# Canine Leishmaniosis Associated with Acute Pleural Effusion and Sudden Death in a Dog

## TL;DR

A dog with leishmaniasis died suddenly due to acute pleural effusion, marking the first known case of this association in canines.

## Contribution

This is the first documented case of canine leishmaniosis linked to acute pleural effusion and sudden death.

## Key findings

- Leishmania amastigotes were identified in the pleural fluid and lymph nodes of a dog with acute pleural effusion.
- The dog exhibited sudden death following weight loss and enlarged lymph nodes.
- Immunohistochemical analysis confirmed Leishmania infection in the lymph nodes.

## Abstract

Pleural effusion is a condition characterized by excessive fluid accumulation in the pleural spaces. This condition is a consequence of an underlying disease and may be caused by many factors, such as kidney, liver, and heart diseases; systemic inflammation; and neoplasms. It can occur acutely or chronically. We diagnosed the occurrence of acute pleural effusion as a result of leishmaniasis and necrotizing lymphadenitis in a dog. The diagnosis was confirmed through necropsy, as well as the identification of Leishmania amastigotes in the pleural fluid, lymph nodes, and other organs. In humans, the occurrence of acute pleural effusion associated with leishmaniasis has also been described, however, to the authors’ knowledge, this association has not yet been described in dogs. This study describes the first report of a dog with leishmaniasis associated with acute pleural effusion that died suddenly.

A two-year-old female crossbreed dog, previously a stray with no known owner, was adopted and subsequently spayed. The dog exhibited weight loss over a period of two months and died suddenly during a leashed walk. Upon necropsy, enlargement of the submandibular, prescapular, and popliteal lymph nodes was noted. The intrathoracic cavity contained a substantial volume of yellowish-white fluid. Lymph nodes in the mediastinal and ventral thoracic centers were also enlarged, hemorrhagic, and friable. Microscopic examination revealed significant architectural changes in the lymph nodes, characterized by a pronounced cellular infiltrate consisting of lymphocytes and histiocytes, along with macrophages containing intracytoplasmic Leishmania amastigotes. Immunohistochemical analysis of the lymph nodes confirmed positive staining for Leishmania amastigotes. This case represents the first report of canine leishmaniasis associated with acute pleural effusion and sudden death.