I would like to clarify a few points and the terminology for desexing animals as there does seem to be some confusion in many of veterinary related threads on myBG:
By UK standards:
Neutering applies to either sex (neuter = neutralize for want of a better description)
Spaying refers to females (ovario-hysterectomy - removal of ovaries and uterus/womb).
Castration refers to males (orchidectomy - removal of testicles)
For neutering to be totally effective the testicles/ovaries should be removed.
Sterilization by "tying the tubes" (eg a vasectomy for males or fallopian occlusion in females) may stop the problem of breeding but does not remove the hormonal influences on the body i.e. b.itches will still have a season and are susceptible to pyometras(womb infections), false pregnancies and mammary tumours. Males will still be under the influence of testosterone therefore more likely to be territorial and fight and go in search of the ladies. Most Bulgarian vets neuter the animal but I have encountered one Bulgarian vet who sterilized only, so it is worth checking. Get all the bits whipped out!
Fertile/mating time may be referred to as "in season", "in heat" and in cats "calling"(you know why if you've heard a horny cat)
As for the timing of the operation...............
CATS
Males:
At any time from when the testicles can be seen/felt. Usually around 6 months of age but can be done earlier or at any time after.
Females:
Usually around 6 months of age. If she is younger than that but seen or heard calling then get her to the vets ASAP! Cats come into season every 21 days. Cats can be spayed at any time i.e. when in season or if pregnant. So if your cat is in early pregnancy you should consider the operation if you do not want to deal with next generation of kittens. She can have the operation in late pregnancy but some vets may not be keen to carry out the procedure so discuss it with them first.
DOGS
Males:
At any time from when the testicles can be seen/felt. Usually around 6 months of age but can be done earlier or at any time after.
Females:
The one rule to adhere to is: DO NOT operate during a season or for at least 9 weeks after the end of the season (at least 12 weeks from the start of the season) unless medically essential. There is a massive increase in blood supply to the uterus during this time and a lot of hormonal activity so complications are more likely.
B.itches usually come into season every 6 months, for around 3 weeks but it may be longer. The timing of the first season varies with the size of dog. Small dogs may have their first season at about 6-7 months, a giant breed may wait until 18 months old, everything else fits in somewhere in between.
There is a lot of discussion and differing views about spaying a bitch before her first season or letting her have a season then operating. There is no truly right or wrong answer but your local vet may think different! One thing a bitch does not need to do is have a litter - one old wive's tale that has hopefully disappeared.
One final point all of these operations should be done under a general anaesthetic. Spaying under sedation and restraints is dangerous and cruel and any vet doing such a thing doesn't give a damn about your animal.
