Intestinal Tumors in Cats and Dogs
What are intestinal tumors?
The intestine is the portion of the digestive tract between the stomach and the anus. It is divided into two major sections:
small intestine and large intestine. Most food products are absorbed in the small intestine while the large intestine is
responsible for absorption of water and excretion of solid waste material. The average age at which intestinal tumors are
diagnosedranges between 10-12 years for cats and 6 to 9 years for dogs. There are many different types of intestinal
tumors, including lymphoma, adenocarcinoma, mast cell tumor, and leiomyosarcoma.
Source: www.vetmed.wsu.edu/ClientED/images/hills_dog_cleaned.GIF
How common are these tumors?
Intestinal tumors account for less than 10% of all tumors in dogs and cats and their incidence increases with age in both
dogs and cats.
What are the symptoms?
The symptoms indicative of intestinal tumors include weight loss, diarrhea, vomiting, anorexia, and less frequently black
colored stool and anemia. The clinical symptoms often relate to the location of the tumor along the gastrointestinal (GI)
tract. For example, vomiting is associated with lesions in the upper region of the GI tract whereas weight loss is
associated with lesions in the small intestine.
How is the diagnosis made?
Upon the presentation of the above symptoms, the veterinarian will typically perform a series of tests, including physical
exam to look for any masses that may be felt, blood tests, chemistry profile and imaging studies. Imaging studies can
include plain X-rays, contrast radiography, and/or abdominal ultrasound. The ultrasound studies can localize the tumor,
evaluate whether the cancer has spread to other nearby organs, and guide biopsy. Ultrasound may also be helpful in
distinguishing between malignant and non-malignant intestinal disease based on the thickness of th intestinal wall. The
most definitive way to confirm/rule out intestinal tumors is to perform a medical procedure called endoscopy. It is a
minimally invasive diagnostic procedure that assesses the interior surfaces of an organ like intestine by inserting a tube
into the body. The instrument may have a rigid or flexible tube and not only provide an image for visual inspection and
photography, but also enable taking biopsies which can then be sent to the lab for analysis. When non- and minimally
invasive diagnostic tests fail to confirm a diagnosis, an exploratory surgery may be performed on pets with persistent
symptoms. The advantages of this procedure are that the entire area can be directly visualized and full thickness biopsy
samples can be taken but the disadvantages include the risks associated with any surgical procedure.
Do these tumors cause pain?
It is imperative that pets with cancer are provided with pain medication to relieve discomfort caused by the disease as
well as by the treatments. To learn more, please visit the Cancer Pain Management section.
What food should be fed to pets with cancer?
Pets with cancer need to be fed diets specifically designed to support a cancer patient. To learn more, please visit the
Cancer Nutrition section.
What are the treatment options?
With the exception of lymphoma, surgery is the primary treatment for intestinal tumors. There have not been enough
clinical studies to determine whether chemotherapy following surgical treatment provides any benefit to the pets. One
retrospective study suggested that cats receiving doxorubicin (a chemotherapeutic drug) did better compared to cats
that did not, but more studies are needed to determine what drugs and what combinations are the most effective for
each particular tumor type. Radiation therapy is not generally used for this particular disease due to concerns regarding
possible damage to surrounding normal tissues in the abdominal cavity.
What are the treatment associated risks?
The risks associated with surgery include life-threatening sepsis (a serious medical condition characterized by a whole-
body inflammatory state caused by infection) and peritonitis (inflammation of the abdominal lining).
Are there any clinical trials investigating new treatments?
There are no clinical trials specifically designed for intestinal tumors in pets, however, there are clinical trials
investigating novel therapies for general malignancy in dogs. To learn more about clinical trials open to enrollment in the
United States, please visit the Clinical Trials for Any Type of Tumor section. To learn more about veterinary clinical trials,
please visit the Pet Clinical Trials section.
To help Pet Cancer Center conduct more intestinal cancer clinical trials across the United States in order to make novel
and more efficacious therapies available to pets, please
What is the prognosis?
The prognosis for pets diagnosed with intestinal tumors will depend on a variety of factors, including the specific tumor
type, the stage of the disease and whether the cancer has spread to other organs. For pets whose cancer has not
spread to other organs, long-term survival is possible. It is estimated that approximately 40% of dogs with small intestinal
tumors remain alive 1 year after diagnosis. Dogs diagnosed with adenocarcinoma and leiomyosarcoma have frequent
metastases to lymph nodes and the liver. Dogs with small intestinal adenocarcinoma have shorter average survivals of
12 days without treatment and between 4-10 months with surgery. Dogs with leiomyosarcoma who survive surgery
survive 1.1-2 years. For cats with adenocarcinoma, approximately 50% will metastasize to the local lymph nodes, 30% to
the peritoneal cavity, and 20% or less to the lungs. Cats with small intestinal adenocarcinoma have a significant risk
associated with surgical treatment but those who live 2 weeks after the surgery may experience long term control of the
cancer. Cats with cancer in the large intestines have survival approximately 3.5 months for lymphoma, 4.5 months for
adenocarcinoma, and 6.5 months for mast cell tumor.
Sources:
The intestine is the portion of the digestive tract between the stomach and the anus. It is divided into two major sections:
small intestine and large intestine. Most food products are absorbed in the small intestine while the large intestine is
responsible for absorption of water and excretion of solid waste material. The average age at which intestinal tumors are
diagnosedranges between 10-12 years for cats and 6 to 9 years for dogs. There are many different types of intestinal
tumors, including lymphoma, adenocarcinoma, mast cell tumor, and leiomyosarcoma.
Source: www.vetmed.wsu.edu/ClientED/images/hills_dog_cleaned.GIF
How common are these tumors?
Intestinal tumors account for less than 10% of all tumors in dogs and cats and their incidence increases with age in both
dogs and cats.
What are the symptoms?
The symptoms indicative of intestinal tumors include weight loss, diarrhea, vomiting, anorexia, and less frequently black
colored stool and anemia. The clinical symptoms often relate to the location of the tumor along the gastrointestinal (GI)
tract. For example, vomiting is associated with lesions in the upper region of the GI tract whereas weight loss is
associated with lesions in the small intestine.
How is the diagnosis made?
Upon the presentation of the above symptoms, the veterinarian will typically perform a series of tests, including physical
exam to look for any masses that may be felt, blood tests, chemistry profile and imaging studies. Imaging studies can
include plain X-rays, contrast radiography, and/or abdominal ultrasound. The ultrasound studies can localize the tumor,
evaluate whether the cancer has spread to other nearby organs, and guide biopsy. Ultrasound may also be helpful in
distinguishing between malignant and non-malignant intestinal disease based on the thickness of th intestinal wall. The
most definitive way to confirm/rule out intestinal tumors is to perform a medical procedure called endoscopy. It is a
minimally invasive diagnostic procedure that assesses the interior surfaces of an organ like intestine by inserting a tube
into the body. The instrument may have a rigid or flexible tube and not only provide an image for visual inspection and
photography, but also enable taking biopsies which can then be sent to the lab for analysis. When non- and minimally
invasive diagnostic tests fail to confirm a diagnosis, an exploratory surgery may be performed on pets with persistent
symptoms. The advantages of this procedure are that the entire area can be directly visualized and full thickness biopsy
samples can be taken but the disadvantages include the risks associated with any surgical procedure.
Do these tumors cause pain?
It is imperative that pets with cancer are provided with pain medication to relieve discomfort caused by the disease as
well as by the treatments. To learn more, please visit the Cancer Pain Management section.
What food should be fed to pets with cancer?
Pets with cancer need to be fed diets specifically designed to support a cancer patient. To learn more, please visit the
Cancer Nutrition section.
What are the treatment options?
With the exception of lymphoma, surgery is the primary treatment for intestinal tumors. There have not been enough
clinical studies to determine whether chemotherapy following surgical treatment provides any benefit to the pets. One
retrospective study suggested that cats receiving doxorubicin (a chemotherapeutic drug) did better compared to cats
that did not, but more studies are needed to determine what drugs and what combinations are the most effective for
each particular tumor type. Radiation therapy is not generally used for this particular disease due to concerns regarding
possible damage to surrounding normal tissues in the abdominal cavity.
What are the treatment associated risks?
The risks associated with surgery include life-threatening sepsis (a serious medical condition characterized by a whole-
body inflammatory state caused by infection) and peritonitis (inflammation of the abdominal lining).
Are there any clinical trials investigating new treatments?
There are no clinical trials specifically designed for intestinal tumors in pets, however, there are clinical trials
investigating novel therapies for general malignancy in dogs. To learn more about clinical trials open to enrollment in the
United States, please visit the Clinical Trials for Any Type of Tumor section. To learn more about veterinary clinical trials,
please visit the Pet Clinical Trials section.
To help Pet Cancer Center conduct more intestinal cancer clinical trials across the United States in order to make novel
and more efficacious therapies available to pets, please
What is the prognosis?
The prognosis for pets diagnosed with intestinal tumors will depend on a variety of factors, including the specific tumor
type, the stage of the disease and whether the cancer has spread to other organs. For pets whose cancer has not
spread to other organs, long-term survival is possible. It is estimated that approximately 40% of dogs with small intestinal
tumors remain alive 1 year after diagnosis. Dogs diagnosed with adenocarcinoma and leiomyosarcoma have frequent
metastases to lymph nodes and the liver. Dogs with small intestinal adenocarcinoma have shorter average survivals of
12 days without treatment and between 4-10 months with surgery. Dogs with leiomyosarcoma who survive surgery
survive 1.1-2 years. For cats with adenocarcinoma, approximately 50% will metastasize to the local lymph nodes, 30% to
the peritoneal cavity, and 20% or less to the lungs. Cats with small intestinal adenocarcinoma have a significant risk
associated with surgical treatment but those who live 2 weeks after the surgery may experience long term control of the
cancer. Cats with cancer in the large intestines have survival approximately 3.5 months for lymphoma, 4.5 months for
adenocarcinoma, and 6.5 months for mast cell tumor.
Sources:
- Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007.
- Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins,
1998.
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Last updated 6/7/09
