Factors contributing to the variation in feline urinary oxalate excretion rate1

Abstract

This study aimed to identify factors (season, animal, and diet) contributing to the variation in urinary oxalate (Uox) excretion rate, Uox concentration, and urine volume in healthy adult cats. A data set (1,940 observations) containing information on Uox excretion rate of 65 cats fed 252 diets (i.e., each diet was fed to a group of 6 to 8 cats), with known dietary oxalate concentrations, collected over a 6 yr period at a feline nutrition facility, were retrospectively analyzed. Data related to season, animal (i.e., age, gender, body weight, and breed), and diet (i.e., nutrient content) characteristics were subjected to stepwise multivariate regression analysis to identify factors significantly correlated to Uox excretion rate (μmol/(kg BW 0.67 ·d)) and concentration (mmol/L) as well as urine volume (mL/(kg BW 0.67 ·d)). Independent factors significantly (P < 0.05) associated with lower Uox concentration (mmol/L) included greater ash, Ca, and Na intake and lower nitrogen-free extract, total dietary fiber, P, and oxalate intake, and a body weight <5 kg. Factors significantly associated with lower Uox excretion rate (μmol/(kg BW 0.67 ·d)) included greater crude fat and Ca intake and lower CP, total dietary fiber, P, and oxalate intake. However, a considerable part of the variation in Uox excretion rate remained unexplained. The majority of the unexplained variation in Uox excretion rate is likely to be related to factors involved in endogenous oxalate synthesis, as the majority of the dietary factors involved in intestinal oxalate absorption were included in the model. Apparent intestinal oxalate absorption was estimated to be 6.2% on average; however, much variation was present. Future research on Uox excretion rate in cats should focus on the influence of dietary protein sources, amino acid composition, vitamin C (that was not included in the present study), and variations in apparent intestinal oxalate absorption.

An imaging investigation of in situ uroliths in hospitalized cats in New Zealand and in the United States

“…For example, urinary calcium oxalate excretion in cats may be related to endogenous calcium oxalate synthesis rather than to dietary factors involved in oxalate absorption (Dijcker et al . ). In a study of feline lower urinary tract disease there was a higher occurrence of uroliths in indoor cats compared with outdoor cats (Dorsch et al .…”

The effect of urine acidification on calcium oxalate relative supersaturation in cats

“…In a study comparing diets with different macronutrient profiles and inducing different urine pH, urinary oxalate excretion was unaffected (Dijcker et al, 2012 ). A follow‐up study identified multiple factors contribute to variation of feline urinary oxalate excretion, but a considerable part of urinary oxalate excretion remained unexplained (Dijcker, Hagen‐Plantinga, Everts, et al, 2014 ). The observations in the current study might therefore be due to endogenous oxalate metabolism rather than a direct effect of diet acidifying properties.…”

Pathology and Epidemiology of Oxalate Nephrosis in Cheetahs

“…Nine of the 10 cheetahs with the highest average number of cortical tubules containing oxalate crystals were from North America (5 different institutions), and the remaining 1 was from a South African institution (24). Among the 10 southern African cheetahs with the highest number of crystals (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24), cheetahs from 1 institution were overrepresented (50%). The 4 cheetahs from 3 French institutions had an average number of cortical tubules containing crystals of 15 (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20).…”

“…However, evaluation of the fluid intake and protein, fat, collagen, feathers, calcium, magnesium, beet pulp, pyridoxine, ascorbic acid, and arachidonic acid levels in captive cheetah diets is needed as these factors can influence oxalate excretion. [17][18][19][20]22,32,33,46,60,71,84 Dietary calcium to oxalate ratios affect O. formigenes colonization of the intestine in rats, so this ratio may be important in cheetah diets. 43 Obesity and stress may contribute to oxalate nephrosis in humans, 54 and their roles in oxalate nephrosis may warrant further study since obesity may be present in underactive captive cheetahs and stress has been documented in captive animals.…”