Well as im in my final year of accounting degree was kind of hoping there might be niche market in horsey accounting where I get to sit in an office looking at pretty ponies rather than being in some box ten floors up in a city anywhere.
As an Accountant of 30 years experience I hate to break it to you but you will spend the vast majority of your career staring at spreadsheets & powerpoint presentations. I did have one job though where F1 drivers used to park their private jets outside my window.
The closest I get to horses in my job is my monthly copy of 'Equestrian Business' magazine appearing on my desk
Although I do have a big name rider and lots of vets amongst my clients, I'm still not a 'horsey' accountant.
Back to the OP - depending on the issue you need help/advice upon, then a rural/agricultural specialist might be the best idea. In all honesty, any decent accountancy practice should be able to apply their existing knowledge to the equestrian sector.
I am a Chartered Accountant and I have a very boring job, which has flashes of brilliance when I get sent to the US.
Accountancy means that you can work 9-5 (if you choose the right sort of accountancy and don't get involved in any of that tax stuff) earn loads of money, can afford a nice horse and lorry and then go competing at weekends. I like having a boring well paid job and be able to do what I like in my spare time.
Not specifically equestrian but my younger bruv is a rural specialist at an accountancy practice in Wiltshire - works with lots of farms and I think they do some trainers / studs as well. He likes it as he gets to go out and visit lots of clients, and also paid to do things like go to Bath and West... it's a tough life.