investigation of the prevalence and clinical significance of the medullary rim sign on renal ultrasound in cats

Objective: This study aimed to investigate the prevalence of the medullary rim sign (MRS) in the kidneys of cats undergoing ultrasonographic examination, to determine whether MRS is associated with any specific final diagnosis, and thereby to assess its clinical significance in feline patients. Materials and Methods: The animal material of the study consisted of 100 cats of different ages, breeds and both sexes brought to Aydın Adnan Menderes University, Faculty of Veterinary Medicine, Research and Practice Hospital Polyclinics due to various complaints from Aydın and surrounding provinces and subjected to abdominal ultrasonography. The presence of MCI, its form (line or band), and lateralisation were evaluated using ultrasonographic examination. Haematological and biochemical analyses were performed to identify the current health issues of the cats. The cats were divided into two groups: MRSpositive (+) and MRS-negative (-). The data were analysed using SPSS 25.0 software. Results: Ultrasound evaluation of the kidneys in 100 cats revealed that 5 cats (all bilateral and band form) had MRS, resulting in a prevalence of 5%. No statistically significant associations were found between MRS presence and age, sex, or healty status. Among the five MRS-positive cats: 3 had chronic kidney disease (CKD), 1 had hepatitis, and 1 tested positive for Feline infectious peritonitis (FIP). A statistically significant association was observed between MRS positivity and CKD, whereas no such association was found with FIP or hepatitis. Among the haematological and biochemical parameters, only lymphocyte count differed significantly between groups. Conclusion: This study demonstrates a 5% prevalence of MRS in cats undergoing abdominal ultrasound and reveals a significant association between MRS and CKD. The presence of a thick, band-form MRS on ultrasound may indicate chronic renal disease, but its diagnostic xiii utility is limited when used in alone; interpretation should always be corroborated with clinical and laboratory findings.