Results of cystometry and urethral pressure profilometry in dogs sedated with medetomidine or xylazine

ACVIM consensus statement on diagnosis and management of urinary incontinence in dogs

Urinary incontinence (UI) is a disorder of micturition that can occur in dogs of any age, sex, and breed depending on the underlying cause and time of onset. Diagnosis and treatment for various causes of UI in dogs have been described by multiple comprehensive single author review articles, but large prospective clinical trials comparing treatment outcomes in veterinary medicine are lacking. The objectives of this consensus statement therefore are to provide guidelines on both recommended diagnostic testing and treatment for various causes of UI in dogs. Specifically, pathophysiology directly related to the canine urinary system will be reviewed and diagnostic and therapeutic challenges will be addressed. A panel of 12 experts in the field (8 small animal internists [L. Adams, J. Bartges, A. Berent, J. Byron, J. Foster, A. Kendall, S. Vaden, J. Westropp], 2 neurologists [J. Coates, N. Olby], 1 radiologist [G. Oetelaar], and 1 surgeon [C. Adin]) was formed to assess and summarize evidence in the peer-reviewed literature and to complement it with consensus recommendations using the Delphi method. Some statements were not voted on by all panelists. This consensus statement aims to provide guidance for management of both male and female dogs with underlying storage or voiding disorders resulting in UI.

Urodynamic and morphometric characteristics of the lower urogenital tract of male Beagle littermates from four months to two years of age

OBJECTIVE

To describe functional and anatomic changes of the lower urogenital tract of healthy male dogs during the sexually immature period and up to 2 years of age by urodynamic and morphometric assessment.

ANIMALS

6 sexually intact male Beagle littermates.

PROCEDURES

Dogs underwent electromyography-coupled urodynamic tests, CT-assisted retrograde urethrography, prostatic washes, and blood sampling monthly from 4 through 12 months of age and then at 3-month intervals. Urodynamic and morphometric variables and serum canine prostate-specific esterase concentrations were analyzed by statistical methods.

RESULTS

Integrated pressure of the urethra was significantly increased beginning at 8 months of age, compared with earlier time points. Urethral pressure peak amplitudes varied among anatomic regions. During bladder filling, few electromyographic signals were concurrent with urethral pressure peaks; these were most commonly detected in the penile portion of the urethra. Urethral length and prostate gland volume were significantly greater from 7 to 24 months of age than at younger ages. Urethral length was approximately 26 to 27 cm after 9 months, and prostate gland volume was approximately 11 to 12 cm³ after 11 months of age. Serum canine prostate-specific esterase concentrations correlated with prostate gland volume. Urinary bladder threshold volume was significantly increased at 6 months of age, compared with that at 4 months, with a maximum of 197.7 mL at 24 months.

CONCLUSIONS AND CLINICAL RELEVANCE

Urethral resistance was acquired at approximately 8 months of age, when growth of the lower urinary tract was incomplete. Electromyographic and integrated pressure measurement results and the distribution and amplitude of urethral pressure peaks highlighted the potential role of the prostate gland and possibly the bulbocavernosus muscles in control of continence.

Optimum anesthesia for reliable urethral pressure profilometry in female dogs and goats

OBJECTIVES

To investigate the effects of propofol and isoflurane on urethral pressure profilometry of female dogs and goats, and to identify the method of anesthesia that least influences urethral pressure profilometry and to assess its reproducibility.

METHODS

The effects of premedication with midazolam, propofol sedation and isoflurane anesthesia were assessed in five female dogs. The effects of propofol and isoflurane were compared in seven goats, whereas in another group of 19 goats, the state of deep propofol sedation was compared with the state of recovery from propofol sedation. The coefficient of reproducibility and within-subject coefficient of variation were calculated to evaluate test-retest reproducibility.

RESULTS

In conscious female dogs, maximal urethral closure pressure and functional area were significantly higher than under propofol or isoflurane (P = 0.04), but not different from the recovery state. In six of seven goats, maximal urethral closure pressure and functional area were higher when measured under propofol sedation than under isoflurane (median maximal urethral closure pressure, 69 vs 47 cmH2 O; P = 0.03). Maximal urethral closure pressure was lower under propofol than during recovery from propofol in 17 of 19 goats (median maximal urethral closure pressure, 54 vs 66 cmH2 O; P < 0.001). The test-retest coefficient of reproducibility for goats was 28 cmH2 O, and the within-subject coefficient of variation was 16%.

CONCLUSIONS

In dogs, urethral pressure profilometry should be measured in conscious animals whenever possible. In goats, urethral pressure profilometry is least affected during recovery from propofol sedation, and it shows acceptable reproducibility under this condition.

Urodynamic and haemodynamic effects of a single oral administration of ephedrine or phenylpropanolamine in continent female dogs

This study investigated the effects of a single oral administration of ephedrine (2 mg/kg) or phenylpropanolamine (PPA) (1.5 mg/kg) on the vesico-urethral and cardiovascular functions in continent female dogs. Urethral pressure profilometry (UPP), arterial blood pressures and heart rate were measured in five control dogs and after single-dose treatment with ephedrine or PPA at T(0), T(2h), T(4h), T(6h), T(12h), T(18h) and T(24h). UPPs were performed under propofol anaesthesia and other measurements were performed on awake dogs. A telemetric urodynamic investigation was performed on three additional dogs for 24 h after the administration of each drug. Urethral pressures increased over 4-6 h and urethral functional lengths increased 2-6h after administration of both drugs. During micturition, a decrease in detrusor pressure coupled with an increase in bladder volume was observed after ephedrine administration and there was also an increase in bladder volume after PPA had been given. With both drugs increased arterial blood pressures at 4-6 h were compensated by a decreased heart rate over 12 h. Urethral function was improved after both ephedrine and PPA, and bladder function also improved during micturition following ephedrine.

In vivo evaluation of alpha(2)-adrenoceptors in cats with idiopathic cystitis

OBJECTIVE

To evaluate the in vivo response of alpha(2)-adrenoceptors to medetomidine administration in cats with feline idiopathic cystitis (FIC) during periods of stress and after environmental enrichment.

ANIMALS

13 cats with FIC and 12 healthy cats. Procedures-Cats were subjected to an acute-onset moderate stressor for 8 days. After stress, 20 microg of medetomidine/kg was administered IM on days 1, 3, and 8. Heart rate, blood pressure, pupil diameter, respiratory rate, and level of sedation were evaluated before and after administration of the drug. After day 8, cats were moved to an enriched environment, and tests were repeated on day 35.

RESULTS

Heart rate decreased and pupil diameter increased significantly after medetomidine administration in healthy cats, compared with cats with FIC. Cats with FIC had significantly lower respiratory rates. No significant differences in blood pressure or sedation level were found.

CONCLUSIONS AND CLINICAL RELEVANCE

Increased plasma catecholamine concentrations during the enrichment phase, which have been reported elsewhere, may have contributed to the differences in alpha(2)-adrenoceptor responses detected in cats with FIC.

Evaluation of a selective neurectomy model for low urethral pressure incontinence in female dogs

OBJECTIVE

To develop a model of low urethral pressure incontinence and compare the relative contributions of the pudendal and hypogastric nerves with urethral function by performing selective neurectomy and ovariohysterectomy in dogs.

ANIMALS

19 healthy Foxhounds.

PROCEDURE

Dogs were allocated into 2 groups. The first group (10 dogs) underwent bilateral hypogastric neurectomy and ovariohysterectomy and subsequent bilateral pudendal neurectomy. The second group (9 dogs) underwent bilateral pudendal neurectomy and subsequent hypogastric neurectomy and ovariohysterectomy. Urethral pressure profilometry and leak point pressure (LPP) tests were performed before and after each neurectomy.

RESULTS

Before surgery, mean +/- SD LPP and maximal urethral closure pressure (MUCP) in all dogs were 169.3 +/- 24.9 cm H2O and 108.3 +/- 19.3 cm H2O, respectively; these values decreased to 92.3 +/- 27 cm H2O and 60.7 +/- 20.0 cm H2O, respectively, after both selective neurectomy surgeries. There was a progressive decline of LPP after each neurectomy; however, MUCP decreased only after pudendal neurectomy. Fifteen dogs had mild clinical signs of urinary incontinence. All dogs appeared to have normal bladder function as indicated by posturing to void and consciously voiding a full stream of urine. Urinary tract infection did not develop in any dog.

CONCLUSIONS AND CLINICAL RELEVANCE

Hypogastric and pudendal neurectomy and ovariohysterectomy caused a maximum decrease in LPP whereas pudendal neurectomy caused a maximum decrease in MUCP. IMPACT ON HUMAN MEDICINE: This model may be useful for evaluation of treatments for improving urinary control in postmenopausal women.

Urodynamic testing in the diagnosis of small animal micturition disorders

Urodynamic testing provides a quantitative assessment of the function of the small animal lower urinary tract. Most commonly these techniques are utilized to assess urethral tone (urethral pressure profile or UPP) and bladder detrusor muscle function (cystometrogram or CMG). A UPP may be indicated in cases of canine and feline micturition disorders. Examples include suspected primary sphincter mechanism incontinence (PSMI), ureteral ectopia, other congenital abnormalities, suspected neurological disorders, and mechanical or functional urethral obstruction. A UPP can be performed effectively utilizing human dedicated equipment. A CMG may be indicated to assess detrusor function in all of the above cases as well as cases of suspected atonic or infiltrated urinary bladder. This procedure can also be performed using the same human equipment. These tests are useful not only in providing an accurate diagnosis, but also in providing a sensitive prognostic indicator for clinical outcome of micturition disorders with and without pharmacological or surgical therapy. A leak pressure point may also be established in dogs with urinary incontinence, and may be even more sensitive than a UPP to predict clinical incontinence in some cases.

Comparison of the effect of propofol and sevoflurane on the urethral pressure profile in healthy female dogs

OBJECTIVE

To compare the effects of propofol and sevoflurane on the urethral pressure profile in female dogs.

ANIMALS

10 healthy female dogs.

PROCEDURE

Urethral pressure profilometry was performed in awake dogs, during anesthesia with sevoflurane at 1.5, 2.0, and 3.0% end-tidal concentration, and during infusion of propofol at rates of 0.4, 0.8, and 1.2 mg/kg/min. A consistent plane of anesthesia was maintained for each anesthetic protocol. Maximum urethral pressure, maximum urethral closure pressure, functional profile length, and functional area were measured.

RESULTS

Mean maximum urethral closure pressure of awake dogs was not significantly different than that of dogs anesthetized with propofol at all infusion rates or with sevoflurane at 1.5 and 2.0% end-tidal concentration. Functional area in awake dogs was significantly higher than in anesthetized dogs. Functional area of dogs during anesthesia with sevoflurane at 3.0% end-tidal concentration was significantly lower than functional area for other anesthetic protocols. Individual differences in the magnitude of effects of propofol and sevoflurane on urethral pressures were observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Sevoflurane is an alternative to propofol for anesthesia in female dogs undergoing urethral pressure profilometry. Use of these anesthetics at appropriate administration rates should reliably distinguish normal from abnormal maximum urethral closure pressures and functional areas. Titration of anesthetic depth is a critical component of urodynamic testing.

Validation and comparison of the use of diuresis cystometry and retrograde filling cystometry at various infusion rates in female Beagle dogs

OBJECTIVES

To compare retrograde filling cystometry at infusion rates of 5, 10, and 20 mL/min with diuresis cystometry for determination of an appropriate infusion rate and to confirm the reproducibility of measurements obtained by urethral pressure profilometry (UPP) and cystometry in female Beagles.

ANIMALS

Adult female Beagles.

PROCEDURE

Successive UPP and cystometry were performed by use of a water perfusion catheter on dogs anesthetized with propofol. Dogs randomly underwent each of the following at 1-week intervals: retrograde filling cystometry at 5, 10, and 20 mL/min, and diuresis cystometry. The maximum urethral pressure and closure pressure, functional and anatomic profile lengths, threshold pressure, threshold volume, and compliance were measured.

RESULTS

For each UPP variable, significant differences were found among dogs, but no significant differences were found in intra- or interstudy measurements for individual dogs. For retrograde filling cystometry, threshold pressure was not significantly different between a 5 and 10 mL/min infusion rate. Threshold pressure was significantly higher during retrograde filling cystometry at 20 mL/min, compared with 5 and 10 mL/min, and was associated with bladder wall damages. Threshold pressure was significantly lower during diuresis cystometry, compared with retrograde filling cystometries. Threshold volume and compliance were not significantly different among retrograde filling cystometries but were significantly higher during diuresis cystometry.

CONCLUSIONS AND CLINICAL RELEVANCE

Retrograde filling cystometry at 20 mL/min leads to unacceptable sudden increase in threshold bladder pressure. Retrograde filling cystometry at 10 mL/min can be recommended in a clinical setting, shortening the anesthesia time. However, diuresis cystometry approximates physiologic bladder filling most accurately.