Effects of a high-protein diet versus dietary supplementation with ammonium chloride on struvite crystal formation in urine of clinically normal cats

Am J Vet Res. 2003 Aug;64(8):1059-64. doi: 10.2460/ajvr.2003.64.1059.

Abstract

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.

Animals: 23 healthy adult cats.

Procedure: 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 and clinical relevance: 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.

Publication types

  • Clinical Trial

MeSH terms

  • Ammonium Chloride / pharmacology*
  • Animal Feed
  • Animals
  • Cat Diseases / prevention & control
  • Cat Diseases / urine
  • Cats*
  • Cross-Over Studies
  • Dietary Proteins / pharmacology*
  • Dietary Supplements*
  • Female
  • Hydrogen-Ion Concentration
  • Magnesium Compounds / urine*
  • Male
  • Phosphates / urine*
  • Struvite
  • Urinary Calculi / prevention & control
  • Urinary Calculi / urine
  • Urinary Calculi / veterinary

Substances

  • Dietary Proteins
  • Magnesium Compounds
  • Phosphates
  • Ammonium Chloride
  • Struvite