Eosinophilic cavitary effusions in cats: 48 cases (2010-2020)

Area of Science:

• Veterinary Medicine
• Comparative Pathology
• Internal Medicine

Background:

• Eosinophilic effusions are typically defined as having ≥10% eosinophils.
• Eosinophilic cavitary effusions are rare in cats, with limited case reports in recent literature.

Purpose of the Study:

• To review disease associations in cats with eosinophilic cavitary effusions.
• To evaluate if a lower eosinophil threshold (5%-9%) indicates similar etiologies as effusions with ≥10% eosinophils.

Main Methods:

• Retrospective review of feline cavitary effusions (2010-2020) with ≥5% eosinophils.
• Cases categorized into 5%-9% and ≥10% eosinophil groups.
• Associated medical conditions were analyzed from patient records.

Main Results:

• Neoplasia was the most common cause for effusions with ≥10% eosinophils (45%) and 5%-9% eosinophils (31%).
• Cardiac and inflammatory diseases were also significant causes in both groups.
• Peripheral eosinophilia was more frequent in cats with ≥10% eosinophils (35%) compared to 5%-9% (5%).

Conclusions:

• Neoplasia, especially lymphoma, is a primary consideration for feline eosinophilic effusions.
• Cardiovascular and inflammatory disorders are previously unreported associated diseases.
• An eosinophil differential of 5%-9% suggests similar etiologies as classically defined eosinophilic effusions.