Veterinary Surgery, 19, 5,348-355,1990
Subtotal Canine Prostatectomy with the Neodymium: Yttrium-Aluminum-Garnet Laser E. M. HARDIE, DVM, PhD, DiplornateACVS, E. A. STONE, DVM, MS, DiplomateAVCS, K. A. SPAULDING, DVM, DiplomateACVR, and J. M. CULLEN, VMD, PhD, DiplornateACVP A technique was developed for subtotal prostatectomy in dogs with the neodymium:yttriumaluminum-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. lntraoperative 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.
for the manageC ment of prostatic cysts and abscesses have a high complication rate.'-4 Two commonly used techniques URRENT SURGICAL TECHNIQUES
Materials and Methods
Normul Dogs are total prostatectomy'.' and drainage with Penrose Nine adult male dogs with prostates palpable per recdrains.'.' Urinary incontinence occurred in 13 of 14 dogs tum were used to develop a safe technique for subtotal with prostatic disease that were treated by total prostatecprostatectomy with the Nd:YAG laser* in a noncontact tomy.' Postoperative complications in 92 dogs with mode. The dogs were anesthetized with pentobarbital prostatic abscesses treated by drainage included postop(30 mg/kg intravenously [IV]). Tracheas were intubated erative sepsis and shock, prostatic urethrocutaneous fisand the dogs were allowed to breath 100%oxygen while tulas, recurrent abscesses, and urinary i n ~ o n t i n e n c e . ~ . ~ surgery was being performed. Isotonic fluids were adThe incidence of recurrent urinary tract infection was ministered at a rate of 10 mL/kg/hr. A urethral catheter not determined, but 16% of the dogs were euthanatized was inserted to facilitate identification of the urethra. 2 to 3 1 months after surgery because of chronic recurrent Surgery was performed with aseptic technique. urinary tract infections or recurrent abscesses. Only 34% Dogs LI-L3 were used to determine the technical feaof the dogs had no long-term complications. sibility of subtotal prostatectomy with the Nd:YAG laThe purpose of this study was to develop a technique ser. The laser was used in a continuous mode at 35-90 for subtotal pro~tatectomy~ with the neodymium:yttriwatts to ablate the prostatic capsule and prostatic tissue. um-aluminum-garnet (Nd:YAG) laser, to minimize the Dogs S I -S6 were used to determine the safety limits risks of urinary incontinence and recurrent prostatic and urinary tract infection. A randomized clinical study was performed to identify complications associated with use * Fiberlase 100 medical laser system. Living Technology Inc, Warminster. PA. of the technique in dogs with prostatic disease. ~
~
From the Departments of Companion Animal and Special Species Medicine (Hardie, Stone), Anatomy, Physiological Sciences and Radiology (Spaulding), and Microbiology, Parasitology, and Pathology (Cullen), College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina. Study supported by the State of North Carolina. Preliminary results presented at the Annual Meeting of the College of Veterinary Surgeons, Reno, Nevada, February 1989. The authors thank Living Technology Inc. for the use of the Nd:YAG laser. Reprint requests: Elizabeth M. Hardie, DVM, PhD. College of Veterinary Medicine, North Carolina State University, 47000 Hillsborough Street, Raleigh, NC 27606.
348
HARDIE, STONE, SPAULDING, AND CULLEN
Dorsal
349
for evidence of urinary incontinence during two daily walks outside the building. On day 7. the dogs were euthanatized with pentobarbital (60-100 mg/kg IV). Each prostate and prostatic urethra was removed, and the urethra was infused with Trump’s solution. Leaks in the urethra were noted. The prostate and prostatic urethra were immersed in Trump’s solution. Fixed tissue was processed for light microscopy, sectioned at 6 pm, and stained with hematoxylin and eosin. Histologic examination of the left side of each prostate and urethra was performed without knowledge of treatment. Tissue from the right side was reserved for duplicate analysis, if needed.
Dogs M-pith Prostutic Disease
Ventr a1 Fig. 1. Subtotal prostatectomy technique used in dogs S1-S6. The region outside the broken lines was removed with scissor dissection. The region indicated with diagonal hatch marks was photoablated with the Nd:YAGlaser.
of lasing close to the urethra. All major vessels leading to the prostate were ligated or clipped with vascular clips because ligation of major vessels is often necessary i n diseased prostates. The prostatic capsule and all prostatic tissue to within approximately 5 mm ofthe lateral aspect of the prostatic urethra were dissected with scissors (Fig. 1). The cut surface of the prostate at the level of the urethra was treated with the laser at six sites. At one of three sites on the right side, lasing was performed at 3.5 watts for 2 seconds. at 60 watts for 1 second, or 60 watts for 0.5 second. The sites were chosen randomly and were separated by at least 5 mm. The lasing pattern determined for the right side was repeated on the left side, The spot sizes averaged 1.5 mm and the end of the laser fiber was 1 cm from the tissue. After closure ofthe abdominal incision, the dogs were castrated because castration is routinely performed at the same time as prostate surgery in clinical cases. After recovery from anesthesia, the dogs were housed in 3.2 mr runs for 7 days. Temperature, pulse, respiralion, attitude, urination, defecation, appetite, and drinking habits were monitored daily. The dogs were watched
Twelve dogs admitted to the North Carolina State University Veterinary Teaching Hospital for surgical treatment of prostatic disease were assigned randomly to treatment by prostatic drainage or by subtotal prostatectomy with the Nd:YAG laser. A coin toss was used to determine the treatment of the first dog in a pair. The next dog was assigned to the opposite treatment. All intact dogs were castrated. Signalment was recorded and a serum chemistry panel, CBC, urinalysis, and ultrasound examination of the prostate were obtained for each dog. Additional diagnostic procedures for prostatic disease (survey radiographs, contrast urethrograms. semen evaluation, prostatic aspirate) and concurrent diseases were performed as necessary. Aerobic and anaerobic cultures of urine and prostatic fluid were obtained before or during surgery. The status of urinary continence (continent, incontinent, obstructed) as determined by the clinician was recorded before surgery. All dogs had urethral catheters in place at the time of surgery. Dogs treated by prostatic drainage were designated D 1-D6. Two to four 0.6cm Penrose drains were placed into prostatic abscess cavities or cysts. Periprostatic fat was minimally dissected by finger dissection. In dogs with multifocal disease, communication was established between the site being drained and other abscess cavities. Drains were placed in each lobe of the prostate and exited through the ipsilateral body wall. The drains were left in place as long as copious drainage was present (2 to 21 days). The urethral catheters were removed at the conclusion of the surgery. Dogs treated by subtotal prostatectomy were designated Pl-P6.Most ofthe prostatic tissue was removed by sharp and electroscalpel dissection. Capsular vessels were ligated or occluded with vascular clips. lfan abscess or cyst was adherent to the rectum or other structure, the abscess cavity was opened and all attachments between the adherent tissue and the prostate were severed. Tissue
350
SUBTOTAL PROSTATECTOMY WITH Nd:YAG LASER
Dorsal
Ventr a1 Fig. 2. Subtotal prostatectomy technique used in dogs Pl-P6. After removal of most of the prostatic tissue with an electroscalpel, the surface of the remaining tissue was photoablated with the Nd:YAG laser (diagonal hatchmarks).
that remained after dissection consisted of small amounts of prostatic tissue around the prostatic urethra and sections of abscessed tissue that could not be dissected free from surrounding structures. If the dorsal region ofthe prostate (particularly around the neck ofbladder) was minimally involved in the disease process, this region was left intact (Fig. 2). The Nd:YAG laser was used in a noncontact continuous mode at 35 watts to control hemorrhage from the cut surface of the prostate and from the lining of abscess cavities. All exposed viscera not being treated were protected with moistened laparotomy pads. Abscess tissue adherent to the surface of the rectum was not treated. In dogs P2-P6, methylene blue dye (0.5 ml) was injected in the bladder and manually expressed through the urethra. Holes identified by escape of the dye were sutured to control leakage. A urethral catheter was left in place for 2 to 4 days. The prostate was within a perineal hernia in dogs D5 and P5. Prostatic surgery was performed through a perineal approach during repair of the hernia, rather than through a ventral midline incision. A suction drain exiting adjacent to the surgical site was used for prostatic drainage in dog D5. Subtotal prostatectomy as described previously was performed in dog P5.
The operative time, total number of procedures performed on a given dog. length of hospitalization, and short-term complications of surgery were recorded. Owners were requested to bring their dogs to the hospital I , 6 and I2 months after surgery for urinalysis, urine culture. and ultrasound examination of the prostate. Owners were questioned about the presence of urinary incontinence and any other complications that might be associated with the urogenital system. Urethral pressure p r o f i l e ~ 'and ~ ~ cystometrograms' were performed in incontinent dogs. Urethral pressure profiles were obtained with the dog awake; cystometrograms were performed after administration of xylazine (2.2 mg/kg subcutaneously). Urodynamic studies were performed in dogs PI and P2 after administration of oxymorphone (0.5 mg/kg IV) for sedation. The cause of death was recorded for dogs that died before the 1 year follow-up. The following grading system for urinary incontinence was used. Major urinary incontinence-dog dribbles urine continually Nocturnal incontinence-dog dribbles urine only when sleeping Minor incontinence-dog spontaneously dribbles urine occasionally; urine dribbling occurs only in association with polyuria or abdominal compression Continent-dog voids urine normally, no urine dribbling observed between voiding episodes Urinary tract infections were defined as recurrent if 1) a urinary tract infection had been treated with antibiotics; 2) a negative urine culture was obtained at least 5 days after cessation of antibiotic therapy; and 3 ) a positive urine culture was subsequently obtained. Results
Norrnal Dogs The laser was found to be slow and inefficient for ablation of large amounts of prostatic tissue in dogs Ll-L3. Hemostasis with the laser was good for parenchymal bleeding, but poor for bleeding from capsular vessels. N o evidence of major urinary incontinence was observed during week 1. At necropsy, necrosis of periprostatic fat and adhesions of periprostatic fat to the cut surface ofthe prostate were present. There was no evidence of urethral disruption. Histologically, the prostatic lesions in dogs L 1-L3 were characterized by replacement of glandular tissue by immature granulation tissue. The lumens of remaining glands at the periphery of the photoablated sites were dilated and lined by flattened, atrophic cells. Veins and arteries within granulation tissue frequently were occluded
HARDIE, STONE, SPAULDING, AND CULLEN
351
Fig. 3. Section of prostate photoablated at 35 watts for 2 seconds.The superficial aspect of the prostate is replaced by granulation tissue and the uroepithelium (arrow) is still intact.
by thrombi. The extent of glandular destruction varied from superficial to nearly full thickness of the remaining prostatic tissue. but all of the urethras were intact and lined by normal uroepithelium. The scissor dissection technique (Fig. I ) was found to be an efficient and reliable method of performing subtotal prostatectomy in dogs S 1 -S6. After most of the prostate was removed, the laser provided precise ablation of prostatic tissue adjacent to the urethra. After sagittal excision of the majority of the prostatic tissue, the remaining prostatic tissue was thinnest lateral to the colliculus seminalis, where the excretory ducts of the prostate enter the urethra. Caution in dissection was indicated in this region. No evidence of major urinary incontinence was observed during week I in dogs S 1 -S6. At necropsy, there was no necrosis of periprostatic fat, but there were adhesions of periprostatic tissues to the cut surface of the prostate. Although no evidence of urine leakage was seen, fixative in the urethra leaked through holes in the right central-lateral prostatic region in two dogs at sites oflasing at 60 watts for I second. Histologically, the prostates from dogs S I 4 6 were similar to those of dogs LI-L3. Moderate to full-thickness destruction of remaining prostatic tissue with replacement by fibrous tissue was observed at sites lased at 60 watts for 1 second. Superficial to moderate injury was observed at other sites (Fig. 3).Histologically, the urethra was intact in all dogs except S6, in which necrosis presumed to be secondary to infarction of the remaining prostatic tissue and urethra was evident.
Dog., ujith Prostatic Disrase The signalment, prostatic diseases, and concurrent diseases of dogs with prostatic disease are listed in Table
I . Intraoperative cultures of the prostate or urine were positive in four of the six dogs undergoing drainage and three of the six dogs undergoing subtotal prostatectomy (Table 2).Urinalysis was consistent with urinary tract infection in three of the five dogs with drains and four of the six dogs with subtotal prostatectomy. Dog D4, which underwent prostatic drainage. had preexisting major urinary incontinence due to lower motor neuron neurologic disease; all other dogs with drains were continent before surgery. Three dogs chosen for subtotal prostatectomy (PI.P5, and P6)were continent, two dogs (P2,P3) had major urinary incontinence, and one dog (P4)was obstructed before surgery. The average surgical time for prostatic drainage was 167 minutes (range, 78-2 15 minutes), and the average surgical time for subtotal prostatectomy was 192 minutes (range, 125-265 minutes). The average hospital stay was I 1 days (range, 4-18 days) for the six dogs with drains and 6.5 days (range, 5-16 days) for the four dogs that survived subtotal prostatectomy. Half of the dogs in each group were alive 1 year after surgery. In the drain group, dog D4 died of sepsis and pulmonary thromboembolism on day 1 1 , dog D2 was euthanatized 3.5 months after surgery due to recurrence of oral fibrosarcoma and a prostatic abscess, and dog D6 died 2.5 months after surgery of gastric dilatation/volvulus. Two dogs undergoing subtotal prostatectomy (P3, P4) died of shock during surgery. Severe sepsis was present in dog P3.Sepsis, extensive blood loss, and long surgery time may have contributed to the development of shock in dog P4. Dog P2 died a t month 10 of cutaneous lymphosarcoma. Immediate postoperative complications in the dogs with prostatic drainage included infection within a drain
352
SUBTOTAL PROSTATECTOMY WITH Nd:YAG LASER TABLE 1. Signalment and Diseases of Dogs in the Clinical Study Group
Prostatic Drainage
Subtotal Prostatectorny
*
Dog
Breed
Age
Prostatic Disease'
Histopathology of Prostate
Concurrent Disease
D1
Doberman pinscher
Unilateral prostatic cyst Bilateral prostatic abscesses
Chronic lymphocytic/plasmacytic prostatitis Abscess; cystic, nonsuppurative prostatitis
7
Unilateral prostatic abscesses
Diffuse subacute chronic prostatitis
Irish setter
8
Severe suppurative prostatitis
D5
Boston terrier
8
Not done
D6
Doberman pinscher
9
Multifocal prostatic abscesses Unilateral prostatic abscess Unilateral prostatic abscess
Suppurative peritoneal fluid Fibrosarcomamandible, ruptured collateral ligarnenthock Wobbler syndrome, von Willebrand's disease, hypothyroidism Fibrocartilaginous emboli Perineal hernia
02
Corgi
D3
Doberman pinscher
D4
Locally extensive severe acute prostatitis
Leiomyoma-pelvic canal, perineal hernia
P1
Doberman pinscher
7
Chronic lymphocytic multifocal prostatitis
GI hemorrhage; chronic osteomyelitis
P2
German shepherd
10
P3
Collie mix
11
Cryptorchid, sertoli cell tumor Diskospondilitis, pneumonia
P4
Cocker spaniel
14
P5
Boston terrier
9
P6
Boxer
8
Severe chronic suppurative prostatitis Severe extensive inflammation adipose tissue (paraprostatic abscess) Severe multifocal suppurative prostatitis Chronic lymphocytic, plasmacytic, neutrophilic prostatitis Cyst, lined with transitional cell epithelium
7
14
Multifocal prostatic abscesses, one unilateral large cyst Unilateral prostatic abscess Paraprostatic abscess Multifocal prostatic abscesses Prostatic cyst containing urine Unilateral prostatic cyst
Hydronephrosis left kidney Bilateral perineal hernias Bilateral perineal hernias
Category based on appearance at surgery and cytology. Cultures were not always positive for abscesses
wound, severe hematuria. anemia, weakness, diarrhea, sepsis. and pulmonary thromboembolism. Complications in the dogs with subtotal prostatectomy included TABLE 2.
hypernatremia, hyperchloremia, oliguria. polyuria and polydipsia, pancreatitis, and urine leakage. Each complication occurred in one dog, except polyuria and polydip-
Prostatic and Urinary Tract lnfections in Dogs in the Clinical Study
Organisms Prostate
No. of Dogs
Organisms Urine
No. of Dogs
Organisms Recurrent UTI
No. of
Prostatic Drainage
E. coli K. pneumoniae
2 2
K. pneumoniae Beta-hemolytic Strep
1 1
E. coli K. pneumoniae P. stuartii Group G strep
2 1 1 1
Subtotal Prostatectorny
E. coli Proteus S. fecalis Group G strep
2 1 1 1
E. coli Proteus Group G strep
2 1 1
Group
Dogs
E. coil-kcherichia coli; K. pneumoniae-Klebsiella pneumoniae; S. fecalls-Streptococcus fecalis; strep-Streptococcus; P. stuartii-Providencia stuartii; No. of Dogs-organism was cultured from this number of dogs. Multiple organisms were cultured from some dogs. UTI-urinary tract infection.
HARDIE, STONE, SPAULDING, AND CULLEN
sia. which occurred in three dogs. The urine leakage occurred i n the first clinical patient to receive subtotal prostatectomy, and a second operation was needed to repair the site of leakage. Checking for potential sites of urine leakage (present in two dogs) and performing direct repair at surgery eliminated this problem. Major urinary incontinence occurred in two dogs with drains (D5, D6) immediately after surgery. Dog D4, which had major incontinence before surgery, died on day 1 1 without regaining urinary continence. Dog D5 continued to dribble urine occasionally at year I . and dog D6 was continent by month 1. A urethral pressure profile and cystometrography were performed on dog D5 at year I . Low urethral pressures (maximal urethral closure pressure: 40 cm H 2 0 )were present.? Dog D 1 developed spastic urination and dysuria 3 months after surgery. urethrography, cystometrography, and a urethral pressure profile were performed. A narrow prostatic urethra, but no obvious site of obstruction, was seen. Overdistention of the bladder, a poor detrusor reflex, and an area of increased urethral pressure in the prostatic urethra were identified. Symptoms resolved with bethanechol (5 mg orally tid) and phenoxybenzamine ( 5 mg orally tid) therapy. Major urinary incontinence was present in two dogs (P2, P6) with subtotal prostatectomy immediately after surgery. Resolution to nocturnal incontinence was observed by months 1 to 2. Dog PI developed occasional nocturnal incontinence 9 to 12 months after surgery. Dog P5 became incontinent while being treated with corticosteroids for a skin problem, but urinary incontinence resolved after cessation of therapy. Cystometrograms and urethral pressure profiles were obtained on dogs P5 and P6. Urethral pressures were extremely low (maximal urethral closure pressures: 26,36 cm H20). The maximal urethral closure pressures measured on dogs PI and P2 were similar (40, 12 cm HzO), but the studies were performed after administration of oxymorphone (0.05 mg/ kg IV). The high-pressure zone associated with the external urethral sphincter' was absent in all dogs with subtotal prostatectomy. Phenylpropanolamine therapy (50 mg orally tid) was initiated in dog P6, which decreased but did not eliminate nocturnal incontinence. The owners of dogs P 1 and P2 refused further therapy because of the minor nature of the problem. Two dogs with subtotal prostatectomy developed postoperative urinary tract infections from the use of indwelling urinary catheters. No recurrent urinary tract infections were detected in dogs with subtotal prostatectomy after resolution of established or acquired infection. No hospital-acquired crinary tract infections ~
iNormal value (nican t SE) at North Carolina State linicci-sit) i s 100 i I S crn H 2 0 .
353
were detected in the dogs with prostatic drainage. Recurrent urinary tract infection occurred in four of the five dogs with drains that survived the immediate postoperative period (Table 2). Results of ultrasonographic measurements indicated that prostatic size decreased in all dogs surviving surgery. Prostatic size continued to decrease in all dogs with resolving disease (DI, D3, D5, P2, P5. P6) over the course of the year. Decreased size of the prostate gland was associated with reduction and disappearance of cystic areas, and development of a heterogeneous hyperechoic echo texture. Three dogs (D5, P2, P5) had unchanging focal hyperechoic areas that were presumed to be scar tissue within the prostate. Increase in prostatic size during year 1 was associated with the presence of previously unidentified cystic areas. This occurred in two dogs in the drain group (D2, D6) and 1 one dog in the subtotal prostatectomy group (PI). Prostatic abscesses recurred in dog D2, dog D6 died shortly after the new cystic lesion was identified, and dog PI had no signs of prostatic disease during year 2.
Discussion The concept of subtotal prostatectomy with capsule removal is not Although descriptions of various techniques exist, no studies evaluating their efficacy in the treatment of canine prostatic disease are available. Previous authors have listed the following potential complications of subtotal prostatectomy: technical difficulty. bleeding from vessels that are difficult to ligate, a need for electrocautery. shock related to blood loss, leaving remnants of prostatic tissue, and urethral leakage.5."' We found that subtotal prostatectomy was technically more difficult than drain placement. Subtotal prostatectomy required skills similar to those needed to perform total prostatectomy. Subtotal prostatectomy required that the surgeon be familiar with the vascular anatomy of the diseased prostate and maintain meticulous hemostasis of larger vessels. Identification of branches of the prostatic artery allowed the surgeon to place vascular clips on the vessels before electroscalpel incision of the capsule. The Nd:YAG laser coagulated vessels up to 4 mm in diameter ' ' and controlled prostatic parenchymal bleeding well. The problems we found to be associated with subtotal prostatectomy were shock, postoperative urine leakage, and urinary incontinence. The long surgical time and increased blood loss associated with subtotal prostatectomy may have contributed to the development of shock in septic patients. Urine leakage occurred through defects already present in the prostatic urethra. not due to delayed necrosis following the use ofthe laser. This complication did not occur after direct suture repair of urethral defects identified with methylene blue dye
354
SUBTOTAL PROSTATECTOMY WITH Nd:YAG LASER
was instituted. The incidence of urinary incontinence appeared to be similar to that seen with total prostatectomy,'.2but was subjectively less severe. The maximal urethral pressures measured in incontinent dogs in both treatment groups (12-40 cm H 2 0 ) were at the low end of the range previously reported for incontinent male dogs,' and much lower than most values reported for dogs with incontinence after total prostatectomy.' If maximal urethral closure pressure can be related directly to the grade of urinary incontinence, we would expect major incontinence in our dogs. Possible explanations of the discrepancy between our measured values and the grade of incontinence include tranquilizer artifact* (dogs PI, P2), widely differing normal values between instituti~ns,"'~~ and wide variation among dogs as to the maximal urethral closure pressure associated with a given grade of incontinence. The advantage of subtotal prostatectomy over drainage was that resolution of prostatic and urinary tract infection was uncomplicated. Hospitalization after subtotal prostatectomy was shorter than after drainage, and no recurrence of infection occurred during the 1 year follow-up period. In contrast, five ofthe six dogs with drainage had uncontrolled or recurrent infection. Two dogs died or were euthanatized as a result of unresolved infection. Availability of the Nd:YAG laser is not mandatory for performing subtotal prostatectomy,' but its use simplified control of hemorrhage and precise tissue ablation. We have performed seven subtotal prostatectomies in addition to those reported here: two with a carbon dioxide laser and five with electrocautery alone. Postoperative hemorrhage occurred in only one dog, which had Von Willebrand's disease and perioperative aspirin 1 herapy. If the Nd:YAG laser is used for subtotal prostatectomy. powers over 35 watts should be used cautiously near the urethra. In particular, results of our preliminary studies indicated that if the central-lateral part of the prostate within 5 mm of the urethra was exposed to 60 watts for I second, the potential existed for urethral perforation and leakage. We performed these studies because necrosis associated with the use of the Nd:YAG laser is not immediately apparent at the time of surgery and may extend up to 4 mm from the impact site." In previous studies examining the safety of the Nd:YAG laser for prostatectomy, an intracapsular technique was used." The presence of avascular necrosis of the prostatic urethra in one of the normal dogs indicated that radical dissection of the prostate could produce infarction of the prostate and associated urethra. No urine leakage occurred in the normal dog. but the I week follow-up time may have been inadequate to determine the full range
of complications associated with necrosis. As we gained experience with the clinical cases, we tended to preserve the dorsal capsule vessels and excise the diseased parenchyma (Fig. 2). In this respect, our technique was similar to subtotal intracapsular prostatectomy.13 The techniques differ in several aspects. First, we believe that it is critical to maintain urethral integrity. Poor urethral healing and urine leakage are more significant problems in dogs with prostatic disease than in normal dogs. Second, we do not suture the capsule. In dogs with large cysts or abscesses, suturing the capsule is often impossible. Even when suturing is possible, a potential space for maintenance of infection is created. Third, if the abscess is located in a dorsal part of the prostate, we remove all infected tissue despite the risk of compromising the blood supply to the prostatic urethra. Overall, dogs in the clinical part of this study were old dogs with multiple diseases. Perineal hernia, neurologic disease. and cancer were the most common concurrent diseases. Despite the presence of multiple diseases, complications related to treatment of prostatic infection were the most common cause of death. Survival would be maximized if the lethal complications associated with each technique could be reduced. We recommend that drainage techniques be used for treatment of unstable patients with large prostatic abscesses. To avoid systemic sepsis and shock, minimal dissection should be used in the placement of drains. Patients treated with drainage should be monitored postoperatively, using ultrasonography and urine cultures, for recurrence of infection. Subtotal prostatectomy should be used for treatment of stable patients with abscesses, dogs with multifocal abscesses, and dogs with cystic disease. We would reserve total prostatectomy for patients with prostatic cancer or severe prostatic urethral trauma. In conclusion. we developed a technique for subtotal prostatectomy in dogs with the Nd:YAG laser. Subtotal prostatectomy controlled infection, but resulted in more operative deaths and a higher rate of nocturnal urinary incontinence than prostatic drainage. The major problems associated with drainage were failure to control prostatic infection and recurrent urinary tract infection.
References I . Hardie EM. Barsanti JA, Rawlings CA. Complications of prostatic surgery. J Am Anim Hosp Assoc 3984:20:50-56. 2. Basinger RR, Rawlings C A . Barsanti JA. Oliver JE. Urodynamic alterations associated with clinical prostatic diseases and prostatic surgery in 23 dogs. J Am Anim Hosp Assoc 1989:25:385392. 3. Mullen HS. Matthiesen DT, Scavelli TD. Abscessation ofthc prostate gland treated with a multiple drain technique: An evaluation of postoperative complications and long-term results in 91 dogs. (Abstract) Vet Surg 19x9: 18:70. 4. Matthiesen DT. Marretta SM. Complications associated with the
HARDIE, STONE, SPAULDING, AND CULLEN
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6. 7.
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surgical trcatment o f prostatic abscessation. Problems in Veterinary Medicine 1989; 1:63-73. Christie T R . Prostate gland and testes. In: Bojrab MJ. ed. ( ' i / l ~ t i i 'lidrniqrw\ 111 ~Stmd/,4ti~tuu/ S i l < q y I , 2nd ed. Philadelphia: I .ea and Febiger, 1983:360-369. Basinger RR. Rawlings CA. Surgical management of prostatic diseases. Compcnd Contin Educ Pract Vet 1987;Y:Y93-1000. Richter KP. Ling GV. Clinical response and urethral pressure profile changes pheny,propanolamine in dogs with prilnary sphincter incompetence. J A m Vet Mcd Assoc 1985: 187:605610. Basinger RR. Rawlings CA. Barsanti J A . et al. Urodynnmic alterations after prostatectomy in dogs without clinical prostatic discase. Vet Surg 1987; I6:405-4 10.
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9. Sparks ER. Prostatectomy in the reduction of perineal hernias in the dog. Vet Med 1933:28:508-5 I I . J. Cawley AJ. Canine prostatectomy, J Am Vet Med Assoc l965;12X:173-177. 1 1 . Absten GT. Laser biophysics for the physician. In: Ralz JL, ed. 1.tr.tcrc in C'i~iutir~oiis, M i d i ( . i t i c mid Si0,oivi'. Chicago: Year Book Medical Publishers, 1986:1-30. I ? . Finkelstein LH. Frantz B. Longcndorfer LH. et al. Elcctroresection followed by neodymium-YAG laser photocoagulation of' the dog prostate for establishment of safety parametcrs. Lasers Surg Med 1985;5:529-533. 13. Robertson JJ, Bojrab MJ. Subtotal intracapsular prostatectomy: Results in normal dogs. Vet Surg 1984: 13:6-10.
10, Archibald
Abstract of Current Literature DIODE LASER A N D DYE-ENHANCED SOLDER REINFORCEMENT OF COLONIC ANASTOMOSES Oz MC, Moazami N, Bass LS, Treat MR Lu.srr.s in Szrrgcq?arid Mcdicinc 1990;Suppl 2:55 The incidence of leakage in colorectal surgery is nearly 10%.The ability of surgeons to reinforce conventional colon anastomoses could reduce the complications associated with leakage during the first postoperative week. We evaluated a technique of laser soldering with indocyanine dye-enhanced fibrinogen in conjunction with an 808 nm diode laser to strengthen conventional two-layer colonic anastomoses. Conventional two-layer anastomoses were performed with polyglycolic acid followed by silk seromuscular inverting sutures. In one-half the animals (n = 30). an additional layer of indocyanine green dye-enhanced fibrinogen (max. absorption 805 nin) was soldered around the anastomosis with the 808 nm diode laser (4.8 W/cm' for 1-2 minutes). Anastomoses studied in vivo immediately after creation had a mean bursting pressure of 108 k 13 in the group anastomosed with conventional sutures and I73 +- 30 in the group for which laser soldering with fibnnogen was used. At days 1, 3, 5 , and 7, the anastomosis became stronger in both groups. Overall, the sutured group had more exceptionally weak (less than 100 mm Hg) bonds than the soldered group. Histologically, there was regeneration ofthe mucosa on day 7 without foreign body reaction to the fibrinogen solder. Laser soldering with fibrinogen enhances conventional sutured anastomoses i n gastrointestinal surgery and may reduce the leakage rate and associated complications.
Subtotal Canine Prostatectomy with the Neodymium: Yttrium-Aluminum-Garnet Laser E. M. HARDIE, DVM, PhD, DiplornateACVS, E. A. STONE, DVM, MS, DiplomateAVCS, K. A. SPAULDING, DVM, DiplomateACVR, and J. M. CULLEN, VMD, PhD, DiplornateACVP A technique was developed for subtotal prostatectomy in dogs with the neodymium:yttriumaluminum-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. lntraoperative 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.
for the manageC ment of prostatic cysts and abscesses have a high complication rate.'-4 Two commonly used techniques URRENT SURGICAL TECHNIQUES
Materials and Methods
Normul Dogs are total prostatectomy'.' and drainage with Penrose Nine adult male dogs with prostates palpable per recdrains.'.' Urinary incontinence occurred in 13 of 14 dogs tum were used to develop a safe technique for subtotal with prostatic disease that were treated by total prostatecprostatectomy with the Nd:YAG laser* in a noncontact tomy.' Postoperative complications in 92 dogs with mode. The dogs were anesthetized with pentobarbital prostatic abscesses treated by drainage included postop(30 mg/kg intravenously [IV]). Tracheas were intubated erative sepsis and shock, prostatic urethrocutaneous fisand the dogs were allowed to breath 100%oxygen while tulas, recurrent abscesses, and urinary i n ~ o n t i n e n c e . ~ . ~ surgery was being performed. Isotonic fluids were adThe incidence of recurrent urinary tract infection was ministered at a rate of 10 mL/kg/hr. A urethral catheter not determined, but 16% of the dogs were euthanatized was inserted to facilitate identification of the urethra. 2 to 3 1 months after surgery because of chronic recurrent Surgery was performed with aseptic technique. urinary tract infections or recurrent abscesses. Only 34% Dogs LI-L3 were used to determine the technical feaof the dogs had no long-term complications. sibility of subtotal prostatectomy with the Nd:YAG laThe purpose of this study was to develop a technique ser. The laser was used in a continuous mode at 35-90 for subtotal pro~tatectomy~ with the neodymium:yttriwatts to ablate the prostatic capsule and prostatic tissue. um-aluminum-garnet (Nd:YAG) laser, to minimize the Dogs S I -S6 were used to determine the safety limits risks of urinary incontinence and recurrent prostatic and urinary tract infection. A randomized clinical study was performed to identify complications associated with use * Fiberlase 100 medical laser system. Living Technology Inc, Warminster. PA. of the technique in dogs with prostatic disease. ~
~
From the Departments of Companion Animal and Special Species Medicine (Hardie, Stone), Anatomy, Physiological Sciences and Radiology (Spaulding), and Microbiology, Parasitology, and Pathology (Cullen), College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina. Study supported by the State of North Carolina. Preliminary results presented at the Annual Meeting of the College of Veterinary Surgeons, Reno, Nevada, February 1989. The authors thank Living Technology Inc. for the use of the Nd:YAG laser. Reprint requests: Elizabeth M. Hardie, DVM, PhD. College of Veterinary Medicine, North Carolina State University, 47000 Hillsborough Street, Raleigh, NC 27606.
348
HARDIE, STONE, SPAULDING, AND CULLEN
Dorsal
349
for evidence of urinary incontinence during two daily walks outside the building. On day 7. the dogs were euthanatized with pentobarbital (60-100 mg/kg IV). Each prostate and prostatic urethra was removed, and the urethra was infused with Trump’s solution. Leaks in the urethra were noted. The prostate and prostatic urethra were immersed in Trump’s solution. Fixed tissue was processed for light microscopy, sectioned at 6 pm, and stained with hematoxylin and eosin. Histologic examination of the left side of each prostate and urethra was performed without knowledge of treatment. Tissue from the right side was reserved for duplicate analysis, if needed.
Dogs M-pith Prostutic Disease
Ventr a1 Fig. 1. Subtotal prostatectomy technique used in dogs S1-S6. The region outside the broken lines was removed with scissor dissection. The region indicated with diagonal hatch marks was photoablated with the Nd:YAGlaser.
of lasing close to the urethra. All major vessels leading to the prostate were ligated or clipped with vascular clips because ligation of major vessels is often necessary i n diseased prostates. The prostatic capsule and all prostatic tissue to within approximately 5 mm ofthe lateral aspect of the prostatic urethra were dissected with scissors (Fig. 1). The cut surface of the prostate at the level of the urethra was treated with the laser at six sites. At one of three sites on the right side, lasing was performed at 3.5 watts for 2 seconds. at 60 watts for 1 second, or 60 watts for 0.5 second. The sites were chosen randomly and were separated by at least 5 mm. The lasing pattern determined for the right side was repeated on the left side, The spot sizes averaged 1.5 mm and the end of the laser fiber was 1 cm from the tissue. After closure ofthe abdominal incision, the dogs were castrated because castration is routinely performed at the same time as prostate surgery in clinical cases. After recovery from anesthesia, the dogs were housed in 3.2 mr runs for 7 days. Temperature, pulse, respiralion, attitude, urination, defecation, appetite, and drinking habits were monitored daily. The dogs were watched
Twelve dogs admitted to the North Carolina State University Veterinary Teaching Hospital for surgical treatment of prostatic disease were assigned randomly to treatment by prostatic drainage or by subtotal prostatectomy with the Nd:YAG laser. A coin toss was used to determine the treatment of the first dog in a pair. The next dog was assigned to the opposite treatment. All intact dogs were castrated. Signalment was recorded and a serum chemistry panel, CBC, urinalysis, and ultrasound examination of the prostate were obtained for each dog. Additional diagnostic procedures for prostatic disease (survey radiographs, contrast urethrograms. semen evaluation, prostatic aspirate) and concurrent diseases were performed as necessary. Aerobic and anaerobic cultures of urine and prostatic fluid were obtained before or during surgery. The status of urinary continence (continent, incontinent, obstructed) as determined by the clinician was recorded before surgery. All dogs had urethral catheters in place at the time of surgery. Dogs treated by prostatic drainage were designated D 1-D6. Two to four 0.6cm Penrose drains were placed into prostatic abscess cavities or cysts. Periprostatic fat was minimally dissected by finger dissection. In dogs with multifocal disease, communication was established between the site being drained and other abscess cavities. Drains were placed in each lobe of the prostate and exited through the ipsilateral body wall. The drains were left in place as long as copious drainage was present (2 to 21 days). The urethral catheters were removed at the conclusion of the surgery. Dogs treated by subtotal prostatectomy were designated Pl-P6.Most ofthe prostatic tissue was removed by sharp and electroscalpel dissection. Capsular vessels were ligated or occluded with vascular clips. lfan abscess or cyst was adherent to the rectum or other structure, the abscess cavity was opened and all attachments between the adherent tissue and the prostate were severed. Tissue
350
SUBTOTAL PROSTATECTOMY WITH Nd:YAG LASER
Dorsal
Ventr a1 Fig. 2. Subtotal prostatectomy technique used in dogs Pl-P6. After removal of most of the prostatic tissue with an electroscalpel, the surface of the remaining tissue was photoablated with the Nd:YAG laser (diagonal hatchmarks).
that remained after dissection consisted of small amounts of prostatic tissue around the prostatic urethra and sections of abscessed tissue that could not be dissected free from surrounding structures. If the dorsal region ofthe prostate (particularly around the neck ofbladder) was minimally involved in the disease process, this region was left intact (Fig. 2). The Nd:YAG laser was used in a noncontact continuous mode at 35 watts to control hemorrhage from the cut surface of the prostate and from the lining of abscess cavities. All exposed viscera not being treated were protected with moistened laparotomy pads. Abscess tissue adherent to the surface of the rectum was not treated. In dogs P2-P6, methylene blue dye (0.5 ml) was injected in the bladder and manually expressed through the urethra. Holes identified by escape of the dye were sutured to control leakage. A urethral catheter was left in place for 2 to 4 days. The prostate was within a perineal hernia in dogs D5 and P5. Prostatic surgery was performed through a perineal approach during repair of the hernia, rather than through a ventral midline incision. A suction drain exiting adjacent to the surgical site was used for prostatic drainage in dog D5. Subtotal prostatectomy as described previously was performed in dog P5.
The operative time, total number of procedures performed on a given dog. length of hospitalization, and short-term complications of surgery were recorded. Owners were requested to bring their dogs to the hospital I , 6 and I2 months after surgery for urinalysis, urine culture. and ultrasound examination of the prostate. Owners were questioned about the presence of urinary incontinence and any other complications that might be associated with the urogenital system. Urethral pressure p r o f i l e ~ 'and ~ ~ cystometrograms' were performed in incontinent dogs. Urethral pressure profiles were obtained with the dog awake; cystometrograms were performed after administration of xylazine (2.2 mg/kg subcutaneously). Urodynamic studies were performed in dogs PI and P2 after administration of oxymorphone (0.5 mg/kg IV) for sedation. The cause of death was recorded for dogs that died before the 1 year follow-up. The following grading system for urinary incontinence was used. Major urinary incontinence-dog dribbles urine continually Nocturnal incontinence-dog dribbles urine only when sleeping Minor incontinence-dog spontaneously dribbles urine occasionally; urine dribbling occurs only in association with polyuria or abdominal compression Continent-dog voids urine normally, no urine dribbling observed between voiding episodes Urinary tract infections were defined as recurrent if 1) a urinary tract infection had been treated with antibiotics; 2) a negative urine culture was obtained at least 5 days after cessation of antibiotic therapy; and 3 ) a positive urine culture was subsequently obtained. Results
Norrnal Dogs The laser was found to be slow and inefficient for ablation of large amounts of prostatic tissue in dogs Ll-L3. Hemostasis with the laser was good for parenchymal bleeding, but poor for bleeding from capsular vessels. N o evidence of major urinary incontinence was observed during week 1. At necropsy, necrosis of periprostatic fat and adhesions of periprostatic fat to the cut surface ofthe prostate were present. There was no evidence of urethral disruption. Histologically, the prostatic lesions in dogs L 1-L3 were characterized by replacement of glandular tissue by immature granulation tissue. The lumens of remaining glands at the periphery of the photoablated sites were dilated and lined by flattened, atrophic cells. Veins and arteries within granulation tissue frequently were occluded
HARDIE, STONE, SPAULDING, AND CULLEN
351
Fig. 3. Section of prostate photoablated at 35 watts for 2 seconds.The superficial aspect of the prostate is replaced by granulation tissue and the uroepithelium (arrow) is still intact.
by thrombi. The extent of glandular destruction varied from superficial to nearly full thickness of the remaining prostatic tissue. but all of the urethras were intact and lined by normal uroepithelium. The scissor dissection technique (Fig. I ) was found to be an efficient and reliable method of performing subtotal prostatectomy in dogs S 1 -S6. After most of the prostate was removed, the laser provided precise ablation of prostatic tissue adjacent to the urethra. After sagittal excision of the majority of the prostatic tissue, the remaining prostatic tissue was thinnest lateral to the colliculus seminalis, where the excretory ducts of the prostate enter the urethra. Caution in dissection was indicated in this region. No evidence of major urinary incontinence was observed during week I in dogs S 1 -S6. At necropsy, there was no necrosis of periprostatic fat, but there were adhesions of periprostatic tissues to the cut surface of the prostate. Although no evidence of urine leakage was seen, fixative in the urethra leaked through holes in the right central-lateral prostatic region in two dogs at sites oflasing at 60 watts for I second. Histologically, the prostates from dogs S I 4 6 were similar to those of dogs LI-L3. Moderate to full-thickness destruction of remaining prostatic tissue with replacement by fibrous tissue was observed at sites lased at 60 watts for 1 second. Superficial to moderate injury was observed at other sites (Fig. 3).Histologically, the urethra was intact in all dogs except S6, in which necrosis presumed to be secondary to infarction of the remaining prostatic tissue and urethra was evident.
Dog., ujith Prostatic Disrase The signalment, prostatic diseases, and concurrent diseases of dogs with prostatic disease are listed in Table
I . Intraoperative cultures of the prostate or urine were positive in four of the six dogs undergoing drainage and three of the six dogs undergoing subtotal prostatectomy (Table 2).Urinalysis was consistent with urinary tract infection in three of the five dogs with drains and four of the six dogs with subtotal prostatectomy. Dog D4, which underwent prostatic drainage. had preexisting major urinary incontinence due to lower motor neuron neurologic disease; all other dogs with drains were continent before surgery. Three dogs chosen for subtotal prostatectomy (PI.P5, and P6)were continent, two dogs (P2,P3) had major urinary incontinence, and one dog (P4)was obstructed before surgery. The average surgical time for prostatic drainage was 167 minutes (range, 78-2 15 minutes), and the average surgical time for subtotal prostatectomy was 192 minutes (range, 125-265 minutes). The average hospital stay was I 1 days (range, 4-18 days) for the six dogs with drains and 6.5 days (range, 5-16 days) for the four dogs that survived subtotal prostatectomy. Half of the dogs in each group were alive 1 year after surgery. In the drain group, dog D4 died of sepsis and pulmonary thromboembolism on day 1 1 , dog D2 was euthanatized 3.5 months after surgery due to recurrence of oral fibrosarcoma and a prostatic abscess, and dog D6 died 2.5 months after surgery of gastric dilatation/volvulus. Two dogs undergoing subtotal prostatectomy (P3, P4) died of shock during surgery. Severe sepsis was present in dog P3.Sepsis, extensive blood loss, and long surgery time may have contributed to the development of shock in dog P4. Dog P2 died a t month 10 of cutaneous lymphosarcoma. Immediate postoperative complications in the dogs with prostatic drainage included infection within a drain
352
SUBTOTAL PROSTATECTOMY WITH Nd:YAG LASER TABLE 1. Signalment and Diseases of Dogs in the Clinical Study Group
Prostatic Drainage
Subtotal Prostatectorny
*
Dog
Breed
Age
Prostatic Disease'
Histopathology of Prostate
Concurrent Disease
D1
Doberman pinscher
Unilateral prostatic cyst Bilateral prostatic abscesses
Chronic lymphocytic/plasmacytic prostatitis Abscess; cystic, nonsuppurative prostatitis
7
Unilateral prostatic abscesses
Diffuse subacute chronic prostatitis
Irish setter
8
Severe suppurative prostatitis
D5
Boston terrier
8
Not done
D6
Doberman pinscher
9
Multifocal prostatic abscesses Unilateral prostatic abscess Unilateral prostatic abscess
Suppurative peritoneal fluid Fibrosarcomamandible, ruptured collateral ligarnenthock Wobbler syndrome, von Willebrand's disease, hypothyroidism Fibrocartilaginous emboli Perineal hernia
02
Corgi
D3
Doberman pinscher
D4
Locally extensive severe acute prostatitis
Leiomyoma-pelvic canal, perineal hernia
P1
Doberman pinscher
7
Chronic lymphocytic multifocal prostatitis
GI hemorrhage; chronic osteomyelitis
P2
German shepherd
10
P3
Collie mix
11
Cryptorchid, sertoli cell tumor Diskospondilitis, pneumonia
P4
Cocker spaniel
14
P5
Boston terrier
9
P6
Boxer
8
Severe chronic suppurative prostatitis Severe extensive inflammation adipose tissue (paraprostatic abscess) Severe multifocal suppurative prostatitis Chronic lymphocytic, plasmacytic, neutrophilic prostatitis Cyst, lined with transitional cell epithelium
7
14
Multifocal prostatic abscesses, one unilateral large cyst Unilateral prostatic abscess Paraprostatic abscess Multifocal prostatic abscesses Prostatic cyst containing urine Unilateral prostatic cyst
Hydronephrosis left kidney Bilateral perineal hernias Bilateral perineal hernias
Category based on appearance at surgery and cytology. Cultures were not always positive for abscesses
wound, severe hematuria. anemia, weakness, diarrhea, sepsis. and pulmonary thromboembolism. Complications in the dogs with subtotal prostatectomy included TABLE 2.
hypernatremia, hyperchloremia, oliguria. polyuria and polydipsia, pancreatitis, and urine leakage. Each complication occurred in one dog, except polyuria and polydip-
Prostatic and Urinary Tract lnfections in Dogs in the Clinical Study
Organisms Prostate
No. of Dogs
Organisms Urine
No. of Dogs
Organisms Recurrent UTI
No. of
Prostatic Drainage
E. coli K. pneumoniae
2 2
K. pneumoniae Beta-hemolytic Strep
1 1
E. coli K. pneumoniae P. stuartii Group G strep
2 1 1 1
Subtotal Prostatectorny
E. coli Proteus S. fecalis Group G strep
2 1 1 1
E. coli Proteus Group G strep
2 1 1
Group
Dogs
E. coil-kcherichia coli; K. pneumoniae-Klebsiella pneumoniae; S. fecalls-Streptococcus fecalis; strep-Streptococcus; P. stuartii-Providencia stuartii; No. of Dogs-organism was cultured from this number of dogs. Multiple organisms were cultured from some dogs. UTI-urinary tract infection.
HARDIE, STONE, SPAULDING, AND CULLEN
sia. which occurred in three dogs. The urine leakage occurred i n the first clinical patient to receive subtotal prostatectomy, and a second operation was needed to repair the site of leakage. Checking for potential sites of urine leakage (present in two dogs) and performing direct repair at surgery eliminated this problem. Major urinary incontinence occurred in two dogs with drains (D5, D6) immediately after surgery. Dog D4, which had major incontinence before surgery, died on day 1 1 without regaining urinary continence. Dog D5 continued to dribble urine occasionally at year I . and dog D6 was continent by month 1. A urethral pressure profile and cystometrography were performed on dog D5 at year I . Low urethral pressures (maximal urethral closure pressure: 40 cm H 2 0 )were present.? Dog D 1 developed spastic urination and dysuria 3 months after surgery. urethrography, cystometrography, and a urethral pressure profile were performed. A narrow prostatic urethra, but no obvious site of obstruction, was seen. Overdistention of the bladder, a poor detrusor reflex, and an area of increased urethral pressure in the prostatic urethra were identified. Symptoms resolved with bethanechol (5 mg orally tid) and phenoxybenzamine ( 5 mg orally tid) therapy. Major urinary incontinence was present in two dogs (P2, P6) with subtotal prostatectomy immediately after surgery. Resolution to nocturnal incontinence was observed by months 1 to 2. Dog PI developed occasional nocturnal incontinence 9 to 12 months after surgery. Dog P5 became incontinent while being treated with corticosteroids for a skin problem, but urinary incontinence resolved after cessation of therapy. Cystometrograms and urethral pressure profiles were obtained on dogs P5 and P6. Urethral pressures were extremely low (maximal urethral closure pressures: 26,36 cm H20). The maximal urethral closure pressures measured on dogs PI and P2 were similar (40, 12 cm HzO), but the studies were performed after administration of oxymorphone (0.05 mg/ kg IV). The high-pressure zone associated with the external urethral sphincter' was absent in all dogs with subtotal prostatectomy. Phenylpropanolamine therapy (50 mg orally tid) was initiated in dog P6, which decreased but did not eliminate nocturnal incontinence. The owners of dogs P 1 and P2 refused further therapy because of the minor nature of the problem. Two dogs with subtotal prostatectomy developed postoperative urinary tract infections from the use of indwelling urinary catheters. No recurrent urinary tract infections were detected in dogs with subtotal prostatectomy after resolution of established or acquired infection. No hospital-acquired crinary tract infections ~
iNormal value (nican t SE) at North Carolina State linicci-sit) i s 100 i I S crn H 2 0 .
353
were detected in the dogs with prostatic drainage. Recurrent urinary tract infection occurred in four of the five dogs with drains that survived the immediate postoperative period (Table 2). Results of ultrasonographic measurements indicated that prostatic size decreased in all dogs surviving surgery. Prostatic size continued to decrease in all dogs with resolving disease (DI, D3, D5, P2, P5. P6) over the course of the year. Decreased size of the prostate gland was associated with reduction and disappearance of cystic areas, and development of a heterogeneous hyperechoic echo texture. Three dogs (D5, P2, P5) had unchanging focal hyperechoic areas that were presumed to be scar tissue within the prostate. Increase in prostatic size during year 1 was associated with the presence of previously unidentified cystic areas. This occurred in two dogs in the drain group (D2, D6) and 1 one dog in the subtotal prostatectomy group (PI). Prostatic abscesses recurred in dog D2, dog D6 died shortly after the new cystic lesion was identified, and dog PI had no signs of prostatic disease during year 2.
Discussion The concept of subtotal prostatectomy with capsule removal is not Although descriptions of various techniques exist, no studies evaluating their efficacy in the treatment of canine prostatic disease are available. Previous authors have listed the following potential complications of subtotal prostatectomy: technical difficulty. bleeding from vessels that are difficult to ligate, a need for electrocautery. shock related to blood loss, leaving remnants of prostatic tissue, and urethral leakage.5."' We found that subtotal prostatectomy was technically more difficult than drain placement. Subtotal prostatectomy required skills similar to those needed to perform total prostatectomy. Subtotal prostatectomy required that the surgeon be familiar with the vascular anatomy of the diseased prostate and maintain meticulous hemostasis of larger vessels. Identification of branches of the prostatic artery allowed the surgeon to place vascular clips on the vessels before electroscalpel incision of the capsule. The Nd:YAG laser coagulated vessels up to 4 mm in diameter ' ' and controlled prostatic parenchymal bleeding well. The problems we found to be associated with subtotal prostatectomy were shock, postoperative urine leakage, and urinary incontinence. The long surgical time and increased blood loss associated with subtotal prostatectomy may have contributed to the development of shock in septic patients. Urine leakage occurred through defects already present in the prostatic urethra. not due to delayed necrosis following the use ofthe laser. This complication did not occur after direct suture repair of urethral defects identified with methylene blue dye
354
SUBTOTAL PROSTATECTOMY WITH Nd:YAG LASER
was instituted. The incidence of urinary incontinence appeared to be similar to that seen with total prostatectomy,'.2but was subjectively less severe. The maximal urethral pressures measured in incontinent dogs in both treatment groups (12-40 cm H 2 0 ) were at the low end of the range previously reported for incontinent male dogs,' and much lower than most values reported for dogs with incontinence after total prostatectomy.' If maximal urethral closure pressure can be related directly to the grade of urinary incontinence, we would expect major incontinence in our dogs. Possible explanations of the discrepancy between our measured values and the grade of incontinence include tranquilizer artifact* (dogs PI, P2), widely differing normal values between instituti~ns,"'~~ and wide variation among dogs as to the maximal urethral closure pressure associated with a given grade of incontinence. The advantage of subtotal prostatectomy over drainage was that resolution of prostatic and urinary tract infection was uncomplicated. Hospitalization after subtotal prostatectomy was shorter than after drainage, and no recurrence of infection occurred during the 1 year follow-up period. In contrast, five ofthe six dogs with drainage had uncontrolled or recurrent infection. Two dogs died or were euthanatized as a result of unresolved infection. Availability of the Nd:YAG laser is not mandatory for performing subtotal prostatectomy,' but its use simplified control of hemorrhage and precise tissue ablation. We have performed seven subtotal prostatectomies in addition to those reported here: two with a carbon dioxide laser and five with electrocautery alone. Postoperative hemorrhage occurred in only one dog, which had Von Willebrand's disease and perioperative aspirin 1 herapy. If the Nd:YAG laser is used for subtotal prostatectomy. powers over 35 watts should be used cautiously near the urethra. In particular, results of our preliminary studies indicated that if the central-lateral part of the prostate within 5 mm of the urethra was exposed to 60 watts for I second, the potential existed for urethral perforation and leakage. We performed these studies because necrosis associated with the use of the Nd:YAG laser is not immediately apparent at the time of surgery and may extend up to 4 mm from the impact site." In previous studies examining the safety of the Nd:YAG laser for prostatectomy, an intracapsular technique was used." The presence of avascular necrosis of the prostatic urethra in one of the normal dogs indicated that radical dissection of the prostate could produce infarction of the prostate and associated urethra. No urine leakage occurred in the normal dog. but the I week follow-up time may have been inadequate to determine the full range
of complications associated with necrosis. As we gained experience with the clinical cases, we tended to preserve the dorsal capsule vessels and excise the diseased parenchyma (Fig. 2). In this respect, our technique was similar to subtotal intracapsular prostatectomy.13 The techniques differ in several aspects. First, we believe that it is critical to maintain urethral integrity. Poor urethral healing and urine leakage are more significant problems in dogs with prostatic disease than in normal dogs. Second, we do not suture the capsule. In dogs with large cysts or abscesses, suturing the capsule is often impossible. Even when suturing is possible, a potential space for maintenance of infection is created. Third, if the abscess is located in a dorsal part of the prostate, we remove all infected tissue despite the risk of compromising the blood supply to the prostatic urethra. Overall, dogs in the clinical part of this study were old dogs with multiple diseases. Perineal hernia, neurologic disease. and cancer were the most common concurrent diseases. Despite the presence of multiple diseases, complications related to treatment of prostatic infection were the most common cause of death. Survival would be maximized if the lethal complications associated with each technique could be reduced. We recommend that drainage techniques be used for treatment of unstable patients with large prostatic abscesses. To avoid systemic sepsis and shock, minimal dissection should be used in the placement of drains. Patients treated with drainage should be monitored postoperatively, using ultrasonography and urine cultures, for recurrence of infection. Subtotal prostatectomy should be used for treatment of stable patients with abscesses, dogs with multifocal abscesses, and dogs with cystic disease. We would reserve total prostatectomy for patients with prostatic cancer or severe prostatic urethral trauma. In conclusion. we developed a technique for subtotal prostatectomy in dogs with the Nd:YAG laser. Subtotal prostatectomy controlled infection, but resulted in more operative deaths and a higher rate of nocturnal urinary incontinence than prostatic drainage. The major problems associated with drainage were failure to control prostatic infection and recurrent urinary tract infection.
References I . Hardie EM. Barsanti JA, Rawlings CA. Complications of prostatic surgery. J Am Anim Hosp Assoc 3984:20:50-56. 2. Basinger RR, Rawlings C A . Barsanti JA. Oliver JE. Urodynamic alterations associated with clinical prostatic diseases and prostatic surgery in 23 dogs. J Am Anim Hosp Assoc 1989:25:385392. 3. Mullen HS. Matthiesen DT, Scavelli TD. Abscessation ofthc prostate gland treated with a multiple drain technique: An evaluation of postoperative complications and long-term results in 91 dogs. (Abstract) Vet Surg 19x9: 18:70. 4. Matthiesen DT. Marretta SM. Complications associated with the
HARDIE, STONE, SPAULDING, AND CULLEN
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6. 7.
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surgical trcatment o f prostatic abscessation. Problems in Veterinary Medicine 1989; 1:63-73. Christie T R . Prostate gland and testes. In: Bojrab MJ. ed. ( ' i / l ~ t i i 'lidrniqrw\ 111 ~Stmd/,4ti~tuu/ S i l < q y I , 2nd ed. Philadelphia: I .ea and Febiger, 1983:360-369. Basinger RR. Rawlings CA. Surgical management of prostatic diseases. Compcnd Contin Educ Pract Vet 1987;Y:Y93-1000. Richter KP. Ling GV. Clinical response and urethral pressure profile changes pheny,propanolamine in dogs with prilnary sphincter incompetence. J A m Vet Mcd Assoc 1985: 187:605610. Basinger RR. Rawlings CA. Barsanti J A . et al. Urodynnmic alterations after prostatectomy in dogs without clinical prostatic discase. Vet Surg 1987; I6:405-4 10.
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9. Sparks ER. Prostatectomy in the reduction of perineal hernias in the dog. Vet Med 1933:28:508-5 I I . J. Cawley AJ. Canine prostatectomy, J Am Vet Med Assoc l965;12X:173-177. 1 1 . Absten GT. Laser biophysics for the physician. In: Ralz JL, ed. 1.tr.tcrc in C'i~iutir~oiis, M i d i ( . i t i c mid Si0,oivi'. Chicago: Year Book Medical Publishers, 1986:1-30. I ? . Finkelstein LH. Frantz B. Longcndorfer LH. et al. Elcctroresection followed by neodymium-YAG laser photocoagulation of' the dog prostate for establishment of safety parametcrs. Lasers Surg Med 1985;5:529-533. 13. Robertson JJ, Bojrab MJ. Subtotal intracapsular prostatectomy: Results in normal dogs. Vet Surg 1984: 13:6-10.
10, Archibald
Abstract of Current Literature DIODE LASER A N D DYE-ENHANCED SOLDER REINFORCEMENT OF COLONIC ANASTOMOSES Oz MC, Moazami N, Bass LS, Treat MR Lu.srr.s in Szrrgcq?arid Mcdicinc 1990;Suppl 2:55 The incidence of leakage in colorectal surgery is nearly 10%.The ability of surgeons to reinforce conventional colon anastomoses could reduce the complications associated with leakage during the first postoperative week. We evaluated a technique of laser soldering with indocyanine dye-enhanced fibrinogen in conjunction with an 808 nm diode laser to strengthen conventional two-layer colonic anastomoses. Conventional two-layer anastomoses were performed with polyglycolic acid followed by silk seromuscular inverting sutures. In one-half the animals (n = 30). an additional layer of indocyanine green dye-enhanced fibrinogen (max. absorption 805 nin) was soldered around the anastomosis with the 808 nm diode laser (4.8 W/cm' for 1-2 minutes). Anastomoses studied in vivo immediately after creation had a mean bursting pressure of 108 k 13 in the group anastomosed with conventional sutures and I73 +- 30 in the group for which laser soldering with fibnnogen was used. At days 1, 3, 5 , and 7, the anastomosis became stronger in both groups. Overall, the sutured group had more exceptionally weak (less than 100 mm Hg) bonds than the soldered group. Histologically, there was regeneration ofthe mucosa on day 7 without foreign body reaction to the fibrinogen solder. Laser soldering with fibrinogen enhances conventional sutured anastomoses i n gastrointestinal surgery and may reduce the leakage rate and associated complications.
