It's actually not a general time limit, but is for ferrets and rabbits the earliest time neutering is reccomended Female rabbits:
Female rabbits sexually mature at around 4 months of age, but many veterinarians prefer to wait until they are 6 months old before attempting a spay, as surgery is riskier on a younger rabbit.
Getting your female rabbit neutered earlier is both very very risky and doesn't allow her body to fully mature with the proper hormones.
Male rabbits:
The testicles descend at around 3-1/2 months of age for the male rabbit, and after this time they can be neutered.Most veterinarians prefer to wait until they are
5 months old to allow for an easier surgery.
Neutering a male rabbit earlier is a more complicated surgery, and it's also riskier on the rabbit. Neither sex does well under anesthetic when young.
Rabbits need a rabbit experienced vet to do any surgery on them. Don't have your rabbit spayed or neutered by a vet with little or no experience in rabbit surgery.
Female ferrets:
Female ferrets have been known to come into heat as early as four months old. They reach sexual maturity between four and six months. Consult with your vet on when would be the best time to neuter.
Neutering is done at a much younger age to pet store ferrets, usually at 5 weeks. This has been shown to lead to health problems not normally suffered by ferrets who are neutered later.
Neutering earlier denies the growing ferret all the proper hormones, and is riskier.
Male ferrets:
Male ferrets can be neutered around the same time as female ferrets, at four months. This allows them to have the proper hormones while maturing. Male ferrets can be altered later, and some vets recommend six months.
Neutering is done at a much younger age to pet store ferrets, usually at 5 weeks. This has been shown to lead to health problems not normally suffered by ferrets who are neutered later.
Neutering earlier denies the growing ferret all the proper hormones, and is riskier. For a male ferret, it's best to wait untill the testicles have dropped before attempting any neutering surgery.
Ferrets need a ferret experienced vet to do any surgery on them. Don't have your ferret spayed or neutered by a vet with little or no experience in ferret surgery.
Female rabbits:
Female ferrets: