Introduction
Megacolon is defined as the persistent and irreversible dilatation of the colon along with severe hypomotility followed by permanent loss of bowel function leading to chronic constipation or obstipation [1,2]. It is likely associated with the paralysis of the peristaltic movements of the bowel. Cats of any age can be affected by megacolon, although cats over 6 years of age are more commonly presented with this disorder [2,3].
Both acute and chronic megacolons have been reported; acute cases result from severe inflammatory conditions of the bowel without any mechanical obstruction, whereas chronic cases appear to be of congenital or acquired origins [4]. A chronic megacolon is often filled with dried feces, which cannot be evacuated and may involve the ascending, transverse, and descending portions of the colon [5]. Acquired cases of megacolon are most often idiopathic; other reported causes of acquired megacolon in cats include pelvic fractures, colonic, rectal, or anal strictures and masses, neurological conditions, and other reasons for pelvic outlet obstruction [1–3]. Congenital megacolon in cats is believed to be the consequence of birth defects similar to Hirschsprung’s disease seen in humans. In this condition, colonic aganglionosis or hypoganglionosis occurs, and lack of peristalsis results in the retention of fecal material [3].
The affected cats are often reported with a history of constipation for several days to weeks, prolonged inappetence, tenesmus, hematochezia, depression, general weakness, vomiting, and dehydration; and the defecated feces have often been dry, hard, and scanty [2,6]. Diagnosis is usually based on abdominal palpation with the presence of a distended colon filled with firm feces. Abdominal radiography is typically used to confirm the diagnosis [7], and surgical intervention, such as subtotal colectomy, is considered the preferred treatment, especially in cases that have failed to respond to medical management [1,3,5,8].
In this case report, the clinical diagnosis of chronic megacolon along with the subsequent surgical treatment is described in a kitten.
Case Description
Case history and clinical examination
A 5-month-old, female (entire), domestic shorthair kitten of 2.27 kg body weight (BW) was presented to the Veterinary Teaching Hospital (VTH) of Bangladesh Agricultural University (BAU) with a history of straining to defecate for more than 6 weeks and a complete absence of defecation for 9 days. The kitten was fed on boiled rice and chicken, cooked fish, and formulated kitten milk. The owner reported that the kitten had shown 8 days of marked hyporexia, progressing to anorexia at the time of presentation. There was no history or clinical evidence of pelvic injury, overt neuromuscular disorders, or congenital anomalies such as atresia ani or rectovaginal fistula; normal feeding, defecation, and urination had routinely been noted by the owner before the reported clinical signs started. Before admission to the hospital, the cat had undergone 3 days of medical management with oral laxatives/purgatives followed by an enema with soap water and lactulose mixture twice daily, as supplied by a nearby vet pharmacist. However, this was unsuccessful, and obstipation persisted. During the clinical examination at the hospital, the kitten was found to be severely dehydrated, emaciated, dull, and recumbent (Fig. 1A). Mild tachycardia was noted alongside intermittent vocalizations (groaning noises). Hematology and biochemistry were not performed at the presentation, but parenteral, i.e., intravenous (IV), fluid therapy was initiated at the outset with 30 ml/kg BW of normal saline (0.9% NaCl solution) being given as a bolus over 12 minutes.
Clinical diagnosis
After initial fluid resuscitation, a thorough physical examination and radiographs were performed. The caudoventral abdomen appeared visually distended (Fig. 1B), with firm tubular structures being evident on deep palpation leading toward the pelvic inlet. The lateral abdominal radiograph (Fig. 2) revealed marked distension of the colon alongside fecal impaction, this was considered most consistent with megacolon. Based on the history, examination, and imaging findings, a presumptive diagnosis of chronic megacolon was made.
Treatment and Outcome
Preoperative procedures, subtotal colectomy, and colo-colonic anastomosis
Preoperatively, the kitten was stabilized with IV administration of a further 50 ml of 5% dextrose in normal saline given over 16 minutes. Following the owner’s consent, a decision was made to proceed with subtotal colectomy. To execute the surgery, the animal was premedicated with atropine sulfate at 0.04 mg/kg BW (Atrovet®, Techno Drugs Ltd., Narsingdi, Bangladesh) followed by deep sedation with xylazine hydrochloride (HCl) at 1.1 mg/kg BW (Xylaxin®, Indian Immunologicals Ltd., Hyderabad, India) intramuscularly (IM). After 7 minutes, ketamine HCl at 15.5 mg/kg BW (KetalarTM, Popular Pharmaceuticals Ltd., Dhaka, Bangladesh) was administered IM for the induction of general anesthesia. Presurgical aseptic preparations were carried out over the surgical field including the ventral abdominopelvic region and adjacent portions of hind quarters. Under general anesthesia, the kitten was placed in dorsal recumbency and a ventral midline incision of 6.5 cm in length was made, beginning approximately 2 cm caudal to the umbilicus and extending in the direction of the pubic symphysis. Exploratory laparotomy initially revealed distension of the urinary bladder, jejunum, and ileum (Fig. 3A). Decompressive cystocentesis was performed to aid visualization of the caudal abdomen, revealing marked distension of the colon and associated fecal impaction. The ascending, transverse, and descending portions of the colon up to the colorectal junction (CRJ) were affected, and distally, the descending colon was severely impacted with dried fecal material, measuring 5.3 cm at the maximum diameter (Fig. 3B). At this level, a colotomy was performed to facilitate the removal of the fecal material (Fig. 3C), and this was closed with an interrupted pattern of modified Gambee suture using polyglactin 910 of size 3–0 (VicrylTM, Ethicon, J & J Medical Devices Companies, United States). The distal portion of the descending colon, adjacent to the CRJ, was subsequently returned to the abdominal cavity along with the urinary bladder. Next, the mesenteric blood vessels supplying the remaining colon were sequentially ligated with VicrylTM of size 4–0 and transected. The majority of the ascending colon, the entirety of the transverse colon, and a portion of the descending colon were then clamped (Fig. 3D) and resected (Fig. 3E). Proximally, a small portion of the ascending colon and associated ileocolic junction (ICJ) were preserved. The luminal disparities in diameter between the larger and smaller ends of the colon were minimized by transecting the antimesenteric border of the smaller end (ascending colon) at an angle more acute than that applied to the larger end. This type of angular transection allowed to increase in the luminal diameter of the smaller end, aligning it with the diameter of the larger end. Then, a hand-sewn, end-to-end colo-colonic anastomosis (Fig. 3F and G) was performed with a single layer of continuous extramucosal suture using VicrylTM of size 3–0 having the bisecting stitches (180° orientation) at the 3 and 9 o’clock positions to prevent the purse string effect due to the possible retraction of the intestine and thereby risks of stricture formation. These stitches were provided to maintain the luminal patency of the anastomosed part. The mesenteric rent was repaired, and thereafter, the intestinal segments were returned to the abdominal cavity. Normal saline at 10 ml/kg BW was used for peritoneal lavage. Then, the laparotomic incision was approximated in a routine manner, which involved layer-by-layer closures of the muscles, fascia, and subcutis with simple interrupted suture (Fig. 3H) using VicrylTM of size 1–0 and the skin with simple interrupted suture (Fig. 3I) using surgical silk (braided) of size 2–0 (Perma-Hand® Silk, Ethicon, J & J Medical Devices Companies, United States). The transected portion of the colon was not further considered for histopathological examinations due to the unwillingness of the owner and was subsequently discarded along with the evacuated fecal materials (Fig. 3J).
Figure 1.
Clinical presentation of the kitten. (A) Hospitalized kitten presenting dehydration, emaciation, lateral recumbency, and (B) distended abdominopelvic region (blue circle).
Figure 2.
The abdominal radiograph (lateral view) of the affected kitten showed the entire distended as well as impacted colon (red arrows) along with other structures, i.e., vertebral column (green dashes), lumbar vertebrae (yellow arrowheads), and surrounding organs. The X-ray film indicated that the maximum colonic diameter was almost more than 1.5 times the length of the L5 vertebral body, which was suggestive of a megacolon.
Postoperative follow-up and outcome
Postoperatively, the kitten was again provided with 50 ml of IV 5% dextrose in normal saline given over 15 minutes, with this fluid therapy set to be repeated twice daily. In addition, ceftriaxone sodium IM at 30 mg/kg BW (Triject®, Eskayef Pharmaceutical Ltd., Dhaka, Bangladesh) at every 12-hour interval, ketoprofen IM at 2.2 mg/kg BW (Ketovet, Techno Drugs Ltd., Narsingdi, Bangladesh) once daily, and pheniramine maleate IM at 1 mg/kg BW (Antihista-Vet®, Square Pharmaceuticals Ltd., Dhaka, Bangladesh) once daily were maintained. However, no appetite or defecation was noted during the postoperative follow-up, except for periodic urination. At approximately 54 hours postoperatively, the kitten showed a sudden decline, precluding the opportunities for further medical treatments. The death was marked by the onset of multiple seizures and intermittent subconsciousness followed by terminal shock, progressing to cardiopulmonary arrest (CPA) refractory to cardiopulmonary resuscitation (CPR). The postmortem examination was declined by the owner.
Figure 3.
Exploratory laparotomy findings, subtotal colectomy, and colo-colonic anastomosis in the kitten. (A) Exteriorized and distended urinary bladder filled with urine (black arrow), jejunum (blue arrow), and ileum (white arrow) and (B) severe distension of the colon affecting the ascending (black arrow), transverse (red arrow), and descending (blue arrow) portions, and the urinary bladder (white arrow) after decompressive cystocentesis. CRJ (yellow arrow) outlined the maximum diameter (5.3 cm) of the distal end of the impacted descending colon, (C) removal of impacted feces from the distal descending colon through an incision (black arrow), close to the urinary bladder (blue arrow), (D) clamping (black arrows) of the affected segments of the colon, (E) resection of the clamped segment including an angular transection at the smaller end (black arrow) to match up the diameter of the larger end (white arrow), (F) initiation of hand-sewn anastomosis (yellow circle) of the larger end (blue arrow) to the transected smaller end (white arrow) of the colon with extramucosal pattern of suture, (G) the completed end-to-end, colo-colonic anastomosis (white rectangle), (H) closure of muscles/fascia with the simple interrupted pattern of suture, (I) closure of skin with the simple interrupted pattern of suture, and (J) the discarded segment of the colon (black arrow) and the evacuated feces (white circle).
Ethics statement
This report describes a case that was managed as part of the BAU VTH’s routine clinical caseload; therefore, ethical approval for animal care and welfare was not required. Informed consent for publication was obtained from the animal owner, along with permission from the director of the hospital.
Discussion
Constipation and megacolon are serious gastrointestinal conditions often observed in middle-aged cats, with males being more commonly affected than females [9]. It has been reported that an increased frequency of megacolon is seen in domestic shorthair and longhair, Siamese, and Manx cats, suggesting a breed predisposition [2,3,10]. This case report describes the diagnosis and treatment of megacolon in a 5-month-old, female, domestic shorthair kitten, representing a very unusual age and less common sex for this condition. To the best of our knowledge, this type of case is not frequently reported.
This case was considered chronic given the reported constipation for 40 days and obstipation for 9 days. Most cases of long-term bowel dysfunctions, such as chronic megacolon, are idiopathic in cats [3,5]. This case was termed idiopathic because the identifiable causal factors associated with feline megacolon, as documented in pertinent investigations [1–3], were not evident in this study. The clinical signs found in this kitten were similar to those previously reported in other cases of megacolon [8,10]. Mild tachycardia of the kitten was noted, which might be because of the slight increase in heart rate to compensate for the circulation, as blood flow per minute through the whole body was insufficient due to suspected hypovolemia from dehydration. Intermittent groaning was found which might be attributed to a typical vocal response to the illness. A hematobiochemical analysis was not performed in this case, although it would have been recommended given the critical presentation. This may have allowed the detection and correction of hypovolemia and electrolyte abnormalities, thus improving preoperative stabilization, as investigated earlier [11].
Abdominal radiography for the large intestine, especially to estimate the size (i.e., diameter) of the colon, is conventionally performed to diagnose the megacolon. The ratio of the maximum diameter of the colon to the length of the fifth lumbar (L5) or seventh lumbar (L7) vertebral body is often considered when assessing radiographs. A ratio of less than 1.28 is highly indicative of a normal colon, whereas a megacolon typically shows a ratio of greater than 1.48 or 1.50 [3,9,12,13]. Although the obtained radiograph was of suboptimal diagnostic quality, it appeared that at least one area of the colon was distended above 1.5 times the length of the L5 vertebra. This led to a presumptive diagnosis of chronic idiopathic megacolon. The primary finding during exploratory laparotomy was severe distension of the colon with a notable impaction in the distal portion, and it confirmed the diagnosis of megacolon.
In this case, the urinary bladder was distended, a finding that has also been reported previously [2]. This might be because the urinary retention, in this case, was physiological secondary to general anesthesia or represented extraluminal urethral obstruction caused by the markedly distended distal colon and rectum.
Surgical treatment was pursued in this case via subtotal colectomy, a procedure that has been reported by several authors for the management of obstipation and megacolon in small animals [5,14]. Other surgical procedures described for the treatment of megacolon in cats include partial colectomy, total colectomy, and coloplasty [1,9,15]. Surgery is indicated in cases of megacolon which are refractory to medical management because prolonged constipation causes irreversible changes in the colonic wall, altering function [8]. In this case, subtotal colectomy with preservation of the ICJ was performed, however subtotal colectomy with or without preservation of the ICJ has been described [16]. The importance of preserving the ICJ where possible has been well documented. The ICJ internally contains the ileocolic sphincter which controls the movement of ingesta, allowing movement in an aboral direction from the ileum to the colon and preventing reflux of ingesta from the colon into the ileum [9,17]. As such, preservation of the ICJ has been found to reduce the development of diarrhea postoperatively [5,18,19]. Conversely, removal of the ICJ may cause intestinal bacterial overgrowth from large intestinal microbial reflux, resulting in diarrhea. In this case, the distal portion of the colon adjacent to the CRJ was preserved after manual evacuation of feces, to facilitate anastomosis without tension. While the decision meant a small portion of the abnormal colon was left in situ, it was felt that the smaller size of this segment would be unlikely to lead to recurrent impaction.
Polyglactin 910 (VicrylTM) was used to perform the intestinal anastomosis and closure of the fascia/muscle, as previously reported [20]. Generally, polydioxanone (PDS) is the suture of choice for intestinal closure for its long durability, tensile strength, and pliability [1,2,8]. PDS was not used in this case due to its unavailability during the emergency surgical intervention. The premedication, sedation, and anesthetic induction protocols used in this kitten are correlated with those of other studies [2,21–23]. Although ketamine injectable anesthesia would not be the gold standard for anesthesia in a critical patient, it was considered in this case as suitable gaseous anesthesia was not available.
Before surgery, several medicinal and conservative treatment protocols can be considered for the management of constipated cats with suspected megacolon. The mainstay of medical management includes high dietary fibers, fluid therapy, fecal softening with laxatives (lactulose/docusate sodium) or emollients (mineral oil), and lubrication with soapy or warm-water enemas; in addition, uses of prokinetic agents (e.g., cisapride, ranitidine, nizatidine, and so on) and sometimes digital manipulation to evacuate feces have been reported [8,19,24–26]. Surgical management is recommended in cases that fail to respond to medical management. Preoperative care and management are important in critically ill patients. In this case, provisional care was taken with tentative fluid therapy before surgery. However, ideally, the preoperative care should have included biochemical and electrolyte analysis and correction of electrolyte imbalance and dehydration, before pursuing megacolon surgery.
Postoperatively, supportive medications including fluid therapy were given to the kitten to manage and prevent further dehydration and complications from infections, pain, and tissue reaction. Intermittent urination was observed during the postoperative phase, a phenomenon that could potentially be attributed to urinary excretion facilitated by fluid therapy. Despite these, the kitten died after 2 days of surgery due to presumed decompensated shock and CPA irresponsive to CPR. The reason for deterioration and death was not confirmed as postmortem examination was declined. The reasonable differential diagnoses included cardiovascular collapse due to ongoing dehydration, stress from anesthesia and surgery, possible electrolyte imbalances and organ dysfunction, versus dehiscence of the anastomosis site and septic peritonitis.
Subtotal colectomy is generally the recommended treatment option for cats with megacolons that have failed medical management [1,8,5]. The surgery is generally well tolerated but occasionally may lead to postoperative complications, i.e., stricture at the anastomosis site, peritonitis from leakage of the anastomosis, persistent diarrhea, tenesmus, and recurrent constipation [4,27–29]. In this case, the kitten was presented in a critical condition, which made its prognosis guarded from the outset. The outcome of the surgical intervention was unsatisfactory due to the uncertain death, which might be ascribed to the ignorance or failure of the animal owner to observe the problem at the proper time and the immediate approach for treatment. That being said, the authors recognize that several points in the management of the case could have been improved, as discussed above, although this may not have changed the outcome.
Conclusion
This case describes an idiopathic megacolon (chronic) in a kitten, which has been anecdotally reported. This condition should be part of the differential diagnoses in kittens with constipation, and it can be life-threatening if not treated appropriately and promptly.
List of Abbreviations
BAU, Bangladesh Agricultural University; BW, Body weight; CPA, Cardiopulmonary arrest; CPR, Cardiopulmonary resuscitation; CRJ, Colorectal junction; HCl, Hydrochloride; ICJ, Ileocolic junction; IM, Intramuscular; IV, Intravenous; L5, Fifth lumbar; L7, Seventh lumbar; PDS, Polydioxanone; VTH, Veterinary Teaching Hospital.
Acknowledgment
The authors highly appreciate the facility provided by the VTH of BAU to perform the surgery.
Conflict of interests
The authors declared that there is no conflict of interest.
Funding
The authors declared that this study has received no financial support.
Authors’ contribution
MRM contributed to the radiographic interpretation, surgical intervention, and postoperative follow-up along with manuscript finalization. MSS assisted during the surgery and collected data and documents for the manuscript draft. Both authors have read and approved the final manuscript.
