Objective—To characterize urodynamic function and
anatomy before and after colposuspension in anesthetized
Animals—12 adult female Beagles.
Procedure—During general anesthesia (thiopental
sodium induction and halothane maintenance), urethral
pressure profiles, leak point pressure measurements
with a 50-ml bladder volume, positive contrast
cystograms, and retrograde vaginourethrocystograms
were performed. A caudal midline laparotomy was
used to perform colposuspension. Urodynamic and
radiographic studies were repeated after surgery.
Results—Leak point pressures were increased (120
to 168.9 cm H2O), and maximum urethral closure
pressures decreased (43.7 to 19.3 cm H2O ) after colposuspension.
The urethra and bladder were moved
cranially; the external urethral orifice was positioned
closer to the pelvic cavity, and the neck of the bladder
was positioned more cranially into the abdomen.
Length of the urethra, as measured by use of vaginourethrocystograms,
was increased by 3%. As measured
by use of urethral pressure profiles, total profile
length was increased by 19.9%, and functional profile
length was increased by 19.2%.
Conclusions and Clinical Relevance—Increased
leak-point pressure correlated with the expected clinical
improvement attributable to colposuspension.
Increased exposure of the urethra to abdominal and
pelvic cavity pressures may be the mechanism by
which incontinent dogs become continent after colposuspension.
Results of the leak-point pressure test
may correlate with clinical behavior before and after
colposuspension for treatment of incontinence. (Am J
Vet Res 2000;61:1353–1357)
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
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 µg/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
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 medetomidinesedated
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
Conclusions and Clinical Relevance—Medetomi
dine 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. (Am J Vet Res