Ultrasonographic features of double intestinal intussusception in a cat

Abstract

Case summary

A 6-year-old male castrated Maine Coon cat was presented with a 3-day history of lethargy, hyporexia and weight loss. Abdominal ultrasonography demonstrated a double intestinal intussusception with the colon intussuscepting a thickened ileal segment, which was in turn intussuscepting the jejunum. A jejunal prolapse through the anus occurred 3 days later as a complication of the double intussusception, at which time the cat underwent surgery. Manual reduction of part of the intussusception was achieved, while the remaining 30 cm, including of the ileocaecocolic junction, was resected followed by functional end-to-end anastomosis. The cat recovered uneventfully without any reported long-term gastrointestinal complications.

Relevance and novel information

Double intussusception is rare in cats. To the best of the authors’ knowledge, this is the first case to describe ultrasonographic features of double intussusception in a cat.

Case description

A 6-year-old male castrated Maine Coon cat was referred for further assessment and investigation after 3 days of hyporexia, lethargy and weight loss that had been unresponsive to symptomatic treatment. On clinical examination, there was a palpable mid-abdominal mass; however, all vital parameters were within normal limits. The patient was admitted for further investigations, including haematology and biochemistry, which were unremarkable. Urinalysis was not carried out.

The cat was sedated with medetomidine hydrochloride (0.003 mg/kg IV, Sedator; Dechra) and alfaxalone (0.25 mg/kg IV, Alfaxan Multidose; Zoetis). An abdominal ultrasound scan was performed in right and left lateral recumbencies using microconvex (5–8 MHz) and linear array (5–18 MHz) probes. The ultrasound scan revealed the presence of a mid-abdominal intestinal lesion surrounded by hyperechoic mesentery in the region of the ileocaecocolic junction (ICCJ). A ‘triple circle sign’ ¹ was observed in the transverse plane (Figure 1). The most external, multilayered circular structure was a moderately dilated ascending colon, filled with echogenic fluid and gas. Surrounded by colonic content, a second multilayered structure was observed that was consistent with the ileum, which showed a moderately dilated lumen and a thickened (7 mm) hypoechoic wall with partial loss of layering. The lumen contained a third multilayered circular structure that was consistent with a segment of the jejunum, as well as hyperechoic mesentery, mesenteric vessels and a jejunal lymph node. Blood flow of the mesenteric vessels, entrapped in the intestinal lesion, was confirmed by colour Doppler examination. The ileocaecal and colic lymph nodes were markedly enlarged and rounded, with the largest being the ileocaecal (Figure 2), which measured 15.9 mm in width (reference interval 2.7–4.8)² with normal echogenicity. Based on these findings, a diagnosis of a double intussusception was made.

Figure 1

Ultrasonographic features of a double intussusception at the level of the ileocaecocolic junction, imaged in (a,b) transverse and (c,d) oblique sections. (a,b) A triple-circle sign is visible. The fluid-filled ascending colon (§) is the most external multilayered structure and represents the intussuscipiens. A thickened and hypoechoic ileum (^), with partial loss of layering, represents the first intussusceptum. (c) Hyperechoic mesentery, mesenteric vessels (*) and a jejunal lymph node (structure between the ‘+’) are visible in its lumen, along with an inner multilayered structure (arrows). This structure represents the second intussusceptum and is consistent with a distal jejunal loop

Figure 2

Ultrasonographic features of the enlarged ileo-caecal lymph node (structure between the ‘+’) showing normal echogenicity. A smaller ileocaecal lymph node (^) is seen next to it

Fine-needle aspiration of two colic lymph nodes, along with an ileocaecal lymph node, was performed. The cytology was consistent with aspiration of reactive lymphoid tissue.

Surgical management was strongly advised; however, the owners elected to take the cat home against medical advice. The owners were made aware of the unlikelihood that the double intussusception would spontaneously resolve and humane euthanasia was once again brought up. Both options were declined. The owners were instructed to monitor for lethargy, vomiting and diarrhoea, in the presence of which immediate treatment or euthanasia would be required. A plan for recheck every 2 days at their referring practice was agreed. Mirtazapine (2 mg PO q48h, Miraz; Mayflower) and buprenorphine (0.02 mg/kg q8h sublingual, Vetergesic Multidose; Ceva) were provided as palliative care. The cat was re-presented as an emergency 3 days later because of an irreducible jejunal prolapse through the anus. As a result of further deterioration, including jejunal prolapse through the anus and the lack of spontaneous resolution of the double intussusception, the owners now consented to surgery. Complications were discussed, and these included, but were not limited to, intestinal wall necrosis and septic peritonitis, dehiscence and ongoing medical management for chronic diarrhoea. On palpation, the mid-abdominal mass appeared unchanged. Ultrasound examination was not repeated before surgery. The cat was premedicated with medetomidine hydrochloride (0.005 mg/kg IV, Sedator; Dechra) and methadone (0.02 mg/kg IV, Comfortan; Dechra), followed by alfaxalone for induction (0.5 mg/kg IV, Alfaxan Multidose; Zoetis). Subsequently, an endotracheal tube was inserted and the patient was maintained on a combination of oxygen and isoflurane.

Exploratory laparotomy confirmed the presence of the double intussusception, centred at the level of the ICCJ that had remained in a normal position. The ileum and jejunum were intussuscepted into the ascending colon through to the anus where a section of the jejunum was prolapsing out. Manual reduction successfully resolved part of the intussusception as well as the jejunal prolapse. The remaining section of the distal jejunum and ileum, approximately 20 cm, ICCJ and approximately 10 cm of the colon proved unable to be reduced. Resection and functional end-to-end anastomosis were consequently performed.

Postoperatively, the patient remained hospitalised for 4 days, where it received intravenous fluid therapy (2 ml/kg/h for 2 days, Aqupharm No 1 Infusion; Animalcare), buprenorphine (0.02 mg/kg IV q8h for 2 days, Vetergesic Multidose; Ceva), maropitant (1 mg/kg IV q24h for 3 days, Cerenia; Zoetis) and amoxicillin with clavulanic acid (20 mg/kg PO q12h for 1 week, Noroclav; Norbrook). The cat went on to make a full recovery with no reported complications at 2, 12 and 24 weeks postoperatively.

The quality of the cat’s faeces remained good with no reported postoperative diarrhoea.

A histopathological examination of the resected tissue showed a severely necrotic intestinal wall of intussusceptum. The mucosa, submucosa and portions of the muscularis layers of the wall were replaced by eosinophilic amorphous material and cellular debris. In addition, extensive large bacterial colonies were observed at the periphery. Deeper sections of the intussusceptum exhibited substantial replacement of the muscularis layer by granulation tissue. There were no signs of neoplastic changes in the examined sections. The underlying cause of the intussusceptions remained unidentified with no evidence of a neoplastic process detected.

Discussion

The occurrence of double intestinal intussusception in dogs is a well-documented phenomenon in the veterinary literature.^3,4 To the best of the authors’ knowledge, there is only one previous case report documenting this condition in the feline population. ⁵ In that case, the diagnosis was achieved during exploratory laparotomy. The use of ultrasonography was not reported.

This is the first time ultrasonographic features of a double intussusception are reported in a cat. Single intussusceptions in feline patients tend to occur more often within the jejuno jejunal axis ⁶ or at the ICCJ, ⁷ similar to our case.

This report describes an unusual presentation of a rare case of a double intussusception complicated by the presence of intestinal wall necrosis, which emphasises the risky nature of delaying surgical intervention, a risk that was discussed with the owner when they initially declined surgery. In the few reports of this pathology in dogs,^3,4 wall necrosis was not described. A recent publication has described a double intussusception caused by intestinal plasmacytoma in a dog. ⁸ In our case, despite both surgical treatment and hospitalisation being strongly recommended upon initial diagnosis, the client opted for palliative treatment instead. The patient was discharged against medical advice. Euthanasia was offered but declined. Because of the hypoechogenicity and partial loss of layering of the portion of the ileum involved in the intussusception, an underlying primary neoplastic disease causing the double intestinal intussusception was considered likely based on imaging,^9,10 while segmental wall necrosis was considered less likely. The radiologist’s interpretation was based on other reports where feline intestinal intussusception has been known to occur in association with intestinal neoplasia,^6,7,9 as well as intestinal parasitism, linear foreign bodies, viral-induced enteritis and previous abdominal surgery. ⁷

Partial loss of wall layering and thickening of the intestinal wall has been reported to occur in chronic cases of intestinal intussusception in dogs and cats. ¹¹

The use of ultrasound proved useful in the diagnosis of double intestinal intussusception in the case presented here. The presence of the characteristic ‘triple circle sign’, visible on the transverse plane as three multilayered structures with alternating echogenicity, is considered pathognomonic for double intussusception in both human ¹ and veterinary patients.^3,4

Histopathological analysis revealed a non-neoplastic process delineated by necrosis and granulation tissue formation, but a predisposing factor for the intussusception was not determined. The cat was recently tested negative for feline immunodeficiency virus and feline leukaemia virus (SNAP FIV/FeLV Combo; IDEXX) at the referring practice.

The jejunal prolapse was considered to be a complication of the double intussusception, which, to the best of the authors’ knowledge, has not been described in dogs or cats with double intussusceptions before.

The patient underwent full recovery with no reported complications postoperatively in the first 6 months, after which the patient was lost to follow-up. Ongoing medical management for chronic diarrhoea after enterectomy was a possible complication ¹² discussed with the client preoperatively; however, this never occurred. In dogs, short bowel syndrome has been reported as a postoperative complication following a case of double intussusception, where 170 cm of the jejunum and ileum, along with 20 cm of the colon, including the caecum (15 cm in length) and ileocaecocolic junction, were resected.^12,13

Conclusions

This is the first report describing the ultrasonographic appearance of a double intestinal intussusception in a feline patient, involving the ascending colon, ileum and jejunum, and the ICCJ. The ultrasonographic presence of the ‘triple-circle sign’ confirms its potential as a pathognomonic indicator of double intussusception in this species, similar to what has been reported in humans and dogs.^2,3,11 Jejunal prolapse through the anus can occur with this condition.