Imaging Diagnosis: Thoracic radiographic features of toxoplasmosis in a 14-month-old Red Kangaroo (Macropus rufus)

Abstract

A privately owned 14-month-old intact female red kangaroo (Macropus rufus) was presented for acute onset respiratory distress and lethargy. On presentation, the kangaroo was laterally recumbent, tachypneic, dyspneic, lethargic, and obtunded. Thoracic radiographs revealed a severe diffuse mixed pulmonary pattern (alveolar pattern superimposed on a bronchial pattern) and subjective mild generalized cardiomegaly. Due to the severity of clinical signs and grave prognosis, euthanasia was elected. Postmortem examination was consistent with systemic toxoplasmosis. Histopathology and immunohistochemistry staining on infected tissues confirmed Toxoplasma gondii. This is the first published report of radiographic findings for confirmed toxoplasmosis in a red kangaroo or marsupial.

Keywords: Apicomplexan; Macropodidae; Marsupial.

FIGURE 1

Right lateral (A), left lateral (B), and dorsoventral (C) thoracic radiographs of a 14‐month‐old red kangaroo (Macropus rufus). The cardiac silhouette is subjectively mildly generally enlarged. The lung has a severe diffuse mixed pattern, characterized by a diffuse alveolar pattern superimposed on a bronchial pattern. Technique 121 kVp and 5.6 mAs, CXDI‐50G, Canon Medical Systems USA, Inc., Tustin, CA

FIGURE 2

Zoomed right lateral views of the lung of a 14‐month‐old red kangaroo (Macropus rufus) demonstrated the underlying bronchial pattern. Arrowheads indicate thick rings/bronchial markings. Technique 121 kVp and 5.6 mAs, CXDI‐50G, Canon Medical Systems USA, Inc., Tustin, CA

FIGURE 3

Gross and microscopic post‐mortem findings in a 14‐month‐old Red Kangaroo with systemic toxoplasmosis. A, Gross post‐mortem findings. The lungs fail to collapse and contain numerous pale tan and dark red foci, corresponding to areas of inflammation and necrosis with hemorrhage, respectively. B, Cytologic touch impression of the lung reveals multiple intracytoplasmic tachyzoites, both within pneumocytes and macropahges. Diff‐Quik 100×. C, Histopathology of the lung identifies protozoal cysts within pneumocytes (black arrow), which contain multiple tachyzoites. Alveolar spaces are flooded with fibrin and cellular debris. H&E. 40×. D, Immunohistochemistry of lung identifies numerous intercellular and extracellular tachyzoites that exhibit strong immunolabeling (red‐orange color) with Toxoplasma gondii. antibody (60×). [Colour figure can be viewed at wileyonlinelibrary.com]