I think the mian issue with all 3 pictures is that the subject is overly centralized. Your main point of interest, mainly the dogs face/body seems to be in the center of the frame. You can try composing following the rule of thirds to make your subject more interesting. Its good that you are down to almost eye level for all 3 pics though as many people tend to take dogs standing up. Looks like you learned form the session at the grooming salon haha.
Some specific comments:
#1 Following rule of thirds to place the dogs head towards the right of the frame keeping the eye towards the upper third while amking sure the ears dont get chopped off would help in this case. A slightly lower perspective would help more too.
#2 Don't really like that drain running though the middle of the frame and perspective wise the dog is not doing anything interesting. You should always ask yourself what is it about the dog you want to show people and then think about how to compose the shot around it.
#3 A tighter crop would have worked better here as the empty space around the dog doesn;t really add to the composition IMO.
Overall pretty good just need more practice practice practice
That pic quite popular..
