Abstract

The Seal Rehabilitation and Research Centre (SRRC), in Pieterburen, The Netherlands, has rehabilitated more than 600 harbor seals (Phoca vitulina) and grey seals (Halichoerus grypus) during 2012. The majority of seals stranded on the Dutch coast are orphaned pups or juvenile seals with parasitic pneumonia. However, occasionally traumatic lesions affecting the extremities are seen in seals when admitted to the SRRC for rehabilitation.¹

During 2012, 19 young seals admitted to the SRRC presented with infection of a hind flipper. Initial treatment consisted of administration of antibiotics and anti-inflammatory drugs, which resolved symptoms in 15 animals. In four harbor seals, estimated to be 3–4 months old, a necrotizing infection developed that resulted in osteoarthritis of the tarsus and or tibiotarsal joint.

Upon diagnosis of an infection in the region of the tarsus, radiographs of that region were taken in the four seals. In three animals, the first radiograph revealed signs of osteoarthritis at different levels in the tarsus: narrowing of articular space and osteolytic lesions, sclerosis, or partial loss due to spontaneous amputation. In the fourth animal, the radiograph taken shortly after admission did not show abnormalities, however, two months later clear signs of osteoarthritis in the whole tarsus were present. Since we have never observed healing of such an infection without ablative surgery, surgical treatment with amputation of the extremity was needed.

The four animals were operated within a period of two days (2–3 October 2012) under general anaesthesia using inhalant (Isoflurane) after a premedication with butorphanol (0.25–0.3 mg/kg) and Propofol (5 mg/kg to effect), with addition of tumescent local anesthesia (diluted lidocaine and adrenaline solution). The surgical procedure consisted of amputation of the hind flipper. In contrast with previous amputations, which were performed at the level of insertion of the hind flipper², amputations were done at the diaphysis of the tibia and fibula. After cutting these bones the flipper was discarded, leaving a good muscle-skin cuff to cover the ends of the bones and close the skin without any tension. This procedure permits surgery of a clean non infected area, with simple access and without the effort of finding a proper amputation level in tarsus or tibiotarsal joint.

The seals were closely monitored during 24 hours post surgery. They were kept for one month in individual enclosures with access to an individual salt water pool since 2 days post-surgery. Antibiotics and analgesics were removed gradually per individual response.

One month after surgery the four animals were moved to an outside larger pool. All of them were able to dive, compete for catching fish and to enter/exit the pool without signs of discomfort or difficulties moving on land.

One week before the seals were released, a final evaluation was performed and first observation of the radiographs demonstrated no surgical complications. However, a radiologist consulted at later stage observed that radiographs of two seals had indicative signs of osteomyelitis in the tibia before release. The four seals were successfully released 9 weeks after surgery at approximately 40 kilograms body weight.

Acknowledgements

The authors wish to thank the SRRC staff members and volunteers who participated in the surgery series and helped with monitoring the seals. We also thank Nynke Osinga for her great help on this presentation.

* Presenting author

Literature Cited

1.  Osinga, N. and Hart, P.'t. 2010. Harbour seals (Phoca vitulina) and rehabilitation. NAMMCO Sci. Publ. 8: 355–372.

2.  Sánchez Contreras, G.J, Rubio García, A, Osinga, N, Morick, D. 2012. Treatment of traumatic flipper injuries in seals. EAAM 40th Symposium Oral Presentation, Madrid. Spain.