I'm not really sure how you can say that...obviously the temp of an animal will change over the course of the day, and in differing environments etc. but one can't just take a single picture (as referred to in the earlier post) and make a determination about the health or soundness of the horse overall. For example: my own horse always has one hot ankle...because he has sh*tty ankles....but that's normal for him. A person who has never seen the horse, looking at him one time would think perhaps that he had some new injury rather than decades of abuse.

Think of it differently. Thermography isn't used to make a determination about overall health or soundness of the horse.

It's simply a diagnostic aid. Used to try and find areas that are abnormally warm. It is far more sensitive to detecting and pinpointing physical warmth than palpation.

If something is found, the diagnostician then determines how to proceed: additional diagnostic workup for a newly suspected problem; change in management (or not) for current known injury.

Example: I would use thermography on a young racehorse being considered for purchase. The horse moves well enough, lameness exam normal, palpation feels normal, pre-purchase routine rads are normal.

But thermography after all that shows that one tendon definitely appears hotter than the corresponding tendon.

Thermography has alerted to a potential problem that needs further investigation. Now do an ultrasound.

Something we never would do routinely prepurchase, and something the other diagnostic aids (rads, hands, eyes) didn't give any indication was needed.

And because something might be going on in there, don't work the horse - or purchase it - until we find out if it's anything to worry about.

None of the above required previous baseline thermographic images.

In the case of your horse with his old ankle injury that always lights up, you still don't need baseline images, you just need a history to know why.

But if you want to use thermography to help in management of that chronic injury, do this:

Measure the differences in temperature gradient between the bad ankle and the contralateral limb on the same day at the same time (include in same image), and compare the variability of the temperature gradients week to week (not the images).

For example, if the horse is trotting sound enough for that horse, and moving well enough for that horse, but has that known old ankle injury that lights up significantly when you look at the horse with thermography - maybe consider increasing the bute dose, or increasing the daily cooling sessions, to decrease the chronic inflammation in that ankle.

Because thermography is showing you that even though the horse is not clinical, there is inflammation there.

Then see if there is an improvement (decrease) in the temperature gradient between the sore ankle and the contralateral ankle after a week of that.

Don't compare to previous pictures (hard to do, due to inability to duplicate all the confounders), but DO compare the measurable temperature gradients between the bad ankle and the contralateral ankle (the machine should be able to do this for you)

Here's a site provided by Phystech if anybody wants to see some good thermography images of horses. It's pretty cool. www.savingthehorse.com