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Intestinal Cancer (Adenocarcinoma) in Dogs

Adenocarcinoma of the Stomach, Intestine, or Rectum in Dogs

Intestinal cancer, specifically adenocarcinoma, is a malignant tumor that originates in the glandular and epithelial tissue lining the internal organs of dogs. This form of cancer can develop in various parts of the gastrointestinal system, including the stomach, small and large intestines, and rectum. Typically, it afflicts older dogs, usually aged six years and above, with no specific breed predisposition, though it tends to affect male dogs more frequently than females. Unfortunately, the prognosis for this type of cancer is generally poor.

Symptoms and Types

The symptoms primarily manifest in the gastrointestinal system and encompass:

  • Vomiting
  • Weight loss
  • Reduced appetite
  • Abdominal discomfort
  • Hematemesis (vomiting blood)
  • Melena (dark feces indicating gastrointestinal bleeding)
  • Passage of bright red blood in feces
  • Tenesmus (urgent but ineffectual defecation)


  • The precise cause remains unidentified.
  • A genetic basis is suspected in Belgian shepherds.


To diagnose the condition, you will need to provide a comprehensive history of your dog’s health leading up to the onset of symptoms. Your veterinarian will conduct a thorough physical examination and may recommend various tests including blood tests, fecal tests, and a biochemistry profile. Blood tests typically reveal varying degrees of anemia, often attributed to gradual blood loss through feces. Fecal samples will be examined under a microscope to detect hidden blood not visible to the naked eye. Contrast radiography may be employed to visualize the presence, location, and size of the tumor. Ultrasound is also a valuable diagnostic tool for detecting adenocarcinoma of the gastrointestinal tract. Your veterinarian may perform a needle biopsy during ultrasound to examine fluid samples for neoplastic cells. Endoscopy, a diagnostic tool inserted into the body, may also be used to obtain biopsy samples. If these methods fail to confirm a diagnosis, surgery may be necessary for definitive identification.


Surgery is the primary treatment for adenocarcinoma of the gastrointestinal system, although achieving a permanent cure is rare due to common metastasis. Complete removal of neoplastic tissue is often challenging, particularly in cases of stomach adenocarcinoma. For intestinal neoplasms, surgical removal of the affected section of the intestine followed by suturing of the healthy portions is typically performed. While chemotherapy may be recommended, its success rate is usually limited. Pain relief medications are prescribed to alleviate associated discomfort.

Living and Management

Following surgery, regular follow-up visits with your veterinarian every three months are recommended for progress assessments. During these visits, your veterinarian will conduct physical examinations and utilize X-ray and ultrasound imaging to monitor for any signs of tumor regrowth.

These tumors tend to grow rapidly and often spread to other organs and parts of the body. Survival time varies, with gastric adenocarcinoma typically resulting in a survival time of around two months, while intestinal neoplasms may extend survival to approximately ten months. However, survival time is subject to individual variability and can only be accurately predicted by your veterinarian after a thorough evaluation of your dog’s condition.

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