Investigations of kidney damage in cats with urolithiasis

In this master' s thesis project, possible kidney damage and loss of kidney function in cats with urolithiasis or crystalluria were investigated. Kidney diseases are quite common in cats, and this rate increases especially in cats fed at home with high protein foods. Urinary tract infections and urinary tract stones are common in these cats. Urinary system stones that are not diagnosed and treated early cause acute kidney damage (AKI) in the kidneys initially and irreversible chronic kidney damage (CKD) as it progresses. Criteria such as blood urea nitrogen (BUN), creatinine, glomerular filtration rate (GFR) and proteinuria are widely used to determine renal failure in animals. However, in cases where these parameters exceed the reference values, more than 70% of the nephrons become disabled, meaning the case becomes chronic and late. Acute kidney injury is reversible and therefore early diagnosis and treatment is of great importance. Therefore, in this study, kidney damage in cats was investigated using biomarkers that detect tubular damage and decrease in GFR earlier in cats with urolithiasis. In the study, 20 cats with urolithiasis and 10 clinically healthy cats were used. The cats included in the study were consisted of different ages, genders and breeds. Serum (s) and urine (u) samples were taken from these cats and biochemical analyzes were performed on these samples. According to the analysis results, 20 cats with urolitiasiz were equally divided into two groups: serum creatinine (sCr) values less than 2mg/dL (sCr<2) and greater (sCr>2). Cat-specific ELISA kits were used to measure symmetric dimethylarginine (SDMA), kidney injury molecule 1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) in serum and urine samples. As a result, significant increases in sSDMA, sKIM-1 and iSDMA, iKIM-1 and iNGAL values were determined in cats with urinary obstruction caused by urolithiasis. Increases in KIM-1 and NGAL values indicate that acute tubular damage develops in 55-70% of cats with urolithiasis. Increases in SDMA values show that GFR is negatively affected in 50-55% of cats with urolithiasis and that some of the cats are in the early stage of CKD (IRIS stage I-II). In the study, increases in KIM-1, NGAL and SDMA levels without increasing creatinine (Group sCr<2mg/dL) reveal that these markers are more sensitive than creatinine in detecting acute tubular damage and early CKD in cats with urolithiasis.