Diet Modulates Proteinuria in Heterozygous Female Dogs with X-Linked Hereditary Nephropathy

Abstract

Young adult heterozygous (carrier) female dogs with X-linked hereditary nephropathy (XLHN) have glomerular proteinuria but are otherwise healthy. Because data regarding dietary influences on the magnitude of proteinuria in dogs with spontaneous glomerular disease are not available, 12 such dogs were studied in a double crossover experiment intended to determine effects of altering dietary protein intake for up to 6 weeks. Dogs were blocked by urine protein : creatinine ratio (UPC) and randomly assigned to receive 2 diets: high protein (34.6% dry matter [DM], HP) or low protein (14.1% DM, LP) fed in HP-LP-HP or LP-HP-LP sequence. Food intake was measured daily, body weight (BW) was measured twice weekly, and UPC, plasma creatinine, blood urea nitrogen, phosphorus, albumin, and protein concentrations were measured at 2-week intervals. Nutrient digestibility was measured during the third treatment period. Diet had a significant effect (P < .0001) on all measured variables except plasma phosphorus (P > .5), but unintended differences in digestibility of protein and energy (P < or = .01) prevented assignment of the diet effect exclusively to protein. Proteinuria was greater (UPC 4.7 +/- 2.2 versus 1.8 +/- 1.1, P < .0001) when the HP diet was fed, but the LP diet did not maintain starting BW or plasma albumin concentration within the normal reference range. Diet greatly affects the magnitude of proteinuria in XLHN carrier females. Dietary protein restriction can reduce proteinuria in dogs with glomerular disease, but BW and blood protein concentrations may not be maintained if the restriction is too severe.

Evaluation of the Effects of a Therapeutic Renal Diet to Control Proteinuria in Proteinuric Non‐Azotemic Dogs Treated with Benazepril

“…Protein restriction is a common dietary modification in therapeutic RDs,22, 23, 24, 25 and can reduce proteinuria in dogs with glomerulopathies 20. However, if protein restriction is too severe (1.83 g of protein/100 kcal of digestible energy), protein malnutrition can occur 20.…”

“…. 1 Finally, non‐azotemic dogs with X‐LHN20 fed a diet with 6.02 g of digestible protein/100 kcal increased proteinuria, whereas diet with 1.83 g of digestible protein/100 kcal reduced it, but caused malnutrition. Dietary supplementation with omega‐3 PUFAs reduced proteinuria and prevented deterioration of glomerular filtration rate in remnant‐kidney model dogs,21 but the benefits of this supplementation in dogs with spontaneous proteinuria are not well documented.…”

“…These diets reduce the incidence of uremic crisis and mortality in dogs and cats with azotemic CKD compared with MDs 24, 25. Although RDs have been used in the management dogs with proteinuria,13, 19, 20 their possible benefits in the control of proteinuria in non‐azotemic dogs are unknown.…”

Day‐to‐Day Variation of the Urine Protein: Creatinine Ratio in Female Dogs with Stable Glomerular Proteinuria Caused by X‐Linked Hereditary Nephropathy

“…The study protocols were reviewed and approved by the Texas A&M University Laboratory Animal Care Committee, and results of the studies have been published 12 or reported at scientific meetings. a,b,c Magnitude of proteinuria was assessed in each dog by measuring the UPC once daily on each of the last 3 days of various periods during which the dog was maintained or treated in a specified manner.…”

“…12,a-c Twelve dogs were treated with a high-or low-protein diet, resulting in 84 3-day evaluation periods (252 UPC determinations) during the 14-week treatment period. 12 Six dogs were treated with prednisone (2.2 mg/kg PO q24h), resulting in 24 3-day evaluation periods (72 UPC determinations) during the 8-week treatment and posttreatment periods. c…”