uretor en gatos.pdf

INTRODUCTION
Disorders of the feline lower urinary tract
encompass a heterogeneous group of con-
ditions, collectively referred to as feline
lower urinary tract disease (FLUTD). Pre-
vious studies have estimated the annual
incidence of FLUTD to be between 0·5
and 1 per cent in Britain and the USA
(Willeberg 1984, Lawler and others 1985).
Irrespective of the cause, the most com-
mon clinical signs of FLUTD are haema-
turia, dysuria, stranguria, pollakiuria,
inappropriate urination and urethral
obstruction (Kalkstein and others 1999a,
Osborne and others 2000).
Recognised causes of FLUTD include
bacterial, fungal or parasitic urinary
tract infection (UTI), uroliths, urethral
crystal and/or matrix plugs, congenital
or acquired anatomical abnormalities,
iatrogenic or traumatic injuries, and
neoplasia (Kalkstein and others 1999b,
Osborne and others 2000). Idiopathic
FLUTD is diagnosed when an under-
lying disorder is not found, and remains
the most common cause of FLUTD
(Kalkstein and others 1999b, Osborne and
others 2000).
Potential causes of idiopathic FLUTD
have been appraised in recent years but
the precise aetiopathogenesis remains
unclear. Sterile struvite (magnesium
ammonium phosphate) uroliths and
crystals were a frequent finding in
both obstructive and non-obstructive
cases of FLUTD up until the mid-1980s
(Osborne and others 2000). The subse-
quent increased use of manufactured
diets designed to reduce the formation
of struvite crystalluria by limiting magne-
sium content and decreasing urine pH
resulted in a diminished incidence of
struvite uroliths and an increased inci-
dence of calcium oxalate uroliths by the
mid-1990s (Osborne and others 2000,
Lekcharoensuk and others 2002).
Urethral obstruction or stenosis in male
cats can be a sequela of any cause of
FLUTD and occurs predominantly in the
narrow distal portion of the urethra
(Osborne and others 1996). Irrespective of
cause, initial treatment must focus on the
restoration of urethral patency and urine
flow. Non-surgical techniques, including
penile massage and retrograde urethral
flushing, can be very effective in dislodging
intraluminal plugs and uroliths. Further
medical management may include treat-
ment of UTI, dietary recommendations
for the dissolution of urocystoliths and/or
crystals, and prevention of their reforma-
tion (Kalkstein and others 1999c, Osborne
and others 2000).
Male cats suffering from distal urethral
disease, including recurrent urethral
obstruction from intraluminal plugs,
obstruction that cannot be relieved by
catheterisation, and urethral strictures,
trauma or neoplasia, can benefit from
surgical procedures designed to create a
permanent opening of the pelvic urethra
(Hauptmann 1984). The most commonly
performed procedure is perineal urethros-
tomy, which was first described by Wilson
t
M. BASS, J. HOWARD*, B. GERBER†
AND M. MESSMER
Journal of Small Animal Practice (2005)
46, 227–231
Retrospective study of indications for
and outcome of perineal urethrostomy
in cats
JOURNAL OF SMALL ANIMAL PRACTICE • VOL 46 • MAY 2005 227
Clinic for Small Animal Surgery,
†Clinic for Small Animal Internal
Medicine, University of Zurich,
Winterthurerstrasse 260,
8057 Zurich, Switzerland
*Department of Clinical Veterinary
Medicine, Clinic for Small Animal
Internal Medicine, University of Bern,
Länggassstrasse 128,
3012 Bern, Switzerland
OBJECTIVES: To evaluate indications for and outcome of perineal
urethrostomy in cats.
METHODS: The medical records of 59 cats that had undergone
perineal urethrostomy were evaluated. Short-term follow up
information (for a period of four weeks following surgery) was
available for all of the cats. Long-term follow up information
(for a period of at least four months) was available for 39 cats.
RESULTS: Early complications occurred in 25·4 per cent of cats
and late complications were observed in 28·2 per cent of cats.
The most frequent late complication was recurring bacterial
urinary tract infection.
CLINICAL SIGNIFICANCE: Despite frequent complications and
recurring signs of lower urinary tract disease, 32·2 per cent
of the cats had a disease-free long-term outcome (mean four
years, median 3·9 years), and 88·6 per cent of clients
interviewed thought that their cats had a good quality of life
after surgery.
Retrospective study of indicati 4/27/05 5:43 PM Page 227

228 JOURNAL OF SMALL ANIMAL PRACTICE • VOL 46 • MAY 2005
and Harrison in 1971. This technique
involves mobilisation of the wide pelvic
urethra and creation of a new stoma by
suturing the urethral mucosa to the
perineal skin, and amputating the narrow
penile urethra (Wilson and Harrison 1971,
Griffin and others 1989).
Complications following perineal ure-
throstomy include haemorrhage from erec-
tile tissue, wound dehiscence, urine leakage
into the perineal tissue, stricture, bacterial
UTI, urinary incontinence, perineal hernia,
urine-scald dermatitis and urethrorectal
fistula (Smith and Schiller 1978, Haupt-
mann 1984, Osborne and others 1996).
Although many of these complications are
uncommon or rare, recurring bacterial
UTI frequently is a long-term postoperative
problem (Osborne and others 1996).
This study aimed to determine the true
prevalence of short- and long-term com-
plications as a result of perineal urethros-
tomy, performed at the University of
Zurich, and to identify trends in patient
selection or postoperative management
that might have influenced the outcome.ll
MATERIALS AND METHODS
The medical records of all cats undergoing
perineal urethrostomy at the Small Animal
Clinic of the University of Zurich between
November 1991 and October 2001 were
reviewed. All surgeries were performed
by residents or faculty members using
the technique described by Wilson and
Harrison (1971). Postoperative treatment
consisted of the use of opiate analgesics
(0·006 mg/kg buprenorphine or 0·4
mg/kg butorphanol) given intravenously
for three days, an Elizabethan collar
for 10 days and antibiotics for three
weeks. Sutures (Polypropylene 5-0; John-
son & Johnson) were removed 10 days
following surgery. In cases of correct-
ive surgery after stricture formation,
the pelvic urethra was further mobilised
and the mucosa was sutured to the skin.
All corrective surgeries were performed
by a faculty member.
Antibiotic selection for cats in which
bacterial culture revealed growth was based
on sensitivity testing. In addition, an
appropriate diet for the prevention of
urolith formation was prescribed for all
cats in which mineral analysis of crystals or
uroliths was performed. Prescription Diet
Feline c/d (Hill’s) was prescribed for the
prevention of struvite crystal and urolith
formation and Prescription Diet Feline k/d
(Hill’s) was fed for the prevention of cal-
cium oxalate urolith formation. A moist
diet was recommended for all of the other
cats.
Data collected included signalment,
clinical signs and preoperative diagnosis
based on the history and physical exam-
ination findings, as well as further in-
vestigative tests including urinalysis,
bacteriological urine culture, and urolith
or urethral plug mineral analysis. Follow-
up data were collected by telephone inter-
views with pet owners and referring
veterinarians and were divided into two
sets: those pertaining to the initial four-
week period following surgery (early
complications) and those collected at
the end of the study period, which was at
least four months post-surgery (late
complications). These data included the
occurrence and nature of complications
or disorders referable to the lower urinary
tract, medication and dietary changes
instigated after surgery, and client satisfac-
tion with the surgical outcome. Owners
were asked if they were satisfied or dissatis-
fied with the surgical outcome and
whether they considered their cat’s quality
of life following surgery to be good,
acceptable or poor.
Statistical differences in the numbers of
cats with recurring uroliths between that
did and did not receive dietary manage-
ment were investigated using Fisher’s exact
test and chi-squared analysis. Fisher’s exact
test determined statistical differences in
the numbers of early-complication stric-
ture formations between surgeries per-
formed by faculty members and those
performed by residents. The level of signif-
icance was set at 5 per cent (P<0·05).
RESULTS
Records were available for 59 male cats that
underwent perineal urethrostomy during
the study period. Of these, 54 cats (91·5 per
cent) had been castrated before the onset of
signs of FLUTD. The mean age was 5·9
years (range 1·2 to 14·8 years). Breeds repre-
sented were domestic short- or longhair
(37 cats), Persian (20 cats), Siamese (one
cat) and Maine coon (one cat).
With the exception of one cat, in which
catheterisation of the urethra proved
impossible on the first day of
hospitalisation, all cats had been treated
conservatively for urethral obstruction on
at least one previous occasion, and perineal
urethrostomy was performed following
short-term management in hospital. On
presentation, cats were either suffering
from recurring obstructive FLUTD or had
been treated for recurring obstructive
disease with only short-term success by
referring veterinarians. Some cats treated
immediately before referral were not con-
sidered to have urethral obstruction on
presentation, and underwent perineal ure-
throstomy to prevent future obstructions.
In addition, 19 cats (32 per cent) received
preoperative medical treatment consisting
of antibiotics and/or a calculolytic diet.
Preoperative clinical signs included
dysuria in 46 cats (78 per cent), urethral
obstruction in 36 cats (61 per cent),
haematuria in 20 cats (34 per cent), pol-
lakiuria in 12 cats (20 per cent) and
stranguria in 11 cats (19 per cent). The
duration of preoperative clinical signs
ranged from one to 1170 days (mean 103
days, median 14 days). Preoperative prob-
lems recorded were obesity (four cats),
purulent self-inflicted perineal wounds
(two cats), urinary bladder rupture (two
cats), peritonitis caused by suspected urine
leakage following cystocentesis and subse-
quent reobstruction (one cat), and fever
(one cat).
The most common preoperative diag-
noses were urolithiasis and bacterial UTI
(Table 1). Urine culture revealed bacterial
growth in 11 of 35 samples (31 per cent)

JOURNAL OF SMALL ANIMAL PRACTICE • VOL 46 • MAY 2005 229
submitted. The average age of cats diag-
nosed with UTI was 6·8 years. The bac-
teria cultured were Escherichia coli (five
cases), Staphylococcus species (four cases),
Streptococcus species (one case) and Entero-
bacter species (one case). Mineral analysis,
performed on urethral and/or bladder
uroliths or crystals in 32 cats, revealed stru-
vite uroliths (15 cats), struvite crystals
(nine cats), calcium oxalate uroliths (six
cats), ammonium urate uroliths (one cat)
and non-mineral organic material (one
cat). Of those uroliths that were predomi-
nantly struvite, additional calcium oxalate
and ammonium urate elements each were
found in one case.
Sixteen early complications (within
four weeks of surgery) were noted in 15 of
59 cats (25 per cent) (Table 2). The most
common of these was urethral stricture
formation at the mucocutaneous junction
of the stoma. Of 16 surgeries performed by
a faculty member, one case of stricture for-
mation as an early complication occurred.
Of the remaining 43 surgeries performed
by a resident supervised by a faculty mem-
ber, six cats suffered stricture formation.
No statistical difference (P=0·661) in stric-
ture formation was found between surg-
eries performed by residents and those
performed by faculty members.
Of the cats with complications, one
died during anaesthesia for reasons unre-
lated to FLUTD, and one was euthanased
due to uroperitonitis and sepsis. In addi-
tion to surgical and post-surgical com-
plications, two cats experienced a
self-limiting recurrence of idiopathic
FLUTD that could not be attributed to
the surgical procedure.
Data for 39 cats were available over a
period greater than four weeks and for at
least four months following surgery (late
complications). This follow-up period
ranged from 0·32 to 9·6 years (mean 4·2
years, median 4·2 years). Of the remaining
20 cats, two had died in the early postoper-
ative period. One of these cats died two
weeks after surgery for unknown reasons.
FLUTD symptoms had not recurred prior
to death. The other cat died following a
road traffic accident three weeks after
surgery. The remaining 18 cats were lost to
follow-up one month after surgery.
Late complications observed were bac-
terial UTI and stricture formation. These
occurred at least once in 11 of 39 cats (28
per cent) (Table 3). Nine cats (23 per
cent), with an average age of 4·8 years
(median 4·9 years), suffered bacterial UTI.
This was symptomatic in all but two cases
in which urine culture revealed bacteria
despite a lack of clinical signs of FLUTD.
Six of these nine cats had more than one
occurrence of bacterial UTI. Of these,
between two and 10 infections per cat were
observed over a period ranging from 43 to
90 months, and 33 infections were
recorded in total. The overall incidence of
UTI for all nine cats was one infection per
14·3 cat months.
One of the nine cats with recurrent
UTI (two episodes within six months) was
euthanased at the owner’s request because
of this problem. Two cats (5 per cent)
developed stricture formation. One of
these cats had suffered stricture formation
in the early postoperative period and had
undergone corrective surgery. This cat was
euthanased at the owner’s request follow-
ing the second stricture four months after
surgery. All of the remaining six cats with
strictures as early complications enjoyed a
complication-free long-term follow-up
period after surgical revision. The second
cat, with stricture formation in the long-
term period (seven months postopera-
tively), had experienced wound dehiscence
in the early postoperative period. The
stricture was surgically revised, after which
the cat had two self-limiting episodes of
idiopathic FLUTD within two months of
surgery.
In addition to late complications, nine
of 39 cats (23 per cent) had recurring
FLUTD. Four of 39 cats (10 per cent)
were diagnosed with at least one episode of
idiopathic FLUTD during the follow-up
period. Urolithiasis was documented in
five cats (13 per cent) and consisted of
three cases of struvite and two cases of cal-
cium oxalate urolithiasis. Uroliths recurred
in one of 12 cats that had been fed a diet
prescribed to prevent urolith formation
following perineal urethrostomy. The
owners of the remaining 19 cats that were
Complications
Stricture 6
UTI 2
Stricture and UTI 1
Sepsis 2
Wound dehiscence 1
Perineal leakage of urine 1
Cellulitis 1
Death during anaesthesia 1
15 (25·4)
Recurrence of iFLUTD 2 (3·4)
No complications or
recurrence 42 (71·2)
UTI Urinary tract infection, iFLUTD Idiopathic feline lower
urinary tract disease
Outcome Number of
cats (%)
Table 2. Short-term outcome of
perineal urethrostomy in 59 cats
Complications
UTI 9
Stricture 2
11 (28·2)
Recurrence of LUTD
Urolithiasis 5
iFLUTD 4
9 (23·1)
No complications
or recurrence 19 (48·7)
UTI Urinary tract infection, LUTD Lower urinary tract
disease, iFLUTD Idiopathic feline lower urinary tract
disease
Outcome Number of
cats (%)
Table 3. Long-term outcome of
perineal urethrostomy in 39 cats
Urethral uroliths or crystals 31 (52·2)
Urethral non-mineral plug 1 (1·7)
Bacterial urinary tract infection 11 (18·6)
Idiopathic FLUTD 7 (11·9)
Urinary bladder uroliths or crystals 5 (8·5)
Urinary bladder rupture 2 (3·4)
Perineal skin infection 2 (3·4)
FLUTD Feline lower urinary tract disease
Diagnosis Number of
cats (%)
Table 1. Preoperative diagnoses of
lower urinary tract disease in 59 cats

230 JOURNAL OF SMALL ANIMAL PRACTICE • VOL 46 • MAY 2005
originally presented with crystals or
uroliths had discontinued the prescribed
diet because of poor acceptance by the cats.
In this group, uroliths recurred in four
cases.
No statistical difference in urolith
recurrence (Fisher’s exact test P=0·64, chi-
squared test P=0·467) was found between
the group that was fed prescription diets
and the group that was fed commercial
non-prescription food.
Of the 15 cats that had died or were
euthanased by the end of the study period,
11 (73 per cent) succumbed for reasons
unrelated to urinary tract disease.
Of 35 cat owners who were asked about
their satisfaction with the outcome of
surgery, two were dissatisfied and 33 (94
per cent) were satisfied. In addition, 31
clients (88·6 per cent) thought their cats
had a very good quality of life and two (6
per cent) thought their cats had only an
acceptable quality of life, due to unrelated
diseases such as asthma and stomatitis. The
remaining two clients described the quality
of life of their cats in the postoperative
period as poor. One of these cats was
euthanased because of recurring UTI and
one due to recurring urethral stricture.
DISCUSSION
Complications of perineal urethrostomy
have been described and documented in
several reports (Smith and Schiller 1978,
Hauptmann 1984, Osborne and others
1996). However, large case studies examin-
ing the outcome of cats undergoing this
procedure have not been undertaken.
Signalment and preoperative clinical
signs were similar to those previously
described in cats deemed to be candidates
for perineal urethrostomy (Griffin and Gre-
gory 1992, Osborne and others 2000). The
frequency of various uroliths was consistent
with reported frequencies for the study
period (Osborne and others 2000). In the
present study, 11 of 35 preoperative urine
samples showed bacterial growth and the
average age of cats with UTI was only 6·8
years. Bacterial UTI is an infrequent find-
ing in young and middle-aged cats
and occurs in approximately 3 per cent of
cats presented with FLUTD (Kruger and
others 1991). In contrast, up to 40 per cent
of cats over 10 years of age that are pre-
sented with FLUTD have positive bacterial
cultures (Bartges and Barsanti 2000). Pre-
disposing factors for UTI include the use of
urethral catheters (Griffin and Gregory
1992). Given that most of the cats in the
present study had been catheterised in the
preoperative period, it is possible that many
of these infections were catheter-related.ll
Previous studies have found a high
frequency of idiopathic FLUTD in both
obstructive and non-obstructive lower uri-
nary tract disease (Kruger and others 1991,
Osborne and others 2000). Perineal ure-
throstomy has been advocated for cats with
recurrent obstructive idiopathic disease,
despite the fact that FLUTD may recur
without obstruction of the distal urethra
(Kruger and Osborne 1995, Kalkstein and
others 1999a, Osborne and others 2000).
A preoperative diagnosis of idiopathic
FLUTD was made in only 12 per cent
of cats in the present study. However,
cats diagnosed with UTI in this study
may have had idiopathic FLUTD and
secondary catheter-related infections.
Stricture formation was the most fre-
quently observed early complication in
this study. Although this must be consid-
ered a serious complication necessitating
surgical correction, eight of nine cats
treated for stricture enjoyed a complica-
tion-free long-term outcome. Only one cat
suffered a second stricture, which was con-
sidered to be, in part, due to severe pre-
operative urethral trauma. Stricture of the
stoma has previously been described
within the first 12 weeks of surgery (Smith
and Schiller 1978). These authors found
that the incidence of stricture formation
following perineal urethrostomy using the
technique described by Wilson and Harri-
son (1971) was considerably lower than
that observed following any of three other
evaluated techniques (11·5 versus 25 to 50
per cent). They postulated that surgeon
inexperience, postoperative use of urethral
catheters and the animal’s grooming of the
surgical site all contributed to an increased
risk of stricture formation.
In the present study, all cats wore an
Elizabethan collar pending suture removal
and no cat was catheterised postopera-
tively. Surgeons with widely varying levels
of experience performed the surgeries. No
statistical difference in stricture formation
was found between cats operated on by a
faculty member and those operated on by
residents. However, the one cat with stric-
ture formation operated on by a faculty
member was also the animal suffering from
severe preoperative urethral trauma. A sta-
tistical difference between surgeon experi-
ence and outcome may have been masked
if faculty members operated on animals in
which surgery was perceived to be more
difficult. Stricture formation was reported
in seven of 59 cases (11·9 per cent) in the
early postoperative period (within four
weeks of surgery), which is consistent
with the incidence reported by Smith and
Schiller (1978).
Previous studies found that between 17
and 57 per cent of cats that underwent
perineal urethrostomy developed UTI
(Smith and Schiller 1978, Gregory 1987,
Osborne and others 1991, 1996, Griffin
and Gregory 1992). During the long-term
follow-up period in the present study, 23
per cent of cats developed UTI and 15 per
cent had more than one episode. Given the
young age of these cats (mean 4·8 years)
and the high frequency of recurring infec-
tions, this finding corroborates an existing
relationship between perineal urethros-
tomy and risk of UTI. Furthermore, signs
of FLUTD were not observed in all cats
with documented UTI, and urine cultures
were not performed on a regular basis in
symptom-free animals. Therefore, the fre-
quency of UTI could be higher than data
from this study suggest.
Uncommon complications, including
wound dehiscence, cellulitis and perineal
leakage of urine, were each observed in
only one cat in this study. This corrobo-
rates findings of other studies, in which

these complications were infrequent
(Smith and Schiller 1978, Hauptmann
1984, Osborne and others 1996). Two cats
in the present study were diagnosed with
sepsis in the early postoperative period. In
one of these cats, signs of sepsis (peritonitis
and fever) were evident before surgery. The
cause of sepsis was not known in the
second cat but ascending infection due to
indwelling catheters are well documented
(Smith and Schiller 1978) and may have
played a role in this case.
To the authors’ knowledge, no previous
studies have investigated the rate of recur-
rence of clinical signs related to idiopathic
FLUTD following perineal urethrostomy,
although perineal urethrostomy is not
expected to alter the incidence of recur-
rence. Of the seven cats diagnosed with
idiopathic FLUTD, three had neither
complications nor recurring clinical signs
postoperatively. It is conceivable that some
cats with idiopathic FLUTD have sub-
clinical disease unless obstruction or UTI
occurs. If this is the case, complete remis-
sion can be expected in some animals with
idiopathic FLUTD that undergo perineal
urethrostomy.
No statistical difference in urolith recur-
rence was found between cats fed with
prescription diets and those receiving non-
prescription diets. However, the numbers
of cats with urolith recurrence was low and
only one of 12 cats (8 per cent) fed a pre-
scription diet suffered urolith recurrence. A
relationship between diet and urolith recur-
rence is therefore difficult to establish in
this study.
Overall, more than half of all cats fol-
lowed up in the long term required veteri-
nary attention due to complications or
disease recurrence. Although this is a high
percentage, most clients were satisfied with
the outcome of surgery and many cats,
including some with idiopathic FLUTD,
experienced a disease-free long-term out-
come.
Conclusions
Early and late complications of perineal
urethrostomy in cats are not uncommon.
However, life-threatening complications
are rare. The most frequent early complica-
tion is stricture formation and the most
frequent late complication is bacterial
UTI, which is often recurrent. In addition,
recurrence of uroliths and idiopathic
FLUTD often mar the long-term outcome
of this procedure. Comprehensive client
information before surgery and adequate
follow-up, including implementing mea-
sures to prevent the recurrence of uroliths
and regularly culturing the urine of cats
suffering an episode of UTI after surgery,
cannot be over-emphasised. Although
complications must prompt surgeons to
carefully select candidates for this interven-
tion, many cats enjoy a long-term disease-
free outcome, and most clients are satisfied
with the outcome of surgery and consider
their cats to have a good quality of life
following surgery.
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© British Small Animal Veterinary Association. All rights reserved

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