Anesthesia and Postoperative Care for a Gastrotomy in a Harbor Seal (Phoca vitulina)
American Association of Zoo Veterinarians Conference 2001
Freeland Dunker1, DVM; Martin Haulena2, DVM; Graham Crawford1, DVM; John Ochsenreiter1, DVM
1San Francisco Zoological Gardens, San Francisco, CA, USA; 2The Marine Mammal Center, Golden Gate National Recreation Area, Sausalito, CA, USA


A 29-year-old female harbor seal (Phoca vitulina) was evaluated because of a 3-week decline in total food consumption. Despite the decline in food quantity consumed, she had a willingness to eat, and appeared to be bright and alert. She was sedated with butorphanol tartrate (Torbugesic, Fort Dodge Animal Health, Fort Dodge, IA, USA) 3 mg IM to assist in the physical exam. The seal weighed 59.8 kg and her body condition was thin. The physical exam was otherwise unremarkable. Abdominal radiographs revealed approximately 75 to 100 rocks of 1 to 4 cm, four to five coins and one AA alkaline battery within the stomach. The complete blood count and serum chemistries were within normal limits. Initial fluid therapy consisted of 2.5% dextrose and 0.45% sodium chloride (Baxter Healthcare Corp. Deerfield, IL, USA) 3 L given SQ, enrofloxacin (Baytril 100, Bayer Corp. Shawnee Mission, KS, USA) 325 mg and vitamin B complex (Butler Company, Columbus, OH, USA) 5 ml were both given by IM injection. Ongoing treatment with enrofloxacin (325 mg IM SID) and 2.5% dextrose and 0.45% sodium chloride 3 L given SQ SID) was continued while further treatment plans were organized.

Two days after the initial evaluation, she was immobilized for gastric foreign body removal. Prior to chemical immobilization, a preanesthetic 1.2 mg dose of atropine sulfate (Atropine SA, Butler Company, Columbus, OH, USA) injection was given IM. Approximately 15 minutes post-atropine injection, tiletamine hydrochloride and zolazepam (Telazol, Fort Dodge Animal Health, Fort Dodge, IA, USA) 50 mg by IV injection into the epidural vein at the level of the lumbar spine was given. After induction, she was then intubated with an 11-mm diameter cuffed silicone endotracheal tube (Jorgensen Laboratories, Inc., Loveland, CO, USA) and placed on isoflurane (Iso-Vet, Schering-Plough Animal Health Corp, Union, NJ, USA) through a precision vaporizer. Mechanically assisted ventilation (MDS Matrix, Orchard Park, NY, USA) was provided at a rate of six breaths per minute and a volume of between 700–1200 ml of oxygen per breath in order to produce an inspiratory pressure of no greater than 25 cm of water. An 18-G×5.1-cm catheter (Quick-Cath, Travenol Laboratories, Inc., Deerfield, IL, USA) was placed into the epidural vein at the mid-lumbar area and lactated Ringer’s solution (Lactated Ringer’s Injection USP, Baxter Healthcare Corporation, Deerfield, IL, USA) given at a rate of 5–10 ml/kg/h. Additional atropine 0.6 mg by intramuscular injection was given 91 minutes after the initial injection.

Isoflurane level (1±0.5%), mechanical ventilation volume (800±100 ml O2), heart rate (86±13 beats/min), respiratory rate (7±2 breaths/min), temperature (34.1±2°C), oxygen saturation (SpO2) (96±4%), and end-tidal carbon dioxide (EtCO2) (41±5 mm Hg) were monitored and recorded every 5 minutes for the duration of the procedure. The total time on isoflurane and the ventilator was approximately 2.5 hours. Recovery was uneventful with the animal starting to spontaneously breathe approximately 11 minutes after the isoflurane was turned off. Butorphanol tartrate 3 mg by intramuscular injection was given approximately 9 minutes after the animal was extubated to provide postoperative analgesia as well as mild sedation to limit movement to prevent additional trauma to the surgical site.

Endoscopic evaluation of the stomach confirmed the presence of the foreign bodies and revealed an inflamed gastric mucosa without evidence of ulceration or necrosis. Endoscopic-assisted retrieval was not attempted due to the quantity of rocks present. Water gastric lavage retrieval using a standard equine stomach tube (Jorgenson Labs, Loveland, CO, USA) 1.2 cm ID attached to a flexible vinyl tube 3.7 cm ID used for outflow was attempted but also unsuccessful. Removal via gastrotomy was elected.

A standard ventral midline approach to the abdomen was used via an incision approximately 18 cm length and the stomach exteriorized. The stomach serosa was unremarkable, and a gastrotomy was performed in a relatively avascular region of the stomach midway between the between the lesser and greater curvatures. The foreign bodies were easily removed manually and with a sterile tablespoon. The gastric mucosa and submucosa were closed with an apposing simple continuous suture pattern using 2-0 monofilament polyglyconate (Maxon, Sherwood Medical, St. Louis MO, USA). The seromuscular layer was closed with an inverting interrupted Lembert suture pattern using 2-0 monofilament polyglyconate. The abdominal wall was closed with simple continuous suture pattern using 0 monofilament polyglyconate. Additional simple interrupted 0 monofilament polyglyconate sutures were placed in the abdominal wall at 2-cm intervals. The subcutaneous fat layer was closed in two layers with 2-0 monofilament polyglyconate in a simple continuous suture pattern. Finally, the subcutis was closed using 2-0 monofilament polyglyconate in a simple continuous suture pattern, and the skin was closed using 35-mm surgical staples (Kendall, Mansfield, MA, USA). The incision was sealed with formulated cyanoacrylate (Nexaband, Veterinary Products Laboratories, Phoenix, AZ, USA).

The postoperative and convalescent care was uneventful. Prophylactic enrofloxacin 300 mg given IM and ceftriaxone sodium (Rocephin, Roche Laboratories Inc., Nutley, NJ, USA) 1.4 g IM were started preoperatively and continued every 24 hours while the animal was NPO. Food and water were withheld for the first 36 hours. A regimen of small multiple meals was then started, and a normal level of food consumption was gradually achieved within 7 days. Once the seal began eating, the injectable antibiotics were discontinued and oral antibiotics, ciprofloxacin (Cipro, Bayer Corporation, West Haven, CT, USA) 375 mg BID administered for 7 days and amoxicillin trihydrate (Amoxi-Tabs, SmithKline Beecham Pharmaceuticals, Philadelphia, PA, USA) 1.2 g BID were administered for 21 days. In addition, cimetidine hydrochloride (Cimetidine, Geneva Pharmaceuticals, Inc., Broomfield, CO, USA) 400 mg BID PO was administered for 7 days.

She was “dry docked” and confined to a 3.5×8 m outdoor run with smooth rubber matting (Rail Trax Mats, Lab Safety Supply, Janesville, WI, USA) and the incision was monitored daily. She was hosed with water 15 minutes three times daily to assist in thermal regulation. Four days post-surgery, she was transferred to a small holding pool of approximately 2,750 L (726 gallons) to which she was allowed access during the day. She was “dry docked” at night and the incision was checked in the morning prior to allowing her access to the pool. Water changes were made when the pool became contaminated with feces.

Seven days post-surgery, there was a 5-cm dehiscence of the most cranial aspect of the surgical incision. At this site, the surgical staples were missing, and the subcutaneous fat layer was exposed. Close monitoring revealed no further dehiscence, and the wound was left to heal by secondary intention. The “pool protocol” was revised and the seal was allowed access to the pool once it was filled with water and 2.5 kg of sodium chloride salt (Solar Salt, Cargill, Inc., Minneapolis, MN, USA). The pool water continued to be changed when fecal contamination was apparent, and salt was added to each fill. The seal continued to be “dry docked” each night and the incision was checked in the morning prior to allowing her access to the pool.

Twenty-one days post-surgery, the cranial area of dehiscence was forming a healthy granulation bed and the rest of the incision appeared fully healed. She was sedated with butorphanol tartrate 4 mg IM injection and the remaining skin staples were removed. Naloxone (Narcan, Endo Pharmaceuticals, Inc., Chadds Ford, PA, USA) 1 mg IM effectively antagonized the effects of the butorphanol tartrate. The next day, she was transferred back to her regular exhibit.

I feel that there were two important factors that were instrumental in the successful outcome of this case. First, the use of a ventilator during the procedure insured good alveolar gas exchange. In our personal experience, unassisted ventilation has produced low SpO2 (<80%) and high EtCO2 (>60 mm Hg) particularly in procedures requiring a surgical plane of anesthesia of long duration. This situation during anesthesia is complicated in phocids by initiation of a dive response that includes bradycardia and apnea potentially leading to hypoxia and anesthetic complications. In this particular case, mechanically assisted ventilation appeared to have helped to prevent hypoxia and contributed to a successful anesthesia.

Secondly, a closely controlled postoperative environment was important to promote good wound healing and maintain proper thermoregulation. There were concerns that constant pressure on the surgical incision and the significant ventral subcutaneous fat layer relatively void of blood supply would be problematic if the animal remained dry docked for the entire postoperative period. On the other hand, though preferred to maintain the animal’s physiologic needs and keep weight off of the surgical incision, the potentially contaminated aquatic environment had the potential to compromise wound healing as well. A balance was struck between keeping the animal out of the water to allow good wound sealing and allowing her in the water to take weight off of the incision and allow proper thermoregulation. In order to give the surgical incision the best chance for uneventful healing, the optimum postoperative environment must include: 1) a smooth surface for “dry docking,” 2) controlled pool access, 3) the ability to monitor the incision site daily, and 4) the ability to maintain the pool water as clean as possible.


The authors want to thank Gail Hedberg, RVT and Bronwyn Koterwas, RVT for their assistance in the medical care of this animal as well as the zookeeper staff for their help with the postoperative husbandry. We also thank Ellen Williams, our office manager, for getting this paper typed and proofread.


Speaker Information
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Freeland Dunker, DVM
San Francisco Zoological Gardens
San Francisco, CA, USA

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