Unless there was some medical reason, no.
The risk of a dog developing certain types of cancer is reduced if the dog is neutered.
get them neutered then introduce them is the best option
Male gerbils can be neutered, but it is not recomended. Female gerbils should not be spayed. In general male gerbils should not be neutered unless there is a good reason for it.
Male dogs are typically recommended to be neutered between 6 to 9 months of age.
have them neutered
at six months old
A cat should typically wear a cone for about 7-10 days after being neutered to prevent them from licking or biting at the surgical site.
Probably not. Once everything is done nothing should be left over. So you wouldn't have to get your pet neutered twice.
Male
A dog should be fully mature before he gets neutered, so he has developed mentally as well as physically. So for a large breed like a Doberman, 18 - 24 months.
If "he" is indeed a male he's probably "marking" territory. Have him neutered by a vet.
It all depends on what kind of pet it is and what you plan on doing with it. I would say that dogs and cats should be neutered because there is an overpopulation. However, if you are planning on breeding any types of animals they should not be neutered. This is just my opinion an I may be wrong.