Nose: nasal discharge in Horses (Equis) | Vetlexicon
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Nose: nasal discharge

ISSN 2398-2977

Synonym(s): Dirty nose, snotty nose


  • Abnormal respiratory secretions emanating from the upper or lower respiratory tract, eg serous, mucus, pus, blood; also from upper gastrointestinal tract, ie digesta, milk.
  • Cause: bacterial, viral, fungal upper or lower respiratory tract infection; neoplasia; trauma; EIPH; severe equine asthma (SEA); gastrointestinal tract obstruction; oronasal fistula; cleft palate.
  • Signs: unilateral or bilateral discharge containing serous, mucus or purulent material; blood, food, aspirated meconium.
  • Diagnosis: endoscopy, radiography, fluid/aspirate analysis, head CT.
  • Treatment: depends on etiology.
  • Prognosis: good to grave depending on cause and duration or primary disease.
Print off the Owner factsheet on Epistaxis - nosebleed to give to your clients.

Presenting signs

  • Serous, mucoid, mucupurulent, purulent, blood or food.
  • Unilateral or bilateral.
  • Acute or chronic.
  • Intermittent or persistent.
  • Associated disease.

Age predisposition

  • Foals <1 week: congenital defect, eg cleft palate Hard/soft palate: cleft.
  • Foals 1-2 weeks old: bacterial or viral pneumonias.
  • Foals 3-6 months old: bacterial or viral pneumonia; Rhodococcus pneumonia Rhodococcus equi infection.
  • Yearlings/young adult horses: infectious respiratory diseases (mainly viral infections, but possibly primary bacterial, eg Streptococcus equi ssp equi, and mycoplasma infections or combinations of these infections).
  • Adults >7 years old: severe equine asthma Severe equine asthma.
  • Adults: neoplasia, sinusitis, sinus cyst, ethmoid hematoma, fungal disease, eg guttural pouch mycosis, fungal sinusitis.

Breed/Species predisposition

  • Arab Anglo-Arab: those affected by inherited immunodeficiency - more susceptible to adenoviruses or Pneumocystis carinii Pneumocystis carinii and other bacterial agents.

Cost considerations

  • Depends on underlying etiology.

Special risks

  • Depends on underlying etiology.



Foals - discharge containing food

  • Aspiration of material as a result of a pharyngeal defect often results in milk or food appearing in the discharge as well as creating a lower respiratory tract disease.
  • Congenital defect:

Adults - discharge with food

  • Cleft palate (diagnosis delayed) Nose: discharge 05 - food.
  • Pharyngeal or esophageal dysphagia:
    • Guttural pouch mycosis Guttural pouch: mycosis:
    • Botulism Botulism.
    • Grass sickness Grass sickness.
    • Choke Esophagus: obstruction.
    • Acute onset dysphagia due to damage to one or more of the 9th (glossopharyngeal), 10th (vagus) or branches of the 11th (accessory) cranial nerves (that run with the vagus nerve) which together form the pharyngeal plexus.
    • Massive epistaxis due to concurrent damage to other vital structures in the guttural pouch Guttural pouch: mycosis 06 - endoscopy.
    • Ipsilateral Horner's syndrome Neurology: Horner's syndrome or neck pain.
    • Streptococcus equi ssp equi infection with involvement of pharyngeal and/or retropharyngeal lymph nodes.
  • Gastric reflux associated with colic Abdomen: pain - adult.


  • Guttural pouch mycosis.
  • EIPH Lung: EIPH (exercise-induced pulmonary hemorrhage).
  • Ethmoid hematoma Ethmoid: hematoma Nose: epistaxis - ethmoid hematoma.
  • Trauma:
    • Iatrogenic, eg nasogastric intubation Gastrointestinal: nasogastric intubation.
    • Head trauma Head: fractures: traumatized sinuses may fill with blood and drain slowly → post-traumatic epistaxis (latterly with dark blood) may remain for a month or so.
    • Traumatic rupture of the ventral rectus capitis muscles that lie beneath the base of the skull within the guttural pouches, eg following falling over backwards.
  • Nasal or sinus mycosis, occasionally primary sinusitis: traces of blood at the ipsilateral nostril accompanied by copious, unilateral purulent and usually malodorous discharge.
  • Sino-nasal neoplasia: intermittent, low-grade, ipsilateral epistaxis plus more prominent signs including unilateral purulent nasal discharge, nasal airflow obstruction and facial swelling.

Bilateral discharge - foals - respiratory tract disease

Bilateral discharge - adults - transmissible infectious disease

Adults - other lower respiratory tract disease

  • Pleuropneumonia (shipping fever) Lung: pleuropneumonia - bacterial (pleuritis).
  • Severe equine asthma (SEA) Severe equine asthma.
  • Post-infectious pulmonary disease: prolonged low-grade respiratory signs following an acute respiratory tract infection.
  • Aspiration pneumonia, eg following esophageal obstruction.
  • Interstitial lung disease: alveolitis and fibrosis of the interstitial pulmonary tissues ( → restricting lung expansion).
  • Lungworm Lungworm infection (Parascaris equorum in weanlings and Dictyocaulus arnfieldi in adults).
  • Foreign bodies.
  • Neoplasia Respiratory: neoplasia.

Adults - other upper respiratory tract disease

  • Rostral (1st-3rd) maxillary cheek teeth abscessation (facial swelling or a facial sinus tract is more common).
  • Sinusitis (paranasal sinus empyema).
  • Dental sinusitis (infection of apices of 3rd-6th maxillary cheek teeth).
  • Primary sinusitis.
  • Sinus (maxillary) cyst.
  • Sino-nasal neoplasia.
  • Nasal foreign bodies.
  • Sino-nasal mycosis (mycotic rhinitis).
  • Guttural pouch empyema/chondroids or mycosis.

Predisposing factors

  • Depends on underlying etiology.


  • When nasal discharge is present, the normal physiological mechanism for recycling respiratory secretions by swallowing is insufficient.
  • Upper respiratory tract inflammation → production of excessive secretions plus absence of the usual clearance mechanism, ie loss of the cilia that normally transport secretions caudally towards the nasopharynx for swallowing.
  • Lower respiratory tract disease → large volumes of secretions are transported from the lower airways by the mucociliary escalator or coughed up into the nasopharynx or nasal cavity (also through the oral cavity).


  • The few drops of bilateral watery discharge present at the nostrils of most normal horses is a serous nasal discharge. This secretion largely emanates from the nasolacrimal duct, ie is composed of tears.

A drop of serous discharge placed between two fingers will not stretch into a "string" if the fingers are separated, indicating a low protein and mucin content.


  • Discharge is clear but relatively viscous because it contains high levels of a mucoprotein (mucus), eg as occurs early in a viral respiratory tract infection (usually with upper and lower respiratory tract involvement).
  • With a mucoid nasal discharge, the increased volume of nasal discharge contains large amounts of mucin proteins produced in response to inflammation of any part of the specialized respiratory mucosa, from the distal bronchiole up to the nasal cavity.

A drop of mucoid secretions placed between two fingers will stretch out into a string when the fingers are separated.


  • Composed of mucoid respiratory secretions containing lower amounts of leukocytes, which are usually neutrophils with bacterial infections.
  • Neutrophils are also the predominant infiltrate even with uncomplicated viral or fungal respiratory infections, and even with allergic respiratory inflammation.
  • The degree of purulence can vary from secretions that are almost mucoid in nature with just a hint of purulence, eg in a severe equine asthma (SEA) case that is in remission following some weeks of environmental control, to secretions with so many leukocytes that they are almost completely purulent.


  • Very viscous secretions, with the viscosity partly due to their neutrophil DNA content.
  • Purulent secretions are opaque, varying from white, yellow to green in color, with their coloration sometimes dependent on the type of bacteria causing the underlying respiratory inflammation. In some cases, purulent respiratory secretions will be malodorous due to the role of anerobic bacteria in the underlying process.

Do not always associate purulent respiratory secretions with bacterial infections, remember that uncomplicated viral, eg equine influenza, infections can also induce temporary (for a week or so) purulent respiratory secretions. In addition, fungal, eg mycotic rhinitis/sinusitis, infections also induce purulent and often malodorous respiratory secretions. Allergic respiratory tract inflammation seldom induces purulent respiratory secretions, more usually mucopurulent secretions.

Nasal discharge with food

  • The presence of food in equine nasal discharge (which is almost always a bilateral nasal discharge) often indicates the presence of pharyngeal or esophageal dysphagia (inability to swallow) or a communicator between the oral and nasal cavities, eg oronasal fistula, cleft palate.
  • Sometimes, food material alone may appear at the nostrils.
  • In horses with colic, a nasal discharge containing food usually indicates the presence of gastric reflux due to a build up of fluid in the rostral small intestines and stomach, and additionally, due to loss of esophageal tone in cases of equine grass sickness.


  • The presence of blood at the nostrils is most commonly due to trauma or exercise-induced pulmonary hemorrhage (EIPH) Lung: EIPH (exercise-induced pulmonary hemorrhage). Being a pulmonary disorder, EIPH should in theory cause a bilateral epistaxis, however because such small volumes of blood (<50 ml) are often present at the nostrils (most of the pulmonary hemorrhage is swallowed), the epistaxis may be unilateral.
  • The presence of chronic unilateral epistaxis is most commonly due to unilateral upper respiratory tract lesions such as progressive ethmoid hematoma (PEH) Ethmoid: hematoma or to traumatic sinus hemorrhage such as caused by a fall or a kick to the head.
  • Even though guttural pouch mycosis is invariably unilateral, the high volume of blood lost from the major vessels it contains causes the nasopharynx to fill with blood and thus usually leads to bilateral epistaxis.


Client history

  • More than one in-contact horse suddenly affected with respiratory disease suggests transmissible infectious disease.
  • Previous bout of viral or bacterial respiratory disease suggests chronic post-infectious syndrome.
  • Seasonal or environmental associations: SEA Severe equine asthma, SPAOPD.
  • Recent prolonged transport: pleuropneumonia.
  • Trauma.

Clinical signs


  • May be serous (normal), mucus, mucopurulent, purulent Nose: discharge 03 - purulentNose: discharge 06 - purulentNose: discharge 09 - purulent, bloody Nose: epistaxis - ethmoid hematomaNose: epistaxis - severe hemorrhage, or contain food Nose: discharge 01 - foodNose: discharge 04 - milkNose: discharge 05 - food.

Unilateral discharge

  • A consistently unilateral nasal discharge usually indicates inflammation that is localized to one side of the upper respiratory tract, rostral to the pharynx, eg paranasal sinusitis.
  • Ipsilateral (same side) submandibular lymphadenitis is supportive evidence of unilateral, upper respiratory tract inflammation.
  • Absence of coughing and/or tachypnea is also useful (but not absolute) evidence of the absence of pulmonary disease (see below).

A small percentage of horses with pulmonary disease are reported by their owners to have a chronic unilateral nasal discharge.

  • Unilateral epistaxis is common with EIPH due to the small volume of hemorrhage involved.

Bilateral discharge

  • Usually indicates the presence of lower airway disease. Respiratory secretions that have passed into the nasopharynx via the mucociliary escalator, or by coughing, either flow down both nasal cavities and/or are swallowed.
  • Tachypnea is confirmatory evidence of lower airway disease.
  • Pulmonary disease where the primary lesion involves the lung parenchyma (which has few cough receptors) and does not greatly involve the airways, eg a pulmonary abscess Lung: abscess that intermittently drains into the airways, may induce a bilateral purulent nasal discharge without coughing. Coughing can also occur with upper respiratory tract disorders.
  • Pharyngeal disorders such as strangles Strangles (Streptococcus equi infection) or profuse guttural pouch discharges can also cause a bilateral nasal discharge.

Consider all cases of respiratory infection to be potential strangles cases, until bacteriology of nasal or preferably, of nasopharyngeal swabs has shown otherwise.

A significant proportion of horses with pulmonary disease associated with the production of excessive lower respiratory secretions, or cases of EIPH, have no nasal discharge, as they appear to swallow all of the abnormal and excessive respiratory secretions; although this may not be readily apparent on examination.

Other clinical signs

  • Focal facial swelling, maxillary cheek teeth infection, maxillary sinus cyst, primary sinusitis Paranasal sinus: facial distortion - cyst, neoplasia, trauma.
  • Submandibular lymph node swelling: sinusitis, strangles Strangles (Streptococcus equi infection), guttural pouch disease, viral infection.
  • Malodorous discharge: fungal infections, dental infections, some cases of primary sinusitis.
  • Halitosis: gangrenous pneumonia, pharyngeal obstruction, dental disorders.
  • Cough: lower respiratory tract disease.
  • Epiphora: obstruction of the nasolacrimal duct due to intra-sinus swelling/inflammation.
  • Increased respiratory effort.
  • Signs of systemic disease:
    • Fever.
    • Malaise.
    • Anorexia.
    • Polyarthritis (in foals).
  • Signs of colic (with nasal discharge containing food).

Diagnostic investigation


  • Endoscopy to locate the source of discharge:
    • Nasal cavity.
    • Sinus Paranasal sinus: hemorrhage - endoscopyParanasal sinus: normal drainage angle - endoscopyParanasal sinus: pus - endoscopyParanasal sinus: sinusitis 07 - sinuscopyParanasal sinus: mycotic plaque - endoscopy.
    • Ethmoid Ethmoid: normal turbinates - endoscopyEthmoid: hematoma 05 - endoscopy.
    • Nasopharynx Nasopharynx: hemorrhage - endoscopyNasopharynx: food material - endoscopyGuttural pouch: retropharyngeal lymph node abscessation - endoscopy.
    • Guttural pouch Guttural pouch: empyema - endoscopyGuttural pouch: chondroids 03 - endoscopy.
    • Trachea Trachea: mucopus - bronchoscopyTrachea: RAO 01 - bronchoscopy.
    • Esophagus Esophagus: obstruction - endoscopy.


Advanced imaging


  • Paired serology, two samples 10 days apart.
  • Virus isolation from blood (buffy coat), eg EHV 1 & 4.
  • Virus isolation from nasopharyngeal swab, eg influenza Equine influenza, equine viral arteritis Equine viral arteritis (EVA).



Confirmation of diagnosis

Discriminatory diagnostic features

  • History.
  • Clinical signs.

Definitive diagnostic features

Gross autopsy findings

  • Findings will depend on etiology.
  • Maxillary sinusitis Head: transverse section - pathology.
  • Pleuropneumonia Lung: septic pleuropneumonia - pathology.
  • Pulmonary abscessation Lung: abscess Lung: abscess - pathologyLung: abscesses - pathology.

Histopathology findings

  • Depends on etiology.

Differential diagnosis

  • See etiology.


Initial symptomatic treatment

  • Refer to specific disease entities.




  • Depends on etiology; varies from good to grave.

Further Reading


Refereed papers