Acute Nontraumatic Hemoabdomen In The Dog

A dog that presents with a hemoabdomen that is not secondary to trauma will often have acute collapse, hypotension, weakness, tachycardia, pale mucous membranes and a distended abdomen. Other history/physical exam findings may include inappetance, dyspnea, abdominal pain, vomiting, diarrhea, muffled heart sounds, cardiac arrhythmias, poor pulse quality, a palpable abdominal mass and hematochezia. Frequent clinicopathologic findings are anemia, decreased total protein and decreased platelet count. Signalment is more commonly medium to large breed, older dogs especially Golden Retrievers, Laborador Retrievers and German Shepherds. Causes of non-traumatic hemoabdomen include benign or malignant intra-abdominal neoplasia, gastric dilatation/volvulus, splenic torsion, liver lobe torsion, vena caval syndrome secondary to dirofilariasis and coagulopathies (anticoagulant rodenticide toxicity).

The most common of these causes is malignant neoplasia (80% of cases in one study) and the majority of those cases are hemangiosarcoma (88%). Additional malignant tumors can include mesothelioma, pheochromocytoma and hepatic metastasis from other abdominal malignancies. The most common non-malignant cause is a ruptured splenic hematoma which actually has a good prognosis with splenectomy alone. Owners must often make rapid decisions regarding stabilization, treatment and surgery for their pet. Therefore, it is vital to inform owners of the likelihood of their pet having malignant neoplasia along with the treatment options as well as the overall poor prognosis associated with hemangiosarcoma (HSA). HSA frequently metastasizes to the lungs, liver, omental surfaces and is the most common sarcoma to metastasize to the central nervous system. Also, approximately 25% of dogs with HSA in one location will have another primary HSA in another location. This is not considered metastatic disease rather metachronous disease. Surgery alone for abdominal hemangiosarcoma with no adjunctive chemotherapy has a 1-4 month median survival time. Adding doxirubricin given every 3 weeks (post surgery) for five treatments may increase the median survival time to 6-8 months. No treatment gives zero to several days (rarely weeks) survival.

Unfortunately there is no way to definitively differentiate splenic hemangiosarcoma from a splenic hematoma without histopathology even when examined grossly at surgery. Clinical staging includes 3-view thoracic radiographs, abdominal ultrasound, echocardiography, CBC, chemistry, urinalysis and coagulation profile. The finding of splenic and hepatic nodules cannot be assumed to be metastatic lesions since nodular hyperplasia is quite common so their presence should not automatically preclude surgery. Abdominal ultrasound is often performed but it also cannot distinguish benign from malignant conditions. Finding a right atrial mass on echocardiography or pulmonary nodules on thoracic radiography, however, would be strong indicators of a malignant process. Fine needle aspirates with cytology of a suspect hemangiosarcoma are often non-diagnostic and can trigger life threatening hemorrhage so are generally contraindicated.

References:
Pintar J, et al: Acute nontraumatic hemoabdomen in the dog: A retrospective analysis of 39 cases (1987-2001), J Am Anim Hosp Assoc 39:518-522, 2003
Hammond T, et al: Prevalence of hemangiosarcoma in anemic dogs with a splenic mass and hemoperitoneum requiring a transfusion: 71 cases: J Am Vet Med Assoc 232:553-558, 2008.
Clifford C, et al: Canine hemangiosarcoma. In Bonagura J, Twedt D, editors: Kirk’s CVT XIV, St. Louis, 2009, Saunders, p 328