Page 933 - Small Animal Clinical Nutrition 5th Edition

Feline Lower Urinary Tract Diseases 965

Several commercially available foods have claims for struvite most likely to be done using dry food, and moist food is pre-
VetBooks.ir prevention; however, only one has been evaluated in cats with ferred for managing urolithiasis and FIC.
Based on information currently available, meal-feeding moist
urethral plugs. In a randomized, prospective study of cats with
food would seem to be best for most cats with struvite disease
urethral plugs, effectiveness of feeding this food was compared
with perineal urethrostomy alone and perineal urethrostomy because of increased water intake and reduced concentration of
f
plus the calculolytic food (Osborne et al, 1991). During the crystal-forming elements. However, less evidence supports this
one-year study, urethral obstruction was not observed in any benefit compared with cats that have calcium oxalate uroliths.
group. This study did not include an untreated control group; If meal feeding is associated with increased urinary pH
however, recurrence rates for urethral obstruction in two other throughout the day and significant struvite crystalluria or recur-
studies were 35 and 36% (Bovee et al, 1979; Gerber et al, 2007). rent uroliths or urethral plugs, another feeding method should
Bacterial UTI occurred in 40 to 50% of cats that had perineal be considered (e.g., feeding dry food or feeding multiple small
urethrostomies, but was not observed in cats managed by the meals of moist food).
calculolytic food alone. Several foods formulated for struvite
prevention have been evaluated by measuring values for struvite Reassessment
saturation in healthy cats (Bartges et al, 1998; Abood et al, Cats eating struvite preventive foods should be monitored peri-
2000; Devois et al, 2000; Xu et al, 2006). odically for evidence of crystalluria and urinary pH values. If no
Urinary tract health claims on pet food labels may be of some episodes of struvite uroliths occur for several years, it would be
help in evaluating foods (Box 46-8). In the U.S., a food with a appropriate to consider switching to a high-quality wellness
“low magnesium” claim contains a maximum of 0.12% DM food that maintains an appropriate urinary pH and avoids ex-
magnesium or 25 mg magnesium/100 kcal ME. cessive magnesium and phosphorus.
Depending on the amount fed, treats and other supplements
can significantly alter the key nutritional factor profile of the Feeding Plan for Calcium Oxalate Urolithiasis
desired dietary regimen and may decrease the effectiveness of Calcium oxalate uroliths are not amenable to medical dissolu-
appropriately formulated therapeutic foods. Some commercial tion and must be removed by surgery, voiding urohydropropul-
cat treats or foods, and processed human foods may have very sion, lithotripsy or other techniques. An alternative to cystoto-
high levels of magnesium or phosphorus and their effect on uri- my is voiding urohydropropulsion if urocystoliths are small
nary pH is hard to predict. Most pet owners give their pets enough to pass through the urethra (Lulich et al, 1993).Voiding
treats or supplement their pets’ primary food with other foods, urohydropropulsion is generally more successful in queens than
either another cat food or human food. Therefore, it is impor- in tomcats because the urethra is larger in females than in males.
tant for veterinary health care team members to educate own- Voiding urohydropropulsion is usually ineffective in cats with
ers about the importance of compliance to the successful out- uroliths lodged in the urethra. After urolith removal, medical
come.This is especially true for cats that are at risk for urethral protocols to minimize recurrence should be implemented.Goals
obstruction. Owners aware of the risks may be more willing to of nutritional management include decreasing urine calcium
avoid feeding other foods or products and encourage their cats and oxalate concentrations, promoting high concentrations of
only to eat the recommended therapeutic food. urolith inhibitors, decreasing urine acidity and decreasing urine
specific gravity (i.e., urine dilution).
Assess and Determine the Feeding Method
Cats should be transitioned gradually to a food formulated to Assess and Select the Food
decrease occurrence of struvite crystalluria.The method of feed- Several commercially available therapeutic foods are marketed
ing influences urinary pH values throughout the day and there- for prevention of calcium oxalate uroliths in cats. No foods have
fore may affect success of the dietary management protocol. In- been studied to determine if they prevent urolith recurrence
e
gestion of food stimulates secretion of acid by gastric parietal and only one food has been evaluated in cats with naturally
cells with subsequent secretion of bicarbonate into the blood in occurring calcium oxalate uroliths (Lulich et al, 2004). In a
exchange for chloride ions. This alkali load transiently increases study of 10 cats with confirmed calcium oxalate uroliths, uri-
urinary bicarbonate and pH (i.e., postprandial alkaline tide) un- nary calcium oxalate saturation was measured before beginning
less offset by absorption of acidifying ingredients.When offered the study and after feeding the therapeutic food. Using a cross-
food free choice, most cats will eat small amounts every few over design, half of the cats were randomly assigned to contin-
hours, resulting in a smaller but more prolonged alkaline tide ue their regular food and the other half were assigned to eat the
than with meal feeding (Figure 46-18) (Taton et al, 1984).The therapeutic food. After eight weeks, the foods were switched
smaller alkaline urinary pH excursions observed with free- and fed for another eight weeks. Urinary calcium oxalate satu-
choice feeding may reduce the likelihood of struvite precipitate ration values (i.e., activity product ratios and relative supersatu-
formation, and thus may be the preferred method of feeding to ration values) were determined and compared between groups
prevent struvite associated disease; however, this has not be con- (regular vs. therapeutic food). Results revealed that hypercalci-
firmed in clinical studies. Free-choice feeding may be associated uria was a consistent abnormality in urolith-forming cats and
with obesity;however,which in turn is a risk factor for lower uri- urinary calcium oxalate saturation was significantly lower in
nary tract diseases in general. In addition, free-choice feeding is cats fed the therapeutic food compared with regular food. This