02/14/2023
BLOODWORK
Some of those hoof cases that confound us, that just seem to have all these nagging problems that won't go away despite good diet and environment, things like the persistent thrush, chronic thin soles, hoof soreness/sensitivity, abscessing, wall quality issues, could simply be suffering from undiagnosed metabolic problems.
I want to be clear that while many of us assume a metabolic horse will be a chunky horse with a cresty neck and fat pads, thin horses can be metabolic as well. In fact, early PPID (Cushing's) often presents itself as a horse becoming a harder keeper, experiencing topline loss, or overall losing condition. Don't assume your horse isn't metabolic just because it's not fat!
To rule out metabolic issues, the first port of call is your vet. Have your vet pull some bloodwork to check that the horse's insulin and ACTH levels are in range. The Tufts Endocrinology Department has a great PDF about current practices, and ECIR is a wonderful resource for blood draws, so you can make sure your management leading up to the appointment will give the most accurate result on the blood test!
Just a note that this time of year (January through June) in the Northern hemisphere, ACTH levels are naturally lower. This can produce a lot of false negatives for early PPID/Cushing's cases - and can make people assume their horse isn't metabolic when the test simply wasn't sensitive enough for them!
During this time of year, ask your vet about a TRH stim test. It is much more sensitive and can help find those early cases of PPID that might be causing hoof issues but nothing else yet. Their coat might look fine, they might seem okay in all other aspects, but their feet are struggling a little.
The stim test is when your vet pulls a baseline ACTH blood draw, then injects a thyroid stimulating hormone, waits a bit, and pulls ACTH bloodwork again. This can help with comparing the pre-stim to the post-stim result to see how the pituitary gland is responding to the injection.
If you're struggling with hoof issues and can't seem to figure out why, bloodwork may be very telling!