Peritoneopericardial hernia is the most common congenital diaphragmatic defect in dogs and cats.1 This condition often goes unnoticed for years, and many cases are discovered incidentally on radiographs. It is often associated
with abnormalities of the sternum, such as pectus excavatum, as seen in this cat. Abdominal viscera can herniate into the
pericardial sac; in most cases, the liver, bowel, or falciform fat are involved.
The radiographic features of peritoneopericardial hernia are
- A dorsal peritoneopericardial mesothelial remnant—a linear soft tissue band ventral to the caudal vena cava connecting the
cardiac silhouette with the diaphragm; this remnant represents the dorsal aspect of the hernia. It is seen better on lateral
views but can sometimes be seen also on a ventrodorsal or dorsoventral view.
- Global enlargement of the cardiac silhouette
- Inhomogeneous opacities within the cardiac silhouette due to abdominal viscera
- A silhouette sign between the cardiac apex and the cranioventral diaphragm
- In some cases, a small or absent liver with cranial displacement of the stomach on abdominal radiographs
Differential diagnoses should include other causes of generalized cardiomegaly, such as pericardial effusion and congenital
or acquired cardiac disease. Further diagnostic tests should include echocardiography. Positive contrast peritoneography may
also aid in diagnosis. If intestinal herniation is suspected, upper gastrointestinal contrast studies are recommended.
Surgical correction is recommended in patients with clinical signs. A patient with an uncorrected hernia may remain free of
clinical signs, but there is always a risk of hepatic or splenic incarceration, bowel obstruction, and, in rare cases, cardiac
In this case, the owners declined additional procedures and the cat was lost to follow-up.
This report was provided by Michal O. Hess, DVM, 620 Stephen Hands Path, East Hampton, NY 11937. Dr. Hess's current address
is 17 Hedges Banks Drive, East Hampton, NY 11937.
1. O'Sullivan ML. Peritoneopericardial diaphragmatic hernia. In: Coté E, ed. Clinical veterinary advisor: dogs and cats. St. Louis, Mo: Mosby Elsevier, 2007;836-837.
1. Biery DN, Owens JM. Radiographic interpretation for the small animal clinician. 2nd ed. Baltimore, Md: Williams & Wilkins, 1999;214-215.
2. Fossum TW. Surgery of the lower respiratory system: pleural cavity and diaphragm. In: Small animal surgery. 1st ed. St. Louis, Mo: Mosby, 1997;685-687.