Finding and treating horse’s ethmoid hematoma aided by CT

View of the ethmoid hematoma bone flap surgery performed by Dr Michael Myhre and Dr Weston Davis.
View of the ethmoid hematoma bone flap surgery performed by Dr Michael Myhre and Dr Weston Davis. © PBEC

Intricate surgery has been performed on a horse with an ethmoid hematoma in the US by veterinarians who learned the extend of the issue using a computed tomography (CT) machine.

An ethmoid hematoma is essentially a mass that fills with blood in the nose or sinus cavity. The horse had been admitted to the Palm Beach Equine Clinic (PBEC), based in Wellington, Florida, with symptoms that included bleeding from the nostril. The patient’s referring veterinarian had diagnosed the horse with an ethmoid hematoma.

The condition is most commonly reported in middle-aged geldings, although it can occur in both young horses and mares as well.

Surgeons Dr Weston Davis and Dr Michael Myhre performed an airway endoscopy to locate and evaluate the hematoma that the referring veterinarian had identified. After confirming the diagnosis, they were eager to ensure that it was the only hematoma they were battling.

A computed tomography (CT) machine gives veterinarians a unique look at the head, neck, and spine of a horse that they would never be able to accomplish with other imaging modalities. After a CT of the patient’s sinuses, more masses were indeed identified.

Ethmoid hematoma bone flap surgery.
Ethmoid hematoma bone flap surgery. © PBEC

“This was a fairly typical presentation of an ethmoid hematoma, but there were certainly more masses than normal,” Myhre said. “It’s for this reason that the CT was very useful. If we were not able to obtain the scans that we did, we may have missed the masses that were located deeper in the sinus.”

The cause of an ethmoid hematoma is unknown, but the mass resembles a tumor in appearance and development without being neoplastic. Horses with extensive masses may have reduced airflow and an expanding hematoma can cause pressure necrosis of the surrounding bones, but rarely causes facial distortion. Treatments of the condition can range from conservative management to surgery. The conservative treatment route includes the injection of formalin – a mixture of formaldehyde gas and water – into the mass using a guarded endoscopic needle. Once injected, the mass typically regresses rapidly, but recurrence is common. For some cases, surgical excision is achieved via a frontonasal bone flap procedure.

Due to the location and advanced nature of the masses in this case, injection was not an option and the CT imaging was used to plan a surgical approach.

Ethmoid hematoma surgery performed by Dr Michael Myhre and Dr Weston Davis.
Ethmoid hematoma surgery performed by Dr Michael Myhre and Dr Weston Davis. © PBEC

“After sedation and a local block, we went into the sinus through a flap approach where we took a section of bone, cut it into a flap, and moved it back so we could go into the sinuses through a nice window,” Myhre said. “We removed a mass four centimeters in diameter as well as several smaller masses two to three centimeters in diameter, then flushed the area and closed.”

He said the advantages of a standing procedure included fewer risks from bleeding and fewer risks of recovering from anesthesia.

Post-surgery, the bone flap will require several weeks to heal, but the skin itself healed within one to two weeks, which is when the horse was cleared to return to normal activity.

The video below shows the CT scan that spotted the additional masses.

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