There are always risks involved in either spaying a female rat or neutering a male rat. There can also be some advantages in doing so.

The most obvious benefit is that they will no longer have any sexual reproductive organs, which is one of the major causes of cancerous tumours later in life. Although testicular cancer in male rats is very low, this will more or less guarantee that it will never occur. With the female, it will greatly reduce any chance of her getting pituitary/mammary tumours and will almost certainly cut out genital Mycoplasmosis. It is also surmised that having your rats neutered/spayed will greatly increase their life span although no scientific evidence can really be found to back this up.

The downsides are enormous, especially for the female rat. The surgical procedure used in spaying is extremely invasive. The Vet must open the female completely to get at the organs, which would mean a general anaesthetic needs to be used (this in itself can be highly dangerous, as it is in humans). The female rat is also under for a lot longer than the male, since the operation is more major, leading to complications maybe arising from too much anaesthetic. Personally, I would choose not to have my female spayed, even if it can prevent problems later in life. To me, this surgery is just too major. I would prefer to do the males, if it needs to be done at all, since this is less invasive.

Neutering males is a less major operation, although general anaesthetic is still required and so should still be considered quite dangerous. Post-operative infections like abscesses have also been known to crop up, although I have yet to see this myself. Since testicular cancer in males is quite rare, neutering is normally done to try and solve aggressive tendencies and to allow the male to live with female rats. Therefore, if you do not see any aggression and the male is NOT going to be living with other rats, I would strongly advise against having the rat neutered.

Please note that if you are considering having a rat spayed/neutered, ask your Vet first about all the ins and outs of the operation so that you know exactly what you are letting yourself and your rat in for. Also make sure that you know your Vet is competent at dealing with small animals (some Vets tend not to treat rats, and are therefore not as competent at it). Also make sure that your Vet sends the rat home with a strong course of antibiotics (or has given an injection of long acting antibiotics) to try and prevent any post-operative infections from occurring.