I probably duped this but when I put invisible wolf in the search nothing came up.

Basically I didn't notice my wolves go invisible until today I started playing the 1.8.1 pre 3 i think it was a few days ago.

The wolves seem to go invisible when you leave the chunk and then when you return to it. The chunk fails to update the wolves visually. I can still hear them. They are sometimes able to come back if something attacks you or a creeper blows up near by.