Stan - here is one possible scenario for Stella - and I speak from bitter experience:
The tick "collar" you used on her started an allergic reaction - the hair fell out around her face and head. You removed the "collar" expecting the reaction to stop and begin to heal. Sometimes it doesn't work that way - especially if a horse has a compromised immune system. The allergic reaction may have continued, as the chemicals in the "collar" were absorbed by her system - this is how the whole body tick protection works. Therefore, until all of the offending chemical leaves her system, the allergic reaction will continue, and may even get worse as more and more of the skin becomes itchy and inflamed.
Now - add to that (this is what set my mind off). You said something about her rug was made in China. Some of the dyes that are used in Chinese manufactured goods have some of the same chemicals that may be upsetting Stella's system. This might help explain why the skin is so irritated and inflamed around her shoulders and her armpits.
Allergic reactions can be a PITA to deal with. I had one horse that was actually allergic to the sun. He was a great horse, but would break out in hives as soon as the days became long enough for the sun to set off a reaction. The hives were barely detectible - even the vet had a hard time finding them. They were itchy, causing my horse to rub himself raw - which at one point caused a skin infection to set in. Daily baths with antibacterial soap were in order, along with oral antibiotics. I'm sure the soap stung on the raw areas, but the poor horse was a trooper, thought he couldn't seem to help dancing around a little when I would gently scrub the particularly raw areas. If he hadn't been such a nice guy, I would really have been in trouble.
Now for the kicker - when he was having a "breakout," anything thing that rubbed his skin would cause a new nasty patch. We couldn't use a halter (is that what you call a collar?) on him, or a fly sheet - absolutely nothing that would rub on the skin. Hubby made a halter for him out of a soft cotton lead rope - and we would only put it on long enough to give him his daily bath, then take it off.
I can sympathize with what you are going through with Stella. If we didn't love our horses so much, we would just sell them down the road to let someone else deal with them. It would be so much easier...but...we do love them, so we have to help them though it, don't we!
Thanks Dee. I did expect the tick collar to have some ongoing effect and that is as you mentioned it is how they work. The Chinese made cover, Yes we have had clothing which tested high in damaging chemicals and a TV programme on the issue advising several washes before using. I buy my shirts from Sheplers and generally get US made but now and again they are made in China.
No cover on her now she has to brave the cold. I noticed tonight (left work early) she had rubbed one of her shoulders even with the neem oil so the itch is still there.
She goes to rub her face on the water trough, I still have some control when I growl she stops, well untill my back is turned.
I have been going over a site that goes into the grasses in NZ and the issues caused by myco toxins. It is very interesting and a number of symptoms have been displayed. So As I said earlier not much hair for me to pull out.
The tick collar is a common denominator as she had one last year same brand and before the first collar I used tick tags. One in her tail and one in her main. Problem first appeared on her rump and neck then worsened over time. Again the comon thing was the collar.
However I have gone back to the start when she had the flue and assume she never fully recovered and that was most likely the beginning. My good intentions with tick control, and the increasing likely hood of myco toxins. Its a mine field
As well my land and the PH level we do get mushrooms that is a sign the PH is low which helps myco toxins etc. So a few tones of lime to go on.
I need to stop rambling. So to every one who has helped with experence and possable cause and options to try Thankyou all. It may appear my mind is made up but it is not, all options are being considered and tried and that includes back to the vet.
Stella is settled a little I notice she was checking my breath for longer than usual. Must be the garlic
And she who must be obeyed went on a cattle drive today
As mormal spelling mistakes are my property and I take a dim view of any one stealing them