Cancer in the digestive system is not common and is less than one per cent of all cancers found in small animals. If it is found, it is often in older dogs, and adenocarcinoma and lymphosarcoma are seen more in male dogs than female. Colorectal tumors are more frequent in German Shepherds, Poodles, Great Danes, Spaniels and Boxers. There have been no specific causes identified for most types of gastrointestinal tumors but intestinal tumors are generally malignant.
The symptoms are dependent on the location, extent and any associated consequences of the tumor. There may be vomiting, which can be bloody, diarrhea, which can also be bloody, constipation, straining when trying to defecate, weight loss, an accumulation of fluid in the abdomen, abdominal pain, and abdominal infection with a ruptured bowel if it has been affected. There may be symptoms of anemia, like pale gums, if the cancer is gastrointestinal.
It is possible for the veterinarian to fell a tumor during a physical examination which will then be confirmed with x-rays and/or abdominal ultrasound. The veterinarian may also notice bleeding of the tumor during a rectal examination. Biopsy samples will be taken through abdominal surgery and the diagnosis will be confirmed by a pathologist after looking at the biopsy samples. Treatment will include removing the tumor surgically. The prognosis is dependent on the type of tumor, if all tumor were removed and the number of tumors. It can vary from excellent to poor.