Page 868 - Small Animal Clinical Nutrition 5th Edition

Canine Struvite Urolithiasis 899

VetBooks.ir Table 43-5. Key nutritional factors in selected commercial veterinary therapeutic foods used for dissolution of struvite uroliths in dogs
compared to recommended levels.*
Dry foods
Recommended levels Protein (%) Phosphorus (%) Magnesium (%) Urinary pH**
≤8
5.9-6.1
<0.02
≤0.1
Royal Canin Veterinary Diet Control Formula 23.9 0.84 0.130 6.0-6.3
Royal Canin Veterinary Diet Urinary SO 14 17.0 0.63 0.066 5.5-6.0
Moist foods Protein (%) Phosphorus (%) Magnesium (%) Urinary pH**
Recommended levels ≤8 ≤0.1 <0.02 5.9-6.1
Hill’s Prescription Diet s/d Canine 7.9 0.10 0.024 5.935
Royal Canin Veterinary Diet Control Formula 22.8 0.66 0.078 6.0-6.3
Royal Canin Veterinary Diet Urinary SO 18.5 0.86 0.059 5.5-6.0
*Manufacturers’ published values; nutrients expressed on a dry matter basis; moist foods are best.
**Protocols for measuring urinary pH may vary.

Table 43-6. Characteristic clinical findings before and after initiation of dietary and medical therapy, or dietary therapy alone, to dissolve
struvite uroliths in nonazotemic dogs.*

Factors Pre-therapy During therapy After successful therapy**
Polyuria ± 1+ to 3+ Negative
Pollakiuria 1+ to 4+ Transient ↑; subsequent ↓ Negative
Gross hematuria 0 to 4+ ↓ by 5 to 10 days Negative
Abnormal urine odor 0 to 4+ ↓ by 5 to 10 days Negative
Small uroliths voided ± Common in females Negative
Urine specific gravity Variable 1.004 to 1.014 Normal
Urinary pH ≥7 Decreased (usually acidic) Variable
Urine protein 1+ to 4+ Decreased to absent Negative
Urine RBC 1+ to 4+ Decreased to absent Negative
Urine WBC 1+ to 4+ Decreased to absent Negative
Struvite crystals 0 to 4+ Usually absent Variable
Other crystals Variable May persist May persist
Bacteriuria 0 to 4+ Decreased to absent Negative
Quantitative bacterial urine culture 0 to 4+ Decreased to absent Negative
Serum urea nitrogen >15 mg/dl <10 mg/dl Dependent on food
Serum creatinine Normal Normal Normal
Serum alkaline phosphatase Normal ↑ by 2 to 5 times Normal
Serum albumin Normal ↓ by 0.5 to 1 g/dl Normal
Serum phosphorus Normal Slight decrease Normal
Urolith size (radiographic) Small to large Progressive decrease Negative
Hemogram Normal Normal Normal

*For dogs with urinary tract infection, therapy consists of a litholytic food and antimicrobial agents. For dogs without urinary tract
infection, therapy consists of a litholytic food.
**All forms of therapy withdrawn.

body condition, serum albumin concentration and packed AZOTEMIC PRIMARY RENAL FAILURE
cell volume for evidence of protein-calorie malnutrition Complete obstruction of urine outflow caused by uroliths in
should be considered. Adjustments in dietary management patients with a concomitant UTI should be regarded as an
should be made if marked reductions in these variables are emergency. In this situation, a combination of obstruction and
observed. The urocystoliths may be removed by voiding uro- pyelonephritis caused by a rapid spread of infection throughout
hydropropulsion (Figure 38-5 and Table 38-7) or lithotripsy, the kidneys is likely to induce acute renal failure and then sep-
if their size has been reduced enough to permit their passage ticemia. Dietary dissolution of struvite uroliths located in the
pass through a distended urethra (Lulich et al, 1993). upper urinary tract should not be considered until adequate
urine flow has been restored, and life-threatening deficits and
ABNORMAL FLUID RETENTION excesses in fluid, electrolyte, acid-base and endocrine balance
Properly formulated struvite litholytic foods are restricted in have been corrected.
protein and supplemented with sodium chloride. Both could Nonobstructing struvite nephroliths have been dissolved in
affect fluid balance. Therefore, the food should not be rou- patients with nonazotemic renal failure caused by ascending
tinely fed to patients with comorbid diseases associated with pyelonephritis (Osborne et al, 1985, 1986). But, protein-re-
positive fluid balance (e.g., heart failure, nephrotic syndrome) stricted litholytic foods should be used with caution in patients
or hypertension. with azotemic primary renal failure. Such foods may induce