Abstract

To our knowledge, we report here the first surgical repair of a hiatal hernia in a marine mammal. Hiatal hernia is a diaphragmatic defect that allows the prolapse of part of the stomach into the thoracic cavity.⁵ The most common type, Type I (or sliding) hiatal hernia, allows part of the stomach to be intermittently displaced through the esophageal hiatus. Only one published case study has described a diaphragmatic hernia in a living marine mammal, a harbor seal,² although cases have been reported post-mortem,^1,3,4,6,7 including in harbor seals, sea lions, dolphins and porpoises.

An underweight (40.5 kg) female northern elephant seal (Mirounga angustirostris) weaned pup was admitted to The Marine Mammal Center for treatment of malnutrition. During rehabilitation the animal intermittently regurgitated during standard tube feedings. Initial thoracic auscultation revealed normal lung sounds, but as the animal's clinical signs progressed (increased regurgitation, poor weight gain, dehydration and lethargy), reexamination revealed diminished breath sounds in all lung fields. Radiographs and endoscopy performed under Telazol^TM sedation suggested a hiatal hernia. Positive contrast study using gastrograffin confirmed this, revealing varying degrees of herniation of the gastric fundus through the diaphragm into the caudal thorax, as well as esophageal reflux. A Type I (sliding) hiatal hernia was diagnosed. The animal was placed on metoclopramide 0.2 mg/kg and famotidine 0.9 mg/kg while a surgical plan was developed to repair the defect.

Type 1 hiatal hernia repair in veterinary medicine typically includes a combination of diaphragmatic hiatal plication, esophagopexy and left sided gastropexy.⁵ In this case, however, it was decided to attempt a single procedure, to reduce anesthesia time and potential complications. Since open abdominal surgery in marine mammals presents unique challenges and increased risks, a laparoscopic approach was chosen.

The animal was sedated with Telazol^TM, intubated, and maintained on isofluorane anesthesia. A laparoscope portal was made just caudal to the umbilicus. A 10mm rigid endoscope was used to explore the abdomen, and a sliding hiatal hernia was confirmed. The stomach was reduced into the abdominal cavity by introducing an orogastric tube and applying gentle traction to the stomach using laparoscopic forceps while the patient was positioned in reverse trendelenberg. To hasten scar formation at the gastropexy site, the serosal surfaces of the gastric fundus and the body wall caudal to the last rib (left and lateral to the umbilicus) were scarified using a monopolar cautery unit. The gastropexy was performed using Dexon^TM suture material on a 16 g straight needle, which was introduced through the skin, into the abdominal cavity, down through the body wall guided by visualization from the laparoscope. The needle was then grasped by forceps and guided to the prepared fundic area of the stomach, driven through the serosa and muscularis layers, then passed back through the body wall. The sutures were then secured with simple interrupted hand ties extracorporeally.

The animal recovered well postoperatively, began to eat within 24 hours, and experienced no further regurgitation. Three weeks later the animal was released back into the wild at 61.5 kg (21 kg above admit weight).

Acknowledgements

The authors thank Marjorie Boor, volunteer cardiac sonographer with The Marine Mammal Center, and Lauren Campbell, RVT at The Marine Mammal Center for their preparation and assistance with the diagnostic procedures, anesthesia, and recovery of the animal. The authors thank the animal care volunteers and veterinary externs at The Marine Mammal Center for all their hard work to help successfully rehabilitate this elephant seal.

*Presenting author

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