As some of you know, I have a tack shop, and one topic that usually generates some spirited discussion is thrush and what products do, or don't work to eliminate it.
What most people do not realize is that thrush is a blanket term for a variety of funguses that can infect the hoof. Not all funguses (errrr - fungi) are sensitive to the same chemicals. The infections are all pretty easy to identify by the black moist "muck" with that very distinctive pungent odor that accompanies the fungi. The fungi are anaerobic, meaning they exist best in oxygen deficient environments. So the goal here is to make sure that the feet are generally clean and dry. If something is not working, try something else. Please, please do not give up on the thrush as a minor chronic ailment and ignore it. Thrush most certainly can develop into a life threatening infection. Many horses do have sort of a low grade chronic case that does not seem to cause much harm, but if this is the case for your horse, be sure to monitor it on a regular basis. If the thrush gets progressively worse and/or causes lameness, seek veteriany intervention. If the infection makes it through the frog or the sole and gets into the blood stream, you have a major problem on your hands that is very difficult to correct, if not life threatening.
There are many over the counter products available to combat an active thrush infection...some have a copper naphthenate base, such as Kopertox and Thrush-XX (you know - that awful green stain); some have a clear salicylic acid (aspirin) base such as Cowboy Magic and Thrush Stop; some have a gentian violet (the purple stuff) base such as Thrush Buster. Other formulations contain chlorhexadine, formaldehyde, and other antifungals. Because of the staining qualities of some of these products, they are not terribly inviting to use on a regular preventative basis, others are kind of tough on the skin. The best preventative is to clean the hooves regularly. Some mild weekly preventative alternatives to try (and again I stress, that if something isn't working - try something else !!!) include flushing the hoof with hydrogen peroxide, or the spraying on of a 10% chlorine solution (ie: 1 part chlorox to 9 parts water), or a soak in a lysol bath (1/4 cup to 1 gallon of water), or a scrub with an Oxyclean solution (1 tbs to 1/2 gallon of water) . These are all relatively pleasant to use, and are quite economical and can be kept by the cross-ties or in the wash area. I would not suggest any of these substitutes if you have an active infection going on - these are more of a regular preventative care. If you care to do any of these more than once a week, they are all pretty safe.
Your farrier should make it a point to help you address eliminating thrush in your horse's feet. If your horse has pads on, many farriers will do a preventative pre-treatment for thrush with one of the over the counter products as moisture will become trapped in the packing under that pad, making it a prime enviornment for fungus to develop. Another related problem is white line disease. White line will benefit by having the area opened up slightly (and the removal of shoes) to facilitate cleaning the area to kill the infection. If white line gets out of control, you will definitely have to have your farrier assist you with a more aggressive treatment which may also include resectioning the hoof wall and soaks with more aggressive products such as Kleen Trax or White Lightning soaks.
There must be other handy hoof hints out there - bring them on !!!!!