B-mode and Doppler ultrasound in the gastrointestinal evaluation of cats

Abstract

Ultrasound (USG) is a valuable diagnostic tool for evaluating the gastrointestinal tract of cats, providing noninvasive and dynamic information. B-mode USG allows evaluation of intestinal wall thickness, stratification, motility, and adjacent structures, such as lymph nodes and peritoneum. The stomach and intestinal segments can be differentiated based on their location, wall stratification, and relationships with surrounding organs. Normal ultrasound parameters, including gastric and intestinal wall thickness, peristaltic activity, and luminal content appearance, have been established for cats. Doppler ultrasound was used to assess vascular flow in the celiac and cranial mesenteric arteries and detect hemodynamic changes associated with gastrointestinal diseases. Alterations in flow velocity, resistivity index, and pulsatility index provide insights into vascular resistance and parenchymal function. Doppler velocimetry can also differentiate normal from pathological flow patterns, thereby aiding in the diagnosis of inflammatory, neoplastic, and ischemic conditions. Ultrasound findings of feline chronic enteropathy include wall thickening, loss of layering, and altered vascular supply. Lymphoplasmacytic enteritis and alimentary lymphoma, which are common in cats, present overlapping USG features, requiring histopathology for definitive diagnosis. Doppler alterations in the mesenteric arteries reflect gastrointestinal inflammation and ischemia, highlighting their potential as complementary diagnostic tools. Although B-mode and Doppler ultrasound are effective in identifying gastrointestinal abnormalities, further studies are needed to establish reference values and refine their clinical applications. The integration of these techniques enhances the noninvasive assessment of feline enteropathies and contributes to improved diagnosis and management. This review explores the use of B-mode and Doppler ultrasound for assessing the stomach and intestines in healthy and diseased felines.

Keywords: Enteropathy; Feline; Hemodynamics; Ultrasonography; Vascularization.

Fig. 1.. Ultrasound (linear transducer, 8 MHz) of the stomach of an adult cat in a cross-section. Stomach (S) with the appearance of a wagon wheel, liver (L) cranial to the stomach, and abdominal wall (AW) ventral to the stomach. Source: Personal archive, 2025.

Fig. 2.. Ultrasound (linear transducer, 8 MHz) of the body of the stomach of a cat in the longitudinal section. Gastric wall (between cursors) with a thickness of 0.29 cm, preservation of stratification, slightly rough aspect. Source: Personal archive, 2025.

Fig. 3.. Ultrasonography of intestinal segments in felines (linear transducer, 10 MHz) with wall thickness assessment (between the cursors). (A) Proximal duodenum measuring 0.23 cm; (B) Proximal jejunum measuring 0.20 cm; (C) Distal ileum measuring 0.30 cm; (D) Cecum measuring 0.24 cm; (E) Ileocolic junction (ICJ) measuring 0.42 cm; (F) Ascending colon measuring 0.12 cm; (G) Transverse colon measuring 0.15 cm; (H) ascending colon measuring 0.11 cm. Source: Personal archive, 2025.

Fig. 4.. Gastric ultrasonography in a longitudinal section of a feline (microconvex transducer, 8 MHz). (A) Gastric wall thickness between the cursors measuring 0.62 cm and (B) 0.53 cm. Both thickened. Source: Personal archive, 2025.

Fig. 5.. Abdominal ultrasonography in felines (linear transducer, 10 MHz) in a longitudinal section with wall thickness assessment (between cursors). (A) Duodenum measuring 0.29 cm; (B) Duodenum measuring 0.30 cm; (C) Ileum measuring 0.55 cm; (D) Jejunum measuring 0.41 cm; (E) Ascending colon measuring 0.24 cm; (F) Transverse colon measuring 0.29 cm. Source: Personal archive, 2025.

Fig. 6.. Image of the abdominal aorta of a cat, showing the sample volume, ultrasound beam, and main flow vector, with the latter overlaid and parallel to the vessel being evaluated with spectral Doppler. Source: Personal archive, 2025.

Fig. 7.. Spectral Doppler of the aorta, characterized by flattened and high-resistance flow. A thin line is observed in systole surrounding a clear space, known as the spectral window. Source: Personal archive, 2025.

Fig. 8.. Spectral Doppler of the celiac artery, characterized by semiparabolic flow, showing a thin line in systole surrounding a clear space, known as the spectral window. Source: Personal archive, 2025.

Fig. 9.. Spectral Doppler images of the renal artery. There is no spectral window, the systolic peaks are broad and continuous, and there is high diastolic flow velocity with a gradual decrease in speed. Source: Personal archive, 2025.