Chronic kidney disease (CKD) predominantly affects middle-aged to aged cats. Feline experts stress the need for annual health screenings in high-risk populations (³ 7 years) as this promotes early diagnosis of the disease in asymptomatic cats and allows the initiation of proactive health care. However, studies on cats with nonazotemic CKD are scarce; simple and straightforward criteria for defining nonazotemic CKD are lacking and more sensitive tools to diagnose this population are needed.

Nonazotemic CKD is expected to be characterized by a mildly decreased Glomerular Filtration Rate (GFR) due to loss of functional kidney tissue which is provoked by diffuse/regional renal hypoxia and hypoperfusion, increased pro-inflammatory cytokines and renal fibrosis. The overall aim of this project is to redefine nonazotemic CKD to evaluate new, promising instruments to diagnose nonazotemic CKD.

This will be achieved with the following specific objectives:

(1) to validate and assess clinical applicability of Volumetric Absorptive Microsampling (VAMS) as an accessible, feline-friendly blood sampling technique in GFR estimation.

(2) to objectify the renal function of nonazotemic CKD cats by estimating GFR.

(3) to evaluate the ultrasonographic Shear Wave Elastography (SWE) and urinary levels of Transforming Growth Factor-b1 (TGF-b1) as early indicators of renal fibrosis in nonazotemic CKD cats.

This project will lead to an improved definition of nonazotemic CKD in cats, which will benefit annual screening of asymptomatic aged cats. Furthermore, this project will shed light on the potential of SWE and TGF-b1 as indicators of fibrotic changes associated with early renal function decline.