To stop a dog from lunging at the fence, increase socialisation by exposing your dog to different environments, people, and animals, as this helps dogs become more confident and less prone to anxiety or aggression. Arrange controlled interactions with other dogs and people, gradually exposing your dog to different situations while maintaining a positive and calm environment. Utilise desensitisation techniques by gradually exposing your dog to stimuli that trigger fence guarding behaviour, such as other dogs walking by the fence, starting at a distance where your dog remains calm and rewarding them for maintaining composure. Over time, gradually decrease the distance while continuing to reward positive behaviour. Implement management techniques, such as limiting your dog's access to the fence line by creating barriers or using visual deterrents like frosted glass or wooden panels, to prevent visual triggers and reduce the opportunity for fence guarding behaviour to occur. Positive reinforcement training is also effective, where you reward your dog with treats, praise, and affection when they display non-guarding behaviour, such as staying calm when another dog or person passes by the fence. Create a positive environment by providing toys, puzzle feeders, or interactive games to keep them mentally stimulated and focused on positive activities, redirecting their attention away from the fence.