Why are my horse's lower legs swollen with mud fever?
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Overview
Lower legs can swell with mud fever because the skin on the legs has become irritated, inflamed or infected, often after wet, muddy turnout. It can also happen alongside pastern scabs, sore skin or a reaction to damp conditions, so there may be more than one reason the legs look puffy.
It’s worth checking the whole leg rather than just the swelling itself, because the skin, mud exposure and how your horse is moving all help give a clearer picture.
Things To Check
1. Check whether the swelling is on one leg or several, and whether it’s the same on both sides.
2. Look closely for scabs, cracked skin, redness, oozing, soreness or crusting around the pastern and fetlock.
3. Feel the leg for heat, and note whether your horse is uncomfortable when you touch it.
4. Check whether the swelling seems worse after turnout, standing in wet bedding or coming in from muddy fields.
5. Watch how your horse walks. Any stiffness, shortness of stride or reluctance to move can be useful to note.
6. Look for scratches, small cuts or feather contamination that could be making the skin more vulnerable.
7. Check the stable, field and grooming routine to see whether the legs are staying damp for long periods.
Common Causes
The most common cause is mud fever itself, where irritated skin on the lower leg becomes inflamed and the area can swell a little or a lot.
Wet, dirty conditions can make the skin more vulnerable, especially if the legs are repeatedly getting damp and muddy.
Scabs, skin soreness or a mild secondary infection can also add to the swelling and make the leg feel warm or tender.
Sometimes what looks like mud fever is made worse by another skin issue, such as insect irritation, rubbing or a minor knock, so it’s sensible to keep an open mind.
Less commonly, marked swelling can be linked to a more significant infection or deeper inflammation, particularly if the leg is very painful, hot or the horse is unwell.
What To Do
Keep the area as clean and dry as you can without over-washing. Gentle, sensible cleaning is usually more useful than repeated scrubbing.
Remove caked mud carefully so you can see the skin, then pat the leg dry thoroughly. Avoid picking scabs off, as that can make the skin more sore.
Reduce time in deep mud where possible, and consider whether turnout, bedding or washing routines are keeping the lower legs damp for too long.
Monitor the swelling, skin and comfort level day by day. A quick note or photo can help you spot whether things are improving or getting worse.
If the swelling is mild and your horse is otherwise bright, sensible home management and close observation are often the first steps.
When To Contact A Vet
Speak to your vet if the swelling is sudden, severe, hot or painful, if your horse is lame, if there’s discharge or spreading sores, or if the leg doesn’t start to settle with sensible care. It’s also sensible to get advice if your horse seems dull, unwell or the problem keeps returning.
Products That May Help
Keeping muddy legs and the surrounding area clean and dry is often part of good day-to-day management with mud fever. This collection may be useful if you’re looking for practical support for routine leg care and muddy turnout.
Related Questions
How do I tell mud fever from mud rash or rain scald?
Should I wash my horse’s legs every day in muddy weather?
When should swollen legs in a horse be checked by a vet?
Atlas is here to support owners with practical, easy-to-understand guidance. It is not a substitute for professional veterinary advice. If you're concerned about your animal's health, symptoms worsen, or something doesn't feel right, contact your vet.