What you see. The starting point for addressing any equine health related issue is your observation.


Sores, Crusts or Scabs on Outside of Lips or on Muzzle


Crusts and scabs outside the lips and on the muzzle can be caused by a variety of disease processes. Importantly the list of possibilities includes Vesicular Stomatitis, a potentially contagious, reportable viral disease. For this reason, this observation should be taken seriously.

Traumatic injury and bites and stings (especially venomous snake bite) can cause visible scabbing and skin damage. Sores and cuts around the corners of the mouth can be caused by injury from the bit. Contact dermatitis from a chemical or medication can cause blistering and scabbing of the lips and muzzle. If the areas affected are unpigmented (pink) skin, then photosensitization or sunburn should be considered.

  • Code Red

    Call Your Vet Immediately, Even Outside Business Hours
    • If you feel the problem is severe or has come on suddenly.
    • If the results of the Whole Horse Exam (WHE) in the resting horse indicate fever (Temp >101F/38.3C) or heart rate greater than 48 BPM.
  • Code Orange

    Call Your Vet at Their First Available Office Hours
    • If you consider this a chronic and relatively mild problem that is not changing rapidly.
    • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.
You also might be observing
Very Common
Less Common
more observations

your role


What To Do

Assess your horse's general health using the Whole Horse Exam (WHE), paying particular attention to attitude and appetite. Assess their mouth (wear gloves), looking for anything abnormal.

Seek veterinary assistance immediately if this sign is accompanied by depression, loss of appetite or fever. Check your other horses carefully for similar signs. Wear gloves when handling the horse, and isolate the horse until a diagnosis is made, and VS is ruled out.

What Not To Do

Do not ignore the possibility of Vesicular Stomatitis, a reportable viral disease that can affect people too.

your vet's role

Your vet will consider the likelihood of Vesicular Stomatitis. if that disease is a consideration, it will affect the procedures significantly. Your vet will consider the horse's environment and management, and a good physical and oral exam will help identify the cause of the lesions.
Questions Your Vet Might Ask:
  • Are the affected areas white haired/pink skinned or dark?
  • Is the horse's attitude and appetite normal?
  • What does the horse eat?
  • Is the horse kept on pasture?
  • When did you first notice this problem?
  • What are the results of the Whole Horse Exam (WHE)?
  • Are the affected areas white haired/pink skinned?
  • Is there anything else new in the horse's environment?
  • Are other horses in the group affected?
  • Have you given the horse any medications?
  • Have you introduced any new feeds recently?

Diagnoses Your Vet May Consider

The cause of the problem. These are conditions or ailments that are the cause of the observations you make.

Very Common
Less Common
more diagnoses

Author: Doug Thal DVM Dipl. ABVP