than are typically observed with wet food ingestion or without added sodium intake delivered through therapeutic dry food.
A greater understanding of feline water intake patterns, water balance, and how these factors influence urine indices of hydration status is still needed. The purpose of the study reported here was to investigate water intake and urine measures in healthy cats provided free-choice access to a water supplement (NWP or NW) at 3 incrementally increased volumes in combination with TW ad libitum. Specifically, we sought to determine whether cats consumed more NWP or NW when larger volumes were offered and whether changes in consumption of the supplements would be associated with changes in variables such as total water intake, urine output volume, and USG. Finally, the study further sought to determine the influence of several ingredients in the supplement by evaluating results when poultry flavor, which putatively acts as a palatability enhancer, was included or excluded. This allowed for evaluation of the effects of NW that contained only whey protein concentrate and glycerin as well as gums and potassium for processing.
All authors are employed in the R&D department of Nestlé Purina PetCare and conduct nutrition research for potential use in future commercial applications and products. None of the authors have any conflict of interest or affiliation to disclose related to the equipment used during the study.
The authors thank Mark Miller and Sarah Dionne for management and care of cats and coordination of sample collection and Patricia Turpin and Dakota Marti for performing assays on urine samples.
Lower urinary tract disease
Nutrient-enriched water with poultry flavoring
Urine specific gravity
Xu H, Greco DS, Zanghi B, et al. The effect of feeding inversely proportional amounts of dry versus canned food on water consumption, hydration, body composition, and urinary parameters in cats (abstr), in Proceedings. 39th World Small Anim Vet Assoc Cong 2014;852.
Xu H, Laflamme D, Bartges J, et al. Effect of dietary sodium on urine characteristics in healthy adult cats (abstr). J Vet Intern Med 2006;20:738.
BBA422-6PM, Mettler Toledo, Columbus, Ohio.
Proximate analysis performed by NP Analytical Laboratories, St Louis, Mo.
Maintenance diet manufactured by Nestlé Purina PetCare, St Louis, Mo.
NOSORB, Catco Inc, Cape Coral, Fla.
HSK-VET veterinary refractometer, Heska, Loveland, Colo.
1. National Research Council. Water. In: Nutrient requirements of dogs and cats. Washington, DC; National Academies Press, 2006;246–250.
3. Greene JP, Lefebvre SL, Wang M, et al. Risk factors associated with the development of chronic kidney disease in cats evaluated at primary care veterinary hospitals. J Am Vet Med Assoc 2014;244:320–327.
4. Rowe E, Browne W, Casey R, et al. Risk factors identified for owner-reported feline obesity at around one year of age: dry diet and indoor lifestyle. Prev Vet Med 2015;121:273–281.
5. Sallander M, Eliasson J, Hedhammar A. Prevalence and risk factors for the development of diabetes mellitus in Swedish cats. Acta Vet Scand 2012;54:61.
6. Buckley CM, Hawthorne A, Colyer A, et al. Effect of dietary water intake on urinary output, specific gravity and relative supersaturation for calcium oxalate and struvite in the cat. Br J Nutr 2011;106(suppl 1):S128–S130.
7. Markwell PJ, Buffington CA, Chew DJ, et al. Clinical evaluation of commercially available urinary acidification diets in the management of idiopathic cystitis in cats. J Am Vet Med Assoc 1999;214:361–365.
8. Hawthorne AJ, Markwell PJ. Dietary sodium promotes increased water intake and urine volume in cats. J Nutr 2004;134(suppl 8):2128S–2129S.
9. Xu H, Laflamme DP, Long GL. Effects of dietary sodium chloride on health parameters in mature cats (Erratum published in J Feline Med Surg 2009;11:735). J Feline Med Surg 2009;11:435–441.
11. Zanghi BM, Gerheart LG, Gardner CL. Effects of a nutrient-enriched water on water intake and indices of hydration in healthy domestic cats fed a dry kibble diet. Am J Vet Res 2018;79:733–744.
12. Finco DR, Adams DD, Crowell WA, et al. Food and water intake and urine composition in cats: influence of continuous versus periodic feeding. Am J Vet Res 1986;47:1638–1642.
13. Laflamme DP. Development and validation of a body condition score system for cats: a clinical tool. Feline Pract 1997;25(5):13–18.
Results of proximate analysis of NW and NWP used in a study to evaluate the effects of each supplementary product on measures of water intake, urine output, and USG in healthy domestic cats fed a dry kibble diet ad libitum.
|Whey protein (%)||1.2||1.2|
|Potassium chloride (%)||0.100||0.100|
|Poultry flavor (%)||1.0||0|
|Crude protein (%)†||1.72||1.20|
|Crude fat (%)†||0.31||< 0.1|
|Crude fiber (%)†||< 0.2||< 0.2|
|Phosphorus(%)†||< 0.01||< 0.01|
|Potassium (ppm [%])†||310 (0.031%)||245 (0.0245%)|
|Magnesium (ppm [%])†||29.3 (0.0029%)||26.0 (0.0026%)|
|Sodium (ppm [%])†||134 (0.0134%)||48.2 (0.0048%)|
Sixteen cats received NW and 16 received NWP in addition to TW ad libitum during the treatment period; a control group of 4 cats received only TW ad libitum for drinking throughout the study.
Mix of guar gum and xanthan gum.
Values determined on an as-fed basis.