I came across this article yesterday and thought it was extremely helpful and informative. I've included the link and article.
Rehab a Puppy Mill Dog
Every mill survivor is different. What works on one or many will completely fail on another. The only thing that is consistent is that they will need lots of patience, understanding and love. And probably most importantly, acceptance: unconditional acceptance of what they are capable of giving and taking.
At first glance, a mill survivor may look like many of your friends' dogs: maybe not a perfect example of the breed, but close. What you won't see is the condition in which they came into rescue. Hair so matted that it all had to be shaved off. Many times, removing the filth and matting have only revealed open sores, usually from flea allergies or sarcoptic mange. Ears are full of filth and usually mites.
Some survivors suffer from permanent hearing loss because of untreated ear infections. Most survivors require the removal of rotten teeth, even young dogs. The gums are usually very infected and the teeth have excessive buildup on them. Many vets who are not familiar with puppy mill rescued dogs will misdiagnose age if going by the teeth. Many survivors also suffer from swollen, splayed and sore feet from a life of walking on wire. Finally, getting some good nutrition and extensive medical care can go a long way on the outside, but the real damage has been done to the inside.
We would love to say that every puppy mill survivor only needs love to become a wonderful family pet, but that would be a lie. Love is definitely needed in large amounts, but so is patience. The damage done during the years in the mill usually can be overcome, but it takes time and dedication. It takes a very special adopter for one of these dogs. Not being "up to it" is no crime, but you need to be honest with yourself, and us, about your expectations. These dogs have been through more than they ever should have already. If the entire family is not willing to make the commitment, the dog is better off staying in our care until the perfect home for them is found.
Handling
Many mill survivors have spent their entire life in the mill. No romping around a living room playing with friends of the family for them. Only a cold wire cage, and one person "tending" to them. Puppies who grow up in a mill miss out on many crucial socialization periods with humans. They don't learn to trust, to love or to play. They have had very minimum physical contact with people. No cuddling and kissing for them.
The physical contact that they have received probably has not been pleasant. For one thing, because they are not handled enough, they are scared. Many mills handle their "stock" by the scruff of the neck. They have work to do, and don't really want to stand around holding some stinky little dog any longer than necessary. So it is not uncommon for these survivors to be sensitive to the backs of their necks, after all, it brings the unexpected.
Many mill dogs will try to always face you, not trusting you enough to give you easy access to them from behind. NEVER startle a mill survivor from behind, you will lose any trust that you may have gained. Always make sure that they are anticipating you picking them up and consistently verbally tell them what you are going to do with the same word, like "up". It is not uncommon for a mill dog to drop their bellies to the floor when they know you are going to pick them up. Some will even roll onto their backs in submission.
Always be gentle and try to avoid picking them up until you see that they are receptive to it. These dogs have to progress at their own pace. Anything you force them to do will not be pleasant to them.
Learning about the house
Many times when you bring a mill survivor into your home, their instinct is to hide in a quiet corner. Optimally, they need to have exposure to the household. If crating, the crate should be in a central location. The ideal spot is one where there is frequent walking and activity. This allows the dog to feel safe in the crate, yet observe everyday activity and become used to it. They need to hear the table being set, the dishwasher running, phones ringing, and people talking. It is fine to cover the back half of the crate with a towel or blanket to give them a sense of security.
Very few mill dogs know what a leash is. During this time when the dog is out of the crate and supervised, it is not a bad idea to let them drag a leash around with them. Let them get used to the feel. It is easy to fall into the mindset that they must be pampered and carried everywhere, but leash training is important. It will make your life easier to have a leash trained dog, but also will offer your dog confidence.
Gaining trust
A mill dog has no reason to trust you. Your trust needs to be earned, little by little. Patience is a very important part. I have seen a lot of mill dogs not want to eat whenever people are around. It is important that your mill dog be fed on a schedule, with you near by. You don't have to stand and watch over them but should be in the same room with them. They need to know that their meal is coming from you. For the majority of mill dogs, accepting a treat right out of your hand is a huge show of trust. Offer treats on a regular basis especially as a reward.
While you shouldn't overly force yourself upon your dog, it does need to get used to you. Sit and talk quietly while gently petting or massaging your dog. It is best to do this in an area where they, not necessarily you, are the most comfortable. They probably won't like it at first, but will get used to it. Some dogs sadly, never do though, and I'll talk more about them later.
Never allow friends to force attention on a mill survivor. Ask them not to look your dog directly in the eyes. It is not uncommon for mill dogs to simply never accept outsiders. Let your dog set the pace. If the dog approaches, ask them to talk quietly and hold out a hand. No quick movements. Ask that any barking be ignored. Remember that dogs bark to warn and scare off intruders. If you acknowledge the barking, you may be reinforcing it with attention. If you bring your guest outside you have just reinforced to your dog that barking will make the intruder go away.