How does a pony suddenly become so grass sensitive?

[Not_so_brave_anymore]

I took on a pony as a companion (for my other pony, not for myself) in March. No previous history of laminitis. She came to me fat, and unfortunately I've not got any weight off her at all. She'd been living in all winter, with turnout in a sand school before she came to me.

She was fine on half an acre of old grass through the dry spring. I then put her on a smaller strip when her weig crept up a bit. Even so, she went a bit pulsey, so I pulled her straight off the grass altogether (I'm lucky to have a well fenced concrete yard, so she's not just been shut in). Soaked hay for 3 weeks, unsoaked hay for another 3 weeks. Tried her on the grass for 1 hour this morning (early morning, cloudy day, smallish barish electric pen). She was fine when I brought her in, but when I checked her 3 hours later her feet were warm and I could feel a ghost of a pulse again.

I feel like I've been so diligent (the other pony, who it turns out has cushings but has only just started medication, has been managed less strictly and has had no hint of laminitis) but at the same time I kinda feel like I've broken this pony! How/why does a pony suddenly become so sensitive?

 

[windand rain]

Insulin resistance a trace of sugar triggers it in some but is reversible to a point if you can get her weight off so you can feel her ribs so a diet of 1.5% of her weight in forage with powdered vitamins. Soaked for a minimum of an hour in hot weather and rinsed well before feeding. soak a bit longer in colder weather but washing it off is vital as the sugar just sits on the surface

 

[Not_so_brave_anymore]

Insulin resistance a trace of sugar triggers it in some but is reversible to a point if you can get her weight off so you can feel her ribs so a diet of 1.5% of her weight in forage with powdered vitamins. Soaked for a minimum of an hour in hot weather and rinsed well before feeding. soak a bit longer in colder weather but washing it off is vital as the sugar just sits on the surface

Can this come on so suddenly? I should have said, the pony is 12. I'm already weighing hay carefully at 1.5%. I guess I'll have to go back to soaking. Should I give up on the idea of grass turnout until her weight is down?

 

[ycbm]

The problem is probably the Cushings and you may have to give up the idea of grass forever. I have known people have to PTS dry lot kept horses because of it.

Yes, it can come on that quick, I had a bigger horse with EMS who couldn't stand an hour at grass without getting raised pulses.
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[Pearlsacarolsinger]

The problem is probably the Cushings and you may have to give up the idea of grass forever. I have known people have to PTS dry lot kept horses because of it.

Yes, it can come on that quick, I had a bigger horse with EMS who couldn't stand an hour at grass without getting raised pulses.
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It's the other pony who has Cushings!

OP, I would have this pony tested for Cushings too, because it is such an easy (if expensive) win if Prascend is indicated.

 

[PinkvSantaboots]

If the pony is fat it's probably ems so you need to get weight off as you can reverse the ems with diet and exercise, but while it is present you risk laminitis.

Do you exercise the pony at all?