Inquisitiveness is a sign of intelligence and a curious dog is great fun to train. A combination of prevention and cure is the best solution.
Remove the Temptation
Put food waste in an outside trash can located in a place where he won’t come into regular contact with it, such as in a locked shed or an inaccessible part of the yard. Dogs are opportunists and often raid the garbage simply because a smell caught their nose. If the first time they raid the bin has the reward of food, they’ll see the bin as a food source.
Dog Proof the Bin
Either invest in a dog proof trash can, such as a pedal-operated version or one that has a lockable lid, or modify your own trash can. You can do this by simply placing a heavy object on the lid. Raiding the garbage is self-rewarding, as the dog typically finds something to eat or chew inside. Stopping him from getting to the reward is an effective method of behavior modification.
Monitor his behavior and identify patterns and gestures that give away his intent. For example, he may check out the contents of the bin as part of his morning routine in the same way he sniffs around the floor when he enters a new space. He may wait for you to throw away food leftovers before poking his nose where it doesn’t belong. By understanding why and when he raids the garbage, you will be better able to prevent this behavior.
When you spot him nudging the garbage can or sniffing it, call his name. When he focuses on you, call him to you. Distraction is an effective technique because it shows the dog that there are always other options. Dogs are habitual and if he’s had even one rewarding experience with your garbage, he’s likely to try and try again.
Give him a food treat as soon as he comes to you when called after distraction. Make sure you don’t give it to him when he’s next to the garbage. It’s essential that the dog can distinguish between the acts of sniffing the garbage and coming to you, otherwise he may think that you’re rewarding him for going in the garbage. Repeat this process for a week, or for as long as it takes for him to reliably come when called.
Instead of calling his name after distracting him, replace his name with the “leave it” command. Reward him with a treat if he focuses on you for five seconds or more. Over time, your dog will learn that when he hears “leave it” he is expected to stop what he’s doing and that in doing so, a positive outcome occurs. Once he’s learned this command, you can use it for all sorts of scenarios, not just garbage raiding.