Make sure the horse is getting enough water. Feed him alfalfa cube soup or beet pulp soup or just a dab of molasses in water, whatever he really likes. Soak his hay, or at least wet it down. Softer hay is probably good.
If the owner is in fact an idiot and can’t or won’t put oil in the mash or switch to a softer hay, they probably won’t take any of the other suggestions either. The vet may be a dolt, or may just have had it with this client.
Anyhow, also realized I don’t totally understand the situation. Has the horse been impacted for 30 days? Really? what are the symptoms? Has he been tubed? Or is this a questions about aftercare?
If the horse has been impacted for 30 days I would be getting another better vet out like 28 days ago and the horse would have been tubed.
My very healthy big mare had a spate of impaction colics, 4 over the course of six months from one December to June. It was a cold winter and spring, and I think she stopped drinking, and she may have developed a dislike to her heated water bucket (slimy, too warm, stray electricity, who knows). I responded by giving her a second water bucket near her hay, and during the period she seemed at risk, giving her lots of soups. Nowadays, if I think she hasn’t drunk enough overnight I give her a soup. I also stopped using the heated bucket, and for her I stopped alfalfa hay because I felt like there was some correlation that I didn’t want to risk investigating more.
I called the vet for tubing on one of these colics, but the other 3 just got Banamine and me sleeping at the barn
and they resolved just as fast as the tubing.
So sometimes it can be something very subtle that comes on, and you really have to investigate the horse and most importantly get water into them.
Make sure the water is clean and changed and scrubbed daily.