Relationship between kidney ultrasound data and blood creatinine and urea levels in cats with autosomal dominant polycystic kidney disease

The results of studying the influence of structural changes in the kidneys on their filtration in cats with polycystic kidney disease are given. The study was conducted on 10 domestic cats, which were divided into two experimental groups based on the results of creatinine determination according to the IRIS (International Renal Interest Society) classification – 5 animals with moderate renal azotemia (group 1) and 5 animals with severe renal azotemia (group 2). Ultrasound examination of the kidneys of cats in both groups was performed using a Mindray device with a microconvection transducer with a frequency of 7.5–10 MHz in B-mode. Both kidneys were examined in each animal. Scanning was performed in the sagittal plane so that the kidney gate was visible. The length, width of the kidney, and thickness of the cortical layer, as well as the number of cysts and their diameter, were counted. The renal area (RA), cyst area (CA), and the ratio of cyst area to renal area (RA/Cyst) were calculated. According to the results of the study of serum creatinine and urea content, the animals were divided into two groups depending on the level of azotemia. 5 cats with stage III chronic renal failure (CRF), serum creatinine levels were 326.40 ± 23.59 μmol/l, and 5 animals with stage IV chronic renal failure serum creatinine – 887.00 ± 61.81 µmol/l, which is 2.7 times higher (P ≤ 0.001) than the creatinine level in cats with stage III CKD. The urea content in the serum was significantly increased compared to the norm and amounted to 22.82 ± 2.09 mol/l in cats with stage III CKD and 42.45 ± 1.05 mol/l in cats with stage IV CKD, which was 2.2 times higher (P ≤ 0.01) compared to stage III. In animals with polycystic kidney disease and stage IV chronic renal failure according to the results of ultrasound examination an increase in the length of the kidney by 6.5 mm (p≤0.001) and a thickening of the cortical layer by 0.8 mm (P ≤ 0.01) was revealed, compared to animals with polycystic kidney disease and stage III chronic renal failure. There was no correlation between the area of cysts in the kidneys and the level of creatinine in the blood serum of animals. Ultrasound signs of chronic renal failure in cats of stage III are enlargement of the kidney in the length of more than 51 mm and cortical thickness of more than 5.5 mm, of stage IV is an increase in kidney length of more than 59 mm and cortical thickness of more than 6.0 mm. According to the results of ultrasonography, the number of cysts or their area cannot be used to assess the degree of renal functional failure.