Abstract
Background – Pyothorax in cats is routinely managed, at least initially, with thoracic tube placement associated with systemic antimicrobial administration. Traditionally, large-bore trocar-type thoracostomy tubes have preferentially been used for the drainage of thick material from the pleural space. In recent years, the use of small-bore wire-guided thoracic drains has increased in both small animals and in humans. Few studies have highlighted the efficacy of small-bore wire-guided thoracostomy tubes.
Aim - The purpose of this study was to describe the use of small-bore wire-guided thoracostomy tubes in feline pyothorax in terms of efficacy, safety and outcome.
Methods - Cats with pyothorax managed with small-bore thoracostomy tubes (2015-2018) were retrospectively studied. The number of drains inserted, the need for anesthesia and analgesia for chest tube placement and maintenance, and related major and minor complications were reviewed. Clinical data, diagnostic results, treatment and outcome were recorded.
Results - Ten cats were enrolled. Thoracostomy tube placement was unilateral in 7/10 cats despite the presence of bilateral effusion in 9/10 cats, and required sedation (8/10) or anesthesia (2/10). Four cats experienced minor complications during the chest tube insertion, including self-limiting pneumothorax (1/4) and malpositioning (3/4). Pain management was adequately achieved using opioids (8/10) or opioids plus nonsteroidal anti-inflammatory drugs (NSAIDs) (2/10). Partial chest tube occlusion occurred in 3 cases and it was resolved with lavage. In one case, the occlusion was complete, requiring drain removal. Three/10 cats were treated medically, combining thoracostomy tubes and antibiotics while 7/10 cats underwent surgery. All the cats survived.
Conclusion - Small-bore thoracostomy tubes represent a safe and effective option for the initial management of feline pyothorax. In fact, mainly minor complications were reported during insertion and usage.
The small-bore thoracostomy tubes were well tolerated by the cats with a satisfactory performance in terms of exudate drainage in most cases. The combined use of a small-bore thoracostomy drain together with the common practice of surgical treatment might have resulted in the successful management of the cases presented.

Key words: cat, pyothorax, thoracic empyema, thoracostomy drain, thoracic surgery