During the course of a telemetry study on three species of Australian frogs (Litoria caerulea, Litoria dahlii and Cyclorana australis), we found that many of the surgically implanted transmitters had migrated into the bladder. We subsequently implanted small beads into L. caerulea and they were expelled from the body in 10-23 days. Beads implanted into cane toads (Rhinella marina) to document the process were either expelled or were enveloped into the bladder. This appears to be a unique pathway for expulsion of foreign objects from the body, and suggests that caution should be employed in telemetry studies when interpreting the separation of some animals from their transmitters as a mortality event.
Tracy, C., Christian, K., & Gienger, C. (2011). Removing the rubbish: frogs eliminate foreign objects from the body cavity through the bladder. Biology Letters, 7(3), 465-467. https://doi.org/10.1098/rsbl.2010.0877