Immune‐mediated thrombocytopenia associated with Angiostrongylus vasorum infection in a dog

Abstract

A three-year-old weimaraner was presented with lethargy, anorexia, neck pain and a soft fluctuant swelling in the thoracic inlet. A cough had been noted previously. Clinical examination revealed tachycardia, tachypnoea, pallor and a large subcutaneous swelling, with bruising, suggestive of a haematoma in the thoracic inlet. Thoracic radiographs revealed a cranial mediastinal mass which had the ultrasonographic appearance of fluid, and there was also a marked generalised interstitial lung pattern. Routine haematology revealed severe anaemia and thrombocytopenia, although coagulation tests were within normal limits. A diagnosis of immune-mediated thrombocytopenia was however made on the basis of a positive antiplatelet antibody test and a rapid response to prednisolone therapy. Furthermore, a tentative diagnosis of Angiostrongylus vasorum infection was suggested on the basis of clinical and radiographic findings, although no lungworm larvae were identified on faecal analysis. Despite initiating treatment with fenbendazole, the dog died suddenly. Postmortem examination revealed myocarditis, thrombosing arteritis, pneumonia and chronic membranoproliferative glomerulonephritis associated with A vasorum infection.

Unexplained bleeding as primary clinical complaint in dogs infected with Angiostrongylus vasorum

“…Basically, one mechanism may be an abnormal primary hemostasis. Immune-mediated thrombocytopenia (ITP) has been described in one dog where low platelets were the suspected cause of bleeding (Gould and McInnes, 1999). In our dogs, thrombocytopenia was not considered an important underlying cause as platelet counts were above 30'000/ul in all dogs ( Scott and Jutkowitz, 2010), and half of the dogs had normal platelet counts.…”

Pathological Findings in Dogs Naturally Infected with Angiostrongylus Vasorum in Newfoundland and Labrador, Canada

“…12,35 Bleeding tendencies caused by acquired von Willebrand factor deficiency and immune-mediated thrombocytopenia have been reported in dogs in association with A. vasorum infection. 13,36 In the latter case, increased monocyte-macrophage activation and platelet consumption caused by the formation of antiplatelet antibodies secondary to A. vasorum infection was proposed as the cause of thrombocytopenia. More commonly, the cause of abnormal bleeding in A. vasorum-infected dogs is postulated to be an intravascular consumptive coagulopathy caused by the chronic formation of intravascular fibrin thrombi in the lung, resulting in the consumption of clotting factors and platelets.…”

Canine angiostrongylosis: The French heartworm: An emerging threat in North America

“…Hemorrhagic diathesis due to coagulopathies of unknown etiology have been frequently associated with angiostrongylosis in both naturally and experimentally infected dogs Cury et al, 2002;Dodd, 1973;Ramsey et al, 1996;Sasanelli et al, 2008;Schelling et al, 1986). The bleeding disorders are most often attributed to disseminated intravascular coagulation; however, immune-mediated thrombocytopenia and von Willebrand factor deficiency have also been reported (Gould and McInnes, 1999;Ramsey et al, 1996;Whitley et al, 2005). In some dogs, the bleeding disorder is the primary presenting clinical sign.…”