INVESTIGATIONS ON STRUVITE DIETARY-TREATMENT .1. INFLUENCE OF FOOD RATIONS ON URINE PH IN THE CAT

In this investigation the base excess of cat foods (sum of alkalogenic compounds calcium, magnesium, sodium and potassium minus sum of acidi fying compounds phosphorus, chloride, methionine and cysteine; base ex cess in mmol/kg dry matter =Ca2+Mg*2+Na+K-(met+cys)*2-P*2-Cl) as a me thod of predicting the influence of food on the urinary pH was tested. The base excess and the effect on urinary pH (feeding experiment with 4 to 6 adult cats per trial) was determined in 10 commercial cat food s (3 moist, 3 dry type foods, 4 struvite diets) as well as the influen ce of several additives (CaCl2, CaCO3, Ca-lactate, CaHPO4, phosphoric acid in 2 doses, NH4Cl, ascorbic acid). After the intake of commercial cat foods the mean urine pH ranged between 6.58 and 7.89, after the i ntake of struvite diets it ranged between 6.36 and 7.57. The addition of Ca-carbonate or -lactate led to a significant increase of urine pH, Ca-phosphate and ascorbic acid had no effect, while Ca-Chloride, phos phoric acid and ammonium chloride led to a decrease. There was a highl y significant correlation between the base excess in the food (x; mmol /kg dry matter) and the mean urine pH (y; y = 6.72 + 0.0021 x; r = 0.9 6*).