Progressive Ethmoidal Haematoma

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Also know as: PEH — Ethmoid Haematoma


This condition is a slowly expanding non-neoplastic mass of horses, that occurs in the submucosa of the ethmoid labyrinth. The cause of the condition is unknown and there are no known risk factors. The mass may sometimes arise subsequently to chronic inflammation. It can occur in either the nasal or sinus portion of ethmoid labyrinth and may rarely occur elsewhere in the sinuses. The mass is usually unilateral and can extend to the nasal cavity, paranasal sinuses and nasopharynx causing destruction of tissue.


It can occur in horses of any age, but any horse younger than three years old rarely contracts the disease. There is a breed predilection for Arabian and Thoroughbred horses. There is no sex predilection.

Clinical Signs

Signs include epistaxis or a serosanguinous nasal discharge, abnormal respiratory noise, halitosis, dyspnoea and coughing. The animal may also shake its head frequently. Some cases will have a facial deformity and there may be a mass at the nares. Other horses may exhibit no clinical signs.


History, signalment and clinical signs can be characteristic of the disease, but differentials such as guttural pouch mycosis, neoplasia, nasal trauma and exercise induced pulmonary haemorrhage need to be excluded by endoscopic evaluation.

Upon endoscopy, a yellow-green mass is present and may be covered in Aspergillus spp.. The location of the mass is usually diagnostic but a grab biopsy by endoscopy will provide a definitive diagnosis.

Other imaging such as radiographs can be undertaken and will show an abnormal opacity with smooth margins. There may also be the presence of fluid lines on radiographs. CT scan will reveal more detail of the lesion.

Treatment and Control

Treatment options include surgical removal via a frontal sinus flap with the horse standing. Cryotherapy can also be performed in the standing horse and causes minimal haemorrhage, however it can only be used on smaller lesions. Laser removal is less effective as it requires multiple treatments, it can however be performed in the standing horse. Chemical ablation is the final treatment option and involves the use of 4% formaldehyde solution. This can also be performed with the horse standing, but requires multiple treatments. The lesion is injected with the solution endoscopically or through a hole in the sinus. This treatment is relatively cheap but complications can include blindness and death if it penetrates the brain.


Prognosis is guarded to poor regardless of treatment and recurrence is common (15 - 45%) regardless of which treatment is undertaken.