# Blood Leukocyte Ratios as Predictive Markers of Chronic Enteropathy Phenotypes in Cats

## TL;DR

This study explores whether blood cell ratios can help identify different types of chronic intestinal diseases in cats, but finds they are not reliable enough for diagnosis.

## Contribution

The study evaluates the diagnostic potential of blood leukocyte ratios in differentiating feline chronic enteropathy subtypes for the first time.

## Key findings

- Cats with small cell lymphoma had significantly higher neutrophil-to-lymphocyte ratios compared to other groups.
- Blood leukocyte ratios showed poor sensitivity and specificity for diagnosing specific chronic enteropathy subtypes.
- Healthy cats had distinct blood cell ratios compared to those with chronic enteropathies.

## Abstract

This retrospective study assessed whether blood leukocyte ratios could help differentiate between types of feline chronic enteropathies (CE). Absolute neutrophil-to-lymphocyte (NLR), neutrophil-to-monocyte (NMR), and lymphocyte-to-monocyte (LMR) ratios were calculated from the hematological data of 221 cats: 73 healthy controls and 148 cats diagnosed with food-responsive enteropathy (FRE), steroid-responsive enteropathy (SRE), or small cell lymphoma (SCL). Cats with SCL had significantly higher NLRs and lower LMRs compared to those with FRE and SRE. Healthy cats showed lower NLRs and higher LMRs than all CE subgroups. While these ratios differed between groups, their ability to accurately classify disease was suboptimal. NLR ≥ 11.6 distinguished SCL from SRE with 87.5% specificity but only 39.4% sensitivity. NMR ≥ 34.5 differentiated FRE from SRE with 52.5% sensitivity and 69.6% specificity, and LMR ≥ 3.72 separated SRE from SCL with 67.9% sensitivity and 60.6% specificity. Overall, blood leukocyte ratios reflect underlying inflammation but lack sufficient accuracy to serve as standalone diagnostic markers for feline CE phenotypes.

This retrospective study assessed the potential of blood leukocyte ratios as diagnostic biomarkers in cats with chronic enteropathies (CE). Absolute neutrophil-to-lymphocyte (NLR), neutrophil-to-monocyte (NMR), and lymphocyte-to-monocyte (LMR) ratios were calculated from the hematological profiles of 221 cats, including healthy controls (n = 73), and those diagnosed with food-responsive enteropathy (FRE, n = 59), steroid-responsive enteropathy (SRE, n = 56), or small cell lymphoma (SCL, n = 33). SCL cats had higher NLRs than SRE (p = 0.002) and FRE (p = 0.028), and lower LMRs than SRE (p = 0.012) and FRE (p = 0.001). Healthy cats had lower NLRs compared to the FRE (p < 0.001), SRE (p < 0.001), and SCL (p < 0.001) cats and higher LMRs compared to the FRE (p < 0.001), SRE (p < 0.001), and SCL (p < 0.001) cats. Receiver operating characteristic (ROC) curve analysis demonstrated that NLR ≥ 11.6 differentiated SCL from SRE with 87.5% specificity but low sensitivity (39.4%). NMR ≥ 34.5 distinguished FRE from SRE with 52.5% sensitivity and 69.6% specificity. LMR ≥ 3.72 differentiated SRE from SCL with 67.9% sensitivity and 60.6% specificity. Although significant differences in leukocyte ratios were observed among groups, their diagnostic accuracy in differentiating CE phenotypes was suboptimal. These findings suggest that the utility of NLR, NMR, and LMR as standalone diagnostic tools is limited.