Urodynamic Measurements by Radiotelemetry in Conscious, Freely Moving Beagle Dogs

Abstract

Urodynamics have been traditionally recorded in anesthetized or conscious animals implanted with a bladder catheter that is used to artificially fill the bladder while measuring intravesicular bladder pressure. Anesthesia alters the urodynamics and in the conscious state this methodology requires that the dogs be tethered/restrained, which evokes stress and limits the period of continuous urodynamic assessment. A more physiological and chronic method of evaluating pharmacological responses on urodynamics is necessary. Adult female beagle dogs were surgically instrumented with radiotelemetry transmitters enabling urodynamic/hemodynamic recordings. Telemetered urodynamics were compared to those measured in anesthetized dogs receiving bladder infusion of saline. The response to diuresis with furosemide (Intervet, Millsboro, Delaware) and the M3 selective antimuscarinic darifenacin (Matrix Laboratories, Hyderabad, India) were evaluated. Saline infused, anesthetized dogs demonstrated lower peak micturition pressure and higher threshold pressure than conscious, freely moving telemetered dogs. In telemetered dogs a single dose of furosemide increased voiding frequency and average urine volume per void. Darifenacin decreased peak voiding pressure without affecting voiding frequency. Telemetry provides the potential to significantly decrease animal use while enabling the continuous monitoring of urodynamics under more physiological conditions without tethering or artificial filling. In addition, this new model facilitates evaluation of the chronic efficacy of new urological therapies.