Council will usually do something about the dog if the noise is excessive, but only after you've lodged a diary of the times it happens. If they feel it's frequent enough, then they're supposed to send a letter or visit the occupier.

I'm surprised the RE hasn't said or done anything. If it's in the contract that there is to be no pets, that would come from the landlord. Surely the RE would be in some sort of breach with the landlord by knowing the dog is there but not getting it removed? (Grasping at straws, have no real idea about that but it might be another angle to take with the RE's lack of action).

Poor pup. Big dog like that, makes me so sad. Hope you get some peace soon.