Aggressive Behaviour towards owner

How old is he now, and how long is it before he fully recovered (or seemed to fully recover) from his last op? Is he aggressive in any other circumstances? Is there always body contact (or fear of body contact) involved? And does it feel to you like a warning/snap rather than full-on losing his rag - if you stop what you're doing, does he then calm down?

 

If you're sure there's no pain - a clue to pain might be if he's happy for you to brush his front but not his hind end, or one hip but not the other - you could try desensitising and counterconditioning. This could look something like this:

1) Pick up the brush - give him a treat - put the brush down. Repeat ad nauseam, till he gets visibly excited when he sees you pick up the brush.

2) Hold the brush close to (or touching if he's OK with that) his body, give him treats, then remove the bruch, then stop treating. Timing is important - the brush is a predictor of good things, removal of the brush means the good things stop. Repeat till he loves the touch of the brush.

3) As above, but pull the brush lightly across his fur in an area he doesn't tend to react to.

Then VERY slowly work to other areas of his body, only moving on when he is clearly delighted that he is being brushed. The idea is that in every step, the emotional response to the treat will transfer to the brushing action, in the same way that the tune of an ice cream van can make you feel happy even in the absence of ice cream itself.

You could also try 'zoom groom' type brushes to see if he's more tolerant of them.

Also, have a look at Chirag Patel's Bucket Game: Chirag Patel- Domesticated Manners (The bucket game) - Animal Training Academy - This may give your dog a better way of telling you that he's not happy with what you're doing.