When you shift, you turn into the animal you shift into, correct? Its not that simple. When you shift, you age as the animal would. If you stayed a dog, you would die when a normal dogs dies. Lets say you are six when you shift. You should be a grown dog, but because you aged normally, the dog would still be a puppy unless you spent a large amount of time as a dog. Shifters often age faster due to this.
Okay, we have gotten that over with. Now, for the issue of when you shift. When you shift, bones are shrunk, connected, re-connected and reshaped. It is extremely painful unless you are an alpha. The pain can change with the animal you are. If you are a chimp, you would have very little pain. If you shifted into a mouse or a horse, it would be extremely painful. Bugs are banned for a reason.
Now the issue of instinct. Instinct is the natural, er, thingy animals get. (I don't know how to explain it.) Instinct is geared towards self-preservance and duplication of genes. A normal animal would be dominated by this, but shifters have a bit more control. I am going to choose the worst way to explain this. Lets say a male saw a dog in heat. He would breed with her with no real restraint. A shifter in dog form would feel attracted and think dirty things, but would keep going. Understand, you perverts?
I will add more when I feel I need to.
Subject: -When in Animal Form- 