Abstract
Increasing water intake and decreasing urine concentration are recommended for cats with urolithiasis and with idiopathic cystitis. Fountains are advocated to encourage drinking; however, effects on drinking of fountains have not been reported in cats living in pet owners homes. Thirteen healthy cats were assigned to have 24-h water intake and urine osmolality and specific gravity measured when water was offered from a bowl or fountain. One cat developed excessive barbering, vomiting, and refusal to drink water offered from the fountain. For the remaining 12 cats, intake was slightly greater from the fountain. However, urine osmolality was not significantly different. In this study, a fountain failed to substantially increase water intake and dilute urine in cats. A similar study including a greater period of time and additional cats may clarify the results of this study.
Disorders leading to lower urinary tract signs and hematuria are diagnosed at 1.5% of cat visits to primary care veterinarians. 1 The most common lower urinary tract disorders of cats are idiopathic conditions, urethral plugs, and uroliths. 2 There is evidence, though minimal, that increasing dietary moisture and urine dilution, in addition to other treatment factors, may reduce the recurrence of calcium oxalate uroliths and idiopathic cystitis in cats. 3,4 Maintaining dilute urine is promoted as part of strategies to prevent recurrence of numerous urolith types in cats. 5 Presumably urine dilution reduces the concentration of irritating and lithogenic substances and increased urine volume leads to more frequent voiding.
Dietary changes used or recommended to increase water intake and promote urine dilution have included feeding canned food, high sodium diets, and addition of water to diets. 4–7 Additions of flavoring to water and water fountains have also been suggested to increase water intake. 6,8 Numerous commercial water fountains are being advertised to provide flowing drinking water for cats. One such product (Drinkwell The Original Pet Fountain, Veterinary Ventures, Reno, NV) claims it is ‘the best way to entice your pet to drink more water’. No studies have prospectively evaluated the efficacy of water fountains to increase intake in cats. The hypotheses of this study were that cats would consume more water and have more dilute urine when water was offered from a fountain versus a bowl.
Materials and methods
All portions of this study were approved by the Virginia–Maryland Regional College of Veterinary Medicine Veterinary Teaching Hospital (VTH) Board and the Institutional Animal Care and Use Committee of Virginia Tech.
Animals
Thirteen client-owned cats housed indoors only with no other pets were determined to be healthy based on a physical examination and results of a complete blood count, biochemistry profile and urinalysis (dipstick tests, microscopic analysis, urine specific gravity, and osmolality (Advanced Microosmometer Model 3300, Advanced Instruments, Norwood, MA)). Cat owners verified their cat was not experiencing any health problem at the time of the study and had no history of the following diseases; diabetes mellitus or insipidus, chronic kidney disease, pyelonephritis, hyperthyroidism, urolithiasis, or cystitis. They were specifically queried to be sure their cat did not have polyuria, polydipsia, or pollakiuria.
Procedures
Cats were randomized in a 2×2 cross-over design to have 24-h water intake and urine specific gravity and osmolality measured when water was offered from a bowl or a fountain; access to water elsewhere in the house was prohibited. Cats were given 7 days to acclimate to the fountain prior to measurement of water intake and 14 days passed between measurements using the bowl or fountain (Drinkwell). The cats were kept in their home environment and water intake and evaporation were measured by the cat owners. For the duration of the study cats were fed their usual food. 24-h water intake was measured on two consecutive days (48 h) and the mean value used for statistical analysis. The bowl and fountain were never allowed to become empty. At the end of the 48 h, water was removed and the cats were brought to the VTH for collection of urine by cystocentesis within 4 h for urinalysis and measurement of urine osmolality and specific gravity.
To determine and correct for the volume of water that may have been spilled by cats playing with their water during all water intake measurements, an absorbent pad was placed under the bowl or fountain. The absorbent pads were sealed in an air-tight plastic storage bag and weighed prior to and after each 24 h period. The difference in weight of the pad was converted to milliliters of water and the volume subtracted from the amount of water offered during that period. To determine and correct for the volume of water that could evaporate, or in the case of the fountain could have been retained within the filtration/pump system or displaced by splashing, a control bowl and fountain were placed in a room in the cat owner's house with no motion, people, or animals for 24 h following the respective water intake measurement. The volume missing from the fountain or bowl was subtracted from the amount placed in the bowl or fountain during each 24 h period.
Cat owners were then queried to determine the following: (1) Did their cat play with its standard water bowl or the water in it? (2) Did their cat play with the fountain or the water in it? (3) Did they feel their cat liked the fountain?
Statistical analysis
Data were summarized as means±standard deviation. Subsequently, both volume of water intake and urine osmolality were compared between the two treatments (water offered from a bowl or fountain) using mixed model analysis of variance with sequence, period, and treatment as fixed effects and cat within sequence as a random effect. For each analysis, a norm plot of the raw data and the residual plots were inspected to assess model adequacy. Statistical significance was set to α=0.05. All analyses were performed using the Statistical Analysis System (version 9.2: SAS Institute Inc, Cary, NC).
Results
One cat, whose first assignment was the fountain, developed excessive barbering, and vomiting and aggression directed at the fountain, and refusal to drink water when the fountain was offered. These behaviors resolved upon removal of the fountain, therefore, the cat was removed from the study. Individual results for the remaining 12 cats can be found in Table 1. Water intake from the fountain was statistically significantly greater than intake from the bowl (31.6±13.5 versus 22.9±10.2 ml/kg/day, P=0.0381). However, no difference was observed in urine osmolality after intake from the fountain versus the bowl (2537.7±440.8 versus 2468.9±367.3 mOsm/l, P=0.6579). The lowest urine osmolality and specific gravity obtained from a cat drinking from the fountain were 1901 mOsm/l and 1.044, respectively. The data were also analyzed after excluding cat 2 because its diet did not remain consistent between these two treatments (canned food was added to the dry diet when the bowl was used). After exclusion of cat 2, no significant difference in urine osmolality or water intake from the fountain versus the bowl could be identified. The 24 h mean volumes of water that disappeared from the control bowls and fountains were 25.3±19.7 ml/day and 108.0±56.0 ml/day, respectively.
Table 1.
Signalment, water intake, and urine specific gravity and osmolality of cats offered water from a bowl and a fountain.
| Cat number | Signalment (age in years, gender, breed) | Bowl, mean water intake (ml/kg/day) | Bowl, urine specific gravity | Bowl, urine osmolality (mOsm/l) | Fountain, mean water intake (ml/kg/day) | Fountain, urine specific gravity | Fountain, urine osmolality (mOsm/l) |
|---|---|---|---|---|---|---|---|
| 1 | 5, MC, DSH | 20.9 | 1.051 | 2044 | 18.1 | 1.044 | 1901 |
| 2 | 7, FS, DSH | 14.7 | >1.060 | 2636 | 52.3† | 1.054 | 1961 |
| 3 | 5, MC, DSH | 21.3 | 1.056 | 2504 | 31.5 | >1.060 | 2500 |
| 4 | 7, MC, DSH | 11.3 | >1.060 | 3040 | 25.4 | >1.060 | 2819 |
| 5 | 0.5, F, DLH | 41.6 | 1.058 | 2442 | 41.6 | >1.060 | 3141 |
| 6 | 8, MC, DLH | 15.8 | 1.053 | 2260 | 37.0 | 1.054 | 2229 |
| 7 | 4, MC, DSH | 9.5† | 1.060 | 2825 | 16.2† | >1.060 | 2901 |
| 8 | 6, FS, DSH | 23.7 | 1.051 | 2206 | 44.1 | 1.051 | 2097 |
| 9 | 10, MC, DSH | 18.8† | 1.046 | 1977 | 14.8† | 1.057 | 2432 |
| 10 | 0.5, F, DSH | 38.0 | 1.054 | 2286 | 50.8 | >1.06 | 3231 |
| 11 | 0.5, F, DSH | 32.3 | >1.060 | 3105 | 28.7 | >1.06 | 2738 |
| 12 | 8, FS, Siamese | 26.9 | 1.052 | 2302 | 18.2 | >1.060 | 2502 |
| Mean | 22.9±10.2 (n=12) 23.3±10.6 (n=11) | 2468.9±367.3 | 31.6±13.5*(n=12) 33.1±13.1*(n=11) | 2537.7±440.8 |
All remaining cats received dry commercial diets.
MC=male, castrated; FS=female, spayed; F=female; DSH=domestic shorthair; DLH=domestic longhair.
Indicates statistically significant difference in mean water intake, P<0.05.
Fed dry commercial feline diet with canned diet added.
Three of 12 (25%) cat owners reported their cat played with its water bowl or the water in it and 5/12(42%) reported their cat played with the fountain or water in it. Ten of 12 (83%) cat owners concluded their cat liked the fountain, one was unsure, and one concluded their cat did not like the fountain.
Discussion
Offering water from a fountain led to greater water intake in cats when compared with water offered from a standard bowl. However, when urine osmolalities following these treatments were assessed, there was no significant difference, suggesting the accuracy of the intake volume from the fountain was falsely elevated. The difference in water intake became insignificant after exclusion of cat 2. One explanation for this discord in intake and urine osmolality could be that while eating dry food only, more water was ingested from the fountain and more water excreted in the feces rather than in the urine of this cat compared with when it was eating dry and moist food while drinking from the bowl. 9 Another possible explanation for the apparent increase in water intake from the fountain but lack of reduction in urine osmolality for the group as a whole could be that cats played with water in the fountain, more so than the bowl, and thus displaced water creating a falsely inflated water intake. In an attempt to account for this confounding factor absorbent pads were placed under the bowls and fountains the cats drank from and weighed before and after. It is possible that with the fountain some cats splashed water beyond the edges of the pads or that the fountain on its own splashes or that water evaporated from the absorbent pads prior to being weighed at the end of the intake period. The much greater amount of water that disappeared from or was retained within the control fountain (108 ml/day) compared with the bowl supports the latter two possibilities. Increased environmental temperature or exercise would increase water intake and result in more concentrated urine but this possibility seems unlikely in this population of cats as they were strictly indoors, the study was randomized and crossed-over, and this study was done at the same time of year in all cats. Similarly, because of the randomized cross-over design, water volume measurement errors by cat owners seem very unlikely. Regardless, the mean urine osmolality of 2537.7 mOsm/l obtained following the water fountain treatment is evidence the fountain did not induce enough water intake to cause substantial urine dilution. Individual variation did occur but even the lowest osmolality and specific gravity was only 1901 mOsm/l and 1.044, respectively. Urine specific gravity <1.020 is a commonly quoted therapeutic target for diluting urine for prevention of urolithiasis and clearly this was not met. 5 The fountain was not uniformly tolerated, as one cat developed aggression and vomiting directed at the fountain and refused to use it. Results of this study do not support replacing a cat's water bowl with a fountain to increase water intake and produce dilute urine. It would be interesting to determine the effect of providing a fountain in addition to a cat's usual bowl but currently this is unknown. While it seems plausible that some cats will drink more from a fountain, not a single cat in this study achieved the desired effect on urine concentration. It is important to note that there is only a single study which has shown that urine dilution, produced by feeding a canned diet, has been associated with reduced recurrence of a feline lower urinary tract disease, that being idiopathic cystitis. 4 In that study, other causes of lower urinary tract signs were not excluded as causes of recurrence for all cats. Additionally, after removal of a cat with urinary tract infection from the analysis, the recurrence rate was not significantly different for the canned versus dry food.
However, the results of this study suggest water fountains may provide a source of enjoyment for some cats. Most cat owners thought their cat liked the fountain and 42% observed them playing with the fountains. It has been proposed that stress and a sedentary lifestyle may play a role in the recurrence of idiopathic cystitis in cats. 10 Provision of activities for indoor cats as part of an uncontrolled multimodal approach to managing idiopathic cystitis resulted in resolution of stranguria, pollakiuria, and periuria. 10 Whether water fountains represent an adequate source of activity for cats is unknown.
The small population size is a limitation of this study. The power of the study to detect small but significant differences in water intake or urine dilution is likely low. However, the main goal of the treatments applied was to produce dilute urine, preferably a urine specific gravity ≤1.020, and this was not met in any cat under any treatment. Repetition of the study using more cats would be optimal to verify or nullify the results of this study. Additionally, similar studies utilizing various flavorings added to water would be interesting.
In summary, water fountains are unlikely to lead to substantial increase in water intake or dilution of urine in cats. However, this does not exclude the possibility of individual variation in preferences of cats for fountains or flavoring.
Acknowledgements
The author thanks Dr Stephen R. Were, PhD for statistical assistance. The author also thanks Mrs Stephanie Milburn, Ms Dana Calicott, and Ms Barbara Kafka for technical and organizational assistance. The author also thanks Veterinary Ventures for donation of the fountains used. Neither Veterinary Ventures nor any other party had any influence on the results of this study or were aware of the results of the study until after such time that it was accepted for publication. This study was funded by an Internal Research Competition Grant for the Virginia–Maryland Regional College of Veterinary Medicine.
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