What is your diagnosis? Pleural fluid from a dog

Pleural effusion is an abnormal fluid accumulation in the pleural cavity, a narrow space between the lungs and the chest wall. It is not a disease per se but rather a symptom or indication of an underlying disease. In normal circumstances, this space contains a small amount of fluid (5 to 15 mL), a lubricant facilitating the non-frictional movement of the pleural surfaces.
There are two main types of pleural effusion: transudative and exudative. They are differentiated using Light's...

Pleural Effusion Overview
A pleural effusion is the abnormal collection of fluid between the parietal and visceral pleura layers of tissue that form the lining of the lungs and chest cavity. It can occur independently or due to surrounding parenchymal diseases, such as infection, malignancy, or inflammatory conditions.
Clinical Manifestations:

Thoracentesis(Thoracocentesis), commonly known as pleural tap, is a medical procedure where a 22 gauge needle is inserted into the pleural space, the area between the lung and chest wall. This procedure is commonly performed to diagnose or treat various respiratory disorders.
Description
Excess pleural fluid or air may accumulate in some respiratory disorders in the thoracic cavity. To treat pleural effusion, a physician conducts thoracentesis by carefully piercing the chest wall and entering...

Pneumonia poses the potential for numerous complications that warrant consideration. These complications include the following:

The pleura is a vital part of the respiratory system. It's a double-layered membrane surrounding the lungs and lining the chest cavity. The two layers of the pleura are:

The lungs are nestled in a cavity, shielded by the pleura. The pleura, a form of serous membrane, wraps around each lung. This membrane arrangement consists of two layers: the visceral and parietal pleurae. The visceral pleura lines the surface of the lungIn contrast, the parietal pleura is the outer layer and contacts to the thoracic wall, the mediastinum, and the diaphragm. The hilum is the point of connection between the visceral and parietal layers. The space between the parietal and...