Veterinary Guide to Canine Gastrointestinal Adenocarcinoma 2025 🩺🐶

By Dr. Duncan Houston BVSc

🧬 What Is Adenocarcinoma?

An adenocarcinoma is a malignant tumor arising from glandular epithelial tissues in the gastrointestinal (GI) tract. In dogs, these tumors most commonly occur in the stomach (especially the distal third), colon, and rectum. They're invasive, often ulcerate, and frequently metastasize to lymph nodes, liver, lungs, and peritoneal surfaces.

👥 Who Is Affected?

• Typically diagnosed in middle-aged to older dogs (6–10+ years).
• Breeds with higher incidence include German Shepherds, Collies, Boxers, Poodles, Dobermans, Shar-Peis, and West Highland White Terriers.
• No strong sex bias, but some studies note rare breed predispositions.

⚠️ Clinical Signs

• Vomiting—often with blood (“coffee ground” appearance), especially with gastric lesions.
• Weight loss, anorexia, lethargy.
• Diarrhea, hematochezia or melena, depending on tumor location.
• Tenesmus or straining with rectal involvement.
• Abdominal pain or palpable mass (intestinal).
• Paraneoplastic signs: anemia, hypoproteinemia, and even hypoglycemia.

🔍 Diagnostic Approach

1. History & exam: Investigate chronic GI signs and assess hydration, palpate abdomen/rectum.
2. Bloodwork & UA: CBC, biochemistry, electrolytes, possible anemia or protein loss.
3. Imaging:
   • Abdominal ultrasound: loss of wall layering, masses, lymph nodes, liver metastases.
   • Thoracic radiographs: assess pulmonary metastasis.
4. Endoscopy: Visualize gastric or colonic lesions and obtain biopsies.
5. Fine-needle aspirate: For accessible masses or lymph nodes; cytology may suggest carcinoma.
6. Histopathology: Gold standard for diagnosis, with grading and margins information.

⚙️ Treatment Options

1. Surgical Resection

• Gastrectomy for gastric tumors; segmental resection for small intestine; colectomy or rectal resection for large intestinal tumors.
• Lymph node sampling and staging are essential.
• Clean margins improve outcomes; partial-thickness resection may be performed for rectal lesions.

2. Medical and Adjunctive Therapy

• Adjuvant chemotherapy: limited benefit; consider for metastatic or incompletely excised tumors.
• Palliative care: antiemetics, antacids, appetite stimulants, analgesics, nutritional support.

3. Prognosis by Location

• Gastric adenocarcinoma: Poor prognosis; survival often <6 months post-surgery.
• Small intestinal: Median survival 7.5–17.5 months if fully excised; metastasis risk ~38–41 %.
• Colorectal: Favorable prognosis; MST 22–44 months with surgery.

📈 Monitoring & Follow-Up

• Re-exam every 2–4 weeks for 3 months, then every 3–6 months: physical exam, CBC, chemistry, ultrasound.
• Monitor quality of life, weight, appetite, and GI function.
• Repeat thoracic imaging if pulmonary signs arise.

🏡 Home Care & Supportive Measures

• Small, frequent meals; low-fat, easily digestible diets.
• Medications for vomiting, pain, and appetite as prescribed.
• Maintain hydration; consider muzzle feeders or syringe feeding.
• Provide comfort: soft bedding, consistent routine, stress reduction.

📱 Ask A Vet Telehealth Support

• 📸 Upload images of vomit, stools, or wound sites for remote evaluation.
• 🔔 Medication, nutrition, and appointment reminders.
• 🧾 Lab order alerts and interpretation via teleconsults.

🎓 Case Spotlight: “Mia” the Boxer

Mia, a 9-year-old Boxer, presented with intermittent vomiting and weight loss. Ultrasound revealed a mass in the pyloric region and enlarged perigastric lymph nodes. Endoscopic biopsies confirmed adenocarcinoma. She underwent partial gastrectomy with lymph node removal. Postoperative care included antiemetics, analgesics, and a GI diet. At 8 months post-surgery, she remains bright, eating well, and maintaining weight. Ask A Vet monitoring allowed timely medication adjustments and remote checkups 🐕⚕️💖

🔚 Key Takeaways

1. Adenocarcinoma arises from glandular epithelium in the GI tract and is often malignant and ulcerative.
2. Signs include vomiting (sometimes bloody), weight loss, diarrhea or tenesmus, depending on tumor location.
3. Diagnosis relies on imaging, endoscopy, cytology, and histopathology.
4. Surgical excision is the treatment cornerstone; prognosis varies by location, with colorectal > small intestinal > gastric.
5. Ask A Vet telehealth supports monitoring, care coordination, nutrition plans, and medication reminders 📲

Dr Duncan Houston BVSc, founder of Ask A Vet. Download the Ask A Vet app today to guide your dog’s journey—from diagnosis and surgery to remote monitoring and comprehensive home care 🐶📲