Macrominerals and urine pH
Effect of Various Acidifying Agents on urine pH and Acid-Base Balance in Adult Cats12 JULIA V. IZQUIERDO3 AND GAIL L. CZARNECKI-MAULDEN* Department
of Animal Sciences,
University of Illinois, Urbana, IL 61801 EXPANDED
ABSTRACT
Indexing Key Words:
periment 3) and 0%, 1.88%, 3.67%, 5.64%, or 7.52% glutamic acid-HCl (Experiment 4). Levels of ammo nium chloride, calcium chloride and glutamic acid • HC1 were isochloride. Diets were fed ad libitum for 2 weeks and feed intake was measured daily. Urine pH, blood pH, blood ionized calcium and blood bi carbonate were measured at the end of the 2-week test period. The urine pH data were analyzed using a brokenline model (ammonium chloride and glutamic acid • HC1) or simple linear regression (calcium chlo ride) to generate the equations used to calculate the amount of each compound that would need to be added to the basal diet to produce a urine pH of 6.4. The urine pH data from phosphoric acid were not suitable for broken-line (breakpoint) or simple linear regression. A urine pH of 6.4 was chosen as desirable because it is between the highest pH at which struvite is known to dissolve (pH 6.6) and the pH that may cause chronic metabolic acidosis and negative calcium and potassium balance (pH 5.8-6.0) (3). Thus, a diet that induces a urinary pH of 6.4 should prevent pre cipitation of struvite crystals without causing meta bolic alterations. The urine pH of cats fed the unsupplemented diet was 6.87 ±0.05. All four of the compounds examined effectively lowered urine pH in adult cats (Table 1). The lowest inclusion level of phosphoric acid (0.17%) decreased urine pH to 6.4. Further increases of phos-
•symposium •cats •feline urologie syndrome struuite uroliths
Urinary acidifiers are often included in the treat ment and prevention programs of cats afflicted with Feline Urologie Syndrome (FUS). Production of an acidic urine is an effective method of dissolving and preventing recurrence of the struvite uroliths that are a major cause of the clinical signs associated with FUS (1,2). Theoretically, any compound that results in the absorption or production of hydrogen ions should produce acidic urine. However, prolonged production of an acidic urine can create disturbances in acid-base balance and mineral metabolism (3). Experiments were conducted to determine the uri nary acidification potential of phosphoric acid, calcium chloride and glutamic acid • HC1 and to determine if feeding ammonium chloride at levels lower than cur rently recommended (1.5% of the diet or 0.8 g/d) would effectively lower urine pH without producing disturbances in acid-base balance. The data generated from these experiments were then used to calculate an estimate of the minimum amount that a particular compound would need to be included in a diet to ef fectively lower the urine pH of cats to 6.4. Graded levels of each compound were added post processing to commercially prepared poultry by-prod uct meal-based dry cat food (Farmland Industries, Kansas City, MO) containing 35% crude protein, 21.5% crude fat and 12% moisture. Each experiment was designed as a randomized complete block with four normal adult cats per treatment. Levels of inclu sion were 0%, 0.55%, 1.10%, 1.65%, or 2.20% am monium chloride (Experiment 1), 0%, 0.17%, 0.34%, 0.51%, or 0.68% phosphoric acid (Experiment 2), 0%, 0.57%, 1.14%, 1.71%, or 2.28% calcium chloride (Ex 0022-3166/91
S3.00 ©1991 American Institute of Nutrition.
1Presented as part of the Waltham International Symposium on Nutrition of Small Companion Animals, at University of California, Davis, CA 95616, on September 4-8, 1990. Guest editors for the symposium were James G. Morris, D'Ann C. Finley and Quinton R. Rogers. 2 Partially supported by Farmland Industries,
Inc., Kansas City,
MO. 3 Current address Paris, France. 4 To whom correspondence should be addressed: Calreco Inc., 3916 Pettis Rd., St. Joseph, MO 64503.
J. Nutr. 121: S89-S90, 1991.
S89 Downloaded from https://academic.oup.com/jn/article-abstract/121/suppl_11/S89/4744084 by Tulane University Library, Serials Acquisitions Dept. user on 09 August 2018
S90
IZQUIERDO
AND CZARNECKI-MAULDEN TABLE 1
Effect of ammonium chloride, phosphoric acid, calcium chloride aadglutamic chloride5. Minimum urine pH2 minimize urine pH3 Dietary level needed Dietary level needed to produce a urine pHAmmonium of 6.43to
acid- HC1on urine plf
acid6.43
chloride5.94
88 ±0.20 ±0.14 1.10%'0.40%"Phosphoric 0.17%0.17%Calcium
acid-HCl5.92
±0.22 ±0.09 2.28%1.25%Glutamic 3.76%'1.52%b
1Values with the same superscript letter are isochloride. 1Values represent the mean minimum urine pH (±pooled SEM) achieved when each compound was fed to 4 cats for 14 days. 3Actual inclusion levels may be different for other basal diets which produce a higher or lower basal pH.
phoric acid supplementation resulted in no further decrease in urine pH. These results were unexpected. The ability of a compound to lower urine pH was not correlated with a reduction in diet pH; for example, 7.52% glutamic acid • HC1 produced a diet pH of 3.65 and 2.20% ammonium chloride produced a diet pH of 5.38, but consumption of each diet produced the same urine pH (5.90). Therefore, when evaluating diets for urine acidifying potential, diet pH is irrelevant. Isochloride dietary levels of ammonium chloride and glutamic acid • HC1 had similar effects on urine pH. Because feed intake was decreased as much as 50% in cats fed calcium chloride, a higher dietary chloride concentration was necessary to achieve the same di etary chloride intake and thus minimize urine pH. Blood pH linearly decreased and blood ionized cal cium increased as level of ingestion of ammonium chloride increased (P < 0.05); both changes are signs of metabolic acidosis. However, blood bicarbonate was not affected by ingestion of ammonium chloride. In addition to decreasing blood pH, ingestion of glutamic acid • HC1 also decreased blood bicarbonate. Calcium chloride had no effect on blood pH but did increase blood ionized calcium and decrease blood bicarbonate. Therefore, some signs of metabolic acidosis were ob served in cats fed each of these three compounds, but not in cats consuming phosphoric acid. Whether os teoporosis would be produced in cats by long-term
Downloaded from https://academic.oup.com/jn/article-abstract/121/suppl_11/S89/4744084 by Tulane University Library, Serials Acquisitions Dept. user on 09 August 2018
consumption of these diets is not known. However, Ching, et al. (3)determined that feeding cats 1.5% am monium chloride for 6 months produced increased blood ionized calcium that was not responsive to parathyroid hormone concentrations. Since cats af flicted with FUS are usually fed diets to lower urine pH for a minimum of 3 months, and more often for the remainder of their lives, this change in ionized calcium could have a serious effect on bone function. It would be prudent, therefore, to avoid production of excessively low urine pH. Consequently, the cur rently recommended dose of 1.5% ammonium chlo ride appears to be too high for cats consuming the basal diets fed by us and by Ching, et al. (3).
LITERATURE
CITED
1. OSBORNE,C. A., KRUGER,J. M., JOHNSTON,G. R., O'BRIEN, T. D., FLETCHER, T., POLZIN,D. J. & LULICH,J. P. (1987) Dis solution of feline uroliths with special emphasis on dietary modification. Companion Anim. Frac. 1(1): 89-98. 2. TATON,G. F., HAMAR,D. W. & LEWIS,L. D. (1984) Urinary acidification in the prevention and treatment of feline struvite uroliths. /. Am. Vet. Med. Assoc. 184(4): 437-443. 3. CHING,S. V., FETTMAN,M. J., HAMAR,D. W., NAGODE,L. A. & SMITH,K. A. (1989) The effect of chronic dietary acidification using ammonium chloride on acid-base balance and mineral metabolism in the adult cat. /. Nutr. 119: 902-915.
Effect of Various Acidifying Agents on urine pH and Acid-Base Balance in Adult Cats12 JULIA V. IZQUIERDO3 AND GAIL L. CZARNECKI-MAULDEN* Department
of Animal Sciences,
University of Illinois, Urbana, IL 61801 EXPANDED
ABSTRACT
Indexing Key Words:
periment 3) and 0%, 1.88%, 3.67%, 5.64%, or 7.52% glutamic acid-HCl (Experiment 4). Levels of ammo nium chloride, calcium chloride and glutamic acid • HC1 were isochloride. Diets were fed ad libitum for 2 weeks and feed intake was measured daily. Urine pH, blood pH, blood ionized calcium and blood bi carbonate were measured at the end of the 2-week test period. The urine pH data were analyzed using a brokenline model (ammonium chloride and glutamic acid • HC1) or simple linear regression (calcium chlo ride) to generate the equations used to calculate the amount of each compound that would need to be added to the basal diet to produce a urine pH of 6.4. The urine pH data from phosphoric acid were not suitable for broken-line (breakpoint) or simple linear regression. A urine pH of 6.4 was chosen as desirable because it is between the highest pH at which struvite is known to dissolve (pH 6.6) and the pH that may cause chronic metabolic acidosis and negative calcium and potassium balance (pH 5.8-6.0) (3). Thus, a diet that induces a urinary pH of 6.4 should prevent pre cipitation of struvite crystals without causing meta bolic alterations. The urine pH of cats fed the unsupplemented diet was 6.87 ±0.05. All four of the compounds examined effectively lowered urine pH in adult cats (Table 1). The lowest inclusion level of phosphoric acid (0.17%) decreased urine pH to 6.4. Further increases of phos-
•symposium •cats •feline urologie syndrome struuite uroliths
Urinary acidifiers are often included in the treat ment and prevention programs of cats afflicted with Feline Urologie Syndrome (FUS). Production of an acidic urine is an effective method of dissolving and preventing recurrence of the struvite uroliths that are a major cause of the clinical signs associated with FUS (1,2). Theoretically, any compound that results in the absorption or production of hydrogen ions should produce acidic urine. However, prolonged production of an acidic urine can create disturbances in acid-base balance and mineral metabolism (3). Experiments were conducted to determine the uri nary acidification potential of phosphoric acid, calcium chloride and glutamic acid • HC1 and to determine if feeding ammonium chloride at levels lower than cur rently recommended (1.5% of the diet or 0.8 g/d) would effectively lower urine pH without producing disturbances in acid-base balance. The data generated from these experiments were then used to calculate an estimate of the minimum amount that a particular compound would need to be included in a diet to ef fectively lower the urine pH of cats to 6.4. Graded levels of each compound were added post processing to commercially prepared poultry by-prod uct meal-based dry cat food (Farmland Industries, Kansas City, MO) containing 35% crude protein, 21.5% crude fat and 12% moisture. Each experiment was designed as a randomized complete block with four normal adult cats per treatment. Levels of inclu sion were 0%, 0.55%, 1.10%, 1.65%, or 2.20% am monium chloride (Experiment 1), 0%, 0.17%, 0.34%, 0.51%, or 0.68% phosphoric acid (Experiment 2), 0%, 0.57%, 1.14%, 1.71%, or 2.28% calcium chloride (Ex 0022-3166/91
S3.00 ©1991 American Institute of Nutrition.
1Presented as part of the Waltham International Symposium on Nutrition of Small Companion Animals, at University of California, Davis, CA 95616, on September 4-8, 1990. Guest editors for the symposium were James G. Morris, D'Ann C. Finley and Quinton R. Rogers. 2 Partially supported by Farmland Industries,
Inc., Kansas City,
MO. 3 Current address Paris, France. 4 To whom correspondence should be addressed: Calreco Inc., 3916 Pettis Rd., St. Joseph, MO 64503.
J. Nutr. 121: S89-S90, 1991.
S89 Downloaded from https://academic.oup.com/jn/article-abstract/121/suppl_11/S89/4744084 by Tulane University Library, Serials Acquisitions Dept. user on 09 August 2018
S90
IZQUIERDO
AND CZARNECKI-MAULDEN TABLE 1
Effect of ammonium chloride, phosphoric acid, calcium chloride aadglutamic chloride5. Minimum urine pH2 minimize urine pH3 Dietary level needed Dietary level needed to produce a urine pHAmmonium of 6.43to
acid- HC1on urine plf
acid6.43
chloride5.94
88 ±0.20 ±0.14 1.10%'0.40%"Phosphoric 0.17%0.17%Calcium
acid-HCl5.92
±0.22 ±0.09 2.28%1.25%Glutamic 3.76%'1.52%b
1Values with the same superscript letter are isochloride. 1Values represent the mean minimum urine pH (±pooled SEM) achieved when each compound was fed to 4 cats for 14 days. 3Actual inclusion levels may be different for other basal diets which produce a higher or lower basal pH.
phoric acid supplementation resulted in no further decrease in urine pH. These results were unexpected. The ability of a compound to lower urine pH was not correlated with a reduction in diet pH; for example, 7.52% glutamic acid • HC1 produced a diet pH of 3.65 and 2.20% ammonium chloride produced a diet pH of 5.38, but consumption of each diet produced the same urine pH (5.90). Therefore, when evaluating diets for urine acidifying potential, diet pH is irrelevant. Isochloride dietary levels of ammonium chloride and glutamic acid • HC1 had similar effects on urine pH. Because feed intake was decreased as much as 50% in cats fed calcium chloride, a higher dietary chloride concentration was necessary to achieve the same di etary chloride intake and thus minimize urine pH. Blood pH linearly decreased and blood ionized cal cium increased as level of ingestion of ammonium chloride increased (P < 0.05); both changes are signs of metabolic acidosis. However, blood bicarbonate was not affected by ingestion of ammonium chloride. In addition to decreasing blood pH, ingestion of glutamic acid • HC1 also decreased blood bicarbonate. Calcium chloride had no effect on blood pH but did increase blood ionized calcium and decrease blood bicarbonate. Therefore, some signs of metabolic acidosis were ob served in cats fed each of these three compounds, but not in cats consuming phosphoric acid. Whether os teoporosis would be produced in cats by long-term
Downloaded from https://academic.oup.com/jn/article-abstract/121/suppl_11/S89/4744084 by Tulane University Library, Serials Acquisitions Dept. user on 09 August 2018
consumption of these diets is not known. However, Ching, et al. (3)determined that feeding cats 1.5% am monium chloride for 6 months produced increased blood ionized calcium that was not responsive to parathyroid hormone concentrations. Since cats af flicted with FUS are usually fed diets to lower urine pH for a minimum of 3 months, and more often for the remainder of their lives, this change in ionized calcium could have a serious effect on bone function. It would be prudent, therefore, to avoid production of excessively low urine pH. Consequently, the cur rently recommended dose of 1.5% ammonium chlo ride appears to be too high for cats consuming the basal diets fed by us and by Ching, et al. (3).
LITERATURE
CITED
1. OSBORNE,C. A., KRUGER,J. M., JOHNSTON,G. R., O'BRIEN, T. D., FLETCHER, T., POLZIN,D. J. & LULICH,J. P. (1987) Dis solution of feline uroliths with special emphasis on dietary modification. Companion Anim. Frac. 1(1): 89-98. 2. TATON,G. F., HAMAR,D. W. & LEWIS,L. D. (1984) Urinary acidification in the prevention and treatment of feline struvite uroliths. /. Am. Vet. Med. Assoc. 184(4): 437-443. 3. CHING,S. V., FETTMAN,M. J., HAMAR,D. W., NAGODE,L. A. & SMITH,K. A. (1989) The effect of chronic dietary acidification using ammonium chloride on acid-base balance and mineral metabolism in the adult cat. /. Nutr. 119: 902-915.
