Feline Diaphragmatic Hernia Study Guide

Overview and Clinical Importance

Diaphragmatic hernia is the disruption of diaphragmatic continuity allowing abdominal viscera to herniate into the thoracic cavity. In cats, this condition can be traumatic (acquired) or congenital (most commonly peritoneopericardial diaphragmatic hernia or PPDH). This represents a significant category on the NAVLE due to its multisystemic presentation, requiring integration of respiratory, cardiovascular, and gastrointestinal knowledge.

The condition compromises respiratory function through pulmonary compression and ventilation-perfusion mismatch, while potentially causing cardiovascular compromise through reduced venous return. The liver is the most commonly herniated organ in cats (greater than 90% of cases), followed by intestines, stomach, and omentum.

Diaphragmatic Anatomy and Embryology

The diaphragm is a musculotendinous dome-shaped partition separating the thoracic and abdominal cavities. It consists of a central tendon (trifoliate in shape) surrounded by three peripheral muscular portions: the pars lumbalis (forming the crura), pars costalis (attaching to the costal arch), and pars sternalis (attaching to the xiphoid process).