I realise you have already attempted to do so with the troll itself, yet perhaps simply befriending/recruiting another dog shall cancel your current companion (whatever it may be). Once done so, you could simply inform the canine to be off, stating 'I think we should part ways' or something along those lines. In the case of that not working, there is one alternative: kill the dog itself. Furthermore, simply check over your home once more even if you have done so already, as it may well have been faulted.
As previously mentioned, I realise you have already attempted this yet I see no harm in trying as I recollect similar actions paying dividends to me in the past.
If your wishes are still yet to come to fruition, I simply suggest that you perhaps trawl through the miscellaneous information