A diaphragmatic hernia is a condition in which a break in the diaphragm allows protrusion of abdominal organs into the chest. In cats, automobile-related trauma is a common cause of diaphragmatic hernia, although defects of the diaphragm that are present at birth (congenital) may also be a cause.

The signs of a hernia can vary. In the case of sudden trauma or injury, the cat has difficulty breathing. The degree of labored breathing may vary from barely detectable to fatal, depending on the severity of the hernia. If the stomach is trapped in the hernia, it may bloat and the animal's condition may worsen rapidly. In milder, longterm cases, general signs such as weight loss may be more noticeable than respiratory signs. During an examination, the veterinarian may note the absence of normal lung sounds and/or the presence of digestive system sounds in the chest.

Careful physical examination by the veterinarian, including listening to and tapping the chest and abdomen, usually suggests the presence of chest disease. A definitive diagnosis is most frequently made from x‑rays, which can reveal changes in the shape of the diaphragm and the displacement of abdominal organs. Specialized x‑rays that use dyes to highlight the digestive organs are sometimes necessary to make the diagnosis. Samples of abdominal or chest fluids, electrocardiograms (ECGs), and blood work may be obtained, and surgical exploration of the abdominal cavity may be necessary in some cases.

Surgical repair of the hernia is the only treatment. If other trauma is present, the animal's condition is usually stabilized before surgical correction of the hernia is performed.

Last full review/revision July 2011 by Ned F. Kuehn, DVM, MS, DACVIM; Stuart M. Taylor, PhD, BVMS, MRCVS, DECVP; Neil W. Dyer, DVM, MS, DACVP; Joe Hauptman, DVM, MS, DACVS