Nutrition and Urolithiasis in Dogs and Cats

Tony Buffington United States

Acute Management

First, relieve any urinary tract obstruction and re-establish urine flow, and correct fluid, electrolyte, and acid-base imbalances associated with obstruction and post-renal azotemia. The stone should be removed, if possible, and submitted for quantitative analysis. Struvite stones in dogs usually are associated with urease-positive urinary tract infection (usually Staphylococci), alkaline urine, struvite crystalluria, and a radiodense stone. All dogs with urolithiasis should have their urine cultured. If urinary tract infection is present, appropriate antibiotic therapy and careful follow-up should be instituted to ensure elimination of infection. Because of the primary role of urinary tract infection by urease-positive organisms in struvite urolithiasis of dogs, careful elimination of infection by appropriate antibiotic therapy and repeated patient follow-up to demonstrate eradication of infection are the most important aspects of medical management to prevent recurrence.

Nutritional Care

Breed predispositions in dogs and cats and results of human studies suggest that affected animals may be genetically predisposed to urolithiasis, making it more likely to be a nutrient-sensitive than a diet-induced disease. Reduce the urine specific gravity and increase the frequency of urination. This can be done by feeding canned food, adding water or other liquids to the patient’s usual diet, or by adding mineral salts to the diet. The aim is to reduce the urine specific gravity to < 1.020 or to double urine output. Patients must be allowed frequent opportunities to void to prevent bladder distension. Sodium chloride supplementation of the diet should be avoided in patients at risk of fluid retention or with oxalate and cystine urolithiasis, because natriuresis may cause hypercalciuria and may increase urinary excretion of cystine. In the interim between stone removal and return for suture removal (and evaluation of the stone composition if available), I ask owners to increase water intake until the urine is clear, colorless, and odorless, using the current diet if feasible. Comparison of the urinalysis of first morning urine with the stone composition determines if further diet change is necessary. In patients with recurrent stone disease in the presence of dilute, sterile urine of appropriate pH, change to a veterinary food may be indicated. Unfortunately, no published randomized controlled trials demonstrating the efficacy of any of these diets is available.

Dog Diets—Listed in alphabetical order of manufacturer

Cat Diets