I have a mare who’s a very good doer; she lives out, on restricted grazing (but in a large area so she’s still moving!), with a muzzle on during the day, though it’s true she’s aren’t being exercise much due to a lack of time (exams…which will soon be over thankfully!).
But she has, despite this regime, definitely gained weight in the last few weeks. So would it be acceptable to trim a ‘bib’ of sorts on her jugular area so she loses more heat so will hopefully burn more calories keeping warm? Obviously she ought to be better when she’s doing more work, but in the mean time until I have time to ride, I don’t want her to develop laminitis and wondered if this might be a solution?
N.B.: I live in the UK and, whilst it’s about 21C / 71 F in the day, it’s going down to about 7C / 44F at night.
ETA - she’s healthy, no EMS/PPID and hasn’t yet laminitis so far but I want to keep it that way…
While it’s fairly common to bib clip natives and turn out in winter to aid weight loss in the uk, 7degC is within the horses thermoneutral zone so the horse won’t expend any extra energy.
Clipping won’t help her lose weight. 
and your nighttime low temp is ideal ambient temp for horses, so not at all cold for her.
When my Shetland got overweight, the vet prescribed a medication…L-Thyroxine or something? Worked to help pull her back from mild laminitis.
I think that’s for a slow metabolism? Interesting anyway but I think I’d prefer to do it without medication. That said I’ll mention it to my vet when I next see them because I’ve not heard of that being done. Thank you 
If she is out 24/7, she should wear the muzzle 24/7. And No clipping will not help with her weight.
15-20 min on the longe will help keep her metabolism up.
