Effects of a high-protein diet versus dietary supplementation with ammonium chloride on struvite crystal formation in urine of clinically normal cats.
OBJECTIVE
To evaluate the effects of a high-protein diet versus dietary supplementation with ammonium chloride (NH4Cl) on struvite crystal formation in the urine of clinically normal cats by measuring the urine concentration of hydrochloric acid (HCl)-insoluble sediment, urine pH, struvite activity product (SAP), number of struvite crystals in urine, and urine volume.


METHODS
23 healthy adult cats.


METHODS
Urine was fractionated by centrifugation with subsequent extraction of the sediment with 1 N HCl (study 1). Diets containing either 29% crude protein or 55% crude protein were fed to cats in a crossover trial of 3 weeks/period (study 2). Diets supplemented with either sodium chloride (NaCl) or NH4Cl were fed, by use of a 3 x 3 Latin-square design with 3 wk/period (study 3). In studies 2 and 3, urine samples were collected for the last 7 days of each period.


RESULTS
The HCl-insoluble sediment contained Tamm-Horsfall glycoprotein (THP; study 1). The high-protein diet (study 2) and dietary supplementation with NH4Cl (study 3) resulted in a decrease in urine pH, SAP, and the number of struvite crystals in urine. However, the high-protein diet decreased urine concentrations of HCl-insoluble sediment containing THP (study 2), in contrast to the NH4Cl supplementation that increased urine volume without a significant effect on the urine concentration of the HCl-insoluble sediment (study 3).


CONCLUSIONS
Our results indicate that compared with dietary supplementation with NH4Cl, the high-protein diet is preferable as a urine acidifier for the prevention of struvite crystal formation in clinically normal cats.
Funaba
Masayuki
M
Laboratory of Nutrition, Azabu University School of Veterinary Medicine, 1-17-71 Fuchinobe, Sagamihara 229-8501, Japan.
Yamate
Takayo
T
Hashida
Yuka
Y
Maki
Kodenta
K
Gotoh
Ken
K
Kaneko
Masahiro
M
Yamamoto
Hiromi
H
Iriki
Tsunenori
T
Hatano
Yoshikazu
Y
Abe
Matanobu
M
D000643:Ammonium Chloride / Q000494:pharmacology*; D000821:Animal Feed; D000818:Animals; D002371:Cat Diseases / Q000517:prevention & control / Q000652:urine; D002415:Cats; D018592:Cross-Over Studies; D004044:Dietary Proteins / Q000494:pharmacology*; D019587:Dietary Supplements; D005260:Female; D006863:Hydrogen-Ion Concentration; D017616:Magnesium Compounds / Q000652:urine*; D008297:Male; D010710:Phosphates / Q000652:urine*; D000069877:Struvite; D014545:Urinary Calculi / Q000517:prevention & control / Q000652:urine / Q000662:veterinary
D004044:Dietary Proteins; D017616:Magnesium Compounds; D010710:Phosphates; D000643:Ammonium Chloride; D000069877:Struvite