Imaging Characteristics of Pylorogastric, Duodenogastric, and True-Gastrogastric Intussusception in 25 Dogs and One Cat.

Gastric intussusception in dogs and cats is uncommon, and there are multiple variations described in the literature. The aim of this study was to describe the imaging characteristics of pylorogastric (PG), duodenogastric (DG), and true-gastrogastric (true-GG) intussusceptions. In this multicenter retrospective study, available medical records and imaging (radiographs, ultrasound [US], and computed tomography [CT]) were evaluated. Group allocation (PG, DG, and true-GG) was based on US/CT findings, or surgical/necropsy findings if only radiographs were available. Available surgical/necropsy follow-up was reported. Twenty-five dogs and one cat (7 weeks-10 years) were included, representing 22 males, four females, and multiple breeds. Twenty-two presented with vomiting. They were diagnosed via US (n = 21), CT (n = 2), or surgery (n = 3). There were 14 PG, 9 true-GG, and 3 DG intussusceptions. A rounded soft tissue opaque mass in the pylorus was present in 8/9 PG and 1/1 DG cases with radiographs. Moderate to marked wall thickening was present in all true-GG and most PG cases on US/CT, predominantly affecting the submucosal layer. Surgical/necropsy follow-up was available in 17 cases diagnosed via imaging and showed spontaneous resolution of five true-GG and one PG intussusception. Two cases classified as PG based on imaging were described as DG at surgery/necropsy. There are some overlapping features of PG and DG intussusceptions on radiographs and US. Moderate to marked submucosal thickening seen with PG and true-GG cases likely represents edema/congestion. Spontaneous resolution of true-GG and PG intussusceptions is possible. US and CT were diagnostic of the type of intussusception in most cases.