Awww I feel so sorry for my puppy. He has lost all 4 canines. The top two are just poking through again but the bottom two have only just fallen out and he is struggling a bit. Have read that the bottom two help to keep his tongue in place and he does seem to be gulping a bit now 
Hoping that they are the last to go and we are nearly done as I have to keep washing his toys to remove the blood.