
There seems to be dozens of different organisations offering diplomas in animal psychology and a lot of these are correspondence courses - at quite a cost as well. Typing pet psychology, training, diploma into yahoo will give you the results.
However, why not ask your vet if they know of any courses. I'm sure the Dick Vet in Edinburgh do one, they certainly have behaviourists and doggy psychologists because I've used them. I would think you would need a course with practical work where you can work with difficult animals and observe their behaviour. You might get a certificate at the end of a correspondence course but it doesn't mean you would be good at working with the animals in reality. Lots of local colleges run animal courses as well, might be worth checking out.
I'm not trying to put you off, have a look on the net and see what's on offer. I should imagine there is loads of work out there for animal behaviourists.
CG :)