I imagine it probably depends on the disorder in question? What are you thinking of? :)
My mare has ERU (commonly know as Moonblindness) which is an autoimmune disease. I find that keeping her on high levels of anti-inflammatories (in her case, I use MSM) really help. I also like to use a mixture of Devils Claw and Yucca for painkilling and extra anti-inflammatory "oomph" during a winter episode and in small doses daily on sunny summer days.
I use bute for summer time episodes since they are usually more severe and the DC+Y is therefore slightly less effective.
There is a product in the UK called NAF D-tox. My panacea for all ails!
It really works with autoimmune problems. Years ago I had a horse with a viral infection - goodness knows what it was because they were unable to find out what.
This was ongoing and it resulted in him getting Cauda Equina, when the immune system turns on the nerves resulting in paralysis. Fortunately I realised what was happening, bloods sent off for testing for CA, of which if positive the only cure is euthanasia.
Whilst waiting for the test results my old vet sent me some D-tox to try. The change around in the horse was phenomenal - within a couple of days he was perkier, eating better and although he always dragged his toes behind, he was in full health within 8 - 10 weeks.
D-tox has been used for Moon Blindness with a great deal of success.
It would take me several hours to put up all that I have used it for - only to say horses, dogs, sheep, cattle and humans, all with good effects. Kicks a cold into touch.