Ryan is a behaviourist and ex-police dog trainer who is highly qualified in the theory and practice of dog training, and this book gives a good multi-step plan for owners of dogs that are problem chasers.
The book is quite thin, but it's useful and easy to read. It starts with basic obedience and the theory behind why dogs choose to chase. I particularly liked the bit where he describes chasing as being like playing for England in the World Cup, and then when the dog is just about to 'score the winning goal', trying to coax him away with the offer of a biscuit!
The book is aimed at controlling chasing that occurs 'out and about' - rabbits, deer etc. It's not aimed at people who are trying to train their dogs to live with other pets such as cats - although the information about prey drive will probably also come in very handy for people who are trying to do this, it would have been nice to have an extra chapter specifically on this topic.
There is no discussion of prey drive in different breeds - as a sighthound owner, I did wonder if Ryan has mostly worked with relatively energetic dogs such as terriers and herding breeds. Some of the information particularly about teaching dogs to retrieve was quite hard work with my dogs! They tend to flip from 'high drive' to 'asleep' with only one change in gear!
None the less, this is a really valuable book that I would definitely recommend to anyone who can't be 100% sure that their dog won't disappear over the horizon if a suitable target presents itself.
The final chapter deals with using a citronella spray collar with lemon juice as an aversive to produce a 'disgust' reaction. It is fenced with warnings about all the things you should do before resorting to this, which is good news, but I am not entirely comfortable about this section. I would certainly not try anything like that myself with the aid of a book, I'd want proper professional advice from a specialist used to training with dogs of a similar breed.