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Read-Only Case Details Reviewed: Oct 2008



September 2017



Signalment (JPC #3134519):  12-year-old female mixed breed dog

HISTORY:  The dog was kept in a kennel and died spontaneously overnight.

HISTOPATHOLOGIC DESCRIPTION:  Lung: There are multifocal to coalescing granulomas that efface the pulmonary architecture. The granulomas are composed of a central core of eosinophilic necrotic debris admixed with myriad metastrongyle larvae and eggs surrounded by macrophages and multinucleated giant cells (foreign body type), which are further rimmed by fibroblasts, concentrically arranged mature collagen, lymphocytes and plasma cells.  The larvae are elongated with a thin eosinophilic cuticle and a primitive intestinal tract. The thin-walled eggs are ovoid, 50-60 μm in diameter, and contain either a morula or larva. The bronchial lumina contain numerous eggs and larva intermixed with few histiocytes and multinucleated giant cells, sloughed epithelial cells and abundant mucus.  Multifocally, pulmonary arteries are severely dilated and the tunica intima is thickened by moderate amounts of fibrous connective tissue and few lymphocytes and plasma cells (proliferative arteritis).  Within the lumen there are few cross sections of two morphologically distinct nematode adults.  The larger adult nematode cross section is 0.5-1 mm in diameter with a thin eosinophilic cuticle, internal cuticular ridges, tall coelomyarian/polymyarian musculature, and a small intestinal tract lined by cuboidal uninucleated cells (consistent with Dirofilaria immitis ).  The cross section of the second smaller adult nematode is 100 to 250 μm in diameter with smooth 3-4 μm cuticle, thin coelomyarian/polymyarian musculature, and a large intestinal tract lined by few multinucleated cells, and a reproductive tract.  Intravascular nematodes are surrounded by thrombi composed of lamellar bands of fibrillar eosinophilic fibrin, which multifocally are adhered to the vessel wall.  Few vessels are occluded with organized fibrous connective tissue containing multiple small blood-filled channels (organized thrombus with recanalization).  The tunica media of numerous pulmonary arteries is markedly thickened (smooth muscle hypertrophy). 

MORPHOLOGIC DIAGNOSIS:  1. Lung, arteries: Endarteritis, proliferative, chronic, multifocal, marked, with organizing thrombosis, dilatation, and few intravascular adult metastrongylid and filarid nematodes, etiology consistent with Angiostrongylus vasorum and Dirofilaria immitis. 2. Lung: Pneumonia, granulomatous, multifocal to coalescing, marked, with hemorrhage, fibrosis, and many nematode larvae and eggs, consistent with Angiostrongylus vasorum.

ETIOLOGIC DIAGNOSIS:  Pulmonary angiostrongyliasis and dirofilariasis

ETIOLOGY: Angiostrongylus vasorum and Dirofilaria immitis










Other pulmonary parasites



  1. Bourque AC, Conboy G, Miller LM, Whitney H. Pathological findings in dogs naturally infected with Angiostrongylus vasorum in Newfoundland and Labrador, Canada. J Vet Diagn Invest. 2008;20(1):11-20.
  2. Caswell JL, Williams KJ. Respiratory system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 2, 6th ed. St. Louis, MO: Elsevier Limited; 2016:586-587.
  3. Eberhard ML. Histopathological diagnosis. In: Bowman DD, ed. Georgis’ Parasitology for Veterinarians. 10th ed. St. Louis, MO: Elsevier; 2014:427.
  4. Gardiner CH, Poynton SL. An Atlas of Metazoan Parasites in Animal Tissues. Washington, D.C.: Armed Forces Institute of Pathology; 1999:5,6,28,38.
  5. Kranjc A, Schnyder M, Dennler M, et al. Pulmonary artery thrombosis in experimental Angiostrongylus vasorum infection does not result in pulmonary hypertension and echocardiographic right ventricular changes. J Vet Intern Med. 2010;24(4):855-62.
  6. Kramer L, Grandi G, Leoni M, et al. Wolbachia and its influence on the pathology and immunology of Dirofilaria immitis infection. Vet Parasitol. 2008;158(3):191-5.
  7. Paes-de-Almeida EC, Ferreira AMR, Labarthe NV, Cladas MLR, McCall JW. Kidney ultrastructural lesions in dogs experimentally infected with Dirofilaria immitis (Leidy, 1856). Vet Parasitol. 2003;113(2):157-68.
  8. Robinson WF, Robinson NA. Cardiovascular system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3, 6th ed. St. Louis, MO: Elsevier Limited; 2016:83-85.
  9. Theis JH. Public health aspects of dirofilariasis in the United States. Vet Parasitol. 2005;133:157-80.





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