I'm not familiar with either of those drugs, but I found this and perhaps it will help you decide:
The authors have successfully used an intravenous combination o? 0.2 mg/kg diazepam (Valium, HoffmanLaRoche) and 5 to 7 mg/kg
ketamine for anesthetic induction.
Xylazine (Rompun, Miles) and phenothiazine tranquilizers (such as acepromazine) should be avoided in animals less than 3 months old because of their potential to cause bradycardia (decreased cardiac output) and hypotension, respectively.
http://members.aol.com/CYorkie/EarlySpayNeuter.html
I wouldn't leave them in tact. The tendency for cancer in later life is too great. Good luck with your decision.