I am not sure if neuter my dog at 4 months or 6 months

Question
The vet told me to neuter my  dog when is 6 months but his trainer that also
study animal behavior told me that is not problem and maybe better at 4
months at soon as possible,
that is a old school of vets that believe that to neuter a dog at 4 months can
cause problems in the future like separation anxiety or that they will not
develop   100 , etc in other words the old school say that is unhealthy
somehow.
Please let me know you point of view,
he is schedule for Rabies vaccine and neuter at the humane society this next
Tuesday, they say is ok at 4 months.

Answer
It depends on breed and size

'Giant breeds' Shouldn't be neutered before a year,as it can cause the leg bones to grow longer,therefore increasing the risk of bone cancer-those are breeds that grow to over 100 pounds

Dogs that weight between 50-100 pounds as an adult no younger then six months

Breeds smaller then 50 pounds is ok before 6 months

and those are they weight of adult dogs-although shelters usually neuter puppies at a young age with few problems,it's mostly 'giant' breeds that shouldn't be done too early