Effects of Dietary Salt Intake on Renal Function: A 2‐Year Study in Healthy Aged Cats

Abstract

Background: Increasing salt intake to promote diuresis has been suggested in the management of feline lower urinary tract disease. However, high dietary salt intake might adversely affect blood pressure and renal function.Objectives: The objective of this study was to assess the long-term effects of increased salt intake on renal function in healthy aged cats.Methods: This study was controlled, randomized, and blinded. Twenty healthy neutered cats (10.1 AE 2.4 years) were randomly allocated into 2 matched groups. One group was fed a high salt diet (3.1 g/Mcal sodium, 5.5 g/Mcal chloride) and the other a control diet of same composition except for salt content (1.0 g/Mcal sodium, 2.2 g/Mcal chloride). Clinical examination, glomerular filtration rate, blood pressure measurement, cardiac and kidney ultrasonography, and urinary and blood tests were performed before and over 24 months after diet implementation. Statistics were performed using a general linear model.Results: Sixteen cats completed the 2 year study. The only variables affected by dietary salt intake were plasma aldosterone and urinary sodium/creatinine ratio, respectively, higher and lower in the control group all over the study period and urinary specific gravity, lower in the high salt diet group at 3 months.Conclusions and Clinical Importance: Glomerular filtration rate (GFR), blood pressure, and other routine clinical pathological variables in healthy aged cats were not affected by dietary salt content. The results of this 2 year study do not support the suggestion that chronic increases in dietary salt intake are harmful to renal function in older cats.

Plasma Renin Activity and Aldosterone Concentrations in Hypertensive Cats with and without Azotemia and in Response to Treatment with Amlodipine Besylate

“…Similar to hypertensive black patients, cats demonstrate a limited antihypertensive response to ACEi therapy, but respond well to calcium channel blockade 7, 12. However, studies that have investigated the effect of sodium intake on SBP and renal function in cats have not reported an association 36, 37, 38, 39. Additional work is warranted to evaluate salt sensitivity in naturally occurring hypertension in cats and the role of angiotensinogen in cats with variable BP and renal function.…”

Cardiovascular Effects of Dietary Salt Intake in Aged Healthy Cats: A 2-Year Prospective Randomized, Blinded, and Controlled Study

“…The present cardiovascular prospective study was performed concomitantly to another protocol, whose aim was to assess the effect of dietary salt intake on renal function using glomerular filtration rate (GFR) measurement, kidney ultrasonography, including renal resistive index assessment, and urinalysis [28]. Both inclusion and exclusion criteria used in the present study were identical to those of the latter protocol [28].…”

“…Both inclusion and exclusion criteria used in the present study were identical to those of the latter protocol [28]. Briefly, 26 Domestic Shorthair neutered aged cats (10.1±2.4 years [5.3–14.5], 4.8±0.7 kg [3.6–6.5]) from a research colony housed in an indoor research facility with a 12 h light/dark cycle, controlled temperature (18–21°C) and ventilation (250 m 3 /h, 12 h/day) were screened for suitability for entry to the study.…”

Consensus Recommendations for Standard Therapy of Glomerular Disease in Dogs

“…Although available evidence suggests that sodium restriction alone generally does not reduce BP, high salt intake may produce adverse consequences in some settings but not others . Although the BP of normal dogs is minimally affected by variations in NaCl intake, it is likely that dogs with kidney disease, particularly those with NS, are salt‐sensitive.…”