Yes, I'm sure you've had to deal with it before. In most cases its when your dog has gone through that period where the vet recommends, as proceeds to accomplish, the removal of the sexual organs. It's an advisable and necessary part of a dogs life. But immediately proceeding this experience is the wait for the dog to get better.
This process usually takes 10 - 14 days. For the first two or three days you dog will be in an amount of pain that will take on various forms depending on the personality of your dog. Some might simply lay down on their bed and only move to eat or drink and go outside. Others will try to act normally but, upon noticing something is missing will spend their time dancing around the room and whining a bit. Don't worry because this is normal and it will go away. The only tough part for dog lovers is having to wait out the recovery time.
In most cases stitches will be used to close any incisions made during the surgery. When it comes to this it's important to watch your dog closely, especially if the dog is a "licker". Licking a wound is the dogs natural way of trying to clean it and sooth pain. But in this case licking can cause irritation to the wound and can help spread bacteria around it. Also, in most cases, licking is a precursor to biting and chewing. Left on their own, most dogs will have stitches removed. This is dangerous and in the event that is happens would require immediate attention and new stitches put in.
This is a bag thing for several reasons. When the dog requires to have stitches put back in the vet will have to readminister anesthetic. Limiting the dogs exposure to this is recommend which is why its used only when necessary. To avoid this from happening most vets recommend a special dog supply in order to stop the dog from chewing or biting their wound. It's a dog cone or e-collar. They're the cone shaped collars that attach to the dogs regular collar. With this the dog is unable to reach it's hind quarters and therefore is stopped from irritating the area.