Topical Area: Experimental Animal Nutrition
Evaluate the effects of renal disease and calcium oxalate stone formation in cats.
Methods : 42 cats were evaluated from one year of age to end of life (21 spayed females and 21 neutered males). There were three groups evaluated: 12 calcium oxalate stone forming cats (CaOx), 11 cats with renal disease (RD) and 19 healthy kidney cats (H). Their condition was defined during life or at the time of death. After death both bioarchive samples and historical data were analyzed. Analysis of serum (calcium, urea, and creatinine), urine (specific gravity) and body composition (lean, fat, bone mineral and bone mineral density) was accomplished. Dual Energy X-ray analysis was used to measure body composition. The Proc Mixed and Proc GLM program of SAS (9.4) was used for statistical analysis. A p value less than or equal to 0.05 was used as a cutoff for statistical significance.
Results : At the time of death circulating symmetric dimethyl arginine (SDMA) concentration was 11.0a, 45.5c and 27.4b ug/dl for H, RD and CaOx respectively. Lean body mass was 3.5a, 2.8b and 3.4a kg (H, RD and CaOx respectively). Body lean was significantly correlated (P< 0.01) with bone mineral content and creatinine, however there was no lean by group interaction. Creatinine concentration was influenced by body lean, before accounting for lean change it was 1.0a, 6.0b and 3.0c mg/dl and after adjustment for body lean was 0.7a, 6.7b, and 2.9c mg/dl (H, RD and CaOx respectively). Bone mineral content was 125a, 133a,b and 140b grams (H, RD and CaOx respectively using lean as a covariant). There was a differential effect of age on circulating calcium and phosphorus concentration. As cats aged both the RD and CaOx groups had increasing calcium concentration with increasing age in comparison to H, The CaOx group had increased calcium and phosphorus when compared to both RD and H.
These data show that SDMA has the advantage of not being influenced by lean body mass (as contrasted to creatinine). The data also leads to the conclusion that nutritional intervention in support of oxalate stone forming cats should include support for appropriate calcium phosphorus homeostasis while nutritional support for cats with renal disease should include optimum support of lean body mass.
Funding Sources :
This study was funded by Hill's Pet Nutrition, Inc.