Instructions
Every time your dog looks like he is even going to start eating bark, raise your voice and give him a firm "No" command. You must be consistent with this, doing it every time your dog approaches the bark.
Watch your dog to make sure you are there to catch him eating bark every time he tries. Do not allow the dog to sneak eating bark behind your back. By reinforcing the fact that eating bark is a bad thing, the dog will eventually learn he should not eat it.
Take your dog out specifically to work on training her not to eat bark. Take her close to her favorite tree or whatever she likes to chew on, then reinforce the fact that she cannot eat it by saying "No" when she tries. Keep these sessions short, no more than about 5 to 10 minutes.
Praise the dog every time he makes a conscious decision not to eat bark, like if he approaches it but then turns around. You can give him a treat, a few pats on the head, or just a "good dog." This praise will reinforce that good dogs don't eat bark.
Always follow a "No" with a positive end to the training. Never leave a negative feeling hanging over the training if you want your dog to learn not to eat bark. You must emphasize that you are only displeased when the dog actually eats the bark, otherwise she will only see you as upset in general.
How to Stop Dogs From Eating Bark
Dogs have funny taste sometimes. Your furry companion probably has several eating habits that range from gross to downright weird, but you have to remember the little guy really does not understand what the big deal is unless you show him. Training a dog to stop eating strange objects, such as bark, can be a little bit of a challenge. However, if you send a clear message and are persistent, your dog will eventually stop his bad habit.