I'm a long-time daily user of fleeceworks pads, and woolite has killed my pads in the past. I since learned that the leather therapy is really the way to go - that and use a saddle pad under your fleece to minimize the times you have to wash it.
I washed my Thinline sheepskin pad several months ago, and according to their website's instructions, I used Ivory Snow with a front load washing machine. Also, I made sure to air dry the pad. I have a Mattes sheepskin pad as well, and that has held up beautifully through lots of washes and I've mostly used Leather Therapy and Woolite on it.
Woolite isn't good for Sheepskins, as you now know. We actually developed a Sheepskin Shampoo made specifically for washing (our) Sheepskin Saddle Pads. http://rittlings.com/product/wool-wash-shampoo/
With this shampoo our saddle pads can be machine washed. Just make sure you use cold water and slowly air dry them away from any direct sunlight. Should work for any other Sheepskin Saddle Pad too, but we can only be certain about our own pads...
The reason you need a special shampoo is because the sheepskin requires lanolin for the wool and leather, and an effective detergent for the major sweat/dirt that saddle pads acquire (unlike, say sheepskins used for babies).
My Mattes pad can be washed and dried in the front load machines, no problem and no special soap. The Fleeceworks could only take front load washer and even then the main seam gave out. If I can find someone to repair it, I will continue to wash and probably start drying it. The fleece doesn't mat down if you put in dryer. No shrinking problem.
weekly washing the in summer and monthly washing in the winter.
Wow, mine takes so damn long to dry that I've taken to washing it pretty much only if I'm showing or if it looks awful. But since I use it over a square pad, it also doesn't get particularly dirty. Plus they don't exactly smell great when they're drying and there's a limit to how much I want to torture others in this house.
I too had a Fleeceworks pad disintegrate also after washing with Leather Therapy. I had bought it at Dover and got a refund. After that had great success with a Mattes pad washed in Leather therapy. Used the detergent and the conditioner. Worked great.