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Faecal calprotectin in the diagnosis and monitoring of canine and feline inflammatory enteropathy

An article authored by Dr Lucy Williams, MRCVS, Vet and Marketing Manager at Carus Animal Health.

Dr Lucy Williams BVSc MRCVS is a veterinarian and marketing manager with a background in general practice and a keen interest in internal medicine and gastrointestinal health. With five years of clinical experience, she now specialises in science-driven and creative strategy in the veterinary marketing space. Outside of work, she enjoys being outdoors, especially by the beach, and spending time with friends.

Canine and feline chronic inflammatory enteropathy (CIE) refers to a group of chronic, relapsing inflammatory disorders of the gastrointestinal tract.1 CIE can affect the small intestine, large intestine, or both and can significantly reduce quality of life. Clinical signs vary but commonly include vomiting, diarrhoea, weight loss, flatulence, melaena and alterations in appetite. 

Although the underlying cause is often unclear, multiple contributory factors are thought to be involved. These include genetic predisposition, an inappropriate immune response to dietary components, environmental factors including stress and alterations in the gut microbiome (dysbiosis).2 

Diagnostic approach

A definitive diagnosis of CIE requires the exclusion of other causes of chronic gastrointestinal (GI) disease, ideally supported by histopathology. However, endoscopic or surgical biopsies carry cost, risk, and practical limitations, so many clinicians rely on presumptive diagnosis following dietary or therapeutic trials.

A standard work-up typically includes haematology, serum biochemistry and faecal analysis alongside GI-specific tests. The GI diagnostic toolbox now also includes faecal calprotectin – a specific, non-invasive marker of GI inflammation.

Faecal calprotectin in CIE

  • What it shows: Non-invasive biomarker of gastrointestinal inflammation
  • Diagnostic accuracy (GIQuest test, University of Bristol data):
    • Dogs – Score ≥3 mg/kg: 96% specificity, 94% sensitivity
    • Cats – Score ≥2.5 mg/kg: 100% specificity, 92% sensitivity
  • Clinical relevance: Supports diagnosis of CIE; can help monitor response to treatment.
  • Advantages: Non-invasive, affordable, stable in faeces, easy to collect, more specific for GI inflammation than serum markers, fast results.

What is faecal calprotectin?

Calprotectin is a calcium- and zinc-binding protein. During GI inflammation, the innate and adaptive immune responses are stimulated, resulting in an influx of phagocytic cells and the release of inflammatory cytokines, which in turn chemoattract neutrophils. This triggers a cascade of events, culminating in neutrophil disintegration.4–6 

Because calprotectin makes up around 60 percent of neutrophil cytosol (the fluid within a cell’s cytoplasm), this disintegration results in calprotectin release into the gut lumen and subsequently into the faeces. Importantly, faecal calprotectin is resistant to degradation by faecal bacteria and stable at room temperature for up to a week. The amount detected in faeces is therefore directly proportional to the degree of neutrophil infiltration in the gastrointestinal mucosa, making it a practical non-invasive marker of intestinal inflammation. This includes inflammation arising from, for example, food responsive enteropathy and oral NSAID use, as well as that associated with CIE.  

Faecal calprotectin in canine and feline CIE

With a direct link between intestinal inflammation and faecal calprotectin levels, it is not surprising that higher concentrations have been associated with greater disease severity in chronic enteropathies. The canine chronic enteropathy clinical activity index (CCECAI) is a semi-objective scoring system used to assess clinical disease activity and treatment response.7 In one study, higher CCECAI scores correlated with higher faecal calprotectin concentrations and a concentration ≥48.9µg/g was associated with severe clinical signs (CCECAI scores ≥12) with moderate sensitivity and high specificity.8  

Building on this, a study conducted at the University of Bristol Vet School evaluated the diagnostic performance of the GIQuest lateral flow test in dogs and cats with chronic inflammatory enteropathy (CIE) compared to healthy controls.9 The test demonstrated excellent accuracy, with clear discrimination between affected and control animals (dogs, Figure 1; cats, Figure 2). In dogs, use of a 3 mg/kg threshold resulted in 94% sensitivity and 96% specificity and in cats, use of a 2.5 mg/kg threshold resulted in 92% sensitivity and 100% specificity. 

These findings are further supported by earlier research showing that faecal calprotectin concentrations in cats were significantly higher before treatment than after treatment initiation, with levels correlating with feline chronic enteropathy activity index (FCEAI) scores.1

Practical application in first-opinion practice

Faecal calprotectin testing is particularly valuable in busy first-opinion settings, where pragmatic, rapid decision-making is essential. Point-of-care tests such as GIQuest are cost-effective, require only a small faecal sample, and provide immediate, semi-quantitative data to guide next steps. For clinicians, this means the test can be easily incorporated into everyday workflows, helping to differentiate inflammatory from non-inflammatory GI disease during the initial consultation. 

Because the test is non-invasive and already widely used in human medicine, it is familiar and understandable to many clients. This can make conversations about intestinal disease easier and more relatable – especially when owners are reluctant to pursue further diagnostics or are concerned about the risks or costs associated with endoscopic or surgical biopsy. 

Role of histopathology 

Of course, histopathology remains a key part of the diagnostic process in many cases. Faecal calprotectin is a useful adjunct that can help guide the need for further work-up. Several human medical studies evaluating the role of calprotectin in the initial investigation of children with suspected inflammatory bowel disease have shown that faecal calprotectin testing accurately helps clinicians decide whether to refer a patient for endoscopy. This may be useful in veterinary settings too. 

Monitoring treatment response 

In human medicine, faecal calprotectin is also used to evaluate treatment efficacy, anticipate relapse and reduce unnecessary endoscopic reassessment. While equivalent data in veterinary patients are still limited, faecal calprotectin could hold similar promise for dogs and cats. It is also possible that, during a dietary trial, immunosuppressive therapy, or both, a reduction in faecal calprotectin may occur before obvious clinical improvement, offering reassurance and potentially guiding adjustments to treatment.  

Summary 

In summary, faecal calprotectin is a non-invasive biomarker that supports the diagnosis and management of CIE in dogs and cats. It offers insight into the presence and severity of intestinal inflammation, correlates with clinical and histological findings, and provides an objective tool for monitoring therapeutic response. While not a definitive diagnostic test, its ease of use and affordability hold great promise. As clinical experience and validation data grow, faecal calprotectin is set to become a cornerstone of non-invasive GI diagnostics in small animal medicine. 

Figure 1. Distribution of faecal calprotectin scores in histologically verified inflammatory enteropathy vs controls 

Figure 2. Distribution of faecal calprotectin scores in diagnosed feline inflammatory enteropathies vs controls 

References

  1. Siel, D., et al. (2022). Elucidating the Role of Innate and Adaptive Immune Responses in the Pathogenesis of Canine Chronic Inflammatory Enteropathy-A Search for Potential Biomarkers. Animals : an open access journal from MDPI, 12(13), 1645. https://doi.org/10.3390/ani12131645.  
  1. Garraway, K. (2017) Inflammatory bowel disease in dogs and cats. TVP. TVP-2018-0102_Garraway_IBD-Dogs-Cats_03.pdf 
  1. Cridge, H. et al. (2018) Evaluation of SNAP cPL, Spec cPL, VetScan cPL Rapid Test, and Precision PSL Assays for the Diagnosis of Clinical Pancreatitis in Dogs. J Vet Intern Med. 32(2):658-664. doi: 10.1111/jvim.15039. 
  1. Dabritz, J. et al. (2014) World J Gastroenterol. 20(2):363–375. 
  1. Jukic A, et al. (2021) Gut. 70(10):1978–1988. 
  1. Heilmann R.M. et al. (2012) Am J Vet Res. 73(12):1900–1907. 
  1. Heilmann, R.M. et al. (2018) Association of fecal calprotectin concentrations with disease severity, response to treatment, and other biomarkers in dogs with chronic inflammatory enteropathies. J Vet Intern Med. 32: 679-692. https://doi.org/10.1111/jvim.15065 
  1. Grellet, A. et al. (2013) Fecal calprotectin concentrations in adult dogs with chronic diarrhea. Am J Vet Res. 74: 706–711. 
  1. Carus Animal Health (2025). Data on file. 
  1. Heilmann, R.M. et al. (2024) Treatment success in cats with chronic enteropathy is associated with a decrease in fecal calprotectin concentrations. Frontiers in Veterinary Science Vol11 DOI=10.3389/fvets.1390681 

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