from what i have learnt recently, there are different types of fighters, some apparently fight due to underlying injury, a limited few might fight due to boredom (dogs around them not fast enough) and others are just instinctive to not let others near them.

obviously with the injured ones when the injury is fixed and they are pain free they wont continue to fight.
Other dogs might be best to have the re-broken in/ refreshed or possibly take them coursing which appears to be a highly recommended way to help them come good again.

Other than that its a very dog to dog situation, on another forum i have heard people mentioning blinkers so the dogs cant see to the side making them concentrate on the bunny in front.

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