Associations between dietary factors in canned food and formation of calcium oxalate uroliths in dogs

OBJECTIVE: To identify dietary factors in commercially available canned foods associated with the development of calcium oxalate (CaOx) uroliths in dogs. ANIMALS: 117 dogs with CaOx uroliths and 174 dogs without urinary tract disease. PROCEDURE: Case dogs were those that developed CaOx uroliths submitted to the Minnesota Urolith Center for quantitative analysis between 1990 and 1992 while fed a commercially available canned diet. Control dogs were those without urinary tract disease evaluated at the same veterinary hospital just prior to or immediately after each case dog. A content-validated multiple-choice questionnaire was mailed to each owner of case and control dogs with the permission of the primary care veterinarian. Univariate and multivariate logistic regressions for each dietary component were performed to test the hypothesis that a given factor was associated with CaOx urolith formation. RESULTS: Canned foods with the highest amount of protein, fat, calcium, phosphorus, magnesium, sodium, potassium, chloride, or moisture were associated with a decreased risk of CaOx urolith formation, compared with diets with the lowest amounts. In contrast, canned diets with the highest amount of carbohydrate were associated with an increased risk of CaOx urolith formation. CONCLUSIONS AND CLINICAL RELEVANCE: Feeding canned diets formulated to contain high amounts of protein, fat, calcium, phosphorus, magnesium, sodium, potassium, chloride, and moisture and a low amount of carbohydrate may minimize the risk of CaOx urolith formation in dogs.     

Association between dietary factors and calcium oxalate and magnesium ammonium phosphate urolithiasis in cats.

OBJECTIVE: To identify dietary factors associated with the increase in occurrence of calcium oxalate (CaOx) uroliths and the decrease in occurrence of magnesium ammonium phosphate (MAP) uroliths in cats. DESIGN: Case-control study. ANIMALS: 173 cats with CaOx uroliths, 290 cats with MAP uroliths, and 827 cats without any urinary tract diseases. PROCEDURE: Univariate and multivariate logistic regression were performed. RESULTS: Cats fed diets low in sodium or potassium or formulated to maximize urine acidity had an increased risk of developing CaOx uroliths but a decreased risk of developing MAP uroliths. Additionally, compared with the lowest contents, diets with the highest moisture or protein contents and with moderate magnesium, phosphorus, or calcium contents were associated with decreased risk of CaOx urolith formation. In contrast, diets with moderate fat or carbohydrate contents were associated with increased risk of CaOx urolith formation. Diets with the highest magnesium, phosphorus, calcium, chloride, or fiber contents and moderate protein content were associated with increased risk of MAP urolith formation. On the other hand, diets with the highest fat content were associated with decreased risk of MAP urolith formation. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that diets formulated to contain higher protein, sodium, potassium, moisture, calcium, phosphorus, and magnesium contents and with decreased urine acidifying potential may minimize formation of CaOx uroliths in cats. Diets formulated to contain higher fat content and lower protein and potassium contents and with increased urine acidifying potential may minimize formation of MAP uroliths.     

Nutrient intake and urine composition in calcium oxalate stone-forming dogs: comparison with healthy dogs and impact of dietary modification

Nutrient intake and urine composition were analyzed in calcium oxalate (CaOx)stone-forming and healthy control dogs to identify factors that contribute to CaOx urolithiasis. Stone-forming dogs had significantly lower intake of sodium, calcium, potassium, and phosphorus and significantly higher urinary calcium and oxalate concentrations, calcium excretion, and CaOx relative supersaturation (RSS). Feeding a diet used in the treatment of canine lower urinary tract disease for 1 month was associated with increased intake of moisture, sodium, and fat; reduced intake of potassium and calcium; and decreased urinary calcium and oxalate concentrations, calcium excretion, and CaOx RSS. No clinical signs of disease recurrence were observed in the stone-forming dogs when the diet was fed for an additional 11 months. The results suggest that hypercalciuria and hyperoxaluria contribute to the formation of CaOx uroliths in dogs and show that dietary modifications can alter this process.     

The effect of urine acidification on calcium oxalate relative supersaturation in cats

There is an apparent reciprocal relationship between magnesium ammonium phosphate (MAP, struvite) and calcium oxalate (CaOx) urolithiasis incidence rate in cats. The number of struvite uroliths submitted for analysis over the past 35 years has been decreasing, with an increase in CaOx urolith submissions. Commercial diets aimed to dissolve struvite uroliths are typically acidified, and it has been suggested that dietary acidification increases urinary calcium excretion and the risk of CaOx crystallization. The objective of this study was to assess the effect of urine acidification on the relative supersaturation (RSS) of CaOx in cats, as a representation of crystallization risk. Four diets were extruded to contain identical nutrient contents, but with gradual acidification (0, 0.6, 1.3 and 1.9% sodium bisulphate substituted sodium chloride in diets A, B, C and D respectively). Thirteen adult cats were fed each diet sequentially for a minimum of 10 days. Average urine pH was 6.4, 6.2, 6.0 and 5.9 on diets A, B, C and D respectively (p < 0.0001). Struvite RSS decreased on diets inducing more acidic urine pH (p < 0.0001). Urinary calcium excretion and concentration increased with diets inducing lower urine pH (p < 0.0001), but oxalate excretion and concentration decreased (p < 0.001). CaOx RSS was not different between diets (p = 0.63). These results suggest that a lower diet base excess and resulting urine pH to support struvite dissolution do not increase the risk for CaOx crystallization in the range of urine pH representative of most commercial feline diets. Long-term studies are needed to confirm this.     

Urine metabolite values in fed and nonfed clinically normal beagles.

Twenty-four-hour excretion of urine metabolites was determined in 33 clinically normal Beagles during periods of consumption of a standard diet and when food was withheld. The goal was to determine normal canine values for urine analytes incriminated in the genesis of calcium oxalate uroliths. During periods when dogs consumed food, dairy urinary excretion of calcium, uric acid, sodium, potassium, magnesium, ammonium, and hydrogen ions were significantly (P = 0.0004, 0.0038, 0.001, 0.0001, 0.0004, 0.0001, and 0.024, respectively) higher than when food was withheld. Urinary excretion of phosphorus, oxalate, and citrate were not significantly different between samples obtained during periods of food consumption and when food was withheld. Male dogs excreted significantly higher quantities of urine oxalate than females during fed (P = 0.003) and nonfed (P = 0.003) conditions. When food was withheld, urinary uric acid excretion was significantly higher in males than females (P = 0.01). Females excreted significantly more urine calcium than males when food was withheld (P = 0.003). Our results indicated that dietary conditions influence the quantity of sodium, potassium, calcium, magnesium, and uric acid excreted in the urine of clinically normal dogs; therefore, dietary conditions should be considered when measuring the concentration of these analytes in urine.     

Effects of dietary supplementation with sodium chloride on urinary relative supersaturation with calcium oxalate in healthy dogs

OBJECTIVE: To evaluate the effect of dietary supplementation with sodium chloride (NaCl) on urinary calcium excretion, urine calcium concentration, and urinary relative supersaturation (RSS) with calcium oxalate (CaOx). ANIMALS: 6 adult female healthy Beagles. PROCEDURE: By use of a crossover study design, a canned diet designed to decrease CaOx urolith recurrence with and without supplemental NaCl (i.e., 1.2% and 0.24% sodium on a dry-matter basis, respectively) was fed to dogs for 6 weeks. Every 14 days, 24-hour urine samples were collected. Concentrations of lithogenic substances and urine pH were used to calculate values of urinary RSS with CaOx. RESULTS: When dogs consumed a diet supplemented with NaCl, 24-hour urine volume and 24-hour urine calcium excretion increased. Dietary supplementation with NaCl was not associated with a change in urine calcium concentration. However, urine oxalate acid concentrations and values of urinary RSS with CaOx were significantly lower after feeding the NaCI-supplemented diet for 28 days. CONCLUSIONS AND CLINICAL RELEVANCE: Dietary supplementation with NaCl in a urolith-prevention diet decreased the propensity for CaOx crystallization in the urine of healthy adult Beagles. However, until long-term studies evaluating the efficacy and safety of dietary supplementation with NaCl in dogs with CaOx urolithiasis are preformed, we suggest that dietary supplementation with NaCl be used cautiously.     

The relative effects of supplemental dietary calcium and oxalate on urine composition and calcium oxalate relative supersaturation in healthy adult dogs

The aim of this study was to establish the relative effects of dietary calcium and oxalate (in the form of oxalic acid) on the composition of urine produced by healthy adult Cairn Terriers and Miniature Schnauzers. A nutritionally complete dry dog food was fed to 7 dogs (4 Cairn terriers and 3 Miniature schnauzers) for 24 weeks. The dogs were fed the diet alone, or supplemented with six different combinations of dietary calcium (as carbonate and sulphate) and oxalate (as oxalic acid) commonly found in dry commercially prepared dog foods. Urine pH, volume, specific gravity, and concentrations of 12 analytes were measured for each dog; urinary relative supersaturation (RSS) with calcium oxalate (CaOx) was calculated from these values. The effects of supplemental calcium and oxalate were established using two-way analysis of variance and multiple range tests (least significant difference); P<0.05 was considered significant. The lowest level of dietary calcium and oxalate resulted in the lowest CaOx RSS. The high calcium, low oxalate diet resulted in the highest CaOx RSS, a low calcium diet with increased dietary oxalate also tended to increase CaOx RSS although results were highly variable. Urinary calcium concentration increased significantly with dietary calcium; urinary oxalate increased, although inconsistently, with dietary oxalic acid only when dietary calcium was low. Measures to reduce both calcium and oxalate should be considered when implementing dietary changes to reduce the risk of calcium oxalate formation in dogs. A reduction in dietary calcium without a concomitant decrease in dietary oxalate may increase the risk of CaOx crystallisation in susceptible dogs.     

Association between patient-related factors and risk of calcium oxalate and magnesium ammonium phosphate urolithiasis in cats

OBJECTIVE: To determine whether breed, age, sex, or reproductive status (i.e., neutered versus sexually intact) was associated with the apparent increase in prevalence of calcium oxalate (CaOx) uroliths and the decrease in prevalence of magnesium ammonium phosphate (MAP) uroliths in cats over time. DESIGN: Case-control study. ANIMALS: Case cats consisted of cats with CaOx (n = 7,895) or MAP (7,334) uroliths evaluated at the Minnesota Urolith Center between 1981 and 1997. Control cats consisted of cats without urinary tract disease admitted to veterinary teaching hospitals in the United States and Canada during the same period (150,482). PROCEDURE: Univariate and multivariate logistic regression were performed. RESULTS: British Shorthair, Exotic Shorthair, Foreign Shorthair, Havana Brown, Himalayan, Persian, Ragdoll, and Scottish Fold cats had an increased risk of developing CaOx uroliths, as did male cats and neutered cats. Chartreux, domestic shorthair, Foreign Shorthair, Himalayan, Oriental Shorthair, and Ragdoll cats had an increased risk of developing MAP uroliths, as did female cats and neutered cats. Cats with CaOx uroliths were significantly older than cats with MAP uroliths. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that changes in breed, age, sex, or reproductive status did not contribute to the apparent reciprocal relationship between prevalences of CaOx and MAP uroliths in cats during a 17-year period. However, cats of particular breeds, ages, sex, and reproductive status had an increased risk of developing CaOx and MAP uroliths.     

The effect of different dietary sodium levels on blood mineral concentrations and tibia mineralization in turkeys

The objective of this study was to determine the effect of different dietary levels of sodium in diets with and without sodium chloride on mineral metabolism, including blood electrolyte levels and tibia mineralization parameters, in young turkeys (to six weeks of age). The influence of diets with a low (L), medium (M) and high (H) sodium content, at 0.34, 1.34 and 2.82 g/kg respectively, was compared. The content of chloride and potassium in turkey diets (1.7 - 5.9 and 11 g/kg, respectively) was above the recommended levels. The sodium-deficient diet L decreased the serum concentrations of sodium, chloride and phosphorus, and it increased the serum levels of calcium and magnesium in turkeys, compared with groups M and H. Relative to group L, different dietary sodium levels in groups M and H contributed to a similar increase in the body weights of birds (1.06 vs. 1.46 and 1.44 kg, p < 0.001) and in the absolute (4.60 vs. 6.83 and 6.62 g, p < 0.001) and relative tibia weight (0.42 vs. 0.46 and 0.46% body weight, p = 0.031). No significant differences were found between groups with respect to the content of ash, calcium and phosphorus in tibia dry matter. Supplemental sodium increased the bone density index (from 50.6 to 68.4 and 66.3 mg/mm in groups L, M and H, respectively, p < 0.001), the maximum bending moment (from 5.27 to 7.40 and 7.33 N/mm, p = 0.002) and the minimum breaking strength of tibia (from 0.136 to 0.191 and 0.189, p = 0.002). In conclusion, our study indicates that the applied dietary treatment with a moderate sodium level (1.34 g/kg) resulted in a rate of bird growth and tibia mineralization similar to those observed with the treatment with much higher Na content (2.82 g/kg).     

Quantitative urinalysis in healthy Beagle puppies from 9 to 27 weeks of age

To evaluate indices of renal function in healthy, growing Beagle puppies from 9 to 27 weeks of age and to determine whether indices change with age during this period. Animals-6 healthy Beagle puppies. PROCEDURE: Urine collections were performed at 2-week intervals in puppies 9 to 27 weeks old. Daily excretion of urinary creatinine, protein, sodium, potassium, chloride, phosphorus, and calcium were determined, as were quantitative urinalyses including endogenous creatinine clearance, urine protein-to-creatinine ratios (UPr/C), and fractional clearances of sodium (FNa), potassium (FK), chloride (FCI), calcium (FCa), and phosphorus (FP). RESULTS: Significant differences among age groups were detected for endogenous creatinine clearance, and daily urinary protein, potassium, calcium, and phosphorus excretion. Significant differences also existed among age groups for UPr/C, FNa, FK, FCI and FP. Age-related effects fit a linear regression model for FNa, UPr/C, daily phosphorus excretion, and daily protein excretion. Quadratic regression models were judged most appropriate for endogenous creatinine clearance, FK, daily chloride excretion, and daily potassium excretion. Endogenous creatinine clearance measurements higher than adult reference ranges were observed from 9 to 21 weeks of age. The FNa, FK, FCI, FCa, and FP were slightly higher than those reported for adult dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Selected results of quantitative urinalyses in healthy 9- to 27-week-old Beagle puppies differ with age and differ from those measured in adult dogs. Diagnostic measurements performed in puppies of this age range should be compared with age-matched results when possible.     

Plasma and urine electrolyte and mineral concentrations in Thoroughbred horses with recurrent exertional rhabdomyolysis after consumption of diets varying in cation-anion balance

OBJECTIVE: To determine whether plasma, urine, and fecal electrolyte and mineral concentrations differ between clinically normal horses and Thoroughbreds with recurrent exertional rhabdomyolysis (RER) after consumption of diets varying in cation-anion balance. ANIMALS: 5 Thoroughbred mares with RER and 6 clinically normal mixed-breed mares. PROCEDURE: Each of 3 isocaloric diets designated as low, medium, and high on the basis of dietary cation-anion balance (DCAB) values of 85, 190, and 380, respectively, were fed to horses for 14 days. During the last 72 hours, 3 horses with RER and 3 control horses had daily urine and fecal samples obtained by total 24-hour collection. Remaining horses had urine samples collected daily by single catheterization. RESULTS: For each diet, no differences existed between horses with RER and control horses in plasma pH, electrolyte concentrations, and creatine kinase activity or in urine pH and renal fractional excretion (FE) values. Plasma pH, strong ion difference, bicarbonate and total carbon dioxide concentrations, and base excess decreased and plasma chloride and ionized calcium concentrations increased with decreasing DCAB. Urine pH decreased with decreasing DCAB. The FE of chloride and phosphorus were greatest for horses fed the low diet. The FE values for all electrolytes exept magnesium did not differ between urine samples obtained by single catheterization and total 24-hour collection. Daily balance of calcium, phosphorus, sodium, chloride, and potassium did not differ significantly among horses fed the various diets. CONCLUSIONS: In clinically normal horses and in horses with RER, the DCAB strongly affects plasma and urine pH and the FE of sodium, potassium, chloride, and phosphorus.     

Dietary magnesium and urolithiasis in growing calves

The effect of high levels of dietary magnesium (1.4%) alone or in combination with elevated calcium (1.8%) or phosphorus (1.6%) on growth and health of male calves was evaluated during a nine week feeding trial after weaning. Twenty calves were randomly divided into 4 feeding groups consisting of controls, high magnesium, high magnesium and calcium or high magnesium and phosphorus. Elevated dietary minerals caused decreased feed intake and growth rate. Blood urea nitrogen and serum creatinine levels were greatly elevated in calves fed high magnesium or magnesium and phosphorus and serum urea nitrogen was moderately elevated in calves fed high magnesium and calcium. These elevations suggested the occurrence of renal damage as a result of microcrystalline obstruction of renal tubules. Serum magnesium levels were three times normal in calves fed high magnesium or magnesium and phosphorus, but only twice normal in calves fed high magnesium and calcium. High dietary magnesium resulted in a significant depression in blood calcium level. This effect was somewhat overcome by additional dietary calcium Three calves fed the high magnesium diet and two calves fed the high magnesium and phosphorus diet developed urinary tract obstruction. The chemical composition of uroliths recovered from these calves was calcium apatite. Elevated dietary magnesium has been shown to be a cause of urolithiasis in growing male calves. Additional dietary calcium, but not phosphorus, appears to protect calves against urolithiasis induced by elevated dietary magnesium.     

Effect of dietary moisture and sodium content on urine composition and calcium oxalate relative supersaturation in healthy miniature schnauzers and labrador retrievers

The aim of this series of studies was to evaluate two possible feeding strategies as methods for reducing the risk of calcium oxalate (CaOx) formation in two breeds of healthy dog. The studies compared the effect of dietary moisture (Study 1) and dietary sodium (Na), (Study 2) on urine composition of labrador retrievers (LR) and miniature schnauzers (MS). A nutritionally complete dry dog food was fed to 16 dogs (eight LR, eight MS; Study 1) and 15 dogs (seven LR, eight MS; Study 2) for 24 days (Study 1), or 36 days (Study 2). The dogs were fed the diet alone (7% moisture, 0.06 g Na/100 kcal), or supplemented with deionised water to 73% moisture (Study 1), or dietary Na, to deliver 0.20 or 0.30 g Na per 100 kcal (Study 2). Urine pH, volume, specific gravity, and concentrations of 12 analytes were measured for each dog. Urinary relative supersaturations (RSS) with CaOx were calculated from these values. The effects of supplemental Na or water were established using t tests (Study 1) or analysis of variance, and multiple range tests (least significant difference) (Study 2); P<0.05 was considered significant. Increasing dietary moisture significantly increased total moisture intake (P=0.001), and reduced urine specific gravity (P=0.003), urinary oxalate concentration (P=0.04), and CaOx relative supersaturation (P=0.04) in the MS. Urinary parameters remained unchanged in the LR, indicating that feeding a high moisture diet may reduce the risk of CaOx formation in high-risk breeds. Increasing dietary Na led to production of urine with a significantly lower CaOx RSS in both breeds, indicating that sodium supplementation to dry diet formats may reduce the risk of CaOx formation. These feeding strategies should be considered when evaluating methods for preventing CaOx formation within high-risk groups.     

Effect of dietary cation-anion balance in mineral balance in anaerobically exercised and sedentary horses

Eight geldings and four mares were randomly assigned treatments within three 4x4 Latin square design experiments to study the effects of dietary cation-anion balance (DCAB) on mineral balance and dry matter digestibility in sedentary and anaerobically exercised horses. Four diets with an average DCAB (calculated as meq ((Na+K+) - Cl-)/kg of diet dry matter) of +24 (Low, L), +127 (Medium Low, ML), +227 (Medium High, MH) and +352 (High, H) were fed for a 21 day adjustment period followed by a 72 hour collection period. Diets consisted of a pelleted base concentrate of com, soybean meal and cottonseed hulls fed with either native prairie grass or bermuda grass hay in a 60:40 ratio. Diet L was formed by adding calcium chloride and ammonium chloride to the base concentrate, diet ML was formed by adding calcium chloride, and diet H was formed by adding potassium citrate and sodium bicarbonate. Diet MI-I received no supplementation and served as the control. Representative samples of feed, feces and urine were analyzed for mineral content and mineral balances were calculated by difference. Fecal output was greater (p <.05), and thus, dry matter digestibility was lower in exercised homes consuming diet L versus diet H. Sodium balance was greater (p <.05) in sedentary horses consuming diet MH as compared to those consuming diets ML and L Sodium balance was greater (p <.05) in exercised homes consuming diet H as compared to those consuming diets ML and L Potassium balance was greater (p <.05) in sedentary horses consuming diet H as compared to those horses consuming diet ML, however, potassium balance was not affected by DCAB in exercised horses. No significant differences were detected in chloride or magnesium balances in the sedentary horses, although chloride balance was greater (p <.05) and magnesium balance was lower (p <.05) in exercised homes consuming diet L as compared to all other diets. In sedentary homes, phosphorus balance was reflective of intake with differences (p <.05) observed between all treatments. However, in exercised homes, phosphorus balance was lower (p <.05) oniy for those consuming diet L. Calcium balance decreased significantly as DCAB decreased between all treatments in sedentary horses, while calcium balance in exercised homes was greater (p <.05) for homes consuming diet H as compared to those consum- ing diet L.Previous research from our laboratory has shown that both exercised and sedentary horses consuming diets with a low DCAB experience a nutritionally induced metabolic acidosis. The current data indicate that anaerobically exercised and sedentary horses consuming these diets excrete significantly more calcium in the urine resulting in decreased calcium balances. Prolonged consumption of diets with a low DCAB may lead to a significant demineralization of bone and a subsequent weakening of the skeleton.     

Comparison of volumetric urine collection versus single-sample urine collection in horses consuming diets varying in cation-anion balance

OBJECTIVE: To determine daily variation in urinary clearance and fractional excretion (FE) of electrolytes and minerals within and between horses and to compare volumetric and single-sample urine collection for determining FE values of diets with a range of dietary cation-anion balance (DCAB). ANIMALS: 5 Thoroughbred and 6 mixed-breed mares. PROCEDURE: 3 isocaloric diets with low, medium, and high DCAB values (85, 190, and 380 mEq/kg of dry matter, respectively) were each fed for 14 days. Daily blood samples, single urine samples collected by using a urinary catheter (5 mares), and volumetric urine collections (6 mares) were obtained during the last 72 hours of each diet. RESULTS: Urine and plasma pH values, plasma concentrations, and FE values of sodium, chloride, potassium, magnesium, phosphorus, and calcium were altered by varying the DCAB. Noticeable variation in clearance and FE values was detected within horses from day-to-day on the same diet as well as between horses. Fractional excretion values were not significantly different between single-sample and volumetric methods, except for magnesium in the high DCAB diet. Volumetric and single-sample collections revealed similar patterns of change in urinary FE values with varying DCAB, except for calcium and magnesium. CONCLUSIONS AND CLINICAL RELEVANCE: Substantial variation in clearance and FE of electrolytes and minerals are evident within horses between 24-hour periods as well as between horses fed a specific diet. Three daily urine samples provide similar information regarding dietary-induced changes in clearance and FE values (excluding calcium and magnesium) as that obtained by volumetric urine collection.     

Effect of excess dietary sodium, potassium, calcium and phosphorus on excreta moisture of laying hens

1. Four experiments were conducted to investigate the effects of dietary concentrations of sodium, potassium, calcium or phosphate on the water intake and excreta moisture of laying hens. A fifth experiment examined the effect on these variables of increasing amounts of 2 different sodium salts (chloride or bicarbonate) and the interactions with 2 levels of dietary phosphorus. 2. All experiments involved individually caged laying hens fed on diets varying in 1 or 2 minerals in replacement for washed sand. The experimental diets contained mineral concentrations that either met or exceeded the expected requirement of the hens. The diets were given for a 7 or 8 d feeding period and food and water intakes were measured and excreta were collected for the last 48 h of each feeding period. These data were corrected for evaporative water loss to the environment during the collection period. 3. Increasing dietary concentrations of sodium, potassium or phosphorus gave linear increases (P<0.001) in the water intake of the laying hens and linear increases (P<0.01) in the moisture content of their excreta. Each 1 g/kg increase in dietary mineral increased the moisture content of the excreta by 9.04 (+/- 1.57), 11.95 (+/- 2.02) and 5.59 (+/- 0.31) g/kg (+/- standard error) for sodium, potassium and phosphorus, respectively. Increasing concentrations of dietary calcium did not significantly affect the water intakes or excreta moisture levels of the laying hens. 4. The fifth experiment showed that, although there was a sodium x phosphorus interaction (P<0.05), the effects of the 2 mineral additions were approximately additive. There were no significant differences (P>0.05) in water intakes or excreta moisture contents due to the 2 different sodium salts (chloride or bicarbonate).     

Influence of prednisolone on urinary calcium oxalate and struvite relative supersaturation in healthy young adult female domestic shorthaired cats

Prednisolone (10 mg PO q24h) or placebo was administered to healthy cats for 2 weeks in a masked, placebo-controlled, crossover-design study, and 24-hour urine samples were collected. When cats received prednisolone, 24-hour urine pH was lower and 24-hour urine excretion of creatinine, magnesium, phosphate, and potassium was higher than when cats received placebo. No significant difference was found in urinary relative supersaturation for calcium oxalate (CaOx) or struvite between treatment groups. Prednisolone administration did not induce diuresis, nor was it associated with increased calcium excretion or urinary saturation for CaOx in these healthy cats. Results of this study, however, should not be extrapolated to cats that form CaOx uroliths associated with idiopathic hypercalcemia.     

日粮不同阴阳离子对45日龄肉鸡胫骨软骨发育不良和某些生化指标的影响

采用３６０只１日龄Ａｖｉａｎ公雏,研究日粮中添加相同毫克当量（１６ｍｅｑ／ｋｇ）的阴阳离子对４５日龄肉仔鸡胫骨软骨发育不良（ＴＤ）和血液某些生化指标的影响。阳离子分别为钙（１．１７％）、钠（０．５３％）、钾（１．５１％）和镁（０．３５％）;阴离子分别为氯（０．８３％）,磷（０．７２％）和硫（０．５７％）。结果表明：高氯、磷、硫均不同程度地诱发４５日龄肉鸡ＴＤ的发生（Ｐ＜０．０５）,而添加阳离子将ＴＤ的发生率降至零。以诱发ＴＤ发生率的能力为指标,磷离子＞氯离子＞硫离子。氯、磷离子显著降低了红细胞血红蛋白浓度（ＭＣＨＣ,Ｐ＜０．０５）,损害了血氧运输效率。阴阳离子对４５日龄肉鸡的血液、胫骨发育其它指标均没有显著性影响（Ｐ＞０．０５）。４５日龄肉鸡的血液酸碱平衡、血红蛋白、胫骨发育及体增重均出现代偿性变化,ＴＤ发生率也有下降的趋势。这说明肉鸡在生长后期（２１～４５日龄）对酸碱平衡的适应或调节能力增强。     

Clinicopathology of gout in growing layers induced by high calcium and high protein diets

1. An experiment was conducted to test the independent and combined effects of high dietary calcium and protein concentrations on the induction of visceral gout in growing birds of a layer strain. 2. One hundred and sixty healthy birds were randomly divided into 4 groups at 35 d of age. The different groups were given 4 diets containing normal or high concentrations of dietary calcium or crude protein in a 2 x 2 factorial experiment for 30 d. The diets contained normal calcium (Ca) and crude protein (CP) (NCNP, 8.5 g Ca/kg and 175g CP/kg), high calcium and normal protein (HC, 36.3 g Ca/kg and 175 g CP/kg), normal calcium and high protein (HP, 8.8 g Ca/kg and 245 g CP/kg) or high calcium and high protein (HCHP, 36.8 g Ca/kg and 242 g CP/kg), respectively. 3. Typical visceral gout was induced by the HCHP diet. The HCHP and HC diet caused severe kidney damage. The HP diet did not cause kidney damage, but significantly increased plasma uric acid and inorganic phosphorus concentrations. 4. The HC diet significantly increased plasma uric acid, calcium and sodium, but significantly decreased plasma inorganic phosphorus, potassium and magnesium concentrations. The HCHP diet significantly increased plasma uric acid, calcium and sodium. 5. Urine volumes were significantly higher on the HCHP and HC diets than on the control. The growers raised on HC and HCHP diets had significantly higher total quantity of 24 h urinary excretion of uric acid, calcium, magnesium, inorganic phosphorus and potassium and a significantly lower 24 h urinary excretion of sodium. The growers fed on the HP diet had a higher 24 h urinary excretion of uric acid and inorganic phosphorus than the control. 6. It is concluded that growing layer birds should not be fed on layer rations.     

Nutrient digestibility,but not mineral absorption,is age‐dependent in cats

Availability of nutrients is influenced by extremes of age, and a better characterization of this influence is necessary for appropriate development of foods and nutritional management throughout life stages of cats. This study investigated nutrient digestibility, mineral absorption, faeces and urine production in three groups of six young, mature and old cats fed two diets containing different energy densities. Apparent digestibility and mineral absorption were calculated by total collection method and values were tested with anova and regression analysis. A quadratic relationship was detected between age and digestibility of dry matter, organic matter, crude protein, acid‐hydrolysed fat and starch in the low‐energy diet. Starch digestibility showed the same response in the high‐energy diet. Young adult cats had intermediate digestibility, mature cats the highest and old cats the lowest. Mineral absorption (calcium, phosphorus, magnesium, sodium, potassium and chloride) and urinary pH were not different among groups. These findings confirm previous studies that found low digestibility of nutrients in some old cats, and support evidence that this trend is even more important in less digestible dry foods. On the contrary, data suggest that mineral formulations do not need to be varied in diets for adult cats of different ages.