explain exactly what you have in your dog TO a trainer and see if they are willing to take on a dog such as you describe.
I have only trained agility, my requirements were, no dog aggressive dogs allowed near any other dogs or running a course with dogs inside the fenced area. IF the dog proved to be to much of a distraction or problem, they are just not allowed. I could nt put other dogs or people in harms way .
BUT that is agility, not obedience, there are many instructors out there that will deal with dog/human aggressive dogs and comfortable doing it.
Danger Danger vom Kleinen Hain aka Masi
"Angel" Jakoda's Bewitchen Sami CD OA OAJ OAC NGC OJC RS-O GS-N JS-O TT HIC CGC
"Angel" Steinwald's Four x Four CGC HIC TT
Harmonyhill's Hy Jynx NA NAJ NAC NJC RS-N JS-N HIC
Jakoda's Jagged Edge