Spay and Neuter policy questions

[Daniel Gray]

I am a veterinarian and a very new landlord (6mo).  I see policies of requirements of spaying and neutering dogs and cats.  People are under the impression that this procedure will "calm down animals" or make them less   _____fill in the blank_____  The evidence is thin but that's not my question.  I've seen clients where their landlords require guinea pigs and hamsters and birds to be spayed.  I don't get it?  Am I missing something?  Or is this a blanket policy that covers all animals?  I know I'm asking you to guess what others are thinking but if you have these clauses... why?

Thanks!