Gastrointestinal Neoplasia in Dogs
Dr. Bari Spielman
A complete blood count (CBC) will evaluate for the presence of infection, inflammation, and anemia, sometimes associated with gastrointestinal neoplasia.
A diagnosis of gastrointestinal neoplasia can be made more easily in some cases than in others. A full diagnostic work up is recommended. A definitive diagnosis can only be made with the evaluation of tissue; therefore, a biopsy is necessary for a bottom line diagnosis of GI neoplasia and specific tumor type.
A biochemical profile evaluates the kidney, liver, electrolytes, total protein, and blood sugar status. All of these parameters are important to establish in the patient with gastrointestinal neoplasia, as these changes can be seen associated with other disorders as well.
A urinalysis helps evaluate the kidneys and hydration status of the patient.
Multiple fecal examinations are important to rule out gastrointestinal parasites as a cause of vomiting, diarrhea, or other gastrointestinal signs.
Abdominal radiographs (X-rays) evaluate the abdominal organs (kidneys, liver) and may help visualize the presence of a foreign body or tumor.
An abdominal ultrasound evaluates the abdominal organs and helps assess for the presence of tumors. Organs, lymph nodes, and masses can be sampled with a needle or biopsy instrument with the guidance of ultrasound. This procedure is relatively safe, however may necessitate a sedative. It is often recommended that a specialist perform the procedure.
Thoracic (chest) radiographs should be obtained to evaluate esophagus and to assess for the presence of metastatic disease (spread of cancer to the chest).
Your veterinarian may recommend additional tests to insure optimal medical care. These are selected on a case-by-case basis.
A coagulogram (clotting profile) may be recommended in cases of GI bleeding to rule out associated thrombocytopenia (decreased platelets) or clotting factor abnormalities.
An ACTH stimulation test may be recommended to rule out hypoadrenocorticism (Addison's disease), which can cause gastrointestinal signs. It is a combination of two blood tests that measures adrenal function. It is safe, and can usually be performed at your local veterinary hospital.
Bile acids are paired blood tests obtained before and after a meal that evaluates liver function, as certain liver diseases can be associated with GI signs. The test is very safe and can be performed at your local veterinary hospital.
A blood lead level should be performed in patients where there has been known or possible lead exposure.
A gastrin level should be run on any patient with multiple or recurrent ulcers. Elevated levels are usually seen in patients with gastrinomas, which are tumors that secrete gastrin, increasing stomach acid production and causing ulceration.
An upper gastrointestinal (GI) barium (dye) series may be helpful in identifying tumors. A safe dye is given to the patient by mouth, and is then watched as it travels through the GI tract. It is a non-invasive test that can often be performed by your regular veterinarian, although in some cases may necessitate transfer to a specialty hospital.
A reticulocyte count should be performed on anemic animals. This will help determine if the type of anemia is consistent with gastrointestinal bleeding (secondary to a tumor) or some other cause.
A bone marrow aspirate may be recommended in some patients with anemia, to determine if it is secondary to a GI bleed or a primary problem in the bone marrow (associated cancer/lymphosarcoma). It is a relatively noninvasive test. It allows us to sample the marrow (substance inside of the bone), which is responsible for producing red blood cells, white blood cells and platelets. With a local anesthetic, a small needle is introduced into the core of the bone, and a small amount of marrow is withdrawn and analyzed. This test may be performed by your local veterinarian, although in some cases, may be best to have performed in a specialty hospital.
Gastroduodenoscopy (upper GI endoscopy) or colonoscopy (large bowel endoscopy) may be of benefit. It may help evaluate these areas for growths, and sample tissue for the presence of inflammation or cancer. Hospitalization is brief, and healing is generally quick and uneventful. It does, however, necessitate general anesthesia, and therefore is associated with minor risks.
Lastly, an exploratory laparotomy should be performed as a diagnostic (and sometimes therapeutic) tool in any individual that has had an extensive diagnostic and sometimes therapeutic (treatment) course, with little or no response. It is an invasive procedure, however is necessary in a handful of cases for a definitive diagnosis.
Treatment of gastrointestinal neoplasia largely depends on surgical excision. If complete excision of the primary tumor is impossible, or metastasis has occurred, other therapy can be attempted. These treatments may reduce severity of symptoms or provide relief for your pet.
Fluid and electrolyte therapy may be necessary in some patients with gastrointestinal neoplasia, and is directed toward correcting dehydration, acid-base, and electrolyte abnormalities. Additionally, blood transfusions may be indicated in the severely anemic patients who have bleeding tumors.
Depending on the location of the neoplasia, dietary recommendations may vary. Patients with esophageal tumors may benefit from a gruel or canned food. Those with gastric or intestinal lymphoma may benefit from small, frequent feedings. Parenteral (intravenous) nutrition or feeding tubes may be of benefit in certain cases.
Drugs that decrease or inhibit acid production by the stomach such as Tagamet® (cimetidine), Pepcid® (famotidine), Zantac® (ranitidine), Cytotec® (misoprostol) and Prilosec® (omeprazole) encourage and expedite the resolution of GI inflammation, especially esophagitis and severe gastritis from excessive vomiting, often associated with GI neoplasia.
Gastrointestinal protectants and adsorbents (medications that protect or sooth) are felt to coat an "irritated" GI lining and bind "noxious" (harmful) agents, and may offer symptomatic relief to patients with upper GI tumors and associated inflammation. Examples include Carafate® (sucralfate) and Pepto-Bismol® (bismuth subsalicylate).
For most solid tumors, surgery is indicated. The complete removal of a tumor prior to metastasis can be curative in some cases. Occasionally, restrictions exist on how much tissue can be removed and preserve normal function, as in the esophagus or stomach. In these cases, surgical debulking may be of benefit, where a part of the tumor is removed, giving the patient temporary relief until the tumor grows back.
Chemotherapy has been used successfully most often in lymphoma cases. There are many protocols available, and the particular regime should be tailored to the patient. Depending on the extent and location of lymphoma, some of these patients do well for months.
Radiation therapy may be used as a sole entity or in conjunction with surgery. Only certain tumor types are responsive. Very specialized equipment and facilities are needed, therefore these patients are best served in a referral institution.