
It is Tardak, and from what I understand it's an injection of progesterone. I'm not sure how it works, but I can tell you I've a friend who had her bullmastiff injected to see what effect it would have - the dog developed severe behavioural issues and went on to try and kill another dog (he was well raised btw). He's fine now, but it's been a long road for the owner with TTouch work, behavioural work and so on.
When I was talking to her about it a while back, she told me how she was discussing the dog's issues with a vet - he said that progesterone wouldn't have been responsible for the aggression, to which she said something along the lines of "haven't you heard of PMT?" :D The injection is, as I understand, supposed to suppress testosterone - but I don't see how it can, it can only mask it as the testosterone is still being produced and is not blocked in any way. There is now a drug that blocks it, designed as a male contraceptive for dogs, but I don't think it's available to the public. I could be wrong.
That aside, she needs to establish if his behavioural quirks are really due to being entire or are just his personality. Wandering off could just be his way - my dog was neutered at 9 months to stop him wandering off and up to strange dogs (I was naive :rolleyes:), it made no difference whatsoever. He's an independant dog, and is much better now due to lots of training. Scent marking might be helped depending on his age - that was another reason for having my boy done, he used to pee up everything in PAH and it stopped immediately - but he was young, and it wasn't a habit yet. I believe the older the dog gets the less likey it is that marking can be stopped. Again, I could be wrong!
Personally I don't see how castration would help with the agility - some dogs do go completely bananas, it's a case of training them to be calmer and focusing their excitement. I've never heard of an example where it's hormonal, in dogs or bitches. Both my youngest and oldest girls go nuts in agility - the oldest (6, spayed) has self control trouble and tends to just run and muck about, and the youngest (15 months, entire) gets so excited at the moment that she can only do one jump before she's trying to climb my leg and bite my elbow :D