crusty armpit skin? Any ideas?

Question
Hello,

I have a 19yo Newforest X, chestnut mare who I have owned for 10yrs. The whole time I have had her she always has scurf/crusty bits in her front armpits (where the skin is creased). The winter coat is much worse then the summer. (I don't know what she is crossed with but some people think TB or Arab, her coat is VERY thin in the summer). It seems to be getting worse as she has got older ie: if I don't clip her winter coat it gets really scurfy there even if she has been in the field, which makes me think it might not be to do with her getting sweated up when I ride?

She lives out alot in the summer (with no rug) and is stabled more in winter (turned out with rug), With the winter coat it tends to get alot worse and become scabby, although there is never bleeding or raw skin. The fur gets matted in a sticky/crusty stuff. On a good day it looks OK, but if you part the fur it will still be flaky skin.
In the summer coat gets a bald patch there but stays dry and does not go scabby.She does get quite sweated up when I ride and when its hot I hose her after, in the winter I just brush the area. I have tried different girths incase they where rubbing to no avail. When it is very bad I ride bareback, because I worry the girth will make it worse. I do not put products on it, just hibi scub once when it was very bad. The only thing that makes any difference is when I clip her in the winter, it looks much better, but is still bald/flaky skin as with her summer coat. It is no where else just the armpits.

Sorry for the long post!  It not a serious issue as I said she has had it for years and is otherwise very healthy but I was just interested in any opinion you may have on what it might be caused by and any tips to help it?

Thankyou very much :)

Answer
Emily,

Your description makes me think this may be an allergy issue since it occurs year round.  What she could be allergic to is anyone's guess unless you get her tested.  Just requires a vet visit and a blood sample but might be helpful.  This is an area where dirt and other material can get trapped when the horse rolls or lays down.  I would suggest you keep the area clipped in the winter time to keep the accumulation of debris in the area down.  It sort of sounds like exzema which is often allergy related.  You seem to be following the right course with it if it's not bothering her by keeping the girth away from the area and trying to keep it clean.  Unless you are going to get her tested to see if it's an allergy I can't offer you much help.  If her skin is generally kind of dry you could add some oil to her diet, vegetable or canola oil is better than corn oil because corn oil has been shown to cause inflammation in horses guts.  If you haven't had a vet look at it this might be the time to do it to find out what is causing the issue before you do anything else.  Let me know what you decide to do and if a vet looks at her what the vet's opinion is.  I hesitate to put anything on something like this for a horse that is out because it will tend to trap crud in the area if you use a balm/oil/etc.  

Lyn