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


METHODS
20 dogs.


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


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


CONCLUSIONS
Medetomidine and xylazine have similar effects on measurement of UPP and cystometry. Medetomidine was less consistent among days for UPP in female dogs and produced fewer valid cystometry tests, compared with xylazine. For urodynamic evaluations, medetomidine administered IM cannot be substituted for xylazine administered IV.
Rawlings
C A
CA
Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602-7390, USA.
Barsanti
J A
JA
Chernosky
A M
AM
Oliver
J E
JE
D000818:Animals; D004285:Dogs / Q000502:physiology*; D005260:Female; D006993:Hypnotics and Sedatives / Q000008:administration & dosage / Q000494:pharmacology*; D007273:Injections, Intramuscular / Q000662:veterinary; D008297:Male; D020926:Medetomidine / Q000008:administration & dosage / Q000494:pharmacology*; D011312:Pressure; D015203:Reproducibility of Results; D012737:Sex Factors; D014521:Urethra / Q000187:drug effects / Q000502:physiology*; D014563:Urodynamics / Q000187:drug effects; D014991:Xylazine / Q000008:administration & dosage / Q000494:pharmacology*
D006993:Hypnotics and Sedatives; D014991:Xylazine; D020926:Medetomidine