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

We provide the following handouts to clients with pets with stone disease who request help to increase water intake or make a diet change. (Copyright 2001: The Ohio State University. Permission to use for patient care with attribution is granted)

Tips to help you help your pet change IT�S diet

The most important thing you can do to help avoid the formation of another stone is to increase your pet�s water intake. Increasing water intake, which will create dilute urine, has three benefits for you and your pet. First, it will reduce the concentration of stone-forming minerals in the urine. Second, by making your pet urinate more often, it reduces the time available for a stone to form. Finally, by reducing the risk of forming a new stone, we may be able to avoid the need to prescribe special diets and/or drug treatments.

Unfortunately, for many pets and owners feeding dry food is a long-standing custom that is not easy to change. Because of this, changing to canned or moistened food is not always easy or convenient at first. To help you and your pet make this important transition, we offer the following suggestions collected from clients and pets that have successfully made the change. If you find another way that works for you, tell us and we�ll add it to the list!

Advice for the pet:

1. Before starting to change diets, be sure that your pet is feeling better and eating it�s usual diet normally.

2. If your pet has food available all the time, start by changing its feeding schedule to meal feeding by only leaving food out for one hour, twice daily.

3. When the new feeding schedule is established, you are ready to introduce the new diet. Start by reducing the amount of regular food by 25% and replace with the new food. Complete the change over a period of one to two weeks by mixing the new diet in with the one your pet currently eats. As your pet begins to eat the new food, reduce the amount of the other diet as much as possible.

4. If canned foods are not acceptable to you or your pet, adding one cup of hot water per cup of dry food may be work as a substitute.

5. We have a variety of foods that may help your pet. Don�t hesitate to try a different food if your pet doesn�t like the first one you try.

6. Small quantities of flavoring agents can be mixed with these foods to make them more appealing; flavoring agents include meat drippings, and tuna, clam or salmon juice. If you want to try other flavors, please check with us first.

7. Feed in a quiet environment where the pet won�t be distracted.

8. You will be given advice on the minimum amount of food your pet should eat each day. If your pet doesn�t eat all its food every day, this may be normal. As long as no more than 10% of weight is lost, you should not be too concerned during the period of transition.

Advice for the client:

1. Start the change process during a period when you have fewer �outside distractions,� if possible, so you can monitor the change process.

2. Plan where to buy the new food, where you will store it in your house, how you will discard the used cans, etc., before you start. A few minutes of thoughtful planning may save hours of frustration trying to �get into� the new routine later.

3. If feeding is a time when you enjoy interacting with your pet, we can suggest some alternative activities for you to substitute, such as play, teaching tricks, walking, and other activities.

4. Consider other methods of increasing the animal�s water intake to help dilute the urine; some are described in the attached handout.

Increasing Water Intake

To help you help your pet sustain dilute urine, we offer the following ways to increase water intake. These tricks can be used by themselves, or in combinations. Please feel free to try the way(s) that are most appealing to you. If you find a way that works well that isn�t on the list, tell us!

1. Place water next to the food. Some animals prefer a full, shallow dish; others seem to like reaching down into a container. You can experiment here to find out what your pet likes best.

2. Offer distilled or bottled water.

3. Try a pet �fountain� that can be purchased from pet stores and magazines.

4. Buy a small aquarium pump and air stone to put bubbles in the pet�s water bowl.

5. Leave some water in the bottom of a sink, bathtub or shower. Putting a shallow bowl under a slow drip ensures a drink of fresh water whenever your pet wants one.

6. Make ice cubes out of meat or fish broth. You can bring the contents of a 6 oz can of tuna or salmon, or a cup of ground meat, to boil in two cups water, simmer for 10 minutes, and strain through cheesecloth into an ice tray. A broth cube in your pet�s water bowl will flavor it and increase water intake in some animals.

We don�t recommend salting the food because it can actually increase the risk that some kinds of stones will form. �Lite� salt however may be used. Unfortunately, most pets don�t like the taste of lite salt, so it must be given in capsules. We can tell if your pet is drinking enough by measuring the concentration of the urine. Please bring a sample of your pet�s urine (we�ll show you how to collect it!) with you to the next re-check so we can determine how well the treatment is working.