Unusual Intra-Abdominal Encapsulated Foreign Body in a Wild Female King Eider (Somateria spectabilis)
During June 1999, 12 adult king eiders (Somateria spectabilis) were captured and transported to a field surgical site in Prudhoe Bay, Alaska. Ventral midline laparotomy was performed under isoflurane anesthesia (Aerrane, Fort Dodge Animal Health, Fort Dodge, IA, USA) for satellite transmitter implantation on these birds. Incision into one of the females revealed the presence of a slightly irregular oval mass that was loosely adhered to adipose and fibrous tissue within the caudal right mid-abdomen. The mass was bluntly dissected free revealing no distinct connection to any vessels or abdominal organs. The abdominal incision was closed in two layers, the linea alba and then skin using 3–0 braided absorbable suture on a cutting needle (Vicryl, Ethicon, Inc., Somerville, NJ, USA) in a simple continuous pattern in each layer. Recovery from anesthesia was uneventful.
The mass measured 4.2 cm × 3.1 cm × 2.3 cm and weighed 30 g. Incision into the mass revealed a thin fibrous capsule surrounding a large concreted mass of smooth round rocks imbedded into a dense dry “chocolate” brown matrix. Aerobic culture of the internal concretion demonstrated no growth after 48 hours. Histopathologic examination of the membrane showed only a well-organized foreign body reaction with an inner layer of amorphous eosinophilic debris. A layer of epithelioid macrophages and multinucleated giant cells, then a layer of fibrous tissue and scattered aggregates of lymphocytes and plasma cells, formed the outer surface. Within the inner debris and also in pockets within the wall were small numbers of bacteria and accumulations of globular to spiculated, brightly refractile yellow or golden material that could be bile or another pigmented material.
The mass appeared to represent the end result of a chronic inflammatory process. The condition may have resulted from aspiration of rocks that settled into the abdominal air sac but the size of the individual stones seems to make this route unlikely. An alternate source could be impaction of a gastrointestinal diverticulum or gallbladder which became strangulated, walled off, and separated from the original structure. There was no evidence of abdominal wall trauma or external injury.
The female was in good breeding condition, weighing 1720 g and showed no other physical or behavioral abnormalities. This animal had been captured with its mate in modified mist nets as they flew onto a recently melted freshwater pond. Both birds were banded but excluded from the tracking study and released at the capture site without transmitters.