Subtotal colectomy for the treatment of megacolon in cats

Authors

  • Vasileia Angelou DVM, MSc - Companion Animal Clinic, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
  • Kyriakos Chatzimisios DVM, MSc, MRCVS - Companion Animal Clinic, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
  • Tzeni Seltsa DVM, MSc - Veterinary Centre of West Thessaloniki, Greece
  • Lysimachos Papazoglou DVM, PhD, MRCVS - Companion Animal Clinic, School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece

MeSH keywords:

cat, colectomy, megacolon

Abstract

Megacolon is a disease characterized by colonic dilatation and hypomotility and can be acquired or congenital. Surgical treatment, including subtotal colectomy, is considered the treatment of choice in cats with episodes of constipation unresponsive to medical management. The aim of this review was to assess all studies of subtotal colectomy as the treatment of choice in cats with megacolon. A systematic literature search was performed using U.S National Library of Medicine (PubMed), Mendeley and Google Scholar databases to identify all studies reporting data on cats with megacolon where a subtotal colectomy was performed. From the 354 studies that were assessed for eligibility, 13 studies finally chosen reporting subtotal colectomy for treatment of megacolon in cats. All these studies were abstract- ed for the following data: demographics (age, sex), cause of megacolon (idiopathic or secondary), type of subtotal colectomy (colocolostomy, ileocolostomy, jejunocolostomy), technique of anastomosis (sutured or stapled), preservation of ileocolic junction, postoperative complications and outcomes. In conclusion this systematic review suggests that subtotal colectomy is a safe technique, with rare postoperative complications and is considered as the treatment of choice for idiopathic megacolon in cats.

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Background

Megacolon is characterized by generalised colonic dilatation and hypomotility (Bright et al. 1986, Gregory et al. 1990, Sweet et al. 1994). Megacolon can be congenital or acquired (Haan et al. 1992, Ryan et al. 2006). The acquired megacolon may be idiopathic, which is the most common form in cats, or secondary to pelvic malformations (Matthiessen et al. 1991, Whasabau & Stalis 1996, Ryan et al.2006) including fracture callus formation, tumours (Haan et al. 1992) or following neurologic dysfunction (Ganesh et al. 2018). The main clinical manifestation is multiple episodes of constipation for a long period that may temporarily respond to medical management but usually the need for surgical intervention is necessary due to irreversible changes in the colonic wall (Gregory et al. 1990, Haan et al. 1992, Ryan et al. 2006). Treatment for megacolon secondary to pelvic malformations includes treatment of the primary cause that results to obstruction (Matthiessen et al. 1991, Schrader 1992). There are many surgical techniques that have been described for the surgical treatment of idiopathic megacolon. These techniques include coloplasty, partial colectomy, subtotal colectomy, and total colectomy (Bruce 1959, Yoder et al. 1968, Leighton & Grain 1978, Bertoy et al. 1989). It is well accepted that subtotal colectomy is considered the treatment of choice for idiopathic megacolon unresponsive to medical treatment. The aim of this study was to systematically review the literature on subtotal colectomy for the treatment of megacolon in cats regarding the techniques for subtotal colectomy, the comparisons between the surgical techniques, the complications and the outcomes that have been reported.

Methods

A systematic literature search was performed using U.S National Library of Medicine (PubMed), Mendeley and Google Scholar databases to identify all studies reporting data on cats with megacolon where a subtotal colectomy was performed. For the purpose of this review the following MeSH keywords were used: subtotal colectomy cat, colectomy cat megacolon and cat megacolon. Two authors searched the literature for relevant studies. The number of studies found in each database is reported in Table 1. Data included in these studies were the cause of megacolon, type of colonic resection and anastomosis related to subtotal colectomy, complications, and outcome of cats with megacolon. This review included retrospective and experimental studies as well as case reports. The following types of studies were not included in this systematic review: studies for megacolon in other species apart from cats, studies of megacolon, where subtotal colectomy was not performed, non-English language studies, review articles and book chapters. Two authors reviewed all selected studies and final studies included were chosen by consensus. All studies that finally chosen were abstracted for the following data: patient characteristics (age, sex), type of subtotal colectomy (colocolostomy, ileocolostomy, jejunocolostomy), technique of anastomosis (sutured or stapled), preservation of ileocolic junction, postoperative complications and outcomes. The systematic research is described in Figure 1. A narrative review was performed, and all the included studies and their results are included in Table 2.

Results

A total number of 7117 studies were found. The 6763 studies were excluded because they were not relevant, they were studies in non-English language, or they were referred to other species. From the 354 studies that were assessed for eligibility, 341 were excluded because they were duplicate, review articles or chapters in books or they did not include subtotal colectomy as treatment for megacolon. Finally, 13 studies reporting subtotal colectomy for treatment of megacolon in cats were chosen. The studies that were selected were published from 1986 until 2018. There were 2 case reports, 8 retrospective studies and 3 experimental studies.

In all studies included in this review megacolon in male cats prevailed. The younger cat reported, aged 1 month and the older 16 years (Haan et al. 1992, Washabau & Stalis 1996). In most reports, megacolon was reported frequently in Domestic short-haired cats (Bright et al. 1986, Gregory et al. 1990, Matthiesen et al. 1991, Haan et al. 1992, Kudisch & Pavletic 1993, Sweet et al. 1994, Ryan et al. 2006, Ganesh et al. 2018). Other breeds that were reported are Siamese, Manx, Domestic long-haired, Himalayan, Maine Coon, Persian, Russian Blue and British short-haired cats (Bright et al. 1986, Haan et al. 1992, Kudisch & Pavletic 1993, Sweet et al. 1994, Ryan et al. 2006, Barnes 2012 ). In most reports, cats that underwent colectomy were diagnosed with idiopathic megacolon. The main indication for surgery was a history of constipation varying in duration from weeks to years that was unresponsive to medical management. Rosin et al. (1988) reported 38 cases of idiopathic megacolon. In this report 4/38 cases had pelvic fractures, but these did not seem to restrict defecation, so all cases were considered as idiopathic. Schrader (1992) -1 case- and Matthiessen et al. (1991) -11 cases- reported subtotal colectomy as a treatment for megacolon secondary to pelvic fracture malunions. Kudisch and Pavletic (1993) reported 1/15 case of megacolon caused by pelvic fracture. In the retrospective study of Sweet et al. (1994), 6/22 cases had megacolon secondary to pelvic fracture treated with subtotal colectomy. Finally, Ganesh et al. (2018) also reported subtotal colectomy as treatment for megacolon caused by neurologic trauma. This diagnosis was based on ruling out all other possible causes.

The types of colonic resection and anastomosis in the reported studies include colocolostomy (colon to colon anastomosis), ileocolostomy (ileum to colon anastomosis) and jejunocolostomy (jejunum to colon anastomosis). Kudisch and Pavletic (1993), Washabau and Stalis (1996) and Ryan et al. (2006) used subtotal colectomy with colon to colon anastomosis as the treatment of choice. Colon to colon anastomosis was also the treatment of choice in some of the cases in the study of Bright et al. (1986) -2/4 cases-, Gregory et al. (1990) -3/4 cases-, Haan et al. (1992) -1/8 cases-, and Sweet et al. (1994) -14/22 cases. An enterocolostomy, either an ileocolostomy or a jejunocolostomy was performed in the remaining studies (Bright et al. 1986, Rosin et al. 1988, Matthiessen et al. 1991, Haan et al. 1992, Sweet et al. 1994, Barnes 2012, Garnesh et al. 2018). The ileocolic junction was preserved in some of cases where a colocolostomy was performed (Bright et al. 1986, Gregory et al. 1990, Kudisch & Pavletic 1993, Sweet et al. 1994, Washabau & Stalis 1996, Ryan et al. 2006, Barnes 2012). The anastomosis was performed by sutures in most of the cases, with surgical stapling instruments (Kudisch & Pavletic 1993) or with the use of a biofragmentable anastomosis ring (Ryan et al. 2006). In most of the reports an end-to-end anastomosis was performed in one or two layers with an absorbable or non-absorbable suture. In some cases of the studies included in this review an end-to-side anastomosis was performed (Bright et al. 1986, Gregory et al. 1990, Haan et al. 1992). The suture pattern of choice in most of the reports was a simple interrupted pattern (Rosin et al. 1988, Bertoy et al. 1989, Gregory et al. 1990, Matthiesen et al. 1991, Haan et al. 1992, Sweet et al. 1994, Ryan et al. 2006, Barnes 2012, Ganesh et al. 2018).

The most common postoperative complications of subtotal colectomy that were reported are vomiting (Rosin et al. 1988, Ryan et al. 2006), anorexia for 1-4 days (Bright et al 1986, Rosin et al. 1988, Matthiessen et al. 1991, Sweet et al. 1994, Ryan et al. 2006), lethargy-depression (Sweet et al. 1994), pyrexia (Bright et al. 1986, Haan et al. 1992), diarrhoea (Rosin et al. 1988, Kudisch & Pavletic 1993, Sweet et al. 1994, Barnes 2012), tenesmus (Bright et al. 1986, Rosin et al. 1988, Kudisch & Pavletic 1993), constipation (Rosin et al. 1988, Sweet et al. 1994), soft stools (Matthiessen et al. 1991, Haan et al. 1992, Sweet et al. 1994, Barnes 2012), faecal incontinence (Haan et al. 1992, Sweet et al. 1994), anaemia and shock (Kudisch & Pavletic 1993, Ryan et al. 2006), abscess formation (Rosin et al. 1988) and dehiscence (Matthiessen et al. 1991, Ryan et al. 2006). The main long-term complications included persisting diarrhoea (Rosin et al. 1988, Haan et al. 1992), soft, semisolid stools (Bright et al. 1986, Rosin et al. 1988, Haan et al. 1992, Ryan et al. 2006, Barnes 2012), faecal incontinence (Sweet et al. 1994, Ryan et al. 2006) and recurrence of obstipation (Rosin et al. 1988, Matthiessen et al. 1991, Haan et al. 1992, Sweet et al. 1994, Ryan et al. 2006).

Discussion

Based to the studies included in this review, subtotal colectomy seems to be the treatment of choice for idiopathic megacolon in cats. It has also been used as treatment following recurrence of obstipation in a cat with a pelvic canal stenosis, which was previously treated with pelvic osteotomy (Schrader 1992). Matthiessen et al. (1991) also described the use of subtotal colectomy for treatment of obstipation due to pelvic fracture malunions, and it is recommended that cats with megacolon secondary to pelvic fractures of 6 months duration can be only treated by subtotal colectomy since after this period the colonic function was permanently disturbed.

In the present study the most common cause of megacolon in cats is idiopathic megacolon. The studies that included cats with megacolon secondary to pelvic malunions, where a colectomy is not performed. From this review it seems that male cats are overrepresented, and the clinical signs were manifested in ages from 1 month to 16 years, with most of the cats being middle aged (Haan et al. 1992, Washabau & Stalis 1996).

In the studies that were reviewed, a colon to colon anastomosis or an enterocolostomy, (ileocolostomy or a jejunocolostomy) were performed. In almost all studies, the distal margin for the colectomy was about 2-4 cm proximal to the pelvic brim. The reason for performing an ileocolostomy or jejunocolostomy was to facilitate the anastomosis due to reduced tension in the anastomosis site (Bright et al. 1986, Rosin et al. 1988, Haan et al. 1992). The disadvantage of this technique is the removal of the ileocolic junction, which can lead to bacterial overgrowth due to reflux of the microorganisms in the small intestine and long-term production of loose stools (Rosin et al. 1988, Sweet et al. 1994). Sweet et al. (1994) compared 22 cats that underwent colectomy because of megacolon with or without preservation of the ileocolic valve and found no difference in the early postoperative period, but those cats where the ileocolic valve was excised had softer stools. However, Haan et al. (1992), Bertoy et al. (1989), and Rosin et al. (1988) suggest subtotal colectomy with excision of the ileocolic valve, because the surgical technique is easier due to the less tension in the anastomosis site. In all these studies cats had softer faeces but only Haan et al. (1992) described one cat with postoperative bacterial overgrowth, which was treated with oral antibiotics.

Another technique for subtotal colectomy that has been described is the use of surgical stapling devices for the colocolonic anastomosis (Kudisch & Pavletic 1993). In this study, 15 cats underwent a subtotal colectomy with the use of a stapling device and no long-term complications were noted. Stapling is an alternative way for the colocolonic anastomosis and the main advantage against suturing is that is less time consuming, as long as the surgeon is experienced in the use of these devices. The use of a biofragmentable anastomosis ring (BAR) showed no difference versus the sutured anastomosis. The BAR cats (8/19) had more intraoperative complications including serosal tearing due to difficulty during the placement of the device (Ryan et al. 2006). Finally, Barnes (2012) described a new technique for subtotal colectomy via a rectal pull-through technique in two cats. This technique seems to have less risk for dehiscence and peritonitis and is an easier technique with no need of pubic osteotomy compared to the conventional colectomy. However, it is suggested that more cases are needed to investigate the efficacy of this method and to compare with the conventional colectomy via midline laparotomy.

In most of the studies, an end-to-end anastomosis of the colon was preferred in either a continuous or a simple interrupted pattern with either an absorbable or non-absorbable suture material. An end-to-side anastomosis was performed in some of the studies (Bright et al. 1986, Gregory et al. 1990, Haan et al. 1992). Gregory et al. (1990) used the end-to-side anastomosis in 1/4 cats due to the increased tension in the anastomosis site. In some of the studies included in this review, a two-layer anastomosis was performed to increase the strength of the anastomosis (Bright et al. 1986, Rosin et al. 1988, Bertoy et al. 1989, Matthiessen et al. 1991). For the second layer a continuous Lembert or Cushing pattern was chosen. It seems that the suture technique does not play an important role in the outcome. For the reduction of the diameter disparity between the two segments of the anastomosis either the large diameter segment was oversewn (Matthiessen et al. 1991) or the small diameter segment was cut in an angle (Rosin et al. 1988) to increase the lumen diameter and then spatulated to the antimesenteric border (Bertoy et al. 1989, Ganesh et al. 2018). Suturing technique does not seem to affect outcome.

Among the postoperative complications of the subtotal colectomy, dehiscence of the anastomosis and bacterial peritonitis were reported in two cases (Matthiessen et al. 1991, Ryan et al. 2006). In one of the cats (Matthiessen et al. 1991) peritonitis was developed in day 14 and was considered to be the result of a large faecalith. The other cat (Ryan et al. 2006) developed a dehiscence 36 hours after surgery because the colon segments were not included in the BAR. Both cats had a second surgery and survived. Sweet et al. (1994) reported one cat with postoperative constipation, which was finally euthanized one month later. Postoperative pyrexia, tenesmus, vomiting, and anorexia seem to be frequent but minor complications, which were resolved during hospitalisation (Bright et al. 1986, Rosin et al. 1988, Matthiessen et al. 1991, Haan et al. 1992, Kudisch & Pavletic 1993, Sweet et al. 1994, Ryan et al. 2006). Only Rosin et al. (1988) reported one cat with postoperative vomiting who had concurrently constipation for three weeks and finally diagnosed with a stricture in the anastomosis site and was finally resolved using 3 balloon-catheter dilatations in 1-month intervals. A stricture was also diagnosed in the study of Ryan et al. (2006) which was treated by revision surgery and re-anastomosis with a stapler device. Almost all cases had diarrhoea with soft, semi-formed faeces postoperatively, usually for 1-8 weeks (Rosin et al. 1988, Matthiessen et al. 1991, Haan et al. 1992, Kudisch & Pavletic 1993, Sweet et al. 1994, Barnes 2012). Another postoperative complication that has been reported is incontinence (Haan et al. 1992, Sweet et al. 1994, Ryan et al. 2006). Haan et al. (1992) reported that in all cases incontinence, which lasted days to weeks, was resolved without treatment. Sweet et al. (1994) reported 4 cats with incontinence that did not resolve due to intermittent diarrhoea or soft stools and Ryan et al. (2006) reported one cat with non-resolving incontinence, which was finally euthanized 254 days postoperatively. Kudisch & Pavletic (1993) also reported two cats with postoperative bleeding and haematocrit reduction, which was resolved with blood transfusion and attributed to a small colic artery bleeding.

The main long-term complication after subtotal colectomy is soft stool defaecation with faeces starting to become more solid 2 months after surgery (Bright et al. 1986, Rosin et al. 1988, Haan et al. 1992, Kudisch & Pavletic 1993, Sweet et al. 1994, Ryan et al. 2006). Sweet et al. (1994) correlated soft stools with the excision of the ileocolic valve and so it is recommended the valve to be preserved if possible. Persisted diarrhoea was reported in two cases that were treated with diet and with metronidazole in one of the cases (Rosin et al. 1988, Haan et al. 1992). Another long-term complication, which was observed is the recurrence of constipation (Rosin et al. 1988, Matthiessen et al. 1991, Haan et al. 1992, Sweet et al. 1994, Ryan et al. 2006). Rosin et al. (1988) reported 3/38 cats with recurrence of constipation, which resolved either with digital removal and stool softeners or with a diet change with dry food. Matthiessen et al. (1991) reported 2/11 cats with recurrence of constipation, which was treated with stool softeners and enemas in one cat and enemas and digital removal in the second cat, who was euthanized 24 months postoperatively due to constipation. Haan et al. (1992) reported 1/8 cats with recurrence of constipation, which was not responsive to medical treatment and was treated with a second colectomy. Sweet et al. (1994) reported 9/22 cats with recurrence of constipation. Four of them were treated with a second colectomy, with excision of the ileocolic junction, 2/9 were successfully treated with enemas and 3/9 were euthanized. Finally, Ryan et al. (2006) reported 1/19 cats with postoperative constipation, which was treated with lactulose, cisapride and one enema. It seems that preservation of ileocolic valve does not affect recurrence of constipation.

The limitations of this study include the small number of studies that entered the analysis, their retrospective nature, and the absence of statistical analyses, which could help drawing conclusions and recommendations for clinical practice.

Conclusions

In conclusion, subtotal colectomy seems to be the treatment of choice for idiopathic megacolon in cats. The technique of colonic resection and anastomosis does not seem to affect the outcome. From this review it becomes obvious that anastomotic dehiscence and bacterial peritonitis are rare, so colectomy is considered as a safe surgical procedure. Owners should be warned about soft stool defecation for about two months after surgery, while incontinence, persistent diarrhoea, and recurrence of constipation seem to be rare.

Conflict of interest

The authors declare no conflicts of interest.

References

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Published

2020-12-31

How to Cite

Angelou, V., Chatzimisios, K., Seltsa, T. and Papazoglou, L. (2020) “Subtotal colectomy for the treatment of megacolon in cats”, Hellenic Journal of Companion Animal Medicine, 9(2), pp. 157–170. Available at: https://hjcam.hcavs.gr/index.php/hjcam/article/view/4 (Accessed: 25June2021).

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