Gastrointestinal Cancers In Dogs And Cats

Cancers of the gastrointestinal (GI) tract affect the stomach, intestines, and associated structures. They are less common than other cancers in dogs and cats, but are profound and challenging. The most common GI cancers in dogs include adenocarcinoma, lymphoma, leiomyosarcoma, and gastrointestinal stromal tumours (GISTs). In cats, alimentary lymphoma is the most frequent, followed by adenocarcinoma.

GI tumors are aggressive, invasive, and can metastasise to local lymph nodes, liver, or distant organs. Because signs are often vague and non-specific, diagnosis may be delayed until the disease is advanced. Accurate imaging and staging are critical in determining whether surgical resection, systemic therapy, or palliative care is the best option.

Pets with GI cancers may show:

• Chronic vomiting or diarrhoea.
• Weight loss and reduced appetite.
• Abdominal pain or distension.
• Blood in the stool or vomit.
• Lethargy or failure to thrive.

Diagnosis typically involves bloodwork, abdominal ultrasound, endoscopy, exploratory surgery with biopsy, and sometimes CT. However, these tests may not always reveal the full extent of disease, especially microscopic metastases or metabolically active lesions. PET-CT provides an added layer of clarity, showing both structure and function.

GI tumours can spread early and behave aggressively. A PET-CT scan provides a comprehensive picture of disease activity, ensuring treatment plans are based on accurate staging. Primary benefits include:

• Whole-body staging. The scan detects metastases in lymph nodes, liver, spleen, and other organs that may not be obvious on ultrasound or CT.
• Differentiates viable tumour tissue from inflammation, scarring, or benign changes.
• Ensures candidates for resection are appropriate by confirming there is no hidden systemic spread.
• Radiation therapy guidance: Maps metabolically active regions of tumours for precise targeting.
• Tracks changes in tumour metabolism following chemotherapy or other systemic therapies, often before visible shrinkage occurs.

Uptake patterns can help indicate disease aggressiveness, guiding discussions with the pet owner.

Integrating a PET-CT scan into gastrointestinal oncology, vets can stage tumours accurately, plan surgeries, and monitor therapy effectiveness earlier in the course of treatment.  Pet Theranostics works side by side with vets to ensure the best possible patient outcomes. For owners, the primary care of your pet remains with your chosen vet. We are currently accepting referrals. Pet owners can speak directly to their vet and ask for a PET-CT scan referral.