Resistivity and pulsatility indexes in feline kidney disease: a systematic review

Long-term safety of dietary salt: A 5-year ProspEctive rAndomized bliNded and controlled stUdy in healThy aged cats (PEANUT study)

BACKGROUND

High-salt diets promote urine dilution and decrease urolithiasis risk.

OBJECTIVE

Prospectively evaluate the safety of chronic high dietary salt intake (randomized controlled trial).

ANIMALS

Twenty research colony neutered, healthy aged cats (11.5 years [10.0-11.6], median [interquartile range]).

METHODS

Healthy cats were randomized to control or high-salt dry diets (sodium: 1.02 ± 0.16 [mean, SD] and 3.26 ± 0.30 g/Mcal metabolizable energy [ME], respectively; chloride: 2.26 ± 0.33 and 5.71 ± 0.28 g/Mcal ME, respectively), fed for up to 60 months. Assessments included CBC, plasma biochemistry, urinalysis, glomerular filtration rate (GFR), blood pressure, renal and cardiac (conventional Doppler and 2-dimensional color tissue Doppler) imaging, annually. Cats that died or were euthanized underwent necropsy. Diet effects over time were evaluated with linear mixed models.

RESULTS

Follow-up duration (median [Interquartile range]) was similar between the control (38.7 months [28.6-48.2]) and high-salt group (51.4 months [45.7-59.0]). Diet had no significant effect on changes in GFR, blood pressure, plasma creatinine concentration, end-diastolic left ventricular (LV) wall thicknesses, LV internal diameters, LV systolic function, left atrial size, or systolic and diastolic Doppler variables. One control cat developed hypertension. One high-salt group cat developed persistent azotemia. Serial plasma biochemistry and urine specific gravity suggested early chronic kidney disease in 4 nonazotemic cats (2 per group), consistent with necropsy findings.

CONCLUSIONS AND CLINICAL IMPORTANCE

In healthy aged cats, a commercial veterinary diet containing 3.26 ± 0.30 g/Mcal ME sodium was safe with regard to renal and cardiac function for up to 5 years.

Evaluating feline lower urinary tract disease: Doppler ultrasound of the kidneys

OBJECTIVES

Ultrasonography is used in the evaluation of urinary disorders, and the resistivity index (RI) and pulsatility index (PI) have been successfully used to detect early hemodynamic changes in the course of kidney diseases in humans and dogs. The aim of this study was to investigate RI and PI in cats with feline lower urinary tract disease (FLUTD).

METHODS

Twenty-nine client-owned cats were selected and divided into a control group (CG; n = 10), a group of animals with obstructive FLUTD (OG; n = 11) and non-obstructive FLUTD (nOG; n = 8). Clinical, laboratory and ultrasound evaluations were performed in all cats.

RESULTS

RI and PI values for cats in the CG were below the upper limit of normal suggested in other studies, while cats with FLUTD showed significantly higher values in the assessment of RI (P = 0.027 and P = 0.034, respectively) and PI (P = 0.044 and P = 0.048, respectively) of the right and left kidneys.

CONCLUSIONS AND RELEVANCE

Alteration in renal blood flow was observed in cats with lower urinary tract disorders, even in the nOG group. To the best of our knowledge, this is the first report of renal blood flow changes related to non-obstructive FLUTD.