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In animals with a suspicion of intestinal Intussusception, careful abdominal palpation may reveal a tubular structure within the cranial or mid‐abdomen. Commonly reported bloodwork abnormalities include hyponatremia, hypochloremia, and hypokalemia [5, 9]. Other reported relevant clinicopathologic abnormalities in dogs include hemoconcentration, hyperlactatemia, hypoalbuminemia, and leukocytosis with neutrophilia [5, 6, 10]. Clinicopathologic findings will vary with location of the intussusception, duration and severity of clinical signs, as well as any concurrent disease processes at the time of intussusception. Lateral and dorsoventral abdominal radiographic projections may reveal a mass effect and evidence of obstruction (Figure 6.1). Gastroesophageal intussusception may be evident on radiographs as a mass effect in the caudal esophagus. Barium contrast material (orally or via enema) may confirm a diagnosis of intussusception and obstruction [11] but ultrasound provides a superior sensitive and specific method for accurate diagnosis [12, 13]. In transverse section, ultrasonographically the intussusception appears as a target like structure consisting of a hyperechoic or anechoic center surrounded by multiple hyper‐ and hypoechoic concentric rings (Figure 6.2). In longitudinal sections, the segment appears as multiple hyper‐ and hypoechoic parallel lines (Figure 6.3) [12, 13]. Color Doppler may be a useful method for predicting reducibility by detecting venous and arterial blood flow in the mesenteric vessels supplying the affected area, although adhesion formation may preclude reducibility even when blood flow is present [14]. To avoid misdiagnosis, multiplane scanning of the lesion is vital. Identification of a semi‐lunar or G‐shaped hyperechoic center of the target lesion, together with confirmation of an overall width greater than 8–9 mm of the concentric rings appear useful in supporting the diagnosis of intussusception [15].

Figure 6.1 Lateral radiographic projection of a cat with an obstruction and gastric dilation secondary to pylorogastric intussusception.

Figure 6.2 Transverse ultrasound image of small intestinal intussusception.

Figure 6.3 Longitudinal ultrasound image of small intestinal intussusception.

More recently, a report of dual‐phase computed tomography (CT) illustrated the superiority of this modality when compared with ultrasound in confirming the diagnosis of a lead‐point intussusception related to an intestinal carcinoid tumor in a dog [16]. The lead point refers to the abnormality in the intestinal anatomy that incites the intussusception. It might be especially prudent to consider dynamic CT in geriatric patients presenting for an intussusception to look for underlying neoplasia, as well as using it as a staging tool. Megaesophagus and aspiration pneumonia are frequent findings in dogs with gastroesophageal intussusception; thus, in cases where such intussusception is identified, or if there is evidence of abnormalities pertaining to the respiratory system (tachypnea, increased respiratory effort, hypoxemia, abnormal thoracic auscultation), thoracic imaging may be indicated.