title: Relevance of dietary protein concentration and quality as risk factors for the formation of calcium oxalate stones in cats.
abstract: The role of dietary protein for the development of feline calcium oxalate (CaOx) uroliths has not been conclusively clarified. The present study evaluated the effects of a varying dietary protein concentration and quality on critical indices for the formation of CaOx uroliths. Three diets with a high protein quality (10-11 % greaves meal/diet) and a varying crude protein (CP) concentration (35, 44 and 57 % in DM) were compared. Additionally, the 57 % CP diet was compared with a fourth diet that had a similar CP concentration (55 % in DM), but a lower protein quality (34 % greaves meal/diet). The Ca and oxalate (Ox) concentrations were similar in all diets. A group of eight cats received the same diet at the same time. Each feeding period was divided into a 21 d adaptation period and a 7 d sampling period to collect urine. There were increases in urinary volume, urinary Ca concentrations, renal Ca and Ox excretion and urinary relative supersaturation (RSS) with CaOx with increasing dietary protein concentrations. Urinary pH ranged between 6·34 and 6·66 among all groups, with no unidirectional effect of dietary protein. Lower renal Ca excretion was observed when feeding the diet with the lower protein quality, however, the underlying mechanism needs further evaluation. In conclusion, although the observed higher urinary volume is beneficial, the increase in urinary Ca concentrations, renal Ca and Ox excretion and urinary RSS CaOx associated with a high-protein diet may be critical for the development of CaOx uroliths in cats.
authors.affiliation: Institute of Animal Nutrition , Department of Veterinary Medicine , Freie Universität Berlin , Königin-Luise-Str. 49 , 14195 Berlin , Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Paßlack
authors.affiliation: Institute of Animal Nutrition , Department of Veterinary Medicine , Freie Universität Berlin , Königin-Luise-Str. 49 , 14195 Berlin , Germany.
authors.forename: Hannes
authors.initials: H
authors.lastname: Burmeier
authors.affiliation: Mars GmbH , Eitzer Straße 215 , 27283 Verden , Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Brenten
authors.affiliation: Institute of Biometry and Clinical Epidemiology , Charité - Universitätsmedizin Berlin , Hindenburgdamm 30 , 12203 Berlin , Germany.
authors.forename: Konrad
authors.initials: K
authors.lastname: Neumann
authors.affiliation: Institute of Animal Nutrition , Department of Veterinary Medicine , Freie Universität Berlin , Königin-Luise-Str. 49 , 14195 Berlin , Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Zentek
keywords: BW, body weight; CP, crude protien; CaOx, calcium oxalate; Cats; Dietary protein; HQ 35 %, high protein quality diet with 35 % CP content; HQ 44 %, high protein quality diet with 44 % CP content; HQ 57 %, high protein quality diet with 57 % CP content; LQ 55 %, low protein quality diet with 55 % CP content; Ox, oxalate; Protein quality; RSS, relative supersaturation; Renal calcium and oxalate excretion; Urinary pH