FYI, there are a couple of alternative ways to take a horse's temperature:
on board temperature thingies (I think Roger R. makes one?), and a thermometer
that you use by placing it on a human's forehead.
I've tested the latter and it is consistently comparable to the rectal, but
(at least mine was) always 3 degrees lower. You slide it under the saddle
in a VC and it beeps in about 10 seconds when its done.
What I'm waiting for is a combination HRM, temp, and Timex GPS.
Roger--are you working on this?