There are only a few reasons why male rats should be neutered and plenty reasons why they shouldn’t be neutered. The only good reason to neuter a male rat is if you must put males and females together in the same cage. Rats do not need to be spayed or neutered like cats and dogs. Neutering is major surgery and your pet should not be put through the stress unless necessary. There are more reasons not to neuter a male rat than there are reasons why you should.
Do not choose to get male and female rats. When getting rats, choose either girls or boys. You do not need a Romeo and Juliet or a Bella and Edward. Girls and boys do have different personalities and that can be considered when choosing a sex. Girls tend to be more playful, but it is more difficult to introduce young female rats to older female rats. Male rats are mellow and can easily be carried around in a hoodie the whole day. It is also easier to introduce young male rats to older male rats.
Behavior changes are minimal in neutered rats. A neutered rat can still be aggressive to other rats. According to a biologist’s article on the behavior or neutered rats, a castrated male can still be aggressive to newcomers in his cage. A male rat that is handled a lot when young will not be aggressive to humans. Even an older male rat that hasn’t been handle at all is more likely to be afraid than aggressive to a human.
A neutered rat will lose dominance, and that does reduce attacks from other male rats. They do not feel the castrated male is a threat because he can’t get the girls pregnant. If it is necessary to introduce two older male rats, neutering one may have to be an option, but only after slowly trying to integrate them. Surprisingly, intact male rats are more open to accepting young male rats than older ones.
Neutering rats will not reduce any “smell.” Male rats, contrary to popular belief, do not have a terrible odor. A male rat that is not neutered will urinate on everything because they are marking their territory. That is probably where the idea of “smelly rat” comes from. Keeping the cage clean will prevent that smell and is something rat owners should be doing anyway.
Castrated male rats urinate less. This might read like a good reason for neutering a rat but it really isn’t. Neutered rats mark their territory less. That means less peeing on you and the cage and everything he deems his own. So what? A rat pees on you. That is not an excuse to put the guy through stressful major surgery. If you are worried about being peed on then why are you getting a pocket pet?
Neutering a rat prevents testicular cancer. Again, this sounds like a good reason for neutering that little boy. Yes, cancer is common in rats but you shouldn’t neuter a male rat “just in case.” Many times, rats will get benign tumors that will have to be removed even if they are neutered. You can never assume that a rat will get cancer. A well taken care of rat is mostly going to die of old age. Neutering is costly and can be dangerous. Think about your rat and talk to a vet who has done many surgeries on rats (not cats and dogs because there is a big difference) before jumping into surgery.
What does neutering do? Ratbehavior.org