Dog nipping

My Staffy Carmal just started nipping at my grandson's friend. The friend has been at my house several times and
Carmal never bothered him and just in the last few days, she nipps at his legs. He can pet her but as soon as he stops, she nipps his legs.
Does anyone have any ideas why she does this and any ideas on how to make her stop?
Thanks,
Bruce.

Hi there.

A little more information would be useful, in particular how old is your dog?

She is 8 yrs. old. And we just recently had her spade if that makes a difference.

It does sound strange to start something like that at her age. I suppose it could be hormonal is she has just been spayed, though I'm not sure.

Is it just this one friend that she does it to and if so, does he do something different with her than others do?

It is difficult to be able to help without seeing exactly what's going on. It may be that she is trying to get what she wants off your friend, e.g. when he stops stroking her she nips.

I would try taking her out the room as soon as she tries to nip. Leave her out of the room for a couple of minutes and then let her back in again. If she does it again, remove her again. This should all be done in a calm manner, not with raised voice

You could also try asking your friend to make your dog do something before he gives her any attention, just something like a 'sit' or a 'paw' would do, just to make her understand that she can't boss your friend around.

She has done this to another friend this morning but I wasn't aware of it until my grandson told me about it.
Thank you for the advice, I will try it.
Thanks,
Bruce.