Tis the season to get muddy, unfortunately. There are several issues that can arise with horses in muddy fields.
The most serious of these comes about when horses are fed their hay in mud. Because horses poop indiscriminately, there is a good chance there will be feces mixed in the mud. These conditions are perfect for bacteria to grow which your horse will then ingest with its hay. This bacteria can cause serious health issues. If your horses must stay in muddy fields, be sure and hay them in an old water trough or hang hay nets, or do something to keep their hay mud free.

The second issue that can arise with mud is a condition known as scratches or or pastern dermatitis. This appears as very pink areas on the back of a horse’s pasterns or if severe, yellow, scabby crusts. To get rid of them, you must first remove the horse permanently from the wet environment. Clip as much hair off as you can, wash the affected area with a Betadine scrub, and dry it with a towel. Last apply a product that contains both an antibacterial and an anitfungal. (Mixing, Desitin, Neosporin and Monastat works pretty well)

Thrush can also be a muddy pasture problem. Hoof walls that are continually wet become porous. This allows bacteria in. Thrush is recognized as black, smelly, slimy stuff in the frog of the foot. Several products are out there that treat thrush successfully. Sugar mixed with Betadine scrub can be a cheap and effective way to clear this gak up.

Though not specifically a mud problem, with excessive rain can also come rain rot, or dermatophilosis. Rain rot can appear as large crust-like scabs, or small 1/4 inch matted tufts of hair. There is usually dozens of tiny scabs that have embedded hair and can be easily scraped off. Underneath the scabs, the skin is usually (but not always) pink with puss when the scabs are first removed, then it becomes gray and dry as it heals. This is a problem that is especially prevalent with winter coats still on and excessive rainfall. Rain rot will not occur without the causal organism being present. The organism is carried on the horse, who has it in his skin. A horse who has this organism in his skin may or may not be affected. It is good practice to have individual grooming tools for each of your horses to avoid spreading this organism. (if you can’t you can bleach them or lysol them heavily in between uses.) We like to use a heavy coating of MTG on rain rot horses (and dang we see this condition a lot!). There are many other things out there that are effective also. In very severe cases, an antibiotic may be necessary. For rain rot treatment….

1. Keep the horse in a dry, clean area that is very well ventilated. Give the horse protection against biting insects. Separate the horse from any others that also have rain rot.

2. Use an antimicrobal shampoo that lathers well. Vigorously lather the horse, let sit for 10 minutes, then rinse. Continue this for daily for 1 week.

3. Remove all scabs that are present. This is usually painful for the horse, so be gentle! The best way I have seen to remove these scabs is to temporarily moisten them (so they become soft and easy to remove). Be sure to dry the horse immediately after scab removal.

4. Coat the affected areas with MTG (or whatever other product you choose)

These conditions are manageable with a little extra effort.
If at all possible, keep run in sheds clean with a dry layer of bedding. Hopefully your horse will choose to stand there rather than emulating Pumba!