Background and Aims

Biopsy or partial resection of the adrenal glands in the dog is infrequently performed and therefore little information is available about the healing of these glands after surgery. The aim of this study was to determine whether the canine adrenal gland heals by regeneration or fibrous tissue deposition following surgical biopsy.

Methods

Ten clinically healthy adult mixed breed dogs (5 male and 5 female) with mean body weight of 21.795±6.174 kg were used in the study. The left adrenal gland in each animal was exposed by paracostal celiotomy and a tissue sample of at least 0.25×0.25 cm was collected from the cranial pole of each gland. The remaining adrenal capsule was sutured over the cut margin using 4/0 nylon suture material and the celiotomy incision closed routinely. The animals were euthanized 30 days after the biopsy and sections of the left adrenal glands examined under light microscope for evidence of tissue repair in the biopsy area.

Results

Tissue repair was evident in the cut margins of all glands macroscopically as invaginated areas of cortical zone with creamy yellow colour with fibrosis and increased thickness of the capsule. Microscopically, wound healing was observed as regeneration of the adrenal cortex leading to the formation of newly formed area of zona glomerulosa at the biopsy site and differentiation of zona glomerulosa cells into zona fasciculata cells in the deeper parenchymal areas. The differentiating cells had active and hyperchromatic nuclei.

Conclusion

To the author's knowledge, this is the first study to demonstrate that the canine adrenal cortex has regenerative capacity which could prove invaluable in adrenal surgery.