Horse Skin Infections — Bacterial vs Fungal, and What Treats Each

Bacterial skin infections in horses, such as rain scald and mud fever, tend to cause crusty scabs and matted hair, while fungal infections like ringworm cause circular patches of hair loss with less crusting. Bacterial cases often respond to antimicrobial washes such as Pendistrin-SH, while fungal cases need antifungal treatment such as a miconazole-based shampoo.

Medically reviewed by Dr. Dinesh Moliya, B.V.Sc & A.H, M.V.Sc & A.H — 16 years of clinical veterinary experience.

Skin infections are common in horses, especially with wet weather and muddy turnout conditions, but bacterial and fungal causes need different treatment approaches. Mistaking one for the other is one of the most common reasons a skin issue drags on longer than it should.

Common Bacterial Skin Conditions

• Rain scald (rain rot) — crusty scabs along the back and rump, linked to prolonged wet conditions
• Mud fever — affects the lower legs, often from standing in wet, muddy ground
• Both are typically caused by bacteria that thrive when skin stays wet for extended periods

Common Fungal Skin Conditions

• Ringworm — circular patches of hair loss, often with minimal crusting
• Spreads through contact with infected horses, shared tack, or grooming equipment
• Can look similar to early rain scald, which is why differentiating matters

How to Tell Them Apart

Bacterial infections tend to produce thicker, matted crusts that can be painful to remove, often concentrated on the back or lower legs depending on exposure. Fungal infections more often present as cleaner circular patches with less crusting and variable itch levels. When in doubt, a vet can confirm with a simple skin scraping or culture rather than guessing from appearance alone.

Treatment Approaches

Bacterial skin conditions typically respond to antimicrobial washes that clean and disinfect the affected area while allowing the skin to dry out and recover — Pendistrin-SH is formulated for this kind of use in horses.

Fungal conditions instead need an antifungal approach, most commonly a medicated shampoo containing an active such as miconazole, applied consistently over several weeks rather than as a one-time treatment.

Bacterial vs. Fungal Skin Infection at a Glance

Frequently Asked Questions

What causes rain scald in horses?

Rain scald is caused by bacteria that thrive when the skin stays wet for prolonged periods, most commonly during rainy seasons or with inadequate shelter.

Is ringworm in horses the same as ringworm in dogs?

The fungal organisms involved can overlap across species, and ringworm can spread between horses, other animals, and people in shared environments.

Can I tell bacterial and fungal skin infections apart just by looking?

Not always reliably — both can look similar at a glance, which is why a vet skin scraping or culture is the more accurate way to confirm the cause before starting treatment.

How long does rain scald take to clear?

With consistent drying and antimicrobial washing, most cases improve within 1–2 weeks, though severe or repeated cases may take longer.

Can wet weather alone cause a fungal infection?

Wet weather is more strongly linked to bacterial conditions like rain scald; fungal infections such as ringworm are more commonly spread through direct or indirect contact with an infected source.

Is mud fever the same condition as rain scald?

They’re related bacterial skin conditions, but mud fever specifically affects the lower legs from standing in wet, muddy ground, while rain scald typically appears along the back and rump.

Does clipping help with either condition?

Clipping affected areas can help both bacterial and fungal treatments work more effectively by allowing better airflow and easier application of topical treatment.

Related Reading & Products

• Related: Fly Strike in Horses — Causes, Wound Care & Prevention
• Related: Horse Wound Care 101 — What to Clean, Cover & When to Call a Vet
• Shop: Pendistrin-SH
• Shop: Miconazole & Chlorhexidine Shampoo