Introduction

Feline gastroenterology deserves critical attention in several areas in special, neoplasias affecting the feline alimentary tract which represent diagnostic and therapeutic challenges for the veterinarian in practice. Gastrointestinal tumors (GIT) correspond to less than 10% of reported domestic small animal's neoplasia, they generally have malignant behavior, making an early and precise diagnosis necessary (Selting 2007). Primary intestinal neoplasia can be originated from mesenchymal, epithelial, neuroendocrine and round cells (Selting 2007). According to its histopathological and immunohistochemical characteristics the main mesenchymal GIT reported in domestic animals are: gastrointestinal stromal tumor, leiomyomas, leiomyosarcomas, schwannoma, liposarcoma, hemangiosarcoma, lymphoma, anaplastic sarcoma (Frost 2003, Selting 2007,). Intestinal neoplasia in general is unusual in cats; and among those, lymphomas correspond to 64% of mesenchymal intestinal tumors (Patinaik et al. 1977, Leibman et al. 2005, Selting 2007). The risk of intestinal neoplasia development is increased in older cats with mean ages between 6 and 9 years old (Selting 2007). In cats GIT do not present sexual predisposition and are preferable found in short haired cats, with prominence to the Siamese breed (Leibman et al. 2005, Selting 2007). The majority of GIT are observed in small bowel segments affecting frequently the ileum and jejunum and more rarely the duodenum; intraluminal or intra-mural obstruction can be seen secondary to its appearance (Fossum 2005). The development of large bowel neoplasia is uncommon and involves mainly the colon once the rectum and cecum are seldom affected (Head 2002, Leibman et al. 2005). Clinical signs and symptoms reported most frequently in GIT cases are weight loss, emesis, hematemesis, diarrhea, melena, fever, jaundice, lethargy and abdominal effusion. Leibman and colleagues (2005) affirm that regional lymph nodes, spleen, liver and bone marrow are the principal metastatic sites. In our environment casuistic and characterization of animal profile studies of animals affected by GIT are rare. The present report aims to determine the punctual prevalence of mesenchymal GIT in felines diagnosed in the Animal Pathology service from January 1997 to June 2008, and parallel to it characterize the epidemiological profile of these animals in our environment.

Materials and Methods

The present study consisted on the survey of feline cases diagnosed with mesenchymal GIT referred to the Animal pathology service of the Department of Pathology of Veterinary Medicine School in University of São Paulo (FMVZ-USP) from January 1997 to June 2008. The data regarding sex, age, breed, clinical signs and symptoms, histological diagnosis, anatomic location, metastases and regional lymph nodes infiltrate; were obtained from the animal's hospital records. The eligibility criteria considered was: cats presenting mesenchymal GIT located on/and esophagus, stomach and intestine. The results were presented in form of frequency, characterizing punctual prevalence of the different mesenchymal neoplasia among the analyzed population.

Results

In 90 cases diagnosed with GIT, 18 belonged to the feline specie with diagnosis of mesenchymal neoplasia (20%). The distribution according to sex was of 11 males (61%) and 7 females (39%). Ages varied from 01 to 15 years old; in males the mean age was 9 years old, whereas in females was 10 years old. The observed breeds were: 15 (83.5%) domestic short hair (DSH), 1 (5.5%) Siamese, 1(5.5%) Persian and 1 (5.5%) British short hair. The principal clinical signs and symptoms listed were: emesis (55.5%), diarrhea (39%), weight loss (33.5%), hyporexia (22%), prostration (16.5%), hematemesis (11%), 5.5% parorexia, cachexia, choluria, jaundice, hematochezia and selective appetite. The histological diagnosis of the mesenchymal neoplasias were: small cells lymphoma in 14 animals (78%), poor differentiated mesenchymal neoplasia in 3 animals (16.5%) and bone differentiated sarcoma in 1 case (5.5%). Anatomical location of mesenchymal neoplasia was predominant on small bowel segments, totalizing 13 cases (72%), whose affected segment corresponded to the duodenum in 5 animals (38.5%), to the jejunum in 4 animals (30.7%), to the ileum in 1 animal (7.7%), to both jejunum and ileum in 1 animal (7.7%), to duodenum, jejunum and ileum in 2 animals (15.4%). In the large bowel segment 1 animal was presented with a neoplastic injury on rectum. The gastric cardia was compromised in 1 case (5.5%). The ileo-ceco-colic valve was affected in 1 animal (5.5%). In 2 animals of this study, multiple sites of neoplastic injury were found in different segments of the gastrointestinal tract: 1 case had the gastric fundus, jejunum and colon compromised (5.5%), the other one had the jejunum and cecum (5.5%). The data obtained regarding regional lymph nodes involvement showed that 12 animals (66,5%) had : mesenteric lymph node in 9 cases (75%), right and left medial iliac lymph nodes in 2 cases (16.5%), sternal lymph node in 1 case (8.5%), sublumbar lymph nodes in 1 case (8.5%) and peri-hepatic lymph node in 1 case (8,5%). Neoplastic infiltration and metastasis were identified on 6 animals (33.5%) and located mainly on the liver in 4 cases (66.5%), spleen in 1 case (16.5%) and thorax in 1 case (16.5%).

Discussion and Conclusions

Malignant mesenchymal neoplasia represented 20% of all intestinal neoplasia diagnosed on our feline routine. Cats affected by mesenchymal GIT were in majority short haired male cats, with mean age of 9 years old, presenting symptoms of emesis, diarrhea and weight loss, whose diagnosis was lymphoma and, in most cases with compromised regional lymph nodes. In scientific literature only a few embracing studies are available regarding the prevalence and incidence of GIT in felines on different diagnostic centers, thus is pointed out the importance of this study, in order to know the real punctual prevalence of these tumors on our feline population, making it possible to do an accurate diagnosis and trace a proper and precocious therapeutic program. The intestinal lymphoma occurrence in older males is in agreement with some authors (MacDonald et al. 1993, Selting 2007). Other researchers report that GIT do not present sexual predisposition, are less specific about breed predisposition, and state that short haired cats have a greater frequency of GIT development (Gabor et al. 1998, Leibman et al. 2005, Alroy et al. 1975). The studied population was predominantly composed by short haired cats; reflecting the population attended at the Veterinary Hospital of FMVZ-USP. In our study we observed that the anatomical location of mesenchymal neoplasia was predominant on small bowel segments, which corroborates with the scientific literature (Head 2002, Leibman et al. 2005,). However, the segment affected most frequently was the duodenum in opposing of those references (Head 2002, Leibman et al. 2005, Fossum 2005, Tams 2005). The main clinical signs and symptoms observed: emesis, diarrhea and weight loss are concordant with the literature (Leibman et al. 2005, Selting 2007,). The regional lymph nodes, spleen and liver are the principal sites of infiltrative/metastasis of the studied neoplasias, as considered by other authors (Leibman et al. 2005). This way, the presentation of mesenchymal intestinal neoplasia varies according to their location on the gastrointestinal tract, and usually when diagnosed, regional lymph nodes are already compromised, representing a challenge for both clinician and surgeon regarding of diagnosis and treatment of these neoplasms. For that reason careful attention to historical details, thorough and repeated examination are of paramount importance when evaluating animals with chronic digestive disturbances. In the same way the knowledge of the profile from animals affected by GIT, as well as the prevalence of these tumors on our environment, assists and makes it possible for the veterinarian to establish a precise diagnosis, an adequate and precocious treatment, and to promote the welfare and increase the lifespan of felines affected by GIT.

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