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
Objective—To develop a model of low urethral pressure
incontinence and compare the relative contributions
of the pudendal and hypogastric nerves with
urethral function by performing selective neurectomy
and ovariohysterectomy in dogs.
Animals—19 healthy Foxhounds.
Procedure—Dogs were allocated into 2 groups. The
first group (10 dogs) underwent bilateral hypogastric
neurectomy and ovariohysterectomy and subsequent
bilateral pudendal neurectomy. The second group (9
dogs) underwent bilateral pudendal neurectomy and
subsequent hypogastric neurectomy and ovariohysterectomy.
Urethral pressure profilometry and leak
point pressure (LPP) tests were performed before
and after each neurectomy.
Results—Before surgery, mean ± SD LPP and maximal
urethral closure pressure (MUCP) in all dogs were
169.3 ± 24.9 cm H2O and 108.3 ± 19.3 cm H2O,
respectively; these values decreased to 92.3 ± 27 cm
H2O and 60.7 ± 20.0 cm H2O, respectively, after both
selective neurectomy surgeries. There was a progressive
decline of LPP after each neurectomy; however,
MUCP decreased only after pudendal neurectomy.
Fifteen dogs had mild clinical signs of urinary incontinence.
All dogs appeared to have normal bladder
function as indicated by posturing to void and consciously
voiding a full stream of urine. Urinary tract
infection did not develop in any dog.
Conclusions and Clinical Relevance—Hypogastric
and pudendal neurectomy and ovariohysterectomy
caused a maximum decrease in LPP, whereas pudendal
neurectomy caused a maximum decrease in
Impact on Human Medicine—This model may be
useful for evaluation of treatments for improving urinary
control in postmenopausal women. (Am J Vet Res 2005;66:695–699)