Dollieh Sanctuary

I know that people who do repaints on Breyer horses often use colored spray primers (like black) as their base coat. In terms of the hair - it's probably synthetic and the ability to dye that stuff is hit or miss from what I've seen or tried. Some people have luck using sharpy pens to "dye" the hair, but you can risk it coming off and staining any doll that comes in contact with it. If possible your best bet is to remove the old hair and re-root the horse with the color you want.

As for taking them apart....good luck on that one, I don't think they were really designed for that but you might want to google something like "barbie horse disassemble"

Yea, I'm not sure how those horses are "rooted" so it's hard to make suggestions. You might try looking for some horse customizing groups. While they mostly seem to work with Breyer horses, some of them may dabble in the other type and have some advice.

I've got one of those HUGE horses they make for the Target Our Generation dolls and those have big gaps in the neck where the mane is inserted so it will be pretty easy for me to pry it out and re-root it.

One thing you could try that some of the Breyer people do is just cut the hair off as close to the body as you possibly can and then get some tibetan mohair in black and make a new mane/tail out of that. You could paint the old hair stubble black and then glue down the new mohair over it to hide it.

Like I said, check some sites that are about model horse customizing and you might find some great ideas.

I made a couple of centaurs out horses like that. I rerooted and repainted the horse. Here is a tut. on how I made a centaur. The tail is just hair folded in half to makes a loop. The maine is attached on a band.
viewtopic.php?f=14&t=3040

Those centaurs are just amazing. The Mohair idea sounds good to me. It would look good and be easy...