No washes. It has been a while, but it was layer painted, I believe the base coat is Rhinox Brown mixed with Castellan Green, then there is Camo added, I believe some Balor Brown... The specific colors may be relevant info to some, but the concept is much easier (I mix mostly like an artist would, by what feels right and looks right). Just be mindful of your mixes, and keep it dirty as you progress from a green/brown up to a sickly yellow/green. If it ever gets too clean then you know you need to dirty it up a bit. A hint from an artist perspective, to make a color dirty, use it's opposite color on a color wheel. in small amounts, the opposite color will move the shade/hue toward grey or brown slightly, thus a crisp vibrant red mixed with a tad of green becomes a bit darker and muted. Well these color lessons are for another thread I think,
The pale horse then contrasts with the color yet still adds to the concept of death/sick. As always when painting a horse, look at pictures of a real horse that fits your concept color so that you are not guessing what real looks like.