would anybody know where i could buy a jacket for my dog with "in training" written on it.  my dog is a big dog and when i take her out for her socialising training i would like everybody to know she is in training so they dont think i have gone totally nuts and understand that she is working at the moment.

You could easily make a light cloth jacket and one of the many screen printers [ usually one somewhere near every town, look up in yellow pages] will be able to put on it what ever you desire, alternitively, ask at the Guide Dogs for the Blind as all their training dogs wear them
Pauline

looks like you will have to make your own.......just picked up this for you.............
Information About Assistance Dog Jackets or Jackets for Dogs that are in Training

Jackets for dogs for the above purpose are only available from the organisations that train dogs for specific purposes and are only available if you and your dog are enrolled on the scheme run by that organisation. There are strict regulations about the training that a dog must have undergone before being allowed to go into Public Places where ordinary dogs are not allowed. Dogs under training must be accompanied by a trainer employed by the organisation.
Assistance Dogs and their owners have to pass a test to a very high standard, having first followed a training programme by the organisation in question.

Pauline

If you have an ink jet printer they make iron-on paper you could print the words on and apply them to a vest like this. Or you could use fabric paint and stencils to paint the words on. I have done this to luggage to make it easy to identify and it's tough stuff.