General Considerations

•ADC and LSA are the most common large intestinal tumors in cats

•other large intestinal tumors include MCT, HSA, and neuroendocrine carcinoma

•intestinal HSA metastatic to regional lymph nodes and carcinomatosis has been reported

•ileocolic junction most common site for large intestinal tumors

Clinical Signs

•hematochezia, vomiting, and weight loss

Diagnosis

Physical Examination

•cachexia is common

•abdominal mass is frequently palpable via either abdomen and rectal palpation

•other findings include dehydration and abdominal pain

Ultrasonography

•circumferential transmural thickening with loss of normal intestinal layering reported in 5 cats with intestinal ADC

Endoscopy

•endoscopy is recommended prior to definitive treatment

•biopsy samples should be interpreted histologically as cytologic misdiagnosis is common with intestinal ADC being misdiagnosed as either septic inflammation or LSA

•biopsy samples are often small and superficial resulting in false-negative diagnosis if lesion is either submucosal or associated with surface ulceration and necrosis

Exploratory Celiotomy

•definitive diagnosis with exploratory celiotomy and biopsy

•feline large intestinal ADC more commonly associated with mucosal ulceration and bowel thickening than annular stenosis

•leiomyoma and sarcoma are usually large solitary masses growing through the intestinal serosa

Treatment

Surgery

•debilitation and hypoproteinemia may complicate treatment

•exploratory celiotomy with resection and end-to-end anastomosis with 4-8 cm margins and serosal patching of anastomosis

•mesenteric and regional lymph nodes should be assessed ± aspirated

Chemotherapy

•multiagent protocols recommended for LSA as either adjuvant therapy or sole treatment for diffuse disease

•chemotherapy is also recommended for cats with intestinal plasmacytoma and MCT

•no effective chemotherapy for ADC

Prognosis

•MST for cats with colonic tumors is significantly better with:

•surgical resection compared to conservative management (198 days v 22 days)

•MCT compared to LSA (199 days v 97 days)

•no metastasis in cats with ADC (49 days v 259 days)

•however, some cats with metastatic disease had prolonged survival time