Increasing concentrations of dietary (n-3) polyunsaturated fatty acids (PUFA), e.g., eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), relative to (n-6) FA, e.g., arachidonic acid (AA), have been shown to increase plasma concentrations of EPA and DHA and reduce AA concentrations. The purpose of this study was to investigate the effects of increasing dietary PUFA concentrations on urine characteristics. We have recently shown that lifespans of cats with non-obstructive kidney stones is shortened compared with control cats indicating a need to prevent stone formation and decrease the rate of chronic kidney disease progression.

Domestic short hair cats (n=12; mean age 5.6 y, range 2 to 9 y) were randomized into two groups and fed one of two diets for 56 d and then crossed over to the other diet for another 56 d. The protocol was reviewed and approved by the Institutional Animal Care and Use Committee, Hill's Pet Nutrition, Inc. For 30 d before study initiation, cats consumed a pretrial (control) food that contained 0.07% AA and no measurable EPA or DHA. After 30 d, cats were split into two groups. Group 1 continued eating control food for 56 d. Group 2 was fed test food for 56 d, which contained 0.16 % AA, and 0.27% EPA and DHA combined. After 56 d, Group 1 cats were fed test food and Group 2 cats were fed control food for another 56 d. Serum was analyzed for FA concentrations at baseline and after each feeding period. Concurrently, urine was analyzed for urine specific gravity (USG), calcium concentration, and relative super saturation for struvite crystals. In addition, a urine calcium oxalate titrimetric test (COTT) was performed.

After consuming test food, cats had increased (all p<0.01) plasma concentrations of AA (36%), EPA (352%) and DHA (200%) compared with cats consuming control food. In addition, urine from cats fed test food had decreased USG (p=0.04), decreased calcium concentration (p=0.03; -9%), decreased struvite super saturation (p=0.03; -51%) and enhanced titratability to added oxalate before forming calcium oxalate crystals (p=0.06; -26%). Resistance to oxalate crystal formation was negatively correlated with blood calcium concentration (r=0.41; p<0.01) and this relationship was unaffected by test food. However, feeding test food decreased USG, decreased urine calcium concentration, and increased resistance to oxalate crystal formation. These data show that there could be significant urinary tract benefit for cats, i.e., reduced urine stone formation, by increasing dietary AA, EPA and DHA.

Disclosures

Disclosures to report.
D.E. Jewell, J.A. Brockman, S. Davidson, J.L. MacLeay are all employees of Hill's Pet Nutrition, Inc. J.A. Hall has received grant money from Hill's Pet Nutrition, Inc.