Question on Hoof Rot

Justin wrote to ask about rot in his horse's hooves. "Hi. What is the best thing to do (about) the rotten smell coming out of my horse's hoofs? Not all of them smell bad, all the time but I'm thinking I need to do something."

Hey Justin, the smell is from a condition called Thrush, or it could be a pre-Thrush condition - meaning if left untreated it could turn into thrush. Thrush is caused by an anaerobic organism, meaning an organism that thrives without air. Air is the enemy of thrush, and sometimes cleaning out the rot to expose to the air will get rid of it for a time.

If left un-checked, Thrush can eat away the surface of the hoof - the part you see when you clean the feet as well as the softer frog - the spongy V shaped portion of the hoof. Hooves degraded from Thrush can actually lame up a horse, but I haven't seen this except for only the most egregious of neglect cases.

In the photo of the hoof at left you can see the white powdery material in the V crevice of the frog and the sole.  The black substance is thrush developing and it will be stinky.  Not as bad as my boot socks, but not smelling good in any case.  Pick the debris and manure out with a hoof pick and as you are scrapping much of the rot should come out too.

The biggest environmental factor for horses getting thrush is manure in the stalls. Removing manure, raking the stall and cleaning the feet can keep your horse(s) relatively Thrush free. Horses will generally clean their own hooves to some degree as they move around and their hooves hit the ground, expand and contract, and the process of their feet hitting the ground can often dislodge manure and it will drop away. If moving on hard or rocky ground, that ground can also chip away at material left in the hoof. However, the manure and wet soil can get lodges in the crevice of the frog and sole and then requires someone to pull it away using a hoof pick.

Good, routine farrier care is important for sound feet including any considering any comments and recommendations from your shoer/trimmer about Thrush in their hooves. Did you farrier say something to you about cleaning the feet more often? 

When you get that nasty Thrush smell and see evidence of black, decaying sole or frog, there are several things you can do to treat the hoof after cleaning it. There are commercial products to treat Thrush like Kopertox, Thrush Buster, No Thrush and many others. You can also use common household bleach or iodine. I use Kopertox for the most part. I don't use it that much, and when I do really only one application is necessary.

Kopertox's active ingredient is a diluted form of Copper Naphthenate, and as other commercial Thrush treatments, Kopertox tends to dry out the hoof. I try not to use Kopertox at least a week before my shoer comes so the feet aren't as hard as Superman's kneecap and therefore hard to trim with a hoof knife.  I live in the desert where you would think the feet wouldn't get Thrush because of the dryness, but we have our rainy seasons and it doesn't take long for wet soil and the Thrush organism present in the soil to make it's arrival on the hoof and particularly in the clefs of the frog. Checking your horse's feet once a day isn't too often.