How do you stop a castrated dog humping his bed and other people. I thaught the last thing a dog would want to do after losing his bits would be to try it on. But no he goes for it like there is no tomorrow.

David.

That's because humping has more meanings to a dog than just sexual ones! Do the same as you would as if he was still entire - tell him "No!" and make him lie down quietly for a minute or so.

How long since he had the op?

As Jeangenie says, it doesn't have to be a sexual thing, there can be an attention seeking element to it.

I dont know when he had the op. We had to give him up last year due to personal circumstances. We got the chance to get him back 2 weeks ago minus a few parts. The original breeder wasnt happy about it as it were her i kept in touch with even when we didnt have him. She got in touch with me 2 weeks ago about getting him back and she didnt know about it. So id be guessing as to about 6 months to a year ago.

David.

Was he mature when he was castrated.  A dog I bred was castrated at 5 months because he humped, and the habit has continued to this day and he will be 7 in November.  His owners unfortunately were not told it was unlikely to be sexual at that age but a way of getting attention.

Is there anything in particular that sets him off?  We had a rescue dog (already castrated when we got him) that mounted us when we were going out.  The reason for him being rehomed was that his previous owners were having to leave him at home alone 8 hours a day (through some sad circumstances and they were broken-hearted on having to part with him) so it is understandable that he had a problem with being left!  We set up a new routine for leaving (sit, get a hard biscuit that takes a bit of chomping, see you later - which goes against the standard advice but it worked!) and the mounting behaviour became very, very rare although it did not disappear altogether.