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

Canine colorectal proliferative lesions: a retrospective study of 217 cases

BACKGROUND

Colorectal proliferative lesions are not common in dogs. However, recently we have observed an increase in the number of diagnosed cases and a lack of publications providing current epidemiological data on lesions of the large intestine in dogs. The aim of this study was a retrospective analysis of 217 canine colorectal non-neoplastic and neoplastic nodular lesions, and assessment of the frequency of occurrence of individual lesions and whether there is a risk of their occurrence depending on age, sex, or dog breed.

RESULTS

Half of the cases (52.5%) were malignant tumours with a significant predominance of adenocarcinoma (42.9%). In the group of malignant non-epithelial lesions, lymphoma and sarcomas predominated (4.1% and 4.1%, respectively) followed by three cases of plasmacytoma. Benign neoplastic tumours constituted almost one-third of all cases (26.7%) with obvious dominance of adenoma (24.0%). Benign mesenchymal tumours were represented only by leiomyoma (2.8%). The non-neoplastic lesions were represented by a heterogeneous group of polyps (20.3%) with a slight advantage of hyperplastic type (9.7%) and less numerous inflammatory, fibroblastic, lymphoid, and hamartomatous polyps. One case of ganglioneuromatosis in hamartomatous polyp was diagnosed. The vast majority of lesions, both non-neoplastic and neoplastic, were found in the rectum. French Bulldogs were the most numerous breeds in our study, especially among adenomas. Furthermore, benign tumours were diagnosed in younger animals than malignant tumours.

CONCLUSIONS

The results of our research provided new data expanding knowledge about the epidemiology of colorectal neoplastic and non-neoplastic proliferative lesions in dogs. Our results indicate that the majority of colorectal proliferative lesions in dogs are malignant, which is alarming. French Bulldogs could possibly be predisposed to proliferative lesions of the large intestine, and this predisposition was statistically confirmed in adenomas. Moreover, benign tumours may occur in animals as young as 1-2 years old.

Rectal mast cell tumour in a dog with lower grade features of biological aggressiveness

An 8-year-old, neutered female, Australian Silky Terrier presented to her primary veterinarian with non-specific clinical signs of general unwellness, shaking, lethargy, inappetence and no defecation for 2-3 days. A rectal mass was found on physical examination. The rectal mass was surgically resected and histopathology was consistent with a mast cell tumour (MCT) with a mitotic count of 0 per 2.37mm2. The dog had follow-up chemotherapy protocol comprising of vinblastine and prednisolone and was doing well with no evidence of tumour recurrence 30 weeks post surgical resection and is still alive and clinically normal at the time of writing, 9 months post initial diagnosis. Primary MCTs of the gastrointestinal tract have previously been reported to be associated with a poor prognosis. This is the first report of a canine rectal mast cell tumour with lower grade features of biological aggressiveness and a possibly more favourable prognosis compared with the current published literature.

Acute hypernatremia and hypocalcemia after oral sodium phosphate administration to a dog

A 15-year-old male neutered mixed breed dog weighing 28 kg presented to a referral center after developing severe tremors and altered mentation. There was hypocalcemia and hypernatremia after oral administration of sodium phosphate as a bowel cleansing agent in preparation for colonoscopy. The dog was treated intravenously with low sodium fluids and calcium gluconate. Neurologic status and electrolyte derangements normalized over the next 12 hours. Oral administration of sodium phosphate appeared to cause clinical electrolyte derangements in this dog.

T-cell lymphoma involving the rectum of a dog

A mediastinal mass was diagnosed in a 7-year-4-month-old neutered female mixed breed dog following a 3-week history of lethargy, hyporexia and pyrexia. Bi-cavitary imaging, needle aspirate cytology and flow cytometry confirmed WHO clinical stage IVb, intermediate to large T-cell lymphoma involving the mediastinum, liver and spleen. The dog initially responded to a multidrug chemotherapy protocol but clinical deterioration occurred 3 months later. The dog presented with anorexia, vomiting and diarrhoea, associated with marked faecal tenesmus and haematochezia, initially believed by the primary care practitioner to be related to chemotherapy toxicity. However, rectal examination revealed multiple sessile and pedunculated masses. Further diagnostic imaging, cytology and flow cytometry confirmed progressive disease, including T-cell lymphoma of the rectum. Histology and immunohistochemistry confirmed an infiltrate of intermediate-sized CD3-positive neoplastic cells that expanded the rectal mucosa. Rectal lymphoma is uncommon in dogs and previous cases have been B cell in origin. In this report we describe the clinical presentation and macro- and microscopic findings of a case of canine T-cell lymphoma involving the rectum.

Recurrence and survival in dogs with excised colorectal polyps: A retrospective study of 58 cases

BACKGROUND

Compared to humans, colorectal polyps are relatively rare in dogs. Epidemiological and prognostic data remain accordingly sparse, although they could help veterinary clinicians in the management of these cases.

OBJECTIVES

To report the epidemiological data of dogs with colorectal polyps and identify factors associated with recurrence and survival.

ANIMALS

Fifty-eight client-owned dogs with colorectal polyps admitted to 7 veterinary hospitals (53 dogs from France, 5 dogs from Spain, and 4 dogs from Portugal) were included.

METHODS

Retrospective multicentric cohort study. Medical records and long-term outcome of the dogs were reviewed. When available, histological samples were reassessed by 2 board-certified pathologists according to the revised Vienna classification (RVC).

RESULTS

The West Highland White Terrier (WHWT) breed was significantly associated with the presence of colorectal polyps (OR: 20; 95% CI: 7.5-52; P < .001). The overall median time to recurrence was not reached after 2000 days. The overall estimated median survival time was 1640 days. WHWT breed and larger polyps were significantly associated with a shorter time of polyp recurrence after surgical removal (respectively, P = .05 and P = .01).

CONCLUSIONS AND CLINICAL IMPORTANCE

The probability of recurrence of colorectal polyps in dogs is low, but increased in WHWTs and larger polyps, which might benefit from routine screening after removal. No effective predictors of polyp recurrence and survival were identified using the RVC.

Molecular, Morphological and Clinical Characteristics of Spontaneous Canine Colorectal Cancer – A Review

Cross-species comparison analysis studies are of immense importance in veterinary and human oncological research. Of the various non-rodent species available, dogs have gained most attention as potential animal models for the study of colorectal cancer. Domestic dogs developed evolutionally through a mutually beneficial relationship with humans. Because dogs share the same environment as humans, they are exposed to the same potentially harmful substances which may act as carcinogens in both species. Intestinal adenocarcinomas in dogs are naturally occurring heterogeneous tumours, which have the characteristics of sporadic human malignancies and therefore are more suitable for detailed oncological study than most xenograft or genetically modified rodent models. Furthermore, the canine genome has been comprehensively analysed and sequenced to a 7.6-fold coverage, and a very accurate version of this sequencing is available for study. The purpose of this manuscript is to present a comprehensive review of published data related to colorectal cancer in dogs. In addition, data regarding interspecies comparison of molecular events driving canine and human intestinal carcinogenesis is presented.

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.

Clinical and histopathological features and prognosis of gastrointestinal adenocarcinomas in Jack Russell Terriers

There has been an increase in the number of Jack Russell Terriers (JRTs) diagnosed with adenomas and adenocarcinomas of the gastrointestinal tract in Japan. This study retrospectively investigated the clinical and histopathological features and prognosis of adenocarcinomas arising in the gastrointestinal tract in JRT dogs. Seven JRTs and 39 dogs of other breeds diagnosed with gastrointestinal adenocarcinoma were included in the study. The most common sites of gastrointestinal adenocarcinoma in JRTs were the pylorus and rectum. On histopathological examination, these adenocarcinomas showed a papillary or tubular growth pattern, and the lesions were confined within the mucosal epithelium and poorly invasive. Among all dogs with gastric adenocarcinoma, the median survival time (MST) for five of the JRTs could not be determined because more than half of the cases remained alive, while the MST for nine non-JRT dogs was 34 days. Among all dogs with adenocarcinoma in the large intestine, the MST for three of the JRTs could not be determined, while the MST for nine non-JRT dogs was 1,973 days. The difference in MST between JRT and non-JRT dogs with gastric adenocarcinoma was significant (P=0.0220). Since gastrointestinal adenocarcinomas in JRTs show distinct characteristics with respect to their clinical features, treatment course, and prognosis, a different surgical and medical treatment plan should be considered compared to the management of gastrointestinal adenocarcinomas in other dog breeds.

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.

Obturator-Assisted Prolapse for Access to and Sampling of Colorectal Masses in Seven Dogs

The gold standard for diagnosis of colorectal masses is surgical biopsy; however, this is not always logistically or economically feasible. The authors present an alternative to established flexible and rigid endoscopic approaches when case limitations require such an approach. In seven dogs, after the identification of a mass on physical exam and computed tomographic evaluation, the colorectum was accessed using obturator-assisted prolapse to isolate discrete masses and perform shielded sampling via core needle biopsy. Histopathologic diagnosis was adequate for treatment planning in all dogs. No major complications were recorded 65-475 days after the procedure. This technique may be useful when traditional endoscopy and surgery for biopsy of colorectal masses is unavailable.