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. Animals-20 dogs. Procedures-Urodynamic testing was performed 6 times in each dog (3 times af ter administration of xylazine [1 mg/kg of body weight, IV] and 3 limes aft er administration of medetomidine (30 mug/kg, IM). Before each episode of s edation, UPP was performed. Heart and respiratory rates and indirect blood pressures were recorded prior to and 5, 10, 20, and 30 minutes after inject ion of sedative. Cystometry measurements included threshold volume, thresho ld pressure, and tonus limb. The UPP measurements included maximal urethral closure pressure (MUCP), functional profile length, and, in male dogs, pla teau pressure. Results-Mean MUCP was decreased markedly in xylazine- and medetomidine-seda ted dogs. Xylazine and medetomidine also decreased plateau pressure in male dogs. The MUCP measurements were consistent among days for conscious and x ylazine-sedated dogs but were inconsistent for medetomidine-sedated female dogs, The proportion of valid cystometry measurements was greater for xylaz ine (39 of 60) than for medetomidine 127 of 60). Cystometry was considered invalid when bladder pressure reached 30 cm H2O without initiation of a mic turition reflex, Conclusions and Clinical Relevance-Medetomi dine and xylazine have similar effects on measurement of UPP and cystometry, Medetomidine was less consist ent among days for UPP in female dogs and produced fewer valid cystometry t ests, compared with xylazine, For urodynamic evaluations, medetomidine admi nistered IM cannot be substituted for xylazine administered IV.