Hi
I have a nineteen month old Golden Retriever called Sherlock.   Still in the first flush of youth, he is a bouncy exuberant boy full of the joys and delight of spring.   In maturing, he has become easier to handle - a lovely dog and pretty well behaved too.   He loves living and he loves life, hes soft and playful with the sweetest nature and has this belief that dogs and humans alike all love him!
I have a friend with a two year old Rottie and a nine year old Golden Retriever.   We meet up every Saturday and Sunday Morning and have some very long walks together no matter what the weather.   My Sherlock and her Rottie are great mates.   Initially when we first became friends, Sherlock would hump Trigger constantly...  He wouldnt stop although I tried distracting him, putting him on the lead, taalking to him, etc, etc.   However, with time, they bounce along together and now and again Sherlock will hump him but stops immediately when I tell him to.   The two dogs are great mates - its a beautiful to see them running free over the fields - one dark head and one pale head - you can almost see the pair of them 'talking'.   They are like a pair of mischievious scool kids!
The nine year old retriever doesnt take part in the playing - hes not a playful kind of dog.   However, he seizes every opportunity to hump Sherlock.    Sherlock just stands there and waits for him to get off.   I would have thought it was a dominance thing but I dont know.
I used to just leave him and then got fed up with the mud on my dog and also sometimes, when the other dog is humping him, Sherlock will  sometimes twist out of his grip and roll in the mud so as to get away from him.   This means that when I get home I get to spend a half an hour with him in the bath, then have to clean the bathroom, wash all the towels, etc, etc.   Her dog is overweight whilst mine is slim and I dont like him having the extra weight on his hips during the humping
Recently, Ive started pulling the other dog off him and saying no.   The lady who he belongs to will call him off, then says 'good boy' and sometimes gives him a treat....   I dont.  I say 'NO' quite sharply and pull him off.   This works for a short while and then hell do it again and it starts all over again.   Im fedup with it.
Please, does anyone know how to stop this for once and for all?
Michelle

I think your first guess that it is a dominance or assertive thing is right.  the old boy not taking part in the play etc sees this way as establishing himself as above the younger ones.  It's a dog thing, and unless your youngster tells the old boy off, that it is unacceptable to him, your only option is training and intervention.

It may be dominance.

A dog does not dominate another dog if he feels secure himself. This starts with everyday life as well as walks, you need to be the dominant one and be assertive in getting him to stop. Dont shout and dont loose your temper, but a sharp 'SH' or 'AA' will do. Its difficult when they are on a walk because if they are off lead, you cant catch the moment when he starts to consider humping him (you'll see his attention goes to the other dog). Put him on a long lead and when you see he is about to, go 'AA' and get in the way.

when you have it cracked im sure he can be off the lead and playing over the fields again.

On the surface it does sound as though the humping is part of their "pack" behaviour. You say Sherlock still occasionally humps the Rottie and this, no doubt, is observed by the older dog who exhibits the same behaviour. It may have started as a way of maintaining some sort of pecking order between the three, with the older dog needing to remind everyone that he is senior dog on a regular basis. The fact that it is continuing may indicate that the older dog is not that secure or just enjoys doing it and the humping has become an enjoyable habit with a gratifying element!

When the humping happens does it go on for a long time or is it quite brief? Are all dogs entire, castrated or a mix?

I would advise no humping by anyone. Humpers get put back on lead straight away end of playtime. You may need to ask your friend to keep the older Goldie on the lead around Sherlock or to leave him at home and just walk Sherlock with the Rottie. Unfortunately it has become ingrained behaviour with the older dog and unless the owner is prepared to manage it and stop him even doing it, I think your best bet is avoidance. For whatever reason, the older Goldie is highly motivated to continue.

Hi Michelle,Here is a cure for Humpers.While at adog show for labradors/goldens etc
I met a lady of great renown in the dog world.
She owned and bred Gundogs.Chamions in Show and Working.
When asked how to stop a dog humping her reply was a Swift Boot up the backside!
It works my dogs never do that.My advice don't stand and stare just do it with toetectors!
  Good luck.

Gundogal, the problem is with someone elses dog not the OP.

Hi Freelancer.   Thanks for your comments.
Only my Sherlock is entire.   With him and the Rottie, it seems to be a part of their play.  They have their special games - sometimes they playfight - teeth snapping; sometimes they just run around together like a couple of 'wild things'.   Sherlock will hump him but it is rare.
I doubt the owner of the older dog would put him on a lead.   At first, she would give him a biscuit and he then he would get off my dog.   Then she said he was doing it so that she would give him a biscuit.....  
I decided that he would NOT hump my dog any more.   So I watch all the time and tell him to get off at once.  It does not last long but I notice that instead of doing it less, he is doing it more.   Sherlock will be walking along ahead and the older dog will suddenly give a run and jump on him.   I usually call him back when he starts running towards him.  He is a very heavy dog and mine is slim.   I ddont want him to have hip problems.

Given that the OP is unwilling to properly address and change the behaviour I think you would be best to avoid walking with the other Goldie. Her reward system is not really working is it LOL.

The only other possibility is if, as Brainless suggested, Sherlock gets fed up and attacks the other Goldie. That might sort things once and for all but you'd probably rather avoid if you can. Because the older dog is castrated Sherlock might be more tolerant of the humping than if it was two entire males. Was the Goldie castrated late I wonder? Perhaps Sherlock's young, potent smell is driving the older Goldie wild, who knows..?

Given that it is happening more and more, even though you are intervening, I do wonder if the older dog has developed some kind of confused fixation with Sherlock. If the OP values her walks with you perhaps you can use this as leverage and say that unless the older dog can be cured of his humping you will have to stop the walks and Rottie will lose his mate. As the older dog is overweight and of a good age I can't imagine all this humping is good for him, let alone yours. See if you can't persuade the OP to keep him on lead when out with you.

Sherlock would hump Trigger constantly...  He wouldnt stop although I tried distracting him, putting him on the lead, taalking to him, etc, etc.   However, with time, they bounce along together and now and again Sherlock will hump him but stops immediately when I tell him to.  

I guess when the boot was on the other foot the lady you walk with was very accomodating for Sherlock to hump Trigger, I dare say he also got Trigger a little muddy at times.  However you now have your dog trained and when you tell him Off! he comes off, but I dare say the Rotti still gets humped quite often by him still?

This other GR is 9 years old, for me too old to be still having to give praise and reward treats the dog should be doing as it is told by it's owner when told off, it should also come off, however the dog is 9 and to be honest as yours also has and does hump her other dog, I don't feel you have a lot of complaining to do.

I fully understand why your complaining, bigger dog, and the mud, but your dog does it too. ;-) I doubt this owner has much command over her dog, luckily you do with yours and that is down to your training so well done, *thumbs up* but I doubt this other one is going to stop, unless as suggested yours turns around and gives him what for. 

I would try oversion with your own dog, when the older is approaching I would call him away to play and just keep him away from him and with the Rotti.  You may well find that once your dog is through adolesence approx 3 years, that the older GR will stop completely, but you may well have this problem if walking with this owner continually, it is up to the woman to train her own dog, as it is 9, don't hold out much hope of that, so you'll have to just keep yours away from him as best you can. :-)