Abstract

Invasive surgical procedures in marine mammals, and especially phocid seals, have been considered problematic due to difficulties in general anesthesia, anatomical challenges and the need to return animals to the marine environment as quickly as possible.^1,2 Recent experiences with intra-abdominal implantation of specialized satellite transmitters (LHX tags) in Steller sea lions and in harbor seals in a rehabilitation setting, have shown that these problems can be overcome with appropriate techniques.^3,4 In September 2016, this procedure was taken a step further by successfully placing dual intra-abdominal LHX2 transmitters in 10 sub-adult and adult pacific harbor seals (Phoca vitulina richardii) with immediate return to the wild in the western Aleutian Islands. Surgeries were performed under aseptic conditions in a portable surgical container on board a research vessel in conjunction with a larger harbor seal tracking project that allowed real time post-operative monitoring of the implanted seals after their release.

The harbor seals were collected and transferred to the ship, weighed and allowed to rest in a hoop net in a quiet area for 2 hours prior to sedation. Butorphanol and midazolam were administered IM under manual restraint, then seals were masked with isoflurane in medical oxygen until sufficiently anesthetized to place a cuffed endotracheal tube. A surgical plane of anesthesia was maintained with isoflurane and respiration supported with intermittent positive pressure ventilation. Experienced veterinarians performed anesthesia and surgical procedures and an onboard autoclave allowed sterile instruments to be used in all surgeries. A blood sample was collected, CBC performed and flunixin meglumide administered IM. The ventral midline caudal to the umbilicus was shaved, scrubbed and infiltrated with bupivacaine, then isolated with a sterile adhesive drape. Two LHX2 transmitters, previously sterilized with ethylene oxide, were unwrapped, rinsed with sterile saline and placed into the abdominal cavity of each animal through a ventral midline incision. The incision was closed in 5 layers with antibacterial synthetic absorbable suture material using a simple interrupted pattern in the linea alba oversewn with a continuous Lembert pattern in the linea and deep blubber layer. The blubber and subcuticular skin layers were separately opposed with continuous sutures. Alternating cruciate and simple interrupted sutures were placed in the skin to relieve pressure on the deeper layers. Isoflurane was turned off, sedation reversed with naltrexone and flumazenil and ventilation continued until swallowing and head movement returned at the end of the procedure. Seals were allowed to complete recovery in a protected enclosure for 2 hours and released from the ship's deck when body temperature and behavior had returned to normal.

Reports from externally attached transmitters confirmed that all 10 seals rapidly returned to normal behavior including foraging dives and remained alive for at least 60 days after the procedures.

* Presenting author

Literature Cited

1.  Manugian S, Van Bonn W, Harvey JT. 2015. Modified technique for the subcutaneous implantation of radio transmitters in harbour seals (Phoca vitulina richardii) under field conditions. Vet Rec Case Rep. 3:e000154. doi:10.1136/vetreccr-2014-0001542.

2.  Higgins JL, Hendrickson DA. 2013. Surgical procedures in pinniped and cetacean species. J Zoo Wildl Med. 44(4):817–836.

3.  Horning M, Haulena M, Tuomi P, Mellish J. 2008. Intraperitoneal implantation of life-long telemetry transmitters in otariids. BMC Vet Res. 4:51.

4.  Horning M, Haulena M, Rosenberg JF, Nordstrom C. 2017. Intraperitoneal implantation of life-long telemetry transmitters in three rehabilitated harbor seal pups. Submitted to BMC Vet Res.