I think the vet needs retraining. It would appear that he has the reproductive system and the waste disposal system mixed up. Bladder control is not usually a problem in spayed bitches unless they have some infection in the urinary tract.
It is a pity when one looses confidence in the vet. I have a happy but very female munsterlander "teenager" who discovered the vet stepped back when she rumbled. Guess what she does all the time at the vets now. Labelled as an untrustworthy dog when she is simply expressing dominance to a nervous vet. A gentle hold of the head and a quick word with eye contact generally sorts her out.
No problem with the last vet who simply looked her in the eye and said in a voice that brooked no nonsense "Shhh!"
