desexed bitch

Question
I have a desexed female staffordshire she always humps everything and i dont know why could you help me  

Answer
You don't mention how long ago this bitch was spayed.  This is an important factor to determine any hormonal influence.  "Humping" is not merely a sexual behavior although hormones can be the cause.  It is primarily a social signal.  It can be related to high levels of stress in the environment, the dog's overall lack of confidence/trust, anxiety due to separation issues or chaotic household, and can also indicate a compulsive disorder.  Your first stop should be to the veterinarian for full evaluation to rule out physical cause.  If the dog is physically healthy and appears to be compulsively humping, there are medications available to assist in relieving this drive but behavior modification is also required.  To find a certified applied animal behaviorist in your area, see the following worldwide link:
http://www.arkanimals.com/ark/dg_expert_referrals.html