I double lunged a small buck last Sat. I hit right behind the front shoulder and the arrow exited out between the second to last and last rib on the other side. Blood all over the arrow, but not one drop could I find after that. As Dampland suggested, I always listen hard after the shot and I had heard the buck crash in a thicket behind me and thats where I found him. Even though I knew thats where he probably lay, I went ahead and found the arrow and tried to blood trail to the deer, but there just was not any blood. The hole had been plugged with some cartilidge.

the cavity has to fill up before it will pour out.
internal bleeding..has to make it to the over pour, which is the hole yer leaving with yer bh.
it is common fer em to run a bit...
take a deep breath and take off running...you can make some distance. but if we taped yer mouth and nose, you'd pass out rather quickly.
one lung can leave alot of room for a deer to run. so, as mentioned, its a good idea to keep yer eyes and ears open to mark the last spot. and dont go trampling through everything looking for blood. find a drop, no one passes until ya find the next drop. good practice is to track back after ya find the animal.

Absolutely - double lunged a six pointer last week (got both lungs and the liver) - though and through shot - bright red but a very sparse blood trail. He went no more that 40 yards and dropped - belly was swollen and cavity was filled with blood. -- A good shot will bring them down - don't rush the tracking - if they're dead, they'll be just as dead an hour later.