Introduction: As with clinical urodynamics, investigations into lower urinary tract physiology using animal models require catheter-based systems to measure bladder pressure while filling the bladder, often under anesthesia. However, anesthesia, and rapid catheter filling of the bladder can affect filling pressures, urinary leakage and voiding reflexes. To enable recordings representative of normal physiology, we developed a catheter-free, wireless, intravesical sensor which is implanted in the feline bladder lumen and wirelessly transmits bladder pressure and volume data. We validated sensor function by recording volume and pressure over 4-week implantations in felines. Methods: The Urological Monitor of Conscious Activity (UroMOCA) measured 18 x 12 x 5.6mm and transmitted data to a radio placed worn by the animal. The UroMOCA battery was recharged wirelessly via a charging mat placed under the subject. Platinum electrodes measuring urine concentration and conductance estimated urine volume and were paired with an onboard pressure sensor. Under anesthesia, a UroMOCA was implanted into the bladder lumen via cystotomy in male felines. Baseline cystometry was performed. Anesthetized cystometry with UroMOCA recording and imaging were repeated 2 and 4 weeks post-implantation. Ambulatory recordings of up to two hours were performed multiple times during the four weeks prior to device explantation. Sham surgeries and sham devices were implanted in some animals to assess the impact of the UroMOCA on the bladder. Bladder tissue was saved for histology. Results: Ten feline cats were enrolled: 3 were sham implants (no device), 1 received an inactive device, and 6 received a functional UroMOCA. Non-anesthetized recordings were performed for more than 73 hours over 33 ambulatory data collection sessions. After 2 weeks, all animals resumed normal voiding volume. Urinary retention requiring intermittent catheterization was seen in 1 feline; there was no evidence of obstruction. Wireless pressure data linearly correlated with anesthetized cystometry (R2=0.96). Volume measurement was variable but decreased during voiding and increased during filling. Histology showed normal bladder tissue. Conclusions: A small, wireless, catheter-free, intravesical sensor enabled conscious recordings of bladder function in felines during natural bladder filling over 4 weeks. The volume sensor enabled detection of bladder filling and emptying phases. SOURCE OF Funding: This work was funded by the NIH Stimulating Peripheral Activity to Relieve Conditions (SPARC) program, NIH grant number OT2OD023873.
