Page 812 - Small Animal Clinical Nutrition 5th Edition

842 Small Animal Clinical Nutrition

altered in such dogs because biotransformation of this drug,
Box 39-1. Nutritional Adequacy of Low-
VetBooks.ir Protein Foods Recommended for Canine which has a very short half-life, to oxypurinol, which has a
longer half-life, requires adequate hepatic function (Osborne
Patients with Urolithiasis.
et al, 1986).
A commercial veterinary therapeutic food that reduces urine con- Immature Dogs with Urate Uroliths
centration, produces alkaline urine and avoids excess levels of Providing safe and effective therapy for urate uroliths in imma-
a
dietary protein, purines, calcium and phosphorus is frequently ture dogs presents a challenge. Formation of urate uroliths asso-
recommended for management of several different types of
canine uroliths. Some of these foods have very low protein con- ciated with portal vascular anomalies and their management are
tent (10 to 11% [dry matter, DM]). This level of dietary protein is discussed above.Growing dogs usually consume greater quanti-
a concern for some veterinarians and their health care teams ties of protein and, thus, greater quantities of purines than adult
because it is less than the recommended dietary allowance for dogs. The safety and efficacy of litholytic foods in young dogs
protein established by the Association of American Feed Control with urate uroliths are unknown. Adding non-purine-contain-
Officials (AAFCO) (minimum 18% DM for adult maintenance). ing protein to the litholytic food may be effective (Box 39-2);
However, based on several criteria, these foods are nutritional- however, no studies have yet been performed to confirm this
ly adequate for maintenance of adult, non-reproducing dogs. hypothesis. The metabolism of allopurinol in young dogs has
First, the National Research Council’s minimum recommended not been evaluated. Surgical removal of large uroliths remains
allowance for foods for maintenance of healthy adult dogs is 10% the option with the most predictable short-term outcome.
DM. Second, many of these veterinary therapeutic foods have
successfully completed AAFCO adult maintenance feeding trials Assess and Determine the Feeding Method:
(see product labels and published product information). In addi- Urate Urolith Dissolution
tion, protein digestibility in some of these low-protein foods
approaches 100%, which means their essential amino acids are Transitioning patients from their current food to a urate
readily available to dogs. The final criterion is practical experience litholytic food should be done gradually (i.e., over a period of a
with these foods; some have been used successfully for long- few days). Begin the transition by feeding 75% of the current
term feeding of thousands of canine patients with urolithiasis. food and 25% of the litholytic food on Day 1. On Day 2, feed
half of each food. On Day 3, feed 75% as the litholytic food. By
ENDNOTE Day 4 or 5, feed only the litholytic food.
a. Hill’s Prescription Diet u/d Canine dry. Hill’s Pet Nutrition, Inc., As discussed above, modification of urinary pH is a signifi-
Topeka, KS, USA. cant part of overall dietary management of urate urolithiasis.
Free-choice feeding is often associated with more persistent
The Bibliography for Box 39-1 can be found at
www.markmorris.org. aciduria compared to meal feeding. However, if moist foods are
fed, as is recommended, free-choice feeding can result in
spoilage if the food is left uneaten for several hours at room
occurred in a two-year-old female miniature schnauzer with a temperature (Chapter 11). Opened containers of moist foods
portal vascular anomaly. The dog was consuming a veterinary should be refrigerated and the feeding bowl should be kept
a
therapeutic food designed for treatment of renal failure. The clean. Ideally, moist foods should be meal fed several times per
mechanisms involved were presumably decreased production of day. If that is not possible, clients should meal feed moist food
ammonium ions from urea and reduced formation of uric acid as often as practical.
from dietary protein. Besides offering moist foods, there are several additional
Likewise, a nephrolith in the right renal pelvis of a seven- ways to facilitate increased water intake. These include: 1)
year-old female malamute with a portal vascular anomaly dis- Ensuring multiple water bowls are available in prominent loca-
appeared while the dog consumed the same veterinary thera- tions in the dog’s environment; this may mean providing sever-
a
peutic food designed for treatment of renal failure. A marked al bowls outside in a large enclosure or a bowl on each level of
reduction of urine uric acid concentration was observed in a the house. 2) Providing clean water bowls that are always filled
three-month-old female miniature schnauzer following surgi- with fresh water. 3) Offering ice cubes as treats or snacks. 4)
cal correction of an extrahepatic portacaval shunt. Furthermore, Adding liberal quantities of water to dry foods. However,
undersaturation of urine with ammonium urate and no recur- potential food safety issues might arise from leaving moistened
rence of urolith formation were observed in two dogs with sur- dry foods out for prolonged intervals (Chapter 11). Using small
gically uncorrectable portal vascular anomalies and ammonium amounts of salt-free bouillon as a flavoring substance in drink-
b
urate uroliths. The dogs were fed a urate litholytic food for ing water to encourage more water consumption is not recom-
prevention of recurrence of the uroliths and for management of mended for management of urate uroliths because meat
hepatic encephalopathy. extracts such as bouillon contain increased levels of purines
Additional clinical studies are needed to evaluate the rela- (Table 39-3).
tive value of litholytic foods, allopurinol and/or alkalinization If the patient has a normal body condition score (BCS 2.5/5
of urine in dissolving ammonium urate uroliths in dogs with to 3.5/5), the amount of food fed previously was probably
portal vascular anomalies. The efficacy of allopurinol may be appropriate. On an energy basis, a similar amount of the new