Page 756 - Small Animal Clinical Nutrition 5th Edition

784 Small Animal Clinical Nutrition

VetBooks.ir Box 37-2. Nutritional Management of Patients with Proteinuria.

Previously, it was recommended to estimate urinary protein loss and
replace a similar amount by increasing dietary protein intake (e.g., treatment period 3 lasted 42 days. The groups were fed in HP-LP-
HP or LP-HP-LP sequence. Proteinuria, as indicated by UPC ratios,
supplementing with hard-boiled eggs) in patients with glomerular was significantly decreased whenever the LP food was fed vs. when
disease. This recommendation seemed prudent based on patho- the HP food was fed (UPC 1.8 ± 1.1 vs. 4.7 ± 2.2; [p <0.0001]).
physiologic rationale, but was not validated. Investigations in people However, an unexpected result was that the dogs lost body weight
and laboratory animals with protein-losing glomerulonephropathy when fed the LP food. Unfortunately, the energy content of the LP
indicate that reductions in dietary protein limit proteinuria and pre- food was approximately 13 to 14% lower than that of the HP food
serve serum albumin concentrations without impairing protein due to energy digestibility differences between the two foods that
nutriture. The advisability of replacing persistent, severe renal pro- were not determined until study completion. Whether or not the
tein loss has therefore been questioned. body weight loss was due to excessively low amounts of dietary
Two studies have evaluated the effects of limiting dietary protein protein or inadequate energy intake could not be determined.
intake in dogs with X-linked hereditary nephritis, a glomerular dis- On the basis of current evidence, dogs with protein-losing
ease that causes proteinuria. Male dogs have rapid progression of glomerulonephropathy should be fed reduced-protein foods
disease during the first year of life whereas females typically have designed for patients with kidney disease. Patients should be mon-
stable disease characterized by proteinuria that may progress to itored periodically (e.g., every two to four weeks initially) to deter-
advanced stages of CKD after five years of age. mine the optimal quantity of dietary protein. The food with reduced
In one study, effects of feeding a veterinary therapeutic renal levels of dietary protein should continue to be fed if the magnitude
a
food were evaluated in male and female dogs with X-linked hered- of proteinuria declines (as measured by UPC ratios) without sub-
itary nephritis. One group of dogs was fed the therapeutic food with stantial evidence of protein malnutrition (i.e., stable or increasing
reduced protein (13.5% dry matter [DM]), phosphorus and sodium serum albumin and total protein concentrations, stable body weight
and the other group was fed a maintenance food (23% DM protein). and body condition score). If evidence of protein malnutrition devel-
Onset and progression of kidney disease were delayed and severi- ops, dietary protein intake should be gradually increased in step-
ty of glomerular basement membrane splitting was reduced in wise fashion while closely monitoring the patient.
affected male dogs eating the commercial veterinary therapeutic Although proteinuria occurs in cats with CKD, glomerular disease
renal food. In addition, these dogs lived 53% longer (362 ± 17 days is infrequently diagnosed. Feeding a veterinary therapeutic renal
vs. 239 ± 14 days) than dogs fed the regular maintenance food. food may benefit cats with glomerular disease or proteinuria; how-
Effects of decreased dietary protein intake on proteinuria have ever, this has not been studied.
also been studied in female dogs with heterozygous X-linked hered-
itary nephropathy. Dogs were blocked by urine protein-creatinine ENDNOTES
(UPC) ratios and randomly assigned to receive either a high-protein a. Prescription Diet k/d Canine. Hill’s Pet Nutrition, Inc., Topeka, KS,
b
food (HP) (34.6% DM) or a veterinary therapeutic renal food with USA.
less protein (LP) (14.1% DM). Phosphorus, sodium, chloride and b. Purina Veterinary Diets NF KidNey Function Canine Formula.
potassium levels were essentially the same in both foods; the first Néstle Purina PetCare Co., St. Louis, MO. USA.
three of these nutrients were decreased, relative to typical amounts
in regular maintenance foods. The study was conducted using a The Bibliography for Box 37-2 can be found at
three-period double-crossover design in which each dog served as www.markmorris.org.
its own control. Treatment periods 1 and 2 lasted 28 days each and

erinary therapeutic renal food with decreased protein, before the was not associated with a significant effect on mortality com-
onset of azotemia, has beneficial effects in dogs with proteinuria pared with feeding a food containing 32% DM protein (Finco
(Valli et al, 1991; Burkholder et al, 2004) (Box 37-2). et al, 1992a). Some differences in treatment in addition to
Effects of decreased dietary protein intake have been studied nutritional management could have affected study outcome,
in dogs with induced CKD (Polzin et al, 1983; Finco et al, however (Box 37-1).
1992a). In a 40-week study, dogs were fed a commercial veteri- Two studies evaluated effects of dietary protein on progres-
d
nary therapeutic food containing 8.2% DM protein, a com- sion of induced CKD for one year in cats (Adams et al, 1993;
e
mercial food with 17.2% DM protein or a control food with Finco et al, 1998). In one study, renal function did not progres-
44.4% DM protein (Polzin et al, 1983). Feeding the lower pro- sively decrease, regardless of dietary protein amount and caloric
tein foods was associated with reduced mortality, serum urea intake (Adams et al, 1993). However, remnant kidneys of cats
nitrogen concentrations and clinical signs of uremia. with induced CKD that were fed a food containing 52% DM
Throughout the study, all dogs fed the highest protein food had protein had significantly more severe glomerular and tubuloin-
reduced physical activity and poorer hair quality compared with terstitial damage than cats with CKD that were fed a food con-
those parameters in dogs fed the lower protein foods. There taining 28% DM protein (Adams et al, 1993). Phosphorus
were other nutrient differences between foods, which may have amounts were similar between study groups (0.54% DM in the
contributed to the beneficial effects observed. In another study high-protein group and 0.61% DM in the low-protein group);
conducted for two years, reduced dietary protein (16% DM) however, cats in the high-protein group consumed significant-