Intestinal fibrosis in feline chronic inflammatory enteropathy

5 February 2024

Dr Aarti Kathrani and Professor Simon Priestnall at the RVC received PetSavers funding for a Master’s Degree by Research investigating feline chronic inflammatory enteropathy. Here, student Yuvani Bandara describes her research and explains what this opportunity has meant to her.

Feline chronic inflammatory enteropathy (CIE) describes a group of idiopathic diseases causing gastrointestinal signs of vomiting, diarrhoea, reduced appetite and weight loss of at least 3 weeks’ duration. Definitive diagnosis requires ruling out all other known causes of chronic gastrointestinal signs, such as infectious, obstructive, neoplastic and extra-intestinal diseases, by final histopathological examination of intestinal biopsy specimens. Classification of feline CIE is based on treatment response into food-responsive enteropathy and immunosuppressive-responsive enteropathy, the latter of which may also be known as inflammatory bowel disease (IBD). Cases refractory to treatment can be classified as non-responsive enteropathy.

The exact cause of feline CIE is currently unknown. However, its hypothesized aetiopathogenesis is extrapolated from human IBD studies, and feline CIE is therefore thought to be similarly complex, multifactorial and polygenic. Intestinal mucosal fibrosis is a common morphological feature noted on histopathological examination of cats with CIE. Fibrosis occurs due to an alteration in collagen metabolism following chronic inflammation. This results in its excessive and irreversible deposition in the extra-cellular matrix, eventually resulting in organ dysfunction. In human IBD, intestinal fibrosis (IF) is a common and expected complication, with it holding significant implications for clinical consequence and patient quality of life. However, the clinical significance of IF in cats with CIE is unknown.

The master’s research project

Our research was two-fold in evaluating clinicopathological factors that may affect the outcome of cats with CIE and in further characterizing the role of IF in CIE, neither of which had been previously described. We also assessed the use of additional Masson’s trichrome staining and immunohistochemical labelling for anti-vimentin, anti-alpha-smooth muscle actin and anti-collagen I antibodies, relative to traditional haematoxylin and eosin staining, in the identification of IF during histopathological examination.

 

Full thickness duodenal biopsy specimen from a cat with chronic inflammatory enteropathy labelled with anti-collagen I antibody. Positive labelling for collagen is depicted as a linear brown band in the mid duodenal mucosa. Magnification ×200.

 

 

 

 

The Royal Veterinary College’s Feline Chronic Enteropathy and Feline Gastrointestinal Biopsy Archives and VetCompass search engine were retrospectively searched for cats diagnosed with CIE between June 2008 and November 2021, with various clinicopathological variables at the time of diagnosis recorded. Sections of formalin-fixed paraffin embedded intestinal biopsy specimens from these cats were re reviewed to confirm a diagnosis of CIE and also re-graded using the World Small Animal Veterinary Association gastrointestinal histopathology guidelines. Referring veterinary surgeons were contacted for follow-up information on each cat including whether the cat was in clinical remission and each cat’s outcome (alive or dead and reason for death).

Research findings and relevance to practice

Our research identified that the use of additional stains at the time of histopathological examination allowed for the better identification of the presence of IF relative to haematoxylin and eosin staining alone. The presence of colonic fibrosis in cats with CIE was correlated with a reduced likelihood of attaining clinical remission and with death due to CIE. Additionally, multiple clinicopathological variables such as history of diarrhoea, history of weight loss, hypoalbuminemia and hypocobalaminemia were associated with the presence of IF when using the additional stains. The results of our research are significant to both owners and veterinary surgeons in anticipating disease course and outlook. However, there still remains a paucity of information regarding the complex underlying mechanism behind intestinal fibrogenesis and how it may influence clinicopathological variables in cats with CIE. We hope that our research acts as a foundation for further investigation in this area.

My experience as a PetSavers-funded master’s student

This has been my first experience of carrying out my own independent research, something I had always wanted to do but was unsure about how to confidently approach and access. Before beginning the year, I had always perceived research as being for those who are statistics-savvy, technically minded and able to process data swiftly. As someone used to working only in clinical practice, I felt that these were skills that I didn’t have. However, undertaking a Master’s by Research under the guidance of my two incredible supervisors, Dr Aarti Kathrani and Professor Simon Priestnall at the Royal Veterinary College, and with the support of the BSAVA PetSavers grant, has developed my ability to critically appraise research and data, formulate and present my own ideas, and turn to literature in order to answer complex questions.
I find gastroenterology fascinating and carrying out research in this particular field has been really fun! The BSAVA PetSavers grant has allowed me to contribute peer-reviewed publications to the field of gastroenterology, present my work at international congresses and learn from specialists in the field. I really encourage anyone who has curiosity in a topic, wants to return to university or wants to turn to a career in research to undertake a Master’s by Research. The entire experience has provided me with the vital skills and confidence necessary for a future in clinical research and I thank my supervisors, PetSavers and my colleagues for their support over the past year.

About the author

Yuvani graduated from the Royal Veterinary College in 2014 and has worked as a first-opinion small animal veterinarian mainly in the charity sector, in the UK and South Pacific. She has completed the RCVS Certificate in Advanced Veterinary Practice (small animal medicine), a small animal rotating internship at the University of Cambridge, a BSAVA PetSavers-funded Master’s by Research at the Royal Veterinary College, and is currently undertaking a residency in Small Animal Internal Medicine at Colorado State University. Yuvani has a strong interest in gastroenterology, particularly in understanding the relationship between the intestinal microbiome and distant organs, the role of clinical nutrition in disease states, and in the management of inflammatory enteropathies.
Yuvani’s research was published in the March 2023 issue of the Journal of Small Animal Medicine¹ and the April 2023 issue of the Journal of Veterinary Internal Medicine.²