EQUINE VETERINARY EDUCATION Equine vet. Educ. (2018) 30 (5) 259-261 doi: 10.1111/eve.12799


Clinical Commentary Caecocolic intussusceptions in horses


S. J. Holcombe* and T. R. Shearer Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA. *Corresponding author email: holcomb6@cvm.msu.edu


Keywords: horse; caecum; colon; intussusception; celiotomy; Anoplocephala perfoliata


The mature horse caecum is a large, bulbous oral portion of the large colon that is approximately 1.5 m long with a 40– 50 L capacity. Caecal circulation is provided by the medial and lateral caecal arteries and veins that travel in the medial and lateral caecal bands, respectively. The caecum is responsible for water and electrolyte absorption and microbial digestion. Four motility patterns coordinate digesta mixing and propulsion of ingesta from the caecum through the caecocolic orifice to the right ventral colon. Disruption of these patterns due to inflammation, ischaemia, masses, or parasitic infections may precipitate caecocolic intussusceptions. Caecocolic intussusception is an uncommon cause of


surgical colic in horses, cattle, people and dogs that occurs when the caecum inverts through the caecocolic orifice into the colon or specifically the right ventral colon in horses (Guffy et al. 1970; Robertson and Johnson 1980; Constable et al. 1997; Cochran et al. 2011). The pathogenesis is unclear but theoretically the intussusception begins at the caecal apex with progressive migration of the caecum telescoping through the caecocolic orifice into the right ventral colon. The intussusception may involve a portion or all of the caecum and the ileocaecal junction. The aetiology is speculative but includes tapeworm (Anoplocephala perfoliata) infestation at the caecocolic orifice, ingestion of organophosphates, caecal wall masses including abscesses and tumours, vascular injury caused by Strongylus vulgaris or Eimeria leukarti infections, and administration of parasympathomimetic medications (Barclay et al. 1982; Gaughan and Hackett 1990; Martin et al. 1999). The advent of praziquantel, the anthelmintic effective against A. perfoliata, coincided with the diminished incidence of caecocolic intussusception, adding to the speculation that A. perfoliata may be associated with caecocolic intussusception occurrence (Barclay et al. 1982; Slocombe et al. 2007). Tapeworm infestation was evident in 8 of 10 horses when the caecal base was examined in the study by Gaughan and Hackett (1990). There is no sex predilection but horses tend to be young, age ≤3 years, and Standardbred horses were overrepresented in one study (Gaughan and Hackett 1990; Martin et al. 1999) . Older horses may be effected as described in the case report included in this issue of caecocolic intussusception in a 12-year-old Arabian cross gelding.


Clinical signs associated with caecocolic intussusception


include acute severe pain and cardiovascular compromise prompting quick referral and surgical exploration, as occurred in the case report published in this issue (de Bont 2018). Some horses exhibit more chronic clinical signs, mild to moderate pain, diminished faecal output, poor appetite,


dehydration and weight loss (Hubert et al. 2000). The intussusception may be palpated per rectum as a firm mass in the right ventral abdomen. Percutaneous abdominal ultrasonography may reveal a large target lesion at the right mid to ventral abdomen (Fig 1). Peritoneal fluid could be normal or abnormal and frequently the diagnosis of caecocolic intussusception is made during emergency celiotomy.


Treatment requires surgical correction under general


anaesthesia. Although the caecocolic orifice would be accessible via a standing flank laparotomy, correction of cecocolic intussusception using this surgical approach has not been reported. Right flank laparotomy would provide excellent access to the caecum and caecal base, however a standard ventral midline celiotomy is typically performed to ensure a full exploratory evaluation of the abdomen, as the diagnosis is frequently made at celiotomy. At surgery, the caecum is palpable within the right ventral colon. The caecum within the right ventral colon can usually be partially exteriorised from the abdomen (Fig 2). Palpation of the caecocolic orifice reveals the invaginating caecum. Reduction of the intussusception is performed by placing traction on the caecal apex, with or without typhlectomy or via colotomy through the lateral band of the right ventral colon to facilitate reduction. When reduction is not possible as occurred in the case presented by de Bont (2018), colotomy through the lateral band of the right ventral colon and partial typhlectomy is performed. Approximately 60% of caecocolic intussusceptions were reducible (Martin et al. 1999; Hubert et al. 2000) while the remaining 40% required typhlectomy through a colotomy incision. Depending on the integrity of the ileum and ileocaecal junction, a jejuno or ileocolostomy may be required to bypass a damaged ileocaecal junction (Ward and Fubini 1994; Martin et al. 1999).


Reducing the caecocolic intussusception using manual


traction on the caecum is possible if the caecum is not too engorged to fit through the caecocolic orifice. The surgeon’s hand is advanced through the caecocolic orifice and the lateral and/or medial bands of the caecal apex are grasped. Gentle traction is applied for up to 10–20 min to reduce the intussusception (Fig 3). An assistant may place pressure on the caecum through the colon, gently squeezing and pushing the caecum orally toward the caecocolic orifice. Caution is advised as the caecum may rupture. If reduction is successful, the viability of the caecum is assessed and, if required, a typhlectomy is performed following ligation of the medial and lateral caecal arteries and veins. If the caecum is too engorged and cannot be manipulated through the caecocolic orifice by traction, reduction may be attempted


© 2017 EVJ Ltd


259


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76