Respiratory obstruction in brachycephalic obstructive airway syndrome (BOAS) can lead to secondary gastrointestinal alterations. This study aimed to quantitatively assess the echogenicity of the stomach, duodenum, and jejunum in dogs affected by brachycephalic syndrome. The correlation of these findings with BOAS severity, hematological alterations, and signs of systemic inflammation was investigated. Fifty-two brachycephalic patients and 15 mesocephalic controls, aged between 1 and 8 years, underwent evaluation including hemogram, biochemical analysis, C-reactive protein, and B-mode ultrasonography of the gastrointestinal tract. Brachycephalic animals were categorized based on the severity of BOAS, and owners provided clinical data via questionnaire. In the quantitative analysis, eight regions of interest were defined within the mucosal layer of the stomach, duodenum, and jejunum, and the mean pixel values were quantified for each structure. Leukocyte count (p≤ 0.001), eosinophils (p = 0.002), monocytes (p < 0.001), creatinine (p≤ 0.001) and total protein (p≤ 0.001) were higher in brachycephalic dogs than mesocephalic dogs. Hematological patterns showed mild leukocytosis, possibly indicating subclinical inflammation. Brachycephalic dogs exhibited elevated echogenicity in the duodenum and jejunum, measured in pixels (duodenum: 18.2 ± 11.3; jejunum: 25.6 ± 15.2), which was significantly higher than mesocephalic dogs (p< 0.05; duodenum: 11.04 ± 4.3; jejunum: 9 ± 7), according to variance analysis. Brachycephalic dogs of grades 0, 1, and 2 exhibited higher values than controls and grade 3 dogs. In conclusion, quantitative ultrasonography reduces subjectivity and provides objective insights into gastrointestinal alterations in BOAS-affected dogs.