Eosinophilic granuloma

[DrHadenough]

Has anyone had experience of this? My mare has developed a patch of little smooth lumps under her skin on the saddle area over the last 2 months. No change to skin/hair, not hot, not tender, not bothered about having the saddle on, no change in how she rides.

I googled it and found it was likely to be eosinophilic granuloma, and that the treatment was high dose steroids. I've had her to the vet twice, vet hadn't seen anything like it (young vet) initially, but then had read up and spoken to colleagues when she reviewed her, and agreed with my diagnosis. We had a long discussion and decided not to biopsy, as diagnosis fairly evident and not keen on potential scarring in saddle area. The vet said that we should wait a couple of months to see if it settles with cooler weather/ fewer flies, and if not then steroids.

I'm a bit worried that the longer we leave it, the less likely it is to settle even with steroids, but can't find any information about this online. It isn't bothering my mare at all, but apparently they can cause rubbing over time. Please does anyone have experience of this, and if so how long did it take to settle with/without treatment?

Apparently also known as collagen granuloma or nodular necrobiosis

I think my boy may have the same, sounds similar anyway although until now I had no idea it had a proper name, he's with me on loan and his owner explained them to me as a mild allergic reaction to insect bites, like a sort of hives? Like your mare's his are smooth, cold and under the skin around his barrel and saddle area and don't seem to bother him at all. And as he is now 20 and never had any particular treatment for them and is in rude health, no particular itchiness, I guess it's fair to say it's safe to just ignore them so long as they aren't causing an issue? I def wouldn't be up for lancing or steroids unless it really was necessary!

In his case they come and go fairly frequently though, do your mare's seem to be permanent? They're also much more prominent/frequent in summer, although again I've always put that down to flies bothering him more in the hotter weather? The only thing I do is try and be vigilant on the fly spray, he won't wear a rug or veil unfortunately so I leave him be but that probably wouldn't be a bad thing for your mare?

Thanks @maxelly, it does sound like the same thing. In our case they've been present continually for about 10 weeks now and are there all the time, although more prominent some days than others. They're different to hives (which she had once before, cause unknown but settled in a couple of days).

Apparently they're not sure what causes them, but they come up more in spring and summer, and the most likely cause is thought to be an allergy to mosquito bites. Info link. I did try a fly rug, but she was sweating up under it, so I took it off and have just been vigilant about fly spray. They're worse again this week, and I wondered if the heavy rain over the past few days has washed off the fly spray.

I've just noticed today, after a longish hack, that there's a bit of rubbing under the saddle cloth in the area where they are most dense, so I think I will have to try the steroids. Luckily she is young, fit, healthy weight and in regular work, so the vet thinks she's at low risk of laminitis from the steroids.