Introduction

3-bromotyrosine (3-BrY) is a stable byproduct of eosinophil activation. In dogs with chronic enteropathy (CE), eosinophils are considered to be the second most common type of inflammatory cell infiltrating the GI mucosa. We previously established and analytically validated a method for measurement of 3-BrY concentration in serum samples from dogs.

Objective

To evaluate serum 3-BrY concentrations in healthy dogs and dogs with CE.

Methods

Serum samples were collected from healthy dogs (n = 41) and dogs with CE (n = 30). 3-BrY concentrations were measured by electron ionization gas chromatography/mass spectrometry. Mann-Whitney U test was used to compare 3-BrY concentrations between healthy dogs and dogs with CE. A Spearman rank sum correlation coefficient (ρ) was used to determine the relationship between serum 3-BrY concentration and the severity of histopathologic lesions (based on the WSAVA GI histopathology grading guidelines) in dogs with CE.

Results

Serum 3-BrY concentrations were significantly higher in dogs with CE (median [range]: 2.98 µmol/L [≤ 0.63–16.52 µmol/L]) than in healthy dogs (median [range]: 0.63 µmol/L [≤ 0.63–1.13 µmol/L]; p < 0.0001). There was a moderate correlation between serum 3-BrY concentrations and severity of eosinophilic infiltrates within the lamina propria in the region of the gastric fundus (ρ = 0.5466, p = 0.0126). Moreover, a strong positive correlation between serum 3-BrY concentrations and the severity of ileal crypt lesions was found (ρ = 0.9258, p = 0.0080).

Conclusions

Serum 3-BrY concentrations were significantly higher in dogs with CE when compared to healthy dogs. Utility of 3-BrY as a diagnostic and/or prognostic marker in dogs with CE should be further assessed.