Bronchopneumonia by Streptococcus equi subsp. zooepidemicus in a horse with inhalation of pine branch of Araucaria angustifolia

Abstract

Respiratory problems due to tracheobronchial foreign bodies (FBs) are unusual in horses; although equines kept in pastures eventually inhale FBs, as conifer twigs of Araucaria angustifolia. A 1,5-year-old Criolle foal was presented with hemoptysis, dyspnea, restlessness and fever (40.9 ºC rectal temperature). Complete blood count showed intense neutropenia, monocytosis, thrombocytopenia and hypoproteinemia. Treatment was carried out but no clinical improvement was observed. At the post-mortem examination, marked amount of dark red liquid was observed in the thoracic cavity (hemothorax). The lung parenchyma was diffusely consolidated, predominantly in the cranioventral area, associated with mild pleural fibrin deposition. The right primary bronchus was obliterated by a Araucaria angustifolia pine branch measuring 18 cm in length, with adjacent darkened areas (lung consolidation). Microscopically, there was diffuse necrosis with severe hemorrhage in the lungs, associated with marked neutrophilic inflammatory infiltrate, numerous coccoid bacterial aggregates, and fibrinous pleuritis. Additionally, there was diffuse alveolar edema and multifocal thrombosis. Lung fragments were submitted for bacterial culture and mixed bacterial growth was observed with a predominance of Streptococcus equi subsp. zooepidemicus. Inhalation of branches is not commonly reported in horses, but it must be included in the differential diagnoses of pneumonia, and attention should be taken when allowing horses to graze in areas where the plant occurs.

Problemas respiratórios devido a corpos estranhos (CEs) traqueobrônquicos são incomuns em equinos, embora cavalos em pastagem possam eventualmente aspirar CEs, como galhos de Araucaria angustifolia. Um potro Crioulo, 1,5 anos, apresentou hemoptise, dispneia, inquietação e temperatura retal de 40,9 ºC. O hemograma revelou intensa neutropenia, monocitose, trombocitopenia e hipoproteinemia. O tratamento foi realizado, mas sem sucesso. Na cavidade torácica, foi observada grande quantidade de líquido avermelhado livre (hemotórax). Os pulmões estavam difusamente consolidados, predominantemente cranioventral e com discreta deposição de fibrina sobre a superfície pleural. O brônquio principal direito estava obliterado por um ramo de pinheiro de Araucaria angustifolia com 18 cm de comprimento. Microscopicamente, notou-se necrose de coagulação pulmonar difusa com hemorragia severa, infiltrado inflamatório neutrofílico marcado, numerosos agregados bacterianos cocoides e pleurite fibrinosa. Fragmentos de pulmão foram submetidos ao isolamento bacteriológico e abundante crescimento misto com predominância de Streptococcus equi subsp. zooepidemicus foi observado. A inalação de grimpas de pinheiro não é comumente relatada em equinos, mas deve ser incluída nos diagnósticos diferenciais de pneumonia e deve-se ter atenção ao introduzir cavalos no campo com a presença da planta.