Article Text

Download PDFPDF
Prevalence and clinical significance of the medullary rim sign identified on ultrasound of feline kidneys
  1. Amy Ferreira1,
  2. Rachel Marwood1,
  3. Daniel Batchelor2,
  4. Thomas Maddox1 and
  5. Jeremy R Mortier1
  1. 1 Diagnostic Imaging, Small Animal Teaching Hospital, Institute of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, UK
  2. 2 Internal Medicine, Small Animal Teaching Hospital, Institute of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, UK
  1. Correspondence to Dr Amy Ferreira; amyjostreet{at}


Objectives The medullary rim sign (MRS) is an ultrasonographic (US) feature identified in normal and diseased feline kidneys. The prevalence and potential clinical significance of the MRS in a referral hospital cat population was investigated.

Methods Retrospective case–control study. US images from 661 cats were reviewed. Cats with an MRS were identified and compared with equal number of time-matched control cats. Medical data and MRS features, including thickness, intensity and symmetry, were collected. Associations between independent variables and the MRS were examined with conditional and unconditional logistic regression, with initial univariable, and subsequent multivariable analysis.

Results Of the 661 reviewed cats, 243 (36.8 per cent) showed a variation of the MRS. A thin MRS (133 cats) was not associated with azotaemic renal disease (P=0.87). A thick MRS (110 cats) was associated with azotaemic renal disease (P=0.001). There was an association between the presence of MRS and a final diagnosis of feline infectious peritonitis (FIP) (P=0.028).

Conclusions The MRS is a common finding in cats. In this cat population, a thick MRS was associated with azotaemic renal disease, while a thin MRS was not. In cases with a clinical suspicion of FIP, the MRS may be related to the underlying disease process and not be an incidental finding.

  • medullary rim sign
  • ultrasound
  • kidneys
  • feline
View Full Text

Statistics from


  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Ethics approval Ethical approval was granted by the Committee on Research Ethics at the Institute of Veterinary Science of the University of Liverpool (VREC451).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement All data relevant to the study are included in the article.

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.