Urodynamic alterations after prostatectomy in dogs without clinical prostatic disease

Diseases of the Canine Prostate Gland

In dogs, the most frequent diseases of the prostate gland are benign prostate gland hyperplasia (BPH), acute and chronic prostatitis, squamous metaplasia, and prostate tumors. New diagnostic tools comprise diagnostic markers in the blood and urine, as well as advanced imaging methods. The therapy can be initialized with the 5α-reductase-inhibitor finasteride or an anti-androgenic compound, and prolonged with a long-acting gonadotropin-releasing-hormone (GnRH)-agonist such as deslorelin. In case of prostatitis, effective antibiotics must be applied for weeks. Antibiotics must be able to penetrate into the prostate tissue; fluoroquinolones, clindamycin, and erythromycin are good choices and are in addition effective against mycoplasms. The chronical prostatitis cannot be differentiated from a neoplasia by sonography; a biopsy, histological, and bacteriological examination are required. Tumors of the prostate gland are seldom and mostly occur in castrated but in intact dogs. For the final diagnosis, a biopsy must be taken. Partial and total resection of the prostate gland by use of laser technique is possible but coincedes with many side effects and the prognosis is still futile. Immunotherapy combined with NSAIDs, targeted noninvasive thermotherapy, BRAF gene inhibitors, or prostate artery chemoembolization are promising methods.

Artificial urethral sphincter in male dogs with urethral sphincter mechanism incompetence: 19 cases (2010-2017)

OBJECTIVE

To assess the outcome and safety of surgically placed artificial urethral sphincters in male dogs with urethral sphincter mechanism incompetence.

MATERIALS AND METHODS

We included dogs with urethral sphincter mechanism incompetence treated by placing an artificial urethral sphincter from January 1, 2010 to December 31, 2017. The continence score (scale 1 to 5, with 5 indicating complete continence) was evaluated before and after implantation. Follow-up information was obtained from the institution's medical records (short-term up to 12 months) and questionnaires were completed by telephone (long-term ≥12 months) for evaluation.

RESULTS

Nineteen Medical therapy was unsuccessful in 18 dogs and unknown in one dog before the artificial urethral sphincter placement. Short-term continence improved in 16 of the 19 (84%) dogs. Four patients were lost to follow-up. Nine of 15 (60%) dogs showed long-term continence improvement, eight of 15 (53%) remained completely continent. The median follow-up was 1785 (range 2 to 3234) days. The complication rate was 56% (9/16). Minor complications, including haematoma, stranguria/temporary dyssynergia and mild inflammation at the port, were reported in four of 16 (25%) dogs. Five of 16 (31%) experienced major complications, including stranguria/mechanical urethral obstruction, persistent dyssynergia, fistula at the port and port rotation.

CLINICAL SIGNIFICANCE

Artificial urethral sphincter placement is a valid option for treating incontinent male dogs that show an insufficient response or become refractory to medical or other prior surgical management. A high-complication rate is associated with this procedure.

Procedural description and prospective evaluation of short-term outcome for the use of prostatic artery embolization in dogs with carcinoma of the prostate

OBJECTIVE

To describe the procedure of prostatic artery embolization (PAE) in dogs with prostatic carcinoma and to evaluate the short-term outcome for treated dogs.

ANIMALS

20 client-owned dogs with prostatic carcinomas between May 2014 and July 2017.

PROCEDURES

In this prospective cohort study, dogs with carcinoma of the prostate underwent PAE with fluoroscopic guidance. Before and after PAE, dogs underwent CT and ultrasonographic examinations of the prostate, and each owner completed a questionnaire about the dog's clinical signs. Results for before versus after PAE were compared.

RESULTS

Prostatic artery embolization was successfully performed in all 20 dogs. Tenesmus, stranguria, and lethargy were significantly less common 30 days after PAE (n = 2, 1, and 0 dogs, respectively), compared with before PAE (9, 10, and 6 dogs, respectively). Median prostatic volume was significantly less 30 days after PAE (14.8 cm3; range, 0.4 to 48.1 cm3; interquartile [25th to 75th percentile] range, 6.7 to 19.5 cm3), compared with before PAE (21.7 cm3; range, 2.9 to 77.7 cm3; interquartile range, 11.0 to 35.1 cm3). All dogs had a reduction in prostatic volume after PAE, with a median prostatic volume loss of 39.4% (95% CI, 20.3% to 59.3%).

CONCLUSIONS AND CLINICAL RELEVANCE

Prostatic artery embolization was associated with decreased prostate volume and improved clinical signs in this cohort. The short-term response to PAE appears promising, and evaluation of the long-term impact on survival time is needed.

Investigation of the use of microwave ablation with and without cooling urethral perfusion for thermal ablation of the prostate gland in canine cadavers

OBJECTIVE

To investigate the use of microwave ablation (MWA) with cooling urethral perfusion and with no perfusion (MWA-UP and MWA-NP, respectively) for prostate gland ablation in canine cadavers.

ANIMALS

Cadavers of 18 sexually intact male dogs.

PROCEDURES

After technique refinement in 2 cadavers, laparotomy with ultrasound-guided MWA-UP (n = 8) or MWA-NP (8) of the prostate gland was performed in 16 cadavers. Normograde cystourethroscopy was performed before and after treatment; recorded images were reviewed in a blinded manner for scoring of urethral mucosal discoloration and loss of integrity. Difficulty with cystoscope insertion was recorded if present. Excised prostate glands were fixed for serial sectioning, gross measurements, and calculation of percentage ablation. Percentages of prostate tissue necrosis from MWA, denuded urethral mucosa, and depth of epithelial surface loss in an adjacent section of the colon were estimated histologically. Variables of interest were statistically analyzed.

RESULTS

Difficulty with cystoscope insertion after treatment was significantly more common and scores for urethral mucosal discoloration and loss of integrity were significantly higher (indicating more severe lesions) for the MWA-NP group than for the MWA-UP group. The histologically assessed percentage of denuded urethral mucosa was also greater for the MWA-NP group. Overall median percentage prostate gland ablation was 73%; this result was not associated with prostate gland volume or chronological order of treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

MWA-UP induced subtotal thermal necrosis of prostate glands in canine cadavers while limiting urethral mucosal injury. Further study is required to optimize the technique and evaluate its safety and efficacy in vivo as a future curative-intent treatment for prostatic tumors in dogs.

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.

Prostatectomy as a treatment for canine prostate cancer: a literature review

Canine prostate cancer is a relatively rare condition that accounts for less than 1% of all cancers diagnosed in dogs (Obradovich et al., 1987; Bryan et al., 2007). Out of 431 dogs with prostatic conditions diagnosed in a Dutch center, 56 suffered from prostatic carcinoma (Teske et al., 2002). Several forms have been identified, of which adenocarcinoma (AC), transitional cell carcinoma (TCC), and undifferentiated cell carcinoma are the most common (Bennett et al., 2018; Cunto et al., 2019).

First robot-assisted radical prostatectomy in a client-owned Bernese mountain dog with prostatic adenocarcinoma

OBJECTIVE

To describe robot-assisted radical prostatectomy (RARP) and report the short-term outcome of a dog with prostatic cancer treated with RARP.

STUDY DESIGN

Case report ANIMALS: Client-owned 6-year-old male-neutered Bernese mountain dog.

METHODS

Robot-assisted radical prostatectomy was performed with a daVinci Si Surgical System through a transperitoneal approach. An interfascial nerve-sparing approach was used to preserve the neurovascular bundles and increase the likelihood of postoperative urinary continence. Urinary continence was assessed by placing white cloth bedding in the kennel during hospitalization and by owners' observation at home.

RESULTS

The console time was 120 minutes, and the estimated intraoperative blood loss was 30 mL. No intraoperative complications were observed. The urinary catheter was removed after 7 days, at which point the dog urinated normally. Peritoneal carcinomatosis was diagnosed 43 days after surgery, and the dog was euthanized.

CONCLUSION

Robot-assisted radical prostatectomy was successfully completed in a dog with prostatic neoplasia and led to postoperative urinary continence.

CLINICAL SIGNIFICANCE

This single-case report provides evidence to justify further evaluation of RARP in dogs with prostatic neoplasms.

Ischial ostectomy in direct end-to-end anastomosis of the pelvic urethra in male dogs

Ischial ostectomy in conjunction with direct end-to-end anastomosis of the pelvic urethra was performed after prostatectomy in cadavers of 10 male dogs with normal bladder and urethra, and in a mongrel dog with an enlarged prostrate and transection injury of the pelvic urethra. In the cadavers, tension on the suture line was assessed from the intravesical pressure (IVP) and volume of normal saline solution (NSS) instilled into the bladder to cause dehiscence of the anastomosis before and after the ostectomy. The experiment found that the IVP and instilled NSS volume after the ischial ostectomy were significantly (p<0.01) higher than those before the ostectomy, suggesting the ostectomy can reduce tension on the suture line and risk of dehiscence. Clinically, the dog had uneventful recovery with normal urination. Fluoroscopic examination of the caudal abdomen at 3 and 16weeks after surgery revealed urethral continuity without perforation and narrowing of the anastomosis site.

Evaluation of palliative stenting for management of malignant urethral obstructions in dogs

OBJECTIVE

To evaluate use of balloon-expandable and self-expanding metallic stents in management of malignant urethral obstructions in dogs.

DESIGN

Original study.

ANIMALS

12 dogs with malignant urethral obstructions.

PROCEDURES

The extent and location of urethral obstructions and the diameter of adjacent unaffected luminal segments were determined by use of fluoroscopically guided wires and measuring catheters. Stents were chosen to extend approximately 1 cm proximal and distal to the obstruction. Stent diameters were chosen to be approximately 10% greater than the diameter of healthy portions of the urethra to prevent displacement. Stents were placed in the urethra under fluoroscopic guidance to restore luminal patency.

RESULTS

3 dogs received balloon-expandable metallic stents, and 9 dogs received self-expanding metallic stents. The placement procedures were rapid, safe, and effective at restoring luminal patency and were not associated with major complications. Complications included recurrent urethral obstruction secondary to blood clot formation and urethral edema in 1 dog and stent dislodgement into the urinary bladder in 1 dog. All dogs were able to urinate immediately after the procedure. Nine dogs (3/4 females and 6/8 males) were continent or mildly incontinent after stent placement. Of the remaining 3 dogs, 2 developed severe incontinence and 1 had an atonic bladder. Seven dogs were considered to have good to excellent outcome, 3 had fair outcome, and 2 had poor outcome.

CONCLUSIONS AND CLINICAL RELEVANCE

Transurethral placement of metallic stents was a safe and effective palliative treatment option for dogs with malignant urethral obstructions.

Partial Prostatectomy Using Nd:YAG Laser for Management of Canine Prostate Carcinoma

OBJECTIVE

To report a technique for partial prostatectomy by laser dissection and to evaluate outcome and complications in dogs with prostate carcinoma (PCA).

STUDY DESIGN

Experimental and clinical case series.

ANIMALS

Four normal dogs and 8 dogs with PCA.

METHODS

Subcapsular partial prostatectomy, sparing the urethra and the dorsal aspect of the prostatic capsule, using Nd:YAG laser dissection to remove the prostatic parenchyma and control hemorrhage was performed in 4 normal dogs and subsequently in 8 dogs with histologically confirmed PCA. Additional treatment of PCA dogs included local application of interleukin-2 and systemic administration of meloxicam. Prostate size, complications, and survival time were recorded. Laser-associated thermal damage to surrounding tissue was evaluated by histology.

RESULTS

In normal dogs, no damage to the dorsal prostatic capsule or urethra was detected. In PCA dogs, median survival was 103 days (range, 5-239 days). Three dogs died from complications within 16 days, whereas 5 (median survival, 183 days; range, 91-239 days) had improvement or resolution of clinical signs. Urinary incontinence did not occur.

CONCLUSION

Laser assisted subcapsular partial prostatectomy can be performed in dogs with PCA without development of postoperative incontinence.

CLINICAL RELEVANCE

Subcapsular partial prostatectomy is a potential palliative treatment for PCA in dogs and may lead to the resolution of clinical signs for several months.

Reproductive oncology

The actual incidence of reproductive tract tumors is difficult to ascertain, presumably because a significant percentage of dogs and cats are neutered, particularly in the United States. Data from European countries, where elective neutering is less common, provides insights. Several studies document the relative frequency of reproductive tumors. Larger studies of the more common tumors, e.g., testicular tumors, provide a substantial amount of information on the clinical presentation and response to treatment of dogs, but overall there is less information available on cats. Numerous case reports document the less commonly reported tumors and will be included in the following discussion.

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

OBJECTIVE

To compare effects of medetomidine and xylazine hydrochloride on results of cystometry and micturition reflexes in healthy dogs and results of urethral pressure profilometry (UPP) in sedated and conscious dogs.

ANIMALS

20 dogs.

PROCEDURES

Urodynamic testing was performed 6 times in each dog (3 times after administration of xylazine [1 mg/kg of body weight, IV] and 3 times after administration of medetomidine (30 microg/kg, IM). Before each episode of sedation, UPP was performed. Heart and respiratory rates and indirect blood pressures were recorded prior to and 5, 10, 20, and 30 minutes after injection of sedative. Cystometry measurements included threshold volume, threshold pressure, and tonus limb. The UPP measurements included maximal urethral closure pressure (MUCP), functional profile length, and, in male dogs, plateau pressure.

RESULTS

Mean MUCP was decreased markedly in xylazine- and medetomidine-sedated dogs. Xylazine and medetomidine also decreased plateau pressure in male dogs. The MUCP measurements were consistent among days for conscious and xylazine-sedated dogs but were inconsistent for medetomidine-sedated female dogs. The proportion of valid cystometry measurements was greater for xylazine (39 of 60) than for medetomidine (27 of 60). Cystometry was considered invalid when bladder pressure reached 30 cm H2O without initiation of a micturition reflex.

CONCLUSIONS AND CLINICAL RELEVANCE

Medetomidine and xylazine have similar effects on measurement of UPP and cystometry. Medetomidine was less consistent among days for UPP in female dogs and produced fewer valid cystometry tests, compared with xylazine. For urodynamic evaluations, medetomidine administered IM cannot be substituted for xylazine administered IV.

Diagnosis and management of urinary retention

Failure to empty the urinary bladder completely can be attributed to failure of detrusor contractile function, inappropriate outlet resistance, or both. For each of these mechanisms, anatomic, neurogenic, and end-organ (myogenic or idiopathic) abnormalities are possible. The approach to urinary retention involves systematic consideration of neurogenic, obstructive, and functional causes and requires understanding of the neurophysiology and pharmacology of micturation.

Vaginal position and length in the bitch: relationship to spaying and urinary incontinence

A study was undertaken to determine if the vagina might be a suitable site for the measurement of intra-abdominal pressure during cystometry in the bitch. The position of the cranial vagina and vaginal length were measured radiographically and the effects of spaying and urinary incontinence on these variables were evaluated in 30 continent and 30 incontinent bitches. The study used retrograde vaginourethrograms which had been obtained from animals used in a previous study. The cranial vagina was intra-abdominal on 36 of the vaginourethrograms, being least commonly intra-abdominal in incontinent bitches (11/30). Vaginal position was related linearly to vaginal length and continence status (P < 0.01), while its length was related to bodyweight (P < 0.01). Allowing for bodyweight, neutered animals had significantly shorter vaginas than entire bitches (P < 0.01). Measurement of intra-abdominal pressure with concomitant measurement of intravesical pressure is essential if accurate assessment of detrusor pressure is to be determined during cystometry. The vagina is unlikely to be a useful location from which to measure intra-abdominal pressure since any pressure-measuring catheter inserted into it may fall outside the abdominal pressure zone. This is particularly true of neutered and/or incontinent bitches, the groups in which urodynamic investigations of urinary incontinence are most frequently indicated.

Intracapsular subtotal prostatectomy in normal dogs: use of an ultrasonic surgical aspirator

In an attempt to reduce postoperative incontinence associated with excisional prostatectomy and the recurrence of prostatic disease after less radical surgeries, a new technique for subtotal prostatectomy was developed using an ultrasonic surgical aspirator. During laparotomy, a longitudinal incision was made in the ventral surface of each lobe of the prostate gland. Biopsies for histology and culture were taken. Through the ventral incisions, the ultrasonic surgical aspirator was used to resect approximately 85% of the glandular tissue from inside the capsule. The ultrasonic surgical aspirator allowed resection of the glandular tissue without damaging the vessels, nerves, and connective tissue stroma. The ventral portion of the capsule was excised. The dorsal portions of the capsule were apposed on the ventral midline by suturing their ventral margins to form a periurethral cuff. As preclinical research, seven intact male dogs were evaluated by physical examination, complete blood cell count, serum urea nitrogen, urinalyses, and urethral pressure profile (UPP) with urethral electromyograms (EMGs). The dogs underwent subtotal prostatectomy and castration. All dogs were continent after surgery. UPPs and EMGs at 1 and 2 months after surgery were no different than before surgery. This contrasts to our previous studies in which excisional prostatectomy reduced maximal urethral closure pressure (MUCP) in dogs without prostatic disease. The use of the ultrasonic surgical aspirator for intracapsular subtotal prostatectomy facilitated removal of glandular tissue with decreased hemorrhage and provided preservation of the prostatic urethra, nerves, and vessels involved in maintaining urinary continence.

Use of a retained urethral catheter in three dogs with prostatic neoplasia

Percutaneous nephrostomy catheters modified by cutting off the tubing connectors were implanted in three dogs with prostatic neoplasia to relieve or prevent stranguria. One catheter was implanted with a guide wire through a perineal urethrotomy, and two catheters were implanted via celiotomy and cystotomy. Morbidity and complications were minimal. Inflammation of the abdominal incision was present from day 4 to day 8 in the dogs with celiotomy. Urinary incontinence was continuous in one dog and intermittent in two dogs. Hematuria occurred in two dogs. The retained urethral catheter was a suitable palliative treatment for urethral obstruction in three dogs with prostatic neoplasia.

Urinary incontinence after prostatectomy in dogs

Eleven dogs with prostatic disease were treated by total prostatectomy. Urinary incontinence persisted in three of nine dogs, two of which were also incontinent before surgery. The incidence of postoperative incontinence may be reduced by undermining the prostatic capsule to preserve as much prostatic urethra as possible. The risk of postoperative incontinence appeared greater if there was prostatic neoplasia or preoperative urinary incontinence.

Subtotal canine prostatectomy with the neodymium: yttrium-aluminum-garnet laser

A technique was developed for subtotal prostatectomy in dogs with the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. In six normal dogs, full-thickness necrosis of the prostate occurred if the central-lateral region within 5 mm of the urethra was photoablated at 60 watts for 1 second. Moderate to superficial necrosis occurred when the prostate within 5 mm of the urethra was photoablated at 35 watts for 2 seconds or 60 watts for 0.5 second. At necropsy, leakage of the urethra occurred in two dogs at sites treated at 60 watts for 1 second. In a clinical study, complications associated with subtotal prostatectomy with the Nd:YAG laser (n = 6) were compared with complications associated with prostatic drainage (n = 6) in dogs with prostatic disease. Intraoperative death (2/6 dogs) and nocturnal incontinence (4/4 surviving dogs) occurred with subtotal prostatectomy. Uncontrolled prostatic infection (2/6 dogs) occurred with prostatic drainage and resulted in the death of one dog on day 11. Four of five dogs surviving prostatic drainage developed recurrent urinary tract infection.

Urodynamic alterations after prostatectomy in dogs without clinical prostatic disease

Prostatectomy in dogs with clinical prostatic disease has been associated with a high incidence of urinary incontinence. In this study, urodynamic alterations after prostatectomy in 10 dogs without clinical prostatic disease were evaluated. Measurements of residual urine volume, simultaneous urethral pressure profilometry and electromyography, and carbon dioxide cystometry were made before and 14 and 20 weeks after prostatectomy. Voiding was observed daily for 20 weeks after prostatectomy. All dogs remained continent for 20 weeks after prostatectomy, and only minor urodynamic abnormalities were noted. Castration had no effect on urodynamic changes associated with prostatectomy. Prostatectomy produced minimal functional changes in dogs without clinical prostatic disease.