Eating Animal Carcasses

I've been taking my Border Collie for long walks in a nearby field for about a year now. Recently I have caught her eating the dead carcasses (mice, birds, etc.) that she comes across in the field. I tell her to drop it as soon as I discover her eating one but she has managed to consume several before I caught up to her. She does well with the drop it command but I can't always keep up with her. I'd really hate to change to walking her on a leash as she loves romping and playing so much. We live in the country and it is almost an impossibility to keep her so confined. I know it can't be healthy for her to eat these dead things as they have to be full of diseases and parasites. Dead animals are a common occurence out here so I can predict that this will happen regularly. Is there a way I can train her not to eat the dead animals when she discovers them?

However, proofing a dog on poisoned food (or dead rats in a field or doggie poop) is a long process requiring a lot of work. I will not go into it in detail (I will leave that for your nearby professional trainer) but if you decide to undertake it (or even the "drop it" command), several points of advice will aid the process dramatically.

1) Start your dog on inedible objects for the "drop it" command.
2) NEVER, EVER (repeat as many times as necessary) let your dog actually swallow and eat the food while training this behavior. If the dog gets a reward just once, it will offset all of your work up to that point. The bonus of food may outweigh any negative reinforcement you give and it will be one step forwards, eight steps back.
3) Make sure you are capable of taking food from your dog, once it is in his mouth. If you are too shy about wrenching Bandit's jaws open and diving in his mouth or the dog won't let you, you need to make sure that this is a weapon in your arsenal before ever moving on to poison-proofing your dog. You need to go back and establish the alpha dog status in your household - preferably with you being the alpha.
4) The leash corrections will be a good start in the process, but eventually your dog will have to go off leash - if your goal was to let the dog roam the fields, or back yard, or whatever. However, I am a firm believer in negative reinforcement only when it is disassociated from the handler (except in establishing alpha dominance). If the dog learns to associate negative corrections with you, you end up having a distrustful dog or one that resents your corrections. IF, however, you can learn to disassociate yourself from the correction, the dog learns that a bad consequence will happen if it tries that behavior, but it is not coming from you. (Picture this - a child burns its hand on the stove and learns real fast not to do such behavior. OR, a child is playing around a stove, mother sees the kid and then places the kid's hand on the hot part; the child still learns real fast but also begins to resent mother).

To disassociate the correction and you, you need a long line (preferably 30 ft. or so), a cool, disinterested attitude, and a quick reaction time. In brief, you correct the dog without the dog knowing it. The fishing line (or light cord) replacing the long line works when the dog figures out the presence of the line.
5) Some people have tried making the meat unpalatable. Unfortunately, this only trains the dog to avoid those morsels that smell like, bitter apple, for example. Some people swear by the addition of unscented agents, but I have the feeling that if some dogs can smell unscented LSD, they can discriminate whatever stuff you put in it.

The object is to get the dog to take food only from its bowl or your hand (preferably your left hand) - not to try and discriminate between good stuff and bad. The dog must trust you to tell it what is OK and should have theBorder Collie self-control to wait before being allowed to eat. The biscuit-on-the-nose trick is a good beginning for this.

In the end, poison proofing your dog takes weeks and months of hard work. It takes lots of dog-to-owner trust, and patience on the part of the owner/trainer. This helps a family if the steak if left on the counter, helps the dog from getting tapeworms from eating rotting field rats. It is also very important with guard dogs (which Border Collies are not, with rare exceptions) but in today's world of whackos and contentious neighbors, it is not a bad thing to teach your dog. It just may save his life.