Endoscopic Techniques for the Collection of Lymphoid Tissue from Pigeons: Evaluation of Splenic and Bursa of Fabricius Biopsy Technique and Histopathologic Quality
As part of a large, ongoing investigation into pigeon circovirus, endoscopic techniques to biopsy lymphoid tissue from 71 juvenile and adult white Carneaux pigeons (Columba livia) were investigated under an Institutional Animal Care and Use Committee (IACUC) license at the College of Veterinary Medicine, University of Georgia. Each pigeon was premedicated using butorphanol. Anesthesia was induced by face mask using isoflurane and oxygen. Each bird was intubated and maintained on oxygen and isoflurane adjusted to individual patient requirements. Cloacoscopy was performed with the pigeon in dorsal recumbency using a 2.7-mm telescope housed within a 14.5-Fr sheath. Sterile saline warmed to 100°F was used for irrigation. The dorsal wall of the urodeum, just caudal to the urodeal fold, was closely examined for the opening of the bursa of Fabricius. If located, 5-Fr biopsy forceps were introduced, and one or two biopsies were collected from within the bursa. Then each pigeon was placed into right lateral recumbency. The left flank was aseptically prepared, and a standard approach was made to the coelom behind the last rib. The telescope, sheath and instruments were cold sterilized using 2% glutaraldehyde solution between every procedure. From within the left abdominal air sac, the spleen was located just caudal to the isthmus of the proventriculus and ventriculus. On occasion, it proved necessary to incise the abdominal air sac membrane using 3-Fr scissors to gain clear access to the spleen. Biopsy forceps (5-Fr) were used to harvest one or two biopsies from the spleen. Single biopsies were submitted for circovirus DNA detection, and where two biopsies were collected the second was submitted for histopathologic examination. All birds except one recovered uneventfully from the procedures. One bird died immediately after the endoscopic procedure due to perforation of the bursa and flooding of the air sac system as a consequence of bursal biopsy. A second bird died 10 days later from severe coelomitis. Post-endoscopy infection cannot be ruled out, as none of the birds received postoperative antibiotics. Of 62 birds examined by cloacoscopy, it was only possible to visualize and biopsy the bursa of 28 individuals (45.2%). Of these 28 birds, 10 were submitted for histopathology (the remainder were submitted for circovirus DNA detection), and only three possessed lymphoid tissue of diagnostic quality (4.8%). Splenic biopsies were successfully obtained from 61 of 71 birds (85.9%). All 10 cases in which the spleen could not be visualized involved female birds exhibiting extensive reproductive activity. Histologically, splenic biopsies were judged as good to excellent for cell preservation and tissue orientation.
In conclusion, endoscopic splenic biopsy appears to be a safe and rewarding diagnostic procedure in pigeons. However, per cloacal endoscopic biopsy of the bursa of Fabricius is problematic and not recommended in the pigeon due to the lack of lymphoid tissue obtained and the potential risks of cloacal perforation.
Dr. Chris Chamness and Linda Scott of Karl Storz Veterinary Endoscopy America, Inc., kindly provided research endoscopy equipment for this project.