Has anyone's dog ever recovered from extremely elevated liver enzymes?

My dog has had extremely elevated liver enzymes that gradually started climbing and eventually topped out at six months with the ALT at around 600 and ALP at 7000.  He has had numerous blood tests, two ultrasounds, bile acid test and a negative Cushings test with no definitive answer as to why his numbers kept going up.  Last month the vet put him on Actigall and I was shocked that in 30 days his numbers dropped drastically.  His ALT is now at the top of normal at 104 and his ALP has dropped to 3900.  This is the first decline we've seen in six months and I'm not sure what to make of it.

Disna