If you happen to find yourself in the Newberg area, I would suggest stopping in at either the WILCO farm store and asking for Dave or the Farm Gro Supply store and asking for Lottie (I am 99.9% sure that is her name - she is the owner of Farm Gro). Either would be able to offer some wonderful suggestions/recommendations. The area, overall, is very "horsey" - I miss it terribly - but I have been gone from there long enough that I am not comfortable throwing out names/places as I'm not sure who is/isn't still open and under the same management, kwim? Actually, the folks at any of the WILCO stores (there are several locations scattered about that area) should be great for referrals/ideas - if Rick Flannigan is still managing for them (I think he was at the Oregon City store last time I talked to him), he's another great brain to pick and get you hooked up with the right network of folks.
Are you looking for full or self-care arrangements? Yahmill County (McMinnville area - probably 45 minutes to the close side of the Portland metro - I could get from my place to my grandmother's in Aloha in about that time or, clear out to St. Helens in just under an hour because I could avoid the main traffic - like I said, it's going to depend a lot on where you end up -- the St Helens/Warren area is nice if you end up working on that side of Portland) has boarding offered through their fairgrounds and, from what I have seen and heard, the facility is pretty darn nice - but it's all self-care.