Hi,
Are you referring to a case book in the format that would be accepted for a certificate? If so I can give you a few pointers as I've just written one.
I'm doing the equine CertAVP and had to write a case report on 10 cases, each involving a different body system e.g. orthopaedics, dermatology, respiratory, repro, cardiovasular, gastro-intestinal, ophthalmology, professsional conduct, welfare and biosecurity (for the B modules).
The required format was as follows: introduction, case hx, clinical exam, differential diagnosis, diagnostic tests, definitive diagnosis, discussion to include references. I wrote mine in word but I don't think the programme you use matters. What's most impoertant is the structure of the report which should also clarify a logical thought process or work-up of the case.
Hope this is of some help x
Forgot to add, photos are ok to add in too.