+ Biologic Behavior

  • Age: mean 9 years (range, 1-14 years)
  • Sites: large intestine and mid-to-distal rectum
  • Pseudomyxoma peritonei has been reported in 1 dog with small intestinal ADC and is characterized by deposition of mucinous pools on serosal surfaces and gelatinous ascites
  • 44% metastatic rate for small intestinal ADC with metastatic sites including the regional lymph nodes, mesentery, and liver ± spinal meninges and testes


+ Clinical Signs

  • Anorexia, weight loss, intermittent vomiting, and diarrhea
  • Severe, persistent vomiting is occasionally observed if proximal small intestinal tumor causes obstruction


+ Physical Examination

  • Palpable abdominal mass and cachexia are common
  • Other findings include dehydration and abdominal pain

+ Laboratory Tests

  • Anemia and leukocytosis are common in dogs with non-lymphoid intestinal tumors
  • Anemia and hypoglycemia are common in dogs with intestinal leiomyosarcoma
  • Mesenchymal tumors are associated with microcytic hypochromic anemia, hypoproteinemia, and mild leukocytosis

+ Abdominal Radiographs

  • Abdominal mass, obstruction, or persistent irregularity of bowel appearance are identified in 25% of small intestinal tumors and nearly 50% of non-lymphoid intestinal tumors
  • Abdominal mass is detected in 60% of canine mesenchymal small intestinal tumors

+ Contrast Radiography

  • Intestinal mass identified in 57% of dogs with non-lymphoid intestinal tumors
  • Contrast radiographs: mural lesions include luminal filling defect, intestinal wall thickening, mucosal ulceration, abnormal positioning of intestinal loops, and constricting annular lesions

+ Ultrasonography

  • Intestinal mass identified in 87% (13/15) dogs with non-lymphoid small intestinal tumors
  • Intestinal ADC are transmural, poorly echogenic, and associated with complete loss of wall layering, increased intestinal wall thickness (median 12 mm), luminal fluid accumulation proximal to the lesion (81%), and regional lymphadenopathy (57%)
  • Loss of wall layering is an excellent predictive factor for differentiating intestinal neoplasia from enteritis in dogs (99% v 12%) with intestinal tumors 50.9-times more likely to have loss of wall layering
  • Intestinal tumors also have significant increases intestinal wall thickness (15 mm v 6 mm) and are significantly less likely to have diffuse intestinal involvement (2% v 72%)

+ Exploratory Celiotomy

  • Definitive diagnosis with exploratory celiotomy and biopsy
  • Majority of small intestinal ADC are associated with annular constrictions
  • Leiomyomas and sarcomas are usually large solitary masses growing through serosa


+ Surgery

  • Debilitation and hypoproteinemia may complicate treatment
  • Exploratory celiotomy with resection and end-to-end anastomosis with 4-8 cm margins and serosal patching
  • Mesenteric and regional lymph nodes should be assessed ± aspirated

+ Chemotherapy

  • No proven chemotherapy for ADC, but combination of 5-fluorouracil and cisplatin may be effective
  • Second-look surgery recommended for evaluation of response to chemotherapy

+ Prognosis

  • MST 272-300 days
  • Sex is a prognostic factor with MST for male dogs 272 days v 28 days for female dogs