Colonic gastrointestinal stromal tumor (GIST) presenting with colocolonic intussusception: A rare case report.

An 8-year-old spayed female British bulldog was presented with vomiting, hyporexia, and large-bowel diarrhea. Abdominal ultrasound revealed a focal colonic mass with an intussusception located immediately oral to the mass. The intussusception encompassed the ascending and transverse colon and was non-reducible. Colonic resection and anastomosis were completed to include the intussusception and colonic mass. Histopathological examination of the mass demonstrated a spindle cell neoplasm arising within the muscular wall of the intussuscepted segment that obliterated normal architecture. Mild-to-moderate cytoplasmic immunoreactivity of the tumor cell population for CD117 and smooth muscle actin was consistent with a diagnosis of a gastrointestinal stromal tumor. The dog described herein remains alive and free of progressive disease at the time of writing. Key clinical message: The entire gastrointestinal tract should be evaluated in any animal with gastrointestinal symptoms. A gastrointestinal stromal tumor remains a plausible differential diagnosis, regardless of the intestinal segment affected, and tumorassociated intussusception is a rare but urgent clinical finding.

Tumeur stromale gastro-intestinale du côlon (GIST) présentant une invagination colocolique : un rapport de cas rare. Une femelle bouledogue anglais stérilisée de 8 ans a présenté des vomissements, une hyporexie et une diarrhée d'origine du gros intestin. L'échographie abdominale a révélé une masse colique focale avec une invagination située immédiatement oralement à la masse. L'intussusception englobait le côlon ascendant et transverse et était non réductible. La résection colique et l'anastomose ont été réalisées pour inclure l'intussusception et la masse colique. L'examen histopathologique de la masse a révélé un néoplasme à cellules fusiformes apparaissant dans la paroi musculaire du segment invaginé qui a oblitéré l'architecture normale. L'immunoréactivité cytoplasmique légère à modérée de la population de cellules tumorales pour le CD117 et l'actine des muscles lisses étaient compatibles avec un diagnostic de tumeur stromale gastro-intestinale. Le chien décrit ici est toujours vivant et exempt de maladie évolutive au moment de la rédaction.Message clinique clé :L'ensemble du tractus gastro-intestinal doit être évalué chez tout animal présentant des symptômes gastrointestinaux. Une tumeur stromale gastro-intestinale reste un diagnostic différentiel plausible, quel que soit le segment intestinal atteint, et l'intussusception associée à la tumeur est une constatation clinique rare mais urgente.(Traduit par Dr Serge Messier).

A case of colonic-colonic intussusception in a dog secondary to lymphoma treated with colonic resection and anastomosis.

A 2-year-old castrated male Great Dane crossbreed dog was presented with a history of diarrhea and suspected intussusception. Abdominal ultrasound revealed a colonic-colonic intussusception. The gastrointestinal tract was explored, and an approximately 5-cm intussusception was discovered mid-colon. All other gastrointestinal structures were normal in appearance. The intussusception could not be reduced manually. A colonic resection and anastomosis were performed together with a left-sided incisional colopexy. The dog recovered from surgery and histopathology revealed the intussusception to be secondary to large cell transmural lymphoma. Sections from the surgical margins revealed proliferation of fibrovascular tissue along the serosal surface segmentally, but no neoplastic cells were identified. The dog was subsequently treated with chemotherapy consisting of doxorubicin and prednisone. No evidence of disease recurrence was noted on ultrasound 9 months after surgery. Approximately 2 years after surgery, the dog is noted to be clinically normal at home with no abnormal findings on physical examination. A complete blood (cell) count and chemistry obtained at this time revealed no significant abnormalities besides mild azotemia. Additional restaging was declined by the owner.

Un cas d'intussusception colon-colon chez un chien secondaire à un lymphome traité par résection c olonique et anastomose. Un grand danois croisé mâle castré âgé de 2 ans a été présenté avec des antécédents de diarrhée et une suspicion d'intussusception. L'échographie abdominale a révélé une intussusception colon-colon. Le tractus gastro-intestinal a été exploré et une intussusception d'environ 5 cm a été découverte au milieu du côlon. Toutes les autres structures gastro-intestinales avaient un aspect normal. L'intussusception n'a pas pu être réduite manuellement. Une résection colonique et une anastomose ont été réalisées avec une colopexie incisionnelle du côté gauche. Le chien a récupéré de la chirurgie et de l'histopathologie a révélé que l'intussusception était secondaire à un lymphome transmural à grandes cellules. Des sections des marges chirurgicales ont révélé une prolifération de tissu fibrovasculaire le long de la surface séreuse de manière segmentaire, mais aucune cellule néoplasique n'a été identifiée. Le chien a ensuite été traité par une chimiothérapie composée de doxorubicine et de prednisone. Aucun signe de récidive de la maladie n'a été noté à l'échographie 9 mois après la chirurgie. Environ 2 ans après la chirurgie, le chien est cliniquement normal à la maison sans résultats anormaux à l'examen physique. Une numération sanguine (cellule) complète et l'analyse chimique obtenues à ce moment n'ont révélé aucune anomalie significative outre une légère azotémie. Une nouvelle restadification a été refusée par le propriétaire.(Traduit par Dr Serge Messier).

Synbiotic sheep milk ice cream reduces chemically induced mouse colon carcinogenesis.

Sheep dairy products containing prebiotic and probiotic ingredients may have health-promoting properties. Thus, this study evaluated the effects of sheep milk ice cream [conventional full-fat (CONV), full-fat enriched with probiotic (PROB, 100 mg % wt/wt of Lacticaseibacillus casei 01), or nonfat synbiotic (SYNB, Lacticaseibacillus casei 01 and inulin, 10% wt/wt)] on carcinogen-induced colonic crypt cytotoxicity and premalignant lesion development. Male Swiss mice received 2 doses of colon carcinogen azoxymethane (AOM, 15 mg/kg of body weight) at wk 3 and 4. Two weeks before and during AOM administrations (4 wk) mice were treated with CONV, PROB, or SYNB by gavage (10 mL/kg). Mice were euthanized at wk 4 or 25 (n = 5 or 10 mice/group, respectively). At wk 4, a significant reduction in micronucleated colonocytes was observed in PROB and SYNB groups, and a significant decrease in both p53 expression and apoptosis indexes in colonic crypts was observed in SYNB group. At wk 25, both PROB and SYNB interventions reduced the mean number of colonic premalignant lesions. However, only SYNB group showed lower incidence and number of high-grade premalignant lesions in the colonic mucosa. These findings indicate that PROB or SYNB sheep milk ice cream, especially SYNB intervention, can reduce chemically induced mouse colon carcinogenesis.

Ultrasonographic features of colonic B-cell lymphoma with mesenteric lymphomatosis in a cat.

A 10-year-old male neutered Domestic Shorthair cat was referred for chronic inappetence, weight loss, and hematochezia and an abdominal mass. Abdominal ultrasonography revealed a heterogeneously hypoechoic transmural colonic mass, which extended beyond the serosa and into the adjacent mesentery. Cytology and clonality assays of fine needle aspirates of the mass and mesenteric nodules yielded a diagnosis of B-cell lymphoma. Colonic lymphoma with mesenteric involvement can have a similar appearance to carcinomatosis, therefore a definitive diagnosis requires sampling and further testing of the mesenteric lesions.

IMAGING DIAGNOSIS - RADIOGRAPHY, ULTRASONOGRAPHY, AND COMPUTED TOMOGRAPHY OF A GIANT FECALOMA CAUSING STERCORAL PERFORATION OF THE COLON IN A DOG WITH A PROSTATIC ABSCESS.

A mixed-breed dog presented with tenesmus, hematochezia, and abdominal distension of 2 weeks duration. Radiography showed a large round mass with a "soap-bubble" appearance and shell-like mineralization in the caudal abdomen. Computed tomography revealed a lamellate mineralized mass 8 cm in diameter and containing air in the descending colon and prostatic abscess. Heterogeneously contrast-enhanced, irregularly thickened colonic wall with intramural and peritoneal free gas indicated stercoral colonic perforation. Surgical intervention revealed a tumor-like giant fecaloma in the descending colon adjoining the prostate with extensive wall rupture and fecal peritonitis. Hypothetically, prostatic inflammation may affect colonic motility with resultant fecaloma formation.

Primary colonic hemangiosarcoma in a dog.

A 13-year-old spayed female miniature dachshund dog was presented with a history of hematochezia, melena, and weight loss. A colonic mass detected by exploratory celiotomy was resected and diagnosed as hemangiosarcoma (HSA). Liver lobectomy for hepatic HSA was performed 894 days after surgery. Adjuvant chemotherapy was declined. This is the first documentation of a canine colonic HSA.

Hémangiosarcome primaire du côlon chez un chien. Une chienne Dachsund miniature stérilisée âgée de 13 ans a été présentée avec une anamnèse d'hématochézie, de méléna et de perte de poids. Une masse du côlon détectée par céliotomie exploratoire a été réséquée et diagnostiquée comme un hémangiosarcome (HSA). La lobectomie pour le HSA hépatique a été réalisée 894 jours après la chirurgie. La chimiothérapie adjuvante a été refusée. Il s'agit de la première documentation d'un HSA canin du côlon.(Traduit par Isabelle Vallières).

COLONIC ADENOCARCINOMAS IN A FAMILIAL GROUP OF CAPTIVE AMUR RAT SNAKES (ELAPHE SCHRENCKI).

This article reports five cases of colonic adenocarcinomas in a family group of captive Amur rat snake (Elaphe schrenckii) from the Réserve Africaine de Sigean, France. This tumor was detected in three females and two males, all adults, and accounted for 16% of causes of death of adults of this species at this institution from 1986 to 2013. Grossly, mild to marked thickening of the intestinal wall cranially to the cloaca was found in four cases; tan to yellow firm masses were noted in the distal intestinal wall in the other case. Microscopically, neoplasms were characterized by infiltrating, poorly circumscribed, and unencapsulated nests of epithelial cells. Marked anisokaryosis and anisocytosis were seen in all neoplasms. The etiology of the neoplasms was not determined, but the familial clustering suggests a common etiologic factor.

The promise of genetically engineered mice for cancer prevention studies.

Sophisticated genetic technologies have led to the development of mouse models of human cancers that recapitulate important features of human oncogenesis. Many of these genetically engineered mouse models promise to be very relevant and relatively rapid systems for determining the efficacy of chemopreventive agents and their mechanisms of action. The validation of such models for chemoprevention will help the selection of appropriate agents for large-scale clinical trials and allow the testing of combination therapies.

Colonic gastrointestinal stromal tumor resulting in recurrent colic and hematochezia in a warmblood gelding.

A 14-year-old Trakehner gelding was evaluated for recurrent colic, with episodes occurring over 1 year. Signs were consistent with intermittent ascending colon obstruction and hematochezia. Necropsy examination revealed an ulcerated mass extending into the lumen of the right dorsal ascending colon. Gross and histologic appearance and immunoreactivity to c-kit (CD117), desmin, vimentin, and smooth muscle actin, were consistent with a diagnosis of gastrointestinal stromal tumor.

Tumeur ventrale gastro-intestinale du côlon produisant des coliques et de l'hématochézie et des coliques récurrentes chez un hongre à sang chaud. Un hongre Trakehner âgé de 14 ans a été évalué pour des coliques récurrentes et les épisodes duraient depuis 1 an. Les signes étaient conformes à une obstruction intermittente du côlon ascendant et à l'hématochézie. La nécropsie a révélé une masse ulcéreuse s'étendant dans la lumière du côlon ascendant dorsal droit. L'apparence brute et histologique et l'immunoréactivité à c-kit (CD117), à la desmine, à la vimentine et à l'actine des muscles lisses étaient conformes au diagnostic de tumeur ventrale gastro-intestinale.(Traduit par Isabelle Vallières).

Geese as reservoirs of human colon cancer-associated Streptococcus gallolyticus.

Recently, an increased number of reports have described pathogens of animal origin that cause a variety of infections and a rise in their transmission to humans. Streptococcus gallolyticus, a member of the Streptococcus bovis/Streptococcus equinus complex (SBSEC), is one of these pathogens and infects a wide range of hosts from mammals to poultry and has a broad functionality ranging from pathogenicity to food fermentation. As S. gallolyticus causes complications including bacteremia, infective endocarditis, and colorectal malignancy in humans, it is important to investigate its occurrence in various hosts, including geese, to prevent potential zoonotic transmissions. This study aimed to investigate the presence of S. gallolyticus in the droppings of clinically healthy and diarrheic geese, which were raised intensively and semi-intensively, by the in vitro culture method, characterize the isolates recovered by PCR and sequence-based molecular methods and determine their antibiotic susceptibility by the disk diffusion and gradient test methods. For this purpose, 150 samples of fresh goose droppings were used. Culture positivity for S. gallolyticus was determined as 8% (12/150). PCR analysis identified 54.55% (n = 6) of the isolates as S. gallolyticus subsp. gallolyticus and 45.45% (n = 5) as S. gallolyticus subsp. pasteurianus. Following the 16S rRNA sequence and ERIC-PCR analyses, S. gallolyticus subspecies exhibited identical cluster and band profiles that could be easily distinguished from each other and were clonally identified. High rates of susceptibility to florfenicol, penicillin, rifampicin, and vancomycin were detected among the isolates, regardless of the subspecies diversity. Both subspecies showed high levels of resistance to bacitracin, clindamycin, doxycycline, tetracycline, trimethoprim-sulfamethoxazole, and erythromycin and multiple MDR profiles, indicating their potential to become superbugs. This first report from Türkiye demonstrates the occurrence of the S. gallolyticus subspecies in geese. In view of the recent increase of geese production and the consumption of goose meat in Türkiye, the occurrence of S. gallolyticus in geese should not be ignored to prevent zoonotic transmission.

A review of 18 cases of feline colonic adenocarcinoma treated with subtotal colectomies and adjuvant carboplatin.

Feline colonic adenocarcinoma is a locally invasive, highly metastatic tumor that is most often treated with wide surgical excision (subtotal colectomy) and systemic chemotherapy either with or without nonsteroidal anti-inflammatory medications. In this retrospective study, the outcome of subtotal colectomy and adjuvant carboplatin in 18 client-owned cats is described. The median carboplatin dose was 200 mg/m(2) (range, 200-254 mg/m(2)) q 4 wk with a median of five doses/cat (range was two to seven doses/cat). Limited toxicities were noted. Positive prognostic factors for the disease-free interval included cats that had weight loss as a presenting sign (P < 0.036) and negative prognostic factors for median survival included nodal and distant metastasis (178 versus 328 days and 200 versus 340 days, respectively). The median disease-free interval was 251 days (range, 37-528 days) and the median survival time was 269 days (range, 40-533 days). Subtotal colectomy and adjuvant carboplatin is a safe and potentially effective treatment for cats with colonic adenocarcinoma.

Enteric peripheral neuroblastoma in a calf.

An 11-month-old female Japanese Black calf had showed chronic intestinal symptoms. A large mass surrounding the colon wall that was continuous with the colon submucosa was surgically removed. After recurrence and euthanasia, a large mass in the colon region and metastatic masses in the omentum, liver, and lung were revealed at necropsy. Pleomorphic small cells proliferated in the mass and muscular layer of the colon. The cells were positively stained with anti-doublecortin (DCX), PGP9.5, nestin, and neuron specific enolase (NSE). Thus, the diagnosis of peripheral neuroblastoma was made. This is the first report of enteric peripheral neuroblastoma in animals. Also, clear DCX staining signal suggested usefulness of DCX immunohistochemistry to differentiate the neuroblastoma from other small cell tumors in cattle.

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.

Age-related tumor growth in mice is related to integrin α 4 in CD8+ T cells.

Cancer incidence increases with age, but paradoxically, cancers have been found to grow more quickly in young mice compared with aged ones. The cause of differential tumor growth has been debated and, over time, attributed to faster tumor cell proliferation, decreased tumor cell apoptosis, and/or increased angiogenesis in young animals. Despite major advances in our understanding of tumor immunity over the past 2 decades, little attention has been paid to comparing immune cell populations in young and aged mice. Using mouse colon adenocarcinoma model MC38 implanted in young and mature mice, we show that age substantially influences the number of tumor-infiltrating cytotoxic CD8+ T cells, which control cancer progression. The different tumor growth pace in young and mature mice was abrogated in RAG1null mice, which lack mature T and B lymphocytes, and upon selective depletion of endogenous CD8+ cells. Transcriptome analysis further indicated that young mice have decreased levels of the Itga4 gene (CD49d, VLA-4) in tumor-infiltrating lymphocytes when compared with mature mice. Hypothesizing that VLA-4 can have a tumor-protective effect, we depleted the protein, which resulted in accelerated tumor growth in mature mice. These observations may explain the paradoxical growth rates observed in murine cancers, point to the central role of VLA-4 in controlling tumor growth, and open new venues to therapeutic manipulation.

The guanine nucleotide exchange factor Tiam1 increases colon carcinoma growth at metastatic sites in an orthotopic nude mouse model.

Alterations in migration and adhesion are critical to invasion and metastasis. To examine signaling pathways important for colon tumor metastasis, cells of increased migratory potential from the low migratory SW480 human colorectal carcinoma parental cell line were biologically selected by serial migration through modified Boyden chambers. Several sublines were obtained with statistically significantly increased migration relative to the parental cell line. One highly migratory population was single-cell cloned and characterized. The migratory clones exhibit a four- to five-fold increase in protein and mRNA expression of T-lymphoma invasion and metastasis gene 1 (Tiam1), a guanine nucleotide exchange factor. To determine directly the role of Tiam1 in the migration of these migratory sublines, the parental SW480 cell line was transfected with a plasmid encoding the Tiam1 protein, and single cell clones were established. Ectopic expression of Tiam1 in these clones led to morphologic changes identical to biologically selected clones and increased migration. Finally, the implantation of clones that overexpress Tiam1 into the cecum of athymic mice resulted in tumor growth in the spleen, liver, and lung, whereas parental cells do not form tumors by this route of injection. These results demonstrate that overexpression of Tiam1 contributes to the metastatic phenotype of colon cancer cells.

In vivo target modulation and biological activity of CHIR-258, a multitargeted growth factor receptor kinase inhibitor, in colon cancer models.

PURPOSE: To evaluate the therapeutic and biological effects of CHIR-258, an orally bioavailable, potent inhibitor of class III-V receptor tyrosine kinases, in colon cancer models. EXPERIMENTAL DESIGN: The pharmacologic activity of CHIR-258 was characterized by monitoring target modulation as well as by evaluating the antitumor and antiangiogenic effects in human colon xenograft models. RESULTS: CHIR-258 inhibits vascular endothelial growth factor receptor 1/2, fibroblast growth factor receptor 1/3, and platelet-derived growth factor receptor beta (PDGFRbeta) and shows both antitumor and antiangiogenic activities in vivo. Treatment of KM12L4a human colon cancer cells with CHIR-258 resulted in a dose-dependent inhibition of vascular endothelial growth factor receptor 1 and PDGFRbeta phosphorylation and reduction of phosphorylated extracellular signal-regulated kinase (ERK) levels, indicating modulation of target receptors and downstream signaling. In vivo administration of CHIR-258 resulted in significant tumor growth inhibition and tumor regressions, including large, established tumors (500-1,000 mm(3)). Immunohistochemical analysis showed a reduction of phosphorylated PDGFRbeta and phosphorylated ERK in tumor cells after oral dosing with CHIR-258 compared with control tumors. These changes were accompanied by decreased tumor cell proliferation rate and reduced intratumoral microvessel density. CHIR-258 inhibited the phosphorylation of PDGFRbeta and ERK phosphorylation in tumors within 2 hours following dosing and the inhibitory activity was sustained for >24 hours. Significant antitumor activity was observed with intermittent dosing schedules, indicating a sustained biological activity. CONCLUSION: These studies provide evidence that biological activity of CHIR-258 in tumors correlates with efficacy and aids in the identification of potential biomarkers of this multitargeted receptor tyrosine kinase inhibitor. CHIR-258 exhibits properties that make it a promising candidate for clinical development in a variety of solid and hematologic malignancies.

Antioxidative and modifying effects of a tropical plant Azadirachta indica (Neem) on azoxymethane-induced preneoplastic lesions in the rat colon.

The purpose of the present study was to examine whether Neem leaf (Azadirachta indica) has short-term chemopreventive effects on endpoint preneoplastic lesions involved in rat colon carcinogenesis and might also exert antioxidative activity. Forty- two male F344 rats were randomly divided into 6 experimental groups. Groups 1 to 4 were given a subcutaneous injection of azoxymethane (AOM, 20 mg/kg body weight) once a week for 2 weeks. Starting one week before the first injection of AOM, rats in groups 2 to 4 received an aqueous extract of Neem leaf (20, 100, and 250 mg/kg, respectively) by gavage 3 times per week, for 5 weeks. Rats in group 5 also were given the Neem extract by gavage feeding 3 times per week for 5 weeks, while group 6 served as untreated controls. The experiment was terminated 5 weeks after the start. Dietary feeding of the Neem extract at all dose levels significantly inhibited the induction of aberrant crypt foci (ACF) (P<0.0002), when compared to the AOM-treated group (group 1). In groups 2 to 4, treatment of rats with the Neem extract also significantly decreased the proliferating cell nuclear antigen (PCNA) labeling indices (P<0.0006) of colon epithelium and ACF. Moreover, the Neem extract also showed antioxidative activity. The finding that dietary Neem has possible chemopreventive effects in the present short-term colon carcinogenesis bioassay suggests that longer-term exposure may cause suppression of tumor development.

Spontaneous colon tumors in rats.

Twenty-eight cases of spontaneous colon tumors were found during autopsy of approximately 3,000 male W rats in our laboratories between 1968 and 1974. Macroscopically, these tumors were multiple and localized in the proximal part of the colon. Many nodules protruded on the serosal surface; polypoid tumors protruding into the lumen were rare. Microscopically, hyperplastic and adenomatous polyps were observed in the mucous membrane of the colon. There was adenomatous downward growth into the submucosal layer, and tubular-type adenocarcinomas invaded all the coats of the colon wall. Structural atypism was frequent and slight cell atypism was also present. Invasive tumors sometimes had an inflammatory reaction, and bacterial growth was observed within the neoplastic glands in thionine-stained sections. Escherichia coli and a gram-negative, facultative anaerobic bacillus, which grew only with E. coli in vitro, were isolated. A cultured epithelial cell line was established from one colon tumor. After a primary tumor was transplanted intraperitoneally into young adult rats, a mass grew in the peritoneal cavity for 4 months. The tumor incidence seemed higher at different times in the animals examined.

Palliative use of a stent for colonic obstruction caused by adenocarcinoma in two cats.

CASE DESCRIPTION-Two adult male castrated cats were evaluated because of a history of constipation, tenesmus, or intermittent vomiting. CLINICAL FINDINGS-Radiography and ultrasonography revealed luminal narrowing in the colon of 1 cat and a colonic mass in the other. A histopathologic diagnosis of colonic adenocarcinoma was made in both cats. TREATMENT AND OUTCOME-Under fluoroscopic guidance, a self-expanding metallic stent was advanced over a wire and across the area of colonic stenosis and deployed. One cat had progressive weight loss but maintained a normal appetite, energy, and a high quality of life. Fecal continence was maintained, and tenesmus was rarely observed. The cat was euthanized because of tumor metastasis 274 days after the colonic stent was placed. The other cat retained fecal continence, and the owners reported subjective improvement in the severity of tenesmus, compared with that prior to stent placement. The cat was euthanized 19 days after stent placement because of perceived decreased quality of life. CLINICAL RELEVANCE-The use of self-expanding metallic stents for alleviation of colonic obstruction secondary to adenocarcinoma in cats appears to be effective. This technique provides a simple, quick, nonsurgical option for palliation in cats with advanced metastatic or systemic disease in which surgical resection may not be possible or warranted.

MutL protein homologue 1(MLH1) in colon adenocarcinomas of the dog: minireview.

The mismatch repair gene MLH1 is a gene encoding the mismatch repair protein MutL homolog 1 (MLH1), important for repairing mutations generated during DNA replication. MLH1 absence has been observed in human gastrointestinal tumours as well as tumours of the female reproductive tract. We describe the functions of MLH 1 in cell cycle regulation and DNA mismatch repair. In this sense we discuss foriegn knowledges, in which the canine colon adencarcinoma is less frequently diagnosed in Czech and Slovak regions. We briefly described a molecular mechanism of evolution of MSI+ and MSI- colorectal carcinomas in human, and this was confronted with the current opinion of canine colon adenocarcinomas. We suppose that canine colon adenocarcinomas may occur in higher frequency, but they are underdiagnosed in the clinical veterinary practice. At the end, we describe two cases of dogs diagnosed with colorectal adenocarcinoma. The authors propose the centralized collection of colon adenocarcinoma samples from dogs, in one reference veterinary histopathological laboratory, which would analyse mismatch repair proteins.