Urodynamic investigation by telemetry in Beagle dogs: validation and effects of oral administration of current urological drugs: a pilot study

Abstract

BackgroundVesico-urethral function may be evaluated in humans and dogs by conventional urodynamic testing (cystometry and urethral pressure profilometry) or by electromyography. These techniques are performed under general anaesthesia in dogs. However, anaesthesia can depress bladder and urethral pressures and inhibit the micturition reflex. The primary objective of this pilot study was to evaluate the use of telemetry for urodynamic investigation in dogs. We also aimed to determine the applicability of telemetry to toxicologic studies by assessing the repeatability of telemetric recordings.ResultsConventional diuresis cystometry was performed in six continent adult female Beagle dogs prior to surgical implantation of telemetric and electromyographic devices. In the first phase of the telemetric study, continuous recordings were performed over 8 days and nights. Abdominal, intravesical and detrusor threshold pressures (Pdet th), voided volume (Vv), urethral smooth muscle electrical activity and involuntary detrusor contractions (IDC) were measured during the bladder filling phase and during micturition episodes.Vv recorded during telemetry was significantly lower than bladder volume obtained by diuresis cystometry. Repeatability of telemetric measurements was greater for observations recorded at night. IDC frequency and Pdet th were both lower and Vv was higher at night compared to values recorded during daytime.In the second phase of the telemetric study, phenylpropanolamine, oestriol, bethanechol, oxybutynin or duloxetine were administered orally for 15 days. For each drug, continuous recordings were performed overnight for 12 hours on days 0, 1, 8 and 15. Electromyographic urethral activity was significantly increased 8 days after oestriol or duloxetine administration. No significant changes in bladder function were observed at any time point.ConclusionsIn dogs, the high repeatability of nocturnal telemetric recordings indicates that this technique could provide more informative results for urologic research. Urethral smooth muscle electrical activity appears to be modified by administration of drugs with urethral tropism. In this pilot telemetric study, bladder function was not affected by oral administration of urological drugs at their recommended clinical dosages. Experimental studies, (pharmacokinetic and pharmacodynamic) and clinical studies are warranted to further define the effects of these drugs on vesico-urethral function in dogs.

Acute Spinal Cord Injury

“…An experimental study of 6 normal dogs given bethanechol for 15 days found no change in urethral or bladder pressures measured via telemetric cystometry and urethral electromyographic recordings. 115 Sympatholytic compounds (eg, dantrolene, prazosin, acepromazine, phenoxybenzamine, diazepam) used to relax the urethral sphincter have also not been tested in the context of SCI. In healthy cats and cats with recent urethral obstructions, urethral pressure profiles in response to various medications were highly variable, with only a few recordings suggesting a minimal (2 mm Hg) drop in urethral pressures.…”

Pathophysiology, Clinical Importance, and Management of Neurogenic Lower Urinary Tract Dysfunction Caused by Suprasacral Spinal Cord Injury

“…However, there are currently no data available to confirm clinical efficacy of these drugs in treating bladder dysfunction as the result of spinal cord injury in companion animals. For instance, in one study on normal dogs, administration of bethanechol for 15 days was not associated with changes in either urethral or bladder pressure . Other potential pharmacological detrusor contraction stimulators including cholinesterase inhibitors like neostigmine and pyridostigmine, beta agonists like propanalol, prostaglandin, and cisapride have not been systematically investigated in veterinary medicine …”

“…For instance, in one study on normal dogs, administration of bethanechol for 15 days was not associated with changes in either urethral or bladder pressure. 105 Other potential pharmacological detrusor contraction stimulators including cholinesterase inhibitors like neostigmine and pyridostigmine, beta agonists like propanalol, prostaglandin, and cisapride have not been systematically investigated in veterinary medicine. 106 Because the smooth and striated urethral sphincters are under sympathetic and somatic nervous system control, respectively, a-sympatholytic drugs, such as prazosin, alfuzosin, and phenoxybenzamine, and striated muscle relaxants like diazepam, dantrolene, and baclofen may seem appropriate for inducing urethral sphincter relaxation and assisting urine voiding.…”

Urinary Incontinence in the Bitch: An Update

“…)), oxybutynin (0.2 mg/kg bid) (Noel et al. ) or the tricyclic antidepressant imipramine (5–20 mg per os bid) (Stone and Barsanti 1992b; Noël et al. ).…”