Progressive ethmoidal hematoma

Veterinary advice should be sought before applying any treatment or vaccine.

Progressive Ethmoidal Hematoma

Progressive ethmoidal hematoma (PEH) is a locally destructive, polyp-like mass which forms in the horse's nose or sinus. The mucosal capsule splits intermittently, resulting in bloody discharge from one or both nostrils. Hematomas can grow quite large, often to the point where they cause decreased airflow through the affected nostrils, resulting in respiratory difficulty and facial deformity.

Most horses present with repeated low-grade bleeding from one nostril. Nasal bleeding is not related to exercise and the discharged blood is not fresh. Between nose bleed episodes, dirty nasal discharge is often seen. Performance horses tend to develop noisy breathing.


Reduced nasal airflow
Intermittent nosebleeds
Unilateral or bilateral, malodorous nasal discharge
Foul odor
Exercise intolerance
Abnormal or difficulty breathing
Facial deformity


  • History
  • Clinical signs
  • Physical exam
  • Endoscopy of the upper airway
  • Radiography



Routine conservative methodDirect transendoscopic injection of formalin (4% formaldehyde) through the fibrous submucosal capsule, repeated at 2- to 4-week intervals until the masses are gone
Surgical excision
Laser photo ablation
Chemical ablation
Periodic endoscopic examinations of nasal passageways to detect possible recurrence



The prognosis is not good unless the horse gets treatment

Scientific Research

General Overviews

Age Range

Horses are usually 4 years of age or colder, with an increasing prevalence with age.