Submucosal resection via a transanal approach for treatment of epithelial rectal tumors - a multicenter study.

OBJECTIVE: To report complications and long-term outcomes after submucosal resections of benign and malignant epithelial rectal masses. STUDY DESIGN: Retrospective multicentric study. SAMPLE POPULATION: Medical records of 93 dogs at 7 referral hospitals. METHODS: Records were reviewed for surgical time, diagnosis, margins, complications, and recurrences. Survival of dogs was evaluated based on tumor types, categorized as benign, carcinoma in situ, and carcinoma. The Kaplan-Meier survival curve and Cox proportional hazards analysis were used to determine the association of a range of variables with recurrence and survival time. RESULTS: Duration of follow up was 708 days (range, 25-4383). Twenty-seven dogs (29%) developed complications. Recurrence was identified in 20/93 (21%), with 12/20 recurrent masses treated with repeat submucosal resection. Median survival was not reached in any group. The 1-,2-, 5-year survival rates for carcinomas were 95%, 89%, and 73% respectively. However, overall survival was longer for benign tumors than carcinomas (P = .001). Recurrence was more likely when complications (P = .032) or incomplete margins (P = .023) were present. Recurrence was associated with an increased risk of death (P = .046). CONCLUSION: Submucosal resection of both benign and malignant rectal masses was associated with a low rate of severe complications and prolonged survival in the 93 dogs described here. CLINICAL SIGNIFICANCE: Submucosal resection is a suitable technique for resection of selected rectal masses.

Evaluation of transanal minimally invasive surgery for submucosal rectal resection in cadaveric canine specimens.

OBJECTIVE: To evaluate the feasibility of transanal minimally invasive surgery (TAMIS) for submucosal rectal resection in large breed dogs. STUDY DESIGN: Cadaveric study. SAMPLE POPULATION: Canine cadavers (n = 6) weighing between 37.5 and 60 kg. METHODS: Dogs were positioned in sternal recumbency. After rectal cleansing, a transanal access platform was placed in the rectum, and a pneumorectum was established. An area of ventral rectal wall approximately 2 × 2 cm was resected in a submucosal plane by using laparoscopic instruments and submitted for histopathological evaluation. The rectal wall defect was closed with a single-layer continuous suture pattern with barbed suture. Postoperatively, the rectum was removed en bloc and evaluated for suture or surgical penetration of the serosal surface. RESULTS: Submucosal rectal resection was successfully completed by using TAMIS in all dogs. The median length of resected specimens after fixation was 24.5 mm (range 9.8-26.5). In two of six dogs, suture was macroscopically visible on the serosal surface, but no dogs had evidence of iatrogenic full-thickness surgical penetration of the rectum. The median distance from the aborad extent of the suture closure line to the anocutaneous junction was 35 mm (range, 35-105). CONCLUSION: Submucosal resection of the canine rectal wall was feasible in large breed dogs by using TAMIS. No evidence of full-thickness penetration of the rectal wall was seen in these cadaveric specimens. CLINICAL SIGNIFICANCE: Transanal minimally invasive surgery may provide an alternative minimally invasive approach for resection for benign adenomatous rectal polyps in large breed dogs that might otherwise require a rectal pull-through.

Temporary end-on colostomy as a treatment for anastomotic dehiscence after a transanal rectal pull-through procedure in a dog.

OBJECTIVE: To describe a temporary end-on colostomy to treat the dehiscence of a transanal rectal pull-through in a dog. STUDY DESIGN: Case report ANIMAL: A 7-year-old intact female Australian shepherd dog that was treated for a rectal adenocarcinoma with a transanal rectal pull-through. METHODS: Partial dehiscence of the previous end-to-end colorectal anastomosis and formation of a perianal sinus tract were diagnosed 4 days after surgery. A pararectal approach was used to revise the surgery with debridement of the sinus tract, rectal wall reconstruction with single interrupted sutures, and placement of a passive drain. Dehiscence occurred 2 days later. The colon was transected cranial to the pelvic brim, and each stump was oversewn prior to salvage temporary end-on colostomy. Postoperative care included analgesia, antibiotic therapy, and local care of the perineal/perianal area and colostomy site. After 90 days, the perineal/perianal sinus tract had healed, the colostomy was eliminated, and an end-to-end anastomosis of the colon was performed. RESULTS: Management of postoperative complications focused on dermatitis of the stoma and perineal/perianal area, stoma incontinence, and perineal/perianal medications of the sinus tract. One year after the final surgery, the dog had occasional episodes of fecal incontinence and a good quality of life without other complications. CONCLUSION: Use of a temporary end-on colostomy prior to revision surgery led to a satisfactory outcome but required long and challenging postoperative management. CLINICAL SIGNIFICANCE: Temporary end-on colostomy may be an option to manage dehiscence and potential recurrent stenosis after transanal rectal pull-through in dogs.

Malignant rectal melanoma in 2 dogs.

Two rare cases of malignant rectal melanoma in dogs are described. Tumors were locally invasive and composed of spindle cells arranged in interweaving bundles, sheets, and nests within preexisting fibrovascular stroma. Mitotic count was high. The diagnosis was achieved based on histopathology and immunohistochemistry for PNL2 and melan-A.

Mélanome rectal malin chez 2 chiens. Deux cas rares de mélanome rectal malin chez les chiens sont décrits. Les tumeurs étaient localement envahissantes et composées de cellules fusiformes disposées en faisceaux entrelacés, de feuilles et de nids dans le stroma fibrovasculaire préexistant. Le compte mitotique était élevé. Le diagnostic a été réalisé sur la base de l'histopathologie et de l'immunohistochimie pour le PNL2 et le melan-A.(Traduit par les auteurs).

ULTRASONOGRAPHIC FEATURES OF CANINE GASTROINTESTINAL STROMAL TUMORS COMPARED TO OTHER GASTROINTESTINAL SPINDLE CELL TUMORS.

Canine gastrointestinal stromal tumors (GISTs) are a recent subtype of gastrointestinal spindle cell tumor recognized with the increasing use of immunohistochemistry. To our knowledge, no imaging features have been described in immunostochemically confirmed canine GISTs. The objective of this retrospective, cross-sectional study was to describe ultrasonographic features of canine GISTs compared with other spindle cell tumors. Thirty-seven dogs with an ultrasonographically visible gastrointestinal mass and a histopathologic diagnosis of spindle cell neoplasia were examined. Immunohistochemistry staining was performed for retrieved tissue samples to further differentiate the tumor type and each sample was interpreted by a single veterinary pathologist. Ultrasonographic features recorded examined included mass echogenicity, homogeneity, presence of cavitation, layer of origin, bowel wall symmetry, and loss of wall layering, location, size, vascularity, and evidence of perforation or ulceration. Tumor types included 19 GISTs, eight leiomyosarcomas, six leiomyomas, and four nonspecified sarcomas. Gastrointestinal stromal tumors were significantly more likely to be associated (P < 0.03) with abdominal effusion than other tumor types. There was overlap between the anatomical locations of all tumors types with the exception of the cecum where all eight tumors identified were GISTs. Besides location, there were no unique ultrasound features of GISTs that would allow distinction from other gastrointestinal spindle cell tumors. Similar to previous studies, GISTs appeared to be the most common spindle cell tumor associated with the cecum in our sample of dogs. The high frequency of abdominal effusion with GIST's was of unknown etiology could possibly have been due to septic peritonitis.

Effect of insufflation pressure during transanal minimally invasive surgery on surgical complications with dissection of the rectal submucosa in canine cadavers.

OBJECTIVE: To determine ideal insufflation pressures during transanal minimally invasive surgery (TAMIS) in canine cadavers for rectal submucosal transection and incisional closure. ANIMALS: 16 canine cadavers. PROCEDURES: Cadavers were placed in lateral recumbency. Urinary catheters were placed to measure intra-abdominal pressure (IAP). A single access port was placed to establish a pneumorectum. Cadavers were placed in insufflation groups of 6 mmHg to 8 mmHg (group 1), 10 mmHg to 12 mmHg (group 2), or 14 mmHg to 16 mmHg (group 3). Defects in the rectal submucosa were created and closed with a unidirectional barbed suture. Duration for each procedure and subjective ease of identifying the transection plane and performing incisional closure were assessed. RESULTS: The single access port was successfully placed in dogs weighing 22.7 kg to 48 kg. The ease of each step of the procedure was not influenced by the insufflation pressure. The median surgical duration for group 1 was 740 seconds (range = 564 to 951 seconds), 879 seconds (range = 678 to 991 seconds) for group 2, and 749 seconds (range = 630 to 1,244 seconds) for group 3 (P = .650). The insufflation pressure increased the IAP (P = .007). Perforation of the rectum happened in 2 cadavers in group 3. CLINICAL RELEVANCE: The duration of each step of the procedure was not significantly influenced by insufflation pressure. Defining the dissection plane and performing resection was more challenging in the highest-pressure group. Rectal perforation occurred only with the 14 mmHg to 16 mmHg insufflation pressure. Single access port usage with TAMIS may provide a readily available, minimally invasive approach for the resection of rectal tumors in dogs.

Mucinous Rectal Adenocarcinoma in a Urutu Snake (Bothrops alternatus).

A 15-year-old captive female Urutu snake (Bothrops alternatus) was presented with anorexia, apathy, dehydration, pale mucous membranes and marked enlargement of the caudal third of the coelomic cavity. Radiographs and ultrasonography were suggestive of faecal impaction or neoplasia. Post-mortem findings consisted of solid faecal impaction of the intestines, secondary to obstruction caused by a rectal tumour. Cytological examination of impression smears of the tumour revealed polygonal to round neoplastic cells arranged in clusters in an abundant extracellular mucinous matrix. Histologically, there was transmural growth of neoplastic epithelial cells arranged in small nests or individually and immersed in abundant extracellular mucin lakes. The neoplastic cells were immunopositive for cytokeratin. Clinical and pathological aspects indicated a diagnosis of mucinous rectal adenocarcinoma.

Rectal plasmacytoma with intracellular hemosiderin in a dog.

An 11-year-old female American Cocker Spaniel was presented with a rectal mass that protruded through the anus. Cytologically, the mass was composed of neoplastic round cells consistent with an extramedullary plasmacytoma. Histiocytic sarcoma, carcinoid tumor, and melanoma were also considered because of the presence of golden-brown cytoplasmic granules. Histopathologic findings and immunohistochemical reactivity for lambda light chains confirmed the cytologic diagnosis of plasmacytoma. Prussian blue staining identified the cytoplasmic granules as hemosiderin. The granules were negative by Fontana Masson and Grimelius histochemistry. To our knowledge, this is the first report of an extramedullary plasmacytoma containing hemosiderin in a dog.

A novel surgical stapling technique for rectal mass removal: a retrospective analysis.

Both benign and malignant rectal masses occur in dogs. The mainstay of treatment is surgical excision with adjuvant therapy based on histopathological diagnosis and completeness of removal. Location of the mass within the rectum helps dictate the approach used. This paper describes the use of a novel technique for removal of rectal masses involving the distal third of the rectum in seven dogs. To perform this technique, the rectum is prolapsed and stay sutures are placed to maintain prolapse. A thoracoabdominal stapling device is placed at the base of the mass with a minimum of 0.5- to 1-cm margins, and the mass is amputated. Mean time to veterinarian follow-up was 564 days, and no dog had recurrence of disease during this time.

Bilateral pubic and ischial osteotomy for surgical management of caudal colonic and rectal masses in six dogs and a cat.

CASE DESCRIPTION: 6 dogs and a cat were evaluated because of caudal colonic and rectal masses. CLINICAL FINDINGS: Tumors were identified in the caudal portion of the colon (n = 2), in the area of the colorectal junction (2), or in the rectum (3). TREATMENT AND OUTCOME: In all 7 animals, bilateral pubic and ischial osteotomy was performed to provide exposure of the rectum and associated tumor. Masses were successfully removed, and all 7 animals were able to ambulate normally within 3 days after surgery. No complications associated with the osteotomy procedure were identified. CLINICAL RELEVANCE: Findings suggested that bilateral pubic and ischial osteotomy provided sufficient exposure for resection of intrapelvic tumors in dogs and a cat with minimal complications.

Evaluation of transanal endoscopic treatment of benign canine rectal neoplasia.

OBJECTIVES: To evaluate transanal endoscopic treatment in the management of benign canine rectal neoplasia. METHODS: A retrospective study was carried out to evaluate the response to transanal endoscopic treatment in 13 dogs with extensive rectal neoplasia that was considered inoperable by conventional surgical techniques but was indicated as benign by previous biopsy. RESULTS: Tumours affected the lengths of rectal mucosa varying from 2 to 13 cm. Between 25 and 100 per cent of the rectal circumference was affected in each case. Transanal endoscopic treatment of canine rectal neoplasia was curative in five dogs, palliative in three and associated with a poor result in the remaining five. Complications of the technique included rectal perforation, leading to peritonitis and death. CLINICAL SIGNIFICANCE: Transanal endoscopic treatment can be recommended as an alternative to radical, full-thickness rectal excision for the management of extensive but benign canine rectal neoplasia. Owners should be informed that the treatment may be palliative rather than curative and that complications, if they occur, can be fatal. Dogs should be hospitalised for at least five days after treatment and observed for signs of potentially fatal complications such as rectal perforation.

Colonoscopic and histologic features of rectal masses in dogs: 82 cases (1995-2012).

OBJECTIVE To evaluate colonoscopic and histologic features of rectal masses in dogs. DESIGN Retrospective case series. ANIMALS 82 client-owned dogs with rectal masses that underwent colonoscopy. PROCEDURES Medical records of dogs with rectal masses that underwent colonoscopy were reviewed. History, signalment, clinical signs, results of physical examination, diagnostic imaging findings, and results of colonoscopy (including complications) were recorded. When available, tissue samples obtained during colonoscopy and by means of surgical biopsy were reviewed by a single board-certified pathologist. Histologic features and tumor grade (when applicable) of tissue samples obtained during colonoscopy versus surgical biopsy were compared. RESULTS Multiple rectal masses were observed during colonoscopy in 6 of the 82 dogs, but no lesions were visualized orad to the colorectal junction. Results of histologic evaluation of surgical biopsy specimens were consistent with a diagnosis of epithelial neoplasia in 58 of 64 dogs, of which 71% were classified as benign adenoma or polyp and 29% were classified as adenocarcinoma in situ or adenocarcinoma. Complications of colonoscopy occurred in 3 of 82 dogs but were considered minor. A discrepancy in diagnosis occurred in 5 of 16 dogs for which both colonoscopic and surgical biopsy samples were available for histologic review. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that multiple rectal masses are uncommon in dogs, and secondary lesions orad to the colorectal junction were not found in this study. Colonoscopy was associated with few complications, but the need for colonoscopic assessment of the entire colon in this patient population may merit reevaluation.

Cohort study of COX-1 and COX-2 expression in canine rectal and bladder tumours.

OBJECTIVES: To determine the role that cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) play in malignant transformation in canine transitional cell carcinoma and rectal tumours. METHODS: Histological sections of 21 canine rectal adenocarcinomas and 18 canine transitional cell carcinomas were stained for COX-1 and COX-2. Mann-Whitney non-parametric tests were applied to determine if there was any relationship between the percentage of cells expressing COX-1 or COX-2, and between COX-1 and COX-2 staining intensity and age, breed or sex. RESULTS: For rectal adenocarcinomas, 19.0 per cent of the sections were negative for COX-1 and COX-2. A further 38.1 per cent of the sections were negative for COX-2 but positive for COX-1, and 38.1 per cent of the sections had rare or occasional single cells positive for COX-2. No significant differences were found in COX staining when compared with age, breed or sex. For transitional cell carcinomas, all of the sections were positive for COX-1 and COX-2. For COX-2 staining, 16.7 per cent had more than 30 per cent positive cells. For COX-1 staining, 38.9 per cent had more than 30 per cent positive cells. There was a significant increase in the percentage of COX-1 positive cells in small breed dogs (P = 0.0337). CLINICAL SIGNIFICANCE: The variations in COX expression reported in this study may explain the differences in the clinical response of transitional cell carcinomas and rectal adenocarcinomas following treatment with non-steroidal anti-inflammatory drugs.

Intestinal multinodular A lambda-amyloid deposition associated with extramedullary plasmacytoma in three dogs: clinicopathological and immunohistochemical studies.

Intestinal extramedullary plasmacytomas (EMPs) are rare tumours in dogs. Three cases of canine intestinal EMP with amyloid deposits are described in this report. These tumours, which were located in the rectal submucosa, had variable numbers of well-differentiated plasma cells and fewer multinucleated giant cells of plasmacytoid and histiocytic morphology, admixed with abundant amyloid. Two cases had metaplastic cartilage and bone within the amyloid deposits. Immunohistochemically, the plasma cells of all three tumours reacted for lambda-light chains of immunoglobulins but not for kappa-chains, indicating monoclonality. Plasma cells of two tumours were also positive to CD79a antiserum. Amyloid deposits were labelled with an A lambda (amyloid of immunoglobulin lambda-light chain origin) antiserum but not with antisera against its precursor protein, the immunoglobulin lambda-light chains, indicating possible conformational changes of amyloidogenic proteins during their transformation into amyloid.

Rectal biopsy diagnosis in horses with clinical signs of intestinal disorders: a retrospective study of 116 cases.

The histology from rectal biopsy specimens taken 1980-1990 on 131 occasions from 116 horses, age 1-18 years, with clinical signs of intestinal disease was evaluated and classified retrospectively. In 40 horses, autopsy results were studied for comparison. Biopsy specimens (21 horses) and post mortem rectal tissue (9 horses) from 30 healthy horses, age 4-22 years, were used as controls. In 105 clinical cases, a biopsy was performed on only one occasion, while repeat biopsy was performed in 11 cases. Specimens showed pathological changes in 60 horses. The findings were classified into acute, chronic or chronic active simple proctitis, granulomatous enteritis, eosinophilic granulomatosis/gastroenteritis, eosinophilic proctitis, erosive/ulcerative proctitis, pseudomembranous proctitis, proctitis with vasculitis and malignant lymphoma. Mild scattered neutrophil infiltration in the lamina propria was found in controls, but neutrophils in crypt or surface epithelia were abnormal findings. Depletion or hyperplasia of goblet cells sometimes accompanied inflammation. Simple proctitis occurred in association with malignant lymphoma and various inflammatory disorders of the gastrointestinal tract apparent at autopsy. Eosinophilic granulomatosis/gastroenteritis and granulomatous enteritis were diagnosed from biopsy specimens in 6 of 12 and 4 of 9 cases, respectively, of these diseases confirmed at autopsy. Reduction of acid mucins in goblet cells was a prominent feature of eosinophilic granulomatosis. Rectal biopsy was found to be a useful adjunct for evaluation of intestinal disease in the horse.

Scirrhous adenocarcinoma of the rectum in a cow.

Clinical and pathological examinations were performed on a 3-year-old Holstein-Friesian cow with scirrhous adenocarcinoma of the rectum. Hemorrhagic diarrhea causing rectal stenosis was a principal clinical manifestation. Microscopically, cancerous transformation of the intestinal epithelium was observed in the rectal crypts. Irregular glandular arrangements containing PAS positive and eosinophilic mucus were observed in the lumen, which were surrounded by scirrhous collagenous fibers. The neoplastic epithelial cell had round or ovoid nucleus and slightly eosinophilic cytoplasm. Metastatic lesions were localized in the marginal and medullary sinuses of the anorectal lymph nodes.

Gastroduodenal adenocarcinomas and rectal adenoma in a cougar (Felis concolor) infected with Helicobacter-like organisms and spirochetes.

A 14-year-old female cougar died from gastroduodenal adenocarcinomas and rectal adenoma. At necropsy, polypoid tumor masses of various sizes were scattered on the mucosal surfaces of the stomach, duodenum, and rectum. Histologically, the gastric tumor was diagnosed as an intestinal type adenocarcinoma and the tumor cells metastasized to the mesenteric lymph nodes, spleen, and lung. Helicobacter-like organisms were detected in the lumina lined by foveolar epithelium. In the duodenum, the carcinoma cells were localized in the limina propria and many of them were intensely positive for proliferating cell nuclear antigen (PCNA). In contrast, the rectal adenoma had a lower number of PCNA-positive cells. In the rectum, chronic inflammation with numerous spirochetes was also noted. These results indicated that the occurrence of the gastrointestinal tumors might be associated with the bacterial infection described above.

Colorectal adenocarcinoma in dogs: 78 cases (1973-1984).

Colorectal adenocarcinoma was diagnosed in 78 dogs. Clinical signs in all 78 dogs included tenesmus, hematochezia, and dyschezia; most of the dogs had clinical signs less than or equal to 12 weeks before examination. Ultimately, most dogs were euthanatized because of the severity of clinical signs. Proctoscopy and colonoscopy were essential for complete assessment of extent of disease. Tumors were classified by gross appearance and included single, pedunculated masses, 2 or more nodular masses, and annular or intraluminal masses. In dogs in which survival time was compared with location and gross appearance of the tumor, dogs with annular masses had the shortest mean survival time (1.6 months), and dogs with single, pedunculated, polypoid tumors had the longest mean survival time (32 months). The rectum was a more common site than the colon, with 48.2% of the tumors developing in the middle portion of the rectum. Six different modes of surgical treatment were used, depending on the location and type of mass. Dogs that did not have surgical treatment had a mean survival time of 15 months. Mean survival time in the surgically treated dogs varied slightly according to mode of treatment; they survived 7 to 9 months longer than the untreated dogs. Dogs that underwent cryosurgery and local excision had the longest survival times (24 and 22 months, respectively). Statistical analysis disclosed a significantly longer survival time for dogs treated by excision or cryosurgery, as opposed to dogs undergoing biopsy only (P = 0.001). Statistical difference in survival times was not found between dogs that had mass excision and those that had cryosurgery.

Rectal leiomyosarcoma in a horse.

A mass originating from the dorsal rectal wall of a 4-year-old mare was diagnosed as a leiomyosarcoma. General anesthesia and meticulous surgical dissection were required to effect removal. In spite of incomplete excision, as indicated by histologic sections, the mass has not recurred in the 18 months since removal.