Is there scientific evidence that castration affects hunting ability? As emilyoliver said, it's hard to measure as you can't make a control situation for each individual dog - you can't measure his hunting ability before castration and ability after AND eliminate all other variables as a cause of change in behaviour. You can only compare dogs to each other, and some are just more genetically driven than others. So measuring what might or might not be affected by castration in terms of hunting ability is incredibly hard to to do.
Is it the case that working dogs are not castrated because it is the long held belief that they shouldn't be, rather than it being actually known is a bad idea? I can see that if you don't have any evidence one way or another, not castrating is the best and least risky option, because it still keeps all options open. But that convention in itself is not proof.
