Colostomies for two lizards with cloacal prolapse

Abstract

Two captive-bred lizards, a Western spiny-tailed iguana (Ctenosaura pectinata) and a bearded dragon (Pogona vitticeps), were evaluated for anorexia and absence of feces. The iguana had a recent cloacal prolapse, whereas the dragon had a repaired prolapse 20 days earlier. Exploratory celiotomy under anesthesia revealed a devitalized distal colon in the iguana and stenosis of ductal organs in the pelvic cavity in the dragon, leading to colostomies. Stomal stenosis, managed through dilation, was the main complication. Both gained weight within 1,000 days post-surgery. At 2,152 days, the iguana weighed 166 g; the dragon, which died at 1,792 days, weighed 274 g. Colostomies may benefit lizards with distal colon or cloaca damage that can still urinate, as demonstrated in this report.

Prolapse in reptiles is a relatively rare condition encountered by clinical veterinarians [8]. This condition has been reported in Sauria, Ophidia, Chelonia, Sphenodontia, and Crocodilia [10, 11, 14,15,16,17], with higher occurrence in chelonians and lizards than in snakes [8]. Prolapse is caused by the reversal of the colon, cloacal tissue, bladder, oviduct, or hemipeni, even without the reversal of the phallus [8]. A common treatment is the restoration of cloacal prolapse with or without celiotomy. For the treatment of prolapse of the oviduct, hemipeni, and phallus, these organs may be removed [3]. However, a colonic prolapse is considered life-threatening and usually indicates deeper medical issues [14]. In cases of colonic prolapse, the colon is often swollen or strangulated, and the tissue may become necrotic or traumatized, making common treatment impossible [9, 13]. In cases of partial colon necrosis, after excision of the necrotic tissue, inverted end-to-end intestinal anastomosis can be performed [13]; however, effective treatment for cases where necrosis of the distal colon extends to the intrapelvic position has not been reported.

In the present report, we describe colostomies performed in two captive-bred lizards (Ctenosaura pectinata and Pogona vitticeps) with damage to the lumen structure of the distal colon or the cloaca due to cloacal prolapse to enable defecation and sustain life.

Case 1: Western spiny-tailed iguana

A captive-bred 1-year-old male Ctenosaura pectinata weighing 48 g was referred to our veterinary hospital for evaluation of anorexia, absence of feces for 14 days, and cloacal prolapse 2 days prior to presentation. The lizard was kept alone in a glass terrarium measuring 45 × 30 × 30 cm, with a wire mesh cover and a coconut fiber substrate. The temperature inside the terrarium was between 30°C, and the relative humidity was not adjusted. Lighting was performed using commercially available halogen lamps and ultraviolet B fluorescent (UVB) lamps, with a light cycle of 12 hr. Fresh drinking water was always available. The lizard was fed only leafy vegetables without calcium supplements. During the initial physical examination, visual observations revealed an unidentified devitalized organ (Fig. 1A) and uric acid excretion from the vent. Analysis of the blood drawn from the caudal vein revealed hypocalcemia (Table 1). X-ray examination revealed bloating of the colon, and 30 hr after the oral administration of iohexol (5 mL/kg oral gavage with sonde, Iohexol 300 injection; Fuji Pharma Co., Ltd., Toyama, Japan), a filling defect from the distal colon to the vent was indicated (Fig. 2A and 2B). Based on these results, colonic prolapse with hypocalcemia was clinically diagnosed, and the urodeum was determined to be functional. To treat hypocalcemia, the patient began to receive oral calcium powder for nutritional improvement. Two days after the initial evaluation, an exploratory celiotomy was performed. Anesthesia and analgesia were induced with midazolam (0.5 mg/kg, intramuscular, Dormicum inj.; Astellas Pharma, Tokyo, Japan), alphaxalone (10 mg/kg, intramuscular, Alfaxan; Meiji Seika Pharma, Co., Ltd., Tokyo, Japan) and morphine (3 mg/kg, subcutaneous, morphine hydrochloride injection; Daiichi Sankyo Co., Ltd., Tokyo, Japan). The lizard was intubated with an uncuffed endotracheal tube and anesthesia was maintained with 3.0−3.5% isoflurane (Isoflurane Inhalation Solution; Pfizer, Tokyo, Japan) in oxygen (2 L/min). A mechanical ventilator (COMPOS X; Metan Co., Ltd., Saitama, Japan) provided an intermittent positive pressure of 6 cmH₂O with a respiratory rate of 3 breaths per minute. The lizard was placed in the dorsal recumbent position on a warming blanket (32°C) and septically prepared for a ventral right paramedian celiotomy. Heart rate was continuously monitored using an electrocardiogram. Local anesthesia was provided by infiltrating lidocaine (1 mg/kg, lidocaine 2% injection local anesthetic, 100 mL; MWI Veterinary Supply Co., Boise, ID, USA) along the incision site. After exposure of the coelom, gentle traction of the colon revealed devitalization of the distal colon (Fig. 1B). Both ends of the devitalized distal colon were ligated at presumed healthy levels, and the devitalized distal colon was resected. A 2-cm longitudinal incision was made on the ventral side of the healthy colon, and the incision margin was sutured to the skin and the coelomic wall using a simple interrupted pattern with a 5–0 polydioxanone monofilament suture (PDS II Suture 5–0; Ethicon, Cincinnati, OH, USA) (Fig. 3A–D).

Fig. 1.

Photograph of the devitalized distal colon in Case 1. (A) The devitalized organ from the vent (arrow). (B) The devitalized distal colon observed during celiotomy (arrow).

Table 1. Blood biochemical variables and packed cell volume for two lizards with cloacal prolapse.

No, species	UA (mg/dL)	Ca (mg/dL)	P (mg/dL)	Glu (mg/dL)	TP (g/dL)	Alb (g/dL)	Glb (g/dL)	Na (mmol/L)	K (mmol/L)	AST (U/L)	PCV (%)
Case 1: Western spiny-tailed iguana	3.1 (0–8.2)	5.9* (6–18)	9.6 (2.5–21)	101 (169–288)	5.6 (4.1–7.4)	2.7 (2.1–2.8)	2.9 (2.5–4.3)	135 (158–183)	2.5 (1.3–3)	32 (0–97)	32
Case 2: Bearded dragon	12.3 (5.2–8.2)	12.1 (12.0–12.3)	3.1 (3.8–5.0)	327 (218–356)	6.5 (4.1–6.2)	2.7 (1.8–2.7)	3.8 (2.2–3.4)	140 (150–155)	3.1 (3.4–4.1)	16 (4–10)	39

UA, Uric Acid; Ca, Total calcium; P, Phosphorous; Glu, Glucose; TP, Total protein; Alb, Albumin; Glb, Globulin; AST, Aspartate transaminase; PCV, Packed cell volume. Reference interval in parentheses [5, 19]. *Values out of the reference ranges.

Fig. 2.

Radiographs for Case 1. Dorsoventral (A) and right lateral (B) radiographs, taken 30 hr after oral administration of iohexol, demonstrate colon bloating and a filling defect extending from the distal colon to the vent (arrow).

Fig. 3.

Photograph of the colostomy in Case 1. (A) The devitalized distal colon was ligated at presumed healthy levels and subsequently resected. (B) 2-cm longitudinal incision was made on the ventral side of the healthy colon. (C) The incision margin was sutured to the skin and coelomic wall using a simple interrupted pattern. (D) Appearance of the stoma immediately after surgery. (E) Stomal stenosis observed 1 month post-surgery. (F) The stoma following dilation.

The histopathological findings of the devitalized distal colon that was resected consisted of degenerated tissue with no evidence of neoplastic changes, and some areas showed infiltration of inflammatory cells.

The lizard was administered ceftazidime (20 mg/kg, subcutaneously; Modacin; Nippon Glaxo Co., Ltd., Tokyo, Japan) every 72 hr for 15 days. Appetite returned to normal within 2 days postoperatively. The plasma calcium value was 12.2 mg/dL in the blood test 21 days postoperatively. The postoperative complications included stomal stenosis on multiple occasions. To date, stomal dilation by incision of the stenotic skin with lidocaine (lidocaine injection 0.5%; Pfizer, Tokyo, Japan) via infiltration has been performed approximately once a month; each time, stomal stenosis was observed (Fig. 3E and 3F). After stomal dilation, topical silver sulfadiazine (GEBEN cream 1%; Mitsubishi Tanabe Pharma Corp., Osaka, Japan) was applied for 7 days. Defecation continued to be observed in small amounts. However, when insufficient defecation was observed, a saline solution (Seishoku 500 mL; Terumo Corp., Tokyo, Japan) was poured into the colon from the stoma to encourage defecation. The final stomal dilation by incision was performed 1965 days postoperatively, after which the stoma did not stenose and was maintained.

The lizard weighed 166 g and was healthy at the time of the final follow-up (2,152 days after surgery).

Case 2: Bearded dragon

A captive-bred 3-year-old male Pogona vitticeps weighing 367 g was referred to our veterinary hospital because it was still suffering from anorexia and absence of feces despite having been treated for cloacal prolapse at another animal hospital 20 days previously. The lizard had been suffering from constipation for approximately a year, defecating only once every 14 days. The lizard was kept alone in a glass terrarium measuring 60 × 30 × 36 cm, with a wire mesh cover and a corn cob substrate. The temperature inside the terrarium was 30–35°C, and the relative humidity was not adjusted. Lighting was provided using commercially available halogen lamps and UVB lamps, with a light cycle of 12 hr. Fresh drinking water was always available. This lizard was fed frozen crickets dusted with calcium powder as its staple food and a few leafy vegetables, fruits, and other foods as supplementary food.

During the initial physical examinations, visual observation revealed uric acid excretion from the vent. Analysis of blood drawn from the caudal vein revealed unremarkable plasma biochemistry and hematological findings. X-ray examination revealed colonic constipation (Fig. 4A and 4B). To confirm continuity from the cloaca to the colon, cloacocolonic lavage was attempted, although the catheter did not reach the colon, and narrowing of the lumen was suspected. Based on these results, a distal colon or cloacal lesion was suspected, and the urodeum was determined to be functional. Two days after the initial evaluation, an exploratory celiotomy was performed. Perioperative anesthetic management was performed in the same manner as in Case 1. After exposure of the coelom, a longitudinal incision was made in the colon to remove the feces that filled the colon. The contents of the feces were mostly made up of the exoskeletons of crickets. A catheter was advanced from the incision wound of the colon toward the vent, and the lumen at the intrapelvic position was confirmed to be stenotic. Therefore, a stoma was created as in Case 1 (Fig. 5A).

Fig. 4.

Radiographs for Case 2. Dorsoventral (A) and right lateral (B) radiographs showing colonic constipation (arrow).

Fig. 5.

Photograph of the stoma in Case 2. (A) The stoma immediately after surgery. (B) Stomal stenosis observed 2 months after the surgery. (C) The stoma after 1 week of dilation.

The lizard was subcutaneously administered ceftazidime (20 mg/kg) every 72 hr for 15 days. Appetite returned to normal within 3 days after surgery. The lizard was mainly fed leafy vegetables high in fiber and small amounts of crickets dusted with calcium powder. Postoperative complications and follow-up care were the same as in Case 1 (Fig. 5B and 5C). The lizard weighed 420 g and was healthy at the time of the final follow-up (1,127 days after surgery). On postoperative days 1,356 and 1,566, the patient experienced fecal impaction in the proximal colon. As there was no response to fluid therapy and lactulose (0.5 mL/kg, per os, Monilac syrup; Chugai Pharmaceutical Co., Ltd., Tokyo, Japan) administered every 24 hr for 7 days, fecal removal was performed via colotomy through a ventral right paramedian celiotomy. Thereafter, the patient’s weight decreased, and he died 1,792 days postoperatively with a weight of 274 g.

A pathological autopsy was performed. The width of the stoma was 1.4 cm, there was no stenosis, the stoma margin and colon were tightly adhered, and the opening immediately led to the colon lumen. The suture between the skin and colon could not be identified. The proximal colon was highly dilated to approximately 5.7 × 3.5 cm, containing a large amount of food residue, and there was an area of induration in part of the colon wall. The lumen of the cloaca contained a small amount of cloudy mucus, and the proximal part of the cloaca was indurated. The liver and spleen were highly atrophic and black. Histopathologically, the tissue lining the stoma was covered with stratified squamous epithelium from the stoma margin to approximately 1.5 mm of the colonic lumen. However, the lumen wall was composed of connective tissue with a highly developed smooth muscle layer around its periphery. The skeletal muscles distributed on the abdominal wall are confined to a portion of the stomatal margin. No inflammation was observed around the stoma or colon, and only a few ligatures were organized (Fig. 6). Hepatocytes were atrophied in the liver, no follicles were observed in the spleen, and numerous melanophages were observed in both organs.

Fig. 6.

Histopathological finding of the stoma in Case 2. The tissue lining the stoma was covered with stratified squamous epithelium from the stoma margin to approximately 1.5 mm of the colonic lumen. However, the lumen wall was composed of connective tissue with a highly developed smooth muscle layer around its periphery. Bar=5 mm.

Prolapse occurs when abdominal pressure increases for some reason [2]. Hypocalcemia is the most common cause of prolapse in young iguanas [2]. Prolapse may also be caused by gastroenteritis and constipation [2].

Constipation is a common presenting sign in bearded dragons, particularly in individuals with a history of not defecating for 1 to 2 weeks [2]. Constipation has various underlying causes, including an inappropriate husbandry environment, hypocalcemia caused by a lack of dietary calcium or UVB lighting, insufficient water sources, insufficient activity due to cages that are too small, and inappropriate food, such as hard-shelled insects [2].

In Case 1, hypocalcemia resulting from the non-use of calcium supplements was detected in the blood chemistry test, which was consistent with the cause of prolapse observed in young green iguanas. In Case 2, constipation was observed, a presenting sign commonly seen in bearded dragons, and the fecal contents were filled with the exoskeletons of crickets. It is recommended that bearded dragons be fed leafy vegetables high in fiber, a variety of insects, and small amounts of simple carbohydrates and high-fat larvae [1]. In Case 2, excessive feeding of crickets was thought to be one of the causes of constipation and prolapse.

A stoma is the exteriorization of a loop of the bowel from the anterior abdominal wall made during a surgical procedure for diversion or decompression of the remaining bowel [12]. A colostomy is a stoma-creation technique in which the colon is exteriorized [12]. It may be performed to treat a disease, relieve obstruction, or prevent contamination of the remaining bowel with fecal matter [12]. Numerous colostomy techniques are used in humans to bypass the distal gastrointestinal tract [12].

In veterinary clinical practice, there have been a few reports of colostomy, primarily involving dogs, cats, and calves [4, 7, 18, 20]. Among the reports on dogs, one case underwent ventral colostomy but died perioperatively as a result of peritoneal leakage of feces [7]. Four cases underwent left flank colostomy and survived for 3.5 to 7 months [7], whereas another case survived for 21 days following a short-term loop colostomy [18]. In a report on cats, one case involved a temporary end-on colostomy for fecal diversion and anal reconstruction [20]. For cows, there were 19 reported cases, all of which died within 2 to 60 days post-colostomy [4].

In the two cases reported here, ventral colostomies were performed rather than flank colostomies to avoid damaging the stoma created by the lizard scratching with its hind legs. The two lizards in this report were healthy and gained weight 1,000 days after stoma creation.

Regarding the management of defecation from the stoma, in dogs with a stoma, the main problem is dealing with fecal leakage due to a large amount of feces, and there are reports of adjusting the amount of feces using colon irrigation [21]. However, in the two cases reported here, defecation was sometimes insufficient after stoma creation. This indicates that the issue with defecation from the stoma is converse in dogs and lizards, emphasizing the necessity of investigating defecation from the stoma in lizards. In lizards, constipation is defined as the absence of defecation for 1 to 2 weeks [2]. Therefore, if defecation from the stoma does not occur within this time frame, it may be necessary to stimulate defecation by instilling saline solution into the colon through the stoma.

Stenosis of the colostomy occurs in 2–15% of human patients and is mainly due to ischemia, the process of skin scarring, nonspecific inflammatory disease of the colon, or residual neoplasia in the stoma [6]. The recommended treatments for stenosis of the colostomy in humans are mild serial dilation, the creation of a new stoma, and stenoplasty with triangular cuts [6]. Histopathologically, since there was no inflammation at the margins of the stoma in Case 2, stomal stenosis was thought to be due to the process of skin scarring. In dogs, interrupted seromuscular vertical mattress suture patterns have been used to prevent stomal stenosis; however, future studies are needed to determine whether this method can be applied to lizard skin composed of scales [18].

In the two cases reported here, stomal stenosis is the main complication and is effectively treated with stomal dilation [6].

In Case 2, stenosis of the ductal organs in the pelvic cavity was observed intraoperatively. The pathological autopsy revealed that the stenosis was due to induration of the proximal portion of the cloaca, which may have contributed to constipation. No cause of death related to the colostomy was identified during the pathological autopsy.

In conclusion, a colostomy was performed on lizards that damaged the lumen structure of the distal colon or the cloaca, which was capable of urinating by themselves. The colostomies described in this report could be clinically useful in lizards under these conditions.

CONFLICT OF INTEREST

The authors have nothing to disclose.