Joker had historically been an active cat but had become listless and begun to hide and avoid mealtimes in the last 24 hours. His owners had adopted him 2 years previously and noted that he frequently exhibited intermittent labored breathing that was not associated with any particular activity or event. Joker was considered an otherwise healthy cat with a historically good appetite and occasional vomiting episodes attributed to hairballs. However, on further questioning, the owners also reported that Joker frequently displayed apparent exercise intolerance when playing with the other 2 cats in the household. No coughing, sneezing, or diarrhea was reported.

On presentation, Joker was quiet but alert and responsive. He was tachypneic (respiratory rate, 60 breaths/min) but had normal lung sounds across all lung fields and no nasal discharge. Cardiac auscultation revealed a muffled heart beat that was otherwise normal in rate and rhythm. Body temperature was normal (101.8°F [38.8°C]). Normal abdominal organs could not be appreciated during palpation. Flow-by oxygen supplementation was provided until diagnostics could be performed.

Initial CBC and serum chemistry results were unremarkable. A mild stress leukogram characterized by mature neutrophilia (9.35 × 10³/μL; reference range, 2.1-8.3 × 10³/μL) was the only notable finding.

Two-view thoracic radiographs (Figure 1) were obtained with Joker under mild sedation (butorphanol [0.2 mg/kg IV]). Marked widening of the cardiac silhouette, both in height and width, with loss of delineation of the caudal cardiac margin, was observed. Superimposition of air tubular opacities to the cardiac silhouette were also noted. The liver was not visible at its physiologic position in the cranial abdomen. Considering these radiographic findings, a presumptive diagnosis of peritoneopericardial diaphragmatic hernia (PPDH) was made.

Joker was kept in a calm environment and continued to receive oxygen supplementation overnight. The following day, he was placed under general anesthesia. He was premedicated with hydromorphone (0.05 mg/kg IV) and acepromazine (0.02 mg/kg IV), induced with propofol (IV) to effect, and maintained with an isoflurane inhalant carried in oxygen. An exploratory laparotomy was performed, and a diagnosis of PPDH was confirmed (Figure 2; see Treatment at a Glance).

The liver, gallbladder, and a portion of the small intestine and omentum were extracted from the pericardial cavity. No adhesions were found between the herniated structures and the pericardium or myocardium. The defect in the ventral diaphragm was identified and closed using a simple continuous suture pattern. The edges of the defect were not debrided. A red rubber catheter was inserted into the pericardial space during herniorrhaphy.

Following completion of the herniorrhaphy, air was removed from the pericardial sac. Primary herniorrhaphy, which closes the pericardium and peritoneal cavity simultaneously without resulting in pneumothorax from entry of air into the thoracic cavity, is feasible in most cases of PPDH. Intraoperative hypotension was noted and was responsive to vasopressor therapy. No additional intraoperative complications were noted.

Thoracic radiographs were obtained immediately postoperation with the patient still under general anesthesia and confirmed reduction of PPDH. Joker recovered well from surgery and was discharged 48 hours postoperation and after resolution of tachypnea.

At the 6-month follow-up, Joker was free of clinical signs. The owner reported resolution of Joker’s previous exercise intolerance observed with the other cats in the household. There had been no incidence of respiratory distress or development of any GI signs.

PPDH is a congenital defect that occurs during embryonic development.^1,2 In cats, PPDH is not traumatic in origin as in humans, as there is no anatomic connection between the pericardium and diaphragm.^1,2 Surgical treatment of PPDH has an excellent long-term prognosis that generally results in resolution of clinical signs (see Take-Home Messages), as observed with Joker.^1-3