What the Muck Is That?

Even seasoned equestrians are sometimes baffled by horse ailments and eccentricities. Each week we will investigate one such conundrum in “What the muck is that?” This week… skin conditions.

Equine Disease Quarterly (April 2001) lists the most common skin lesions:

  • Papule–a solid skin elevation
  • Pustule–a skin elevation with an inflamed base that contains pus
  • Vesicle–a membranous and usually fluid-filled pouch
  • Bulla–an elevation containing watery fluid
  • Wheal–a flat, burning, or itching lesion
  • Macule–a patch of discolored skin
  • Nodule–an abnormal, knobby protrusion

Being able to identify which lesion is present and where on the body it’s located could mean the difference between a friendly (and free) phone call with your veterinarian or a pricey exam fee. Now let’s talk about four of the most common skin conditions.


  1. Fungal infection
  2. Highly contagious
  3. Round, crusty patches that when removed leave skin red and scaly
  4. Can be passed through tack, brushes, even the dirt in your paddocks for up to 1 year
  5. Loves dark, warm, moist conditions
  6. Usually resolves within six weeks to three months

What do we do?

  • Isolate the infected horse immediately.
  • Clip hair around infected areas and dispose in a SEALED bag
  • Wash with anti-fungal shampoo specifically designed for ringworm
  • Wash your hands with anti-fungal soap after EVERY treatment
  • Use sunlight and soap to disinfect all tack and equipment
  • Use chlorine bleach to sanitize wash stall, box stall, cross-ties, fences, posts, and wooden gates

Rain Rot


  1. Bacterial infection
  2. Lives in soil
  3. Undernourished or immune suppressed horses most at risk
  4. Believed to be contagious
  5. Small bumps progress into circular scabs with matted hair

What do we do?

  • Detach scabs during bath to reduce pain
  • Wash with medicated shampoo
  • Properly dispose of scabs in a SEALED bag
  • Keep the horse as dry as possible and protected from biting insects
  • Disinfect all tack and equipment
  • Penicillin injections may be needed



  1. Can be caused by bacteria, fungus, parasites or allergies
  2. Found in horses exposed to moisture for long periods of time
  3. Causes inflammation, redness, and ulceration
  4. Can progress into infection if skin “cracks”

What do we do?

  • Clip the area
  • Wash thoroughly once a day
  • Towel dry
  • Keep the horse as dry as possible
  • Disinfect all boots, wraps and grooming equipment
  • Contact your veterinarian for bloodwork or antibiotics with severe cases


  1. Systemic reaction to allergen
  2. Possible triggers could be feed, insect bites, pollen, molds, compounds found in dewormers, antibiotics, bedding, heat, light, or even exercise
  3. Localized, soft, pitted swellings

What do we do?

  • Systematically rule out possible triggers
  • Veterinarians can perform “interdermal testing”
  • Antihistamines or steroids might be needed to control reaction until trigger is found or to help speed recovery

Have you ever said, “What the muck is that?”  Send us your questions and we’ll do our best to answer!

Go Riding!


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