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


Discharge from One Nostril (White, Yellow or Green)


Drainage from one nostril is usually indicative of a disease process originating in the head, as opposed to one originating in the lower airway or lungs. One sided discharge is commonly associated with diseases of the sinuses and nasal passages.

Small amounts of clear discharge from equine nostrils is considered a normal finding. White discharge is commonly associated with viral or allergic processes. Yellow discharge tends to be associated with bacterial infection. Green nasal discharge can indicate feed material within it. One-sided yellow nasal discharge is not usually a result of an infectious (contagious) disease, but it can be. Discharges with bad odor usually indicate a disease process that involves tooth or bone and is usually a sign of more serious disease. Dental disease is a common cause of sinusitis.

  • Code Orange

    Call Your Vet at Their First Available Office Hours
    • If this problem seems severe and has come on suddenly.
    • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.
  • Code Yellow

    Contact Your Vet at Your Convenience for an Appointment
    • 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
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your role


What To Do

Assess your horse's general health using the Whole Horse Exam (WHE), paying particular attention to whether or not there is a fever, and/or a cough, and whether there swelling or discharge from the face, jaw or throat. Share your findings and concerns with your vet.

There is a small chance that the underlying condition is contagious (far less than if the discharge were from both nostrils). Wash your hands with antiseptic soap before touching other horses. Do not share tack or equipment with other horses, until your vet has seen the horse and determined the nature of the problem.

your vet's role

Your vet may treat the problem symptomatically, or attempt to make a diagnosis. Because true one-sided nasal discharges usually are a sinus or nasal passage problem, we often use radiography and endoscopy to help us make a diagnosis.
Questions Your Vet Might Ask:
  • What is the horse's age, sex, breed and history?
  • Does the discharge have an odor?
  • Does the horse's appetite and attitude seem normal?
  • Does the horse have a cough?
  • When did you first notice this?
  • Do you see swelling below or behind the jaw, drainage or discharge from areas around the face?
  • Do you notice a cough?
  • Does the horse have a fever?
  • Are other horses on the premise acting sick?
  • Has the horse (or any other horses in contact with this one) been exposed to other horses from off p

Diagnoses Your Vet May Consider

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

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Treatments Your Vet May Recommend

A way to resolve the condition or diagnosis. Resolving the underlying cause or treating the signs of disease (symptomatic treatment)

Very Common
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Author: Doug Thal DVM Dipl. ABVP