Feasibility of using a point-of-care analyser for faecal calprotectin (fCAL) to diagnose and differentiate intestinal disease in cats

11 September 2023

Dr. Silke Salavati, small animal internal medicine specialist, and Holly Grenville, Royal (Dick) School of Veterinary Studies undergraduate 4^th year veterinary student, report on their BSAVA PetSavers-funded research which was carried out as a student research project: Feasibility of using a point-of-care analyser for faecal calprotectin (fCAL) to diagnose and differentiate intestinal disease in cats.

Gastrointestinal conditions can have a significant impact on the health and wellbeing of feline patients, especially chronic conditions including inflammatory bowel disease (IBD). Therefore, advancing the diagnostic procedures for gut diseases in felines to facilitate clinical decision-making and influence treatment outcomes could have important implications for feline IBD diagnosis and management in clinical practice.

Currently, the diagnostic work-up for IBD in cats involves a number of blood tests and either endoscopic or surgical small intestinal biopsies. This can be lengthy, and has significant financial implications, possibly also delaying the start of treatment. There is also a paucity of non-invasive diagnostic tests or biomarkers that can be used for early IBD diagnosis.

Faecal calprotectin (fCAL) is a non-invasive diagnostic marker for IBD in humans, which can additionally be used to assess response to treatment and monitor remission. The availability of bedside Point-of-Care-Analyser (POCA) measuring fCAL has facilitated fast diagnosis and decision-making in people with IBD.

fCAL has been measured in dogs and cats, but current veterinary studies are limited. Therefore, the potential for the use of fCAL as a diagnostic aid for IBD in cats is still to be fully determined.

 

Study Aims

The objective of this study was to determine if a POCA for fCAL could be used in the diagnosis of IBD in feline samples.

This would serve a dual purpose: it would establish the measurement of fCAL as a useful adjunctive diagnostic marker in feline IBD, and assess its usefulness in a clinical environment for rapid decision-making. 

 

Methods and Study Findings

We measured fCAL in 12 faecal samples from healthy cats and 10 faecal samples from cats with chronic gut diseases

The commercially available POCA used for this study was unable to detect fCAL from feline samples, despite attempting the use of higher sample loading volumes and altering the buffer concentration.

Following this, an attempt was made to set up fCAL measurements as an in-house turbidimetric test, but there were significant difficulties in establishing assay precision at the lower end of the measuring range (which is where the values from cat samples were expected to lie). Optimisation of this is ongoing.

Finally, samples of the same cats were sent to an external commercial laboratory for the measurement of fCAL using an established turbidimetric assay. This allowed the comparison of fCAL values, which were shown not to be significantly different between healthy cats and those with gut disease. Overall, fCAL values were in the low range of the assay for most cats from both groups.

 

Importance Of Study Findings for Clinical Practice

fCAL measurements in faecal samples from cats with gut conditions is feasible using a commercially available laboratory assay, but it has not been possible using the available POCA tested in this study. However, even the commercial assay was not able to differentiate between healthy and diseased cats. These findings make the current usefulness of fCAL to the practitioner questionable.

 

Research Challenges

A significant challenge encountered was that the POCA did not detect fCAL from feline faecal samples, despite altering the sample loads and buffer concentrations. This is likely due to the detection threshold of the POCA in relation to the relatively low fCAL values in cats compared to people with IBD.

Another challenge was to obtain faecal samples from cats newly diagnosed with IBD. Some of the cats in our study group were already receiving treatment, so could have low fCAL values due to the inflammation within the gut subsiding. This could have led to an underestimation of the “true” fCAL value in cats with IBD, and the inability to find a significant difference between the diseased and healthy groups.

 

Current and Future Research Activity

Work continues to optimise the turbidimetric assay for in-house use, which will then allow future studies to be conducted. It would be pertinent to measure fCAL in a larger group of newly diagnosed cats with IBD to determine a potential diagnostic cut-off value, as well as to obtain serial measurements from cats with IBD on treatment.

 

Carrying Out Research with The BSAVA PetSavers Grant

We are extremely grateful for the support that BSAVA PetSavers has provided for this project, enabling us to carry out this pilot study. We feel encouraged to continue undertaking research to fill important knowledge gaps in small animal medicine, like the continued search for diagnostic and prognostic biomarkers for IBD.

BSAVA PetSavers were very supportive throughout the process of undertaking the research project and the various stages of producing the reports, article, and presentation. We have gained valuable insights whilst planning and conducting this research, especially when navigating the challenges that arose. Overall, it has been a great experience to work with and receive excellent support and guidance from BSAVA PetSavers to undertake this project.

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