Bilateral paranasal sinus diseases are rarely reported in horses. Treatment using a bilateral frontonasal bone flap on a standing, regular-sized adult horse has not been described previously. A 13-year-old Thoroughbred gelding was evaluated for bilateral mucopurulent nasal discharge. Radiographic, endoscopic and computed tomographic examinations revealed bilateral sinus pathological changes consistent with an ethmoid haematoma involving the maxillary and frontal sinuses. A bilateral frontonasal bone flap was created under standing sedation and local anaesthesia. A tracheotomy was performed initially to ensure a patent airway during the procedure. Additional analgesia had to be given to transect the dorsal part of the nasal septum while elevating the flap. The sinus masses were removed and communications with the nasal cavities created uneventfully. Small sequestra were removed transendoscopically from the left caudal maxillary sinus 4 weeks after the initial procedure. The horse made a complete recovery with an excellent cosmetic outcome. Histopathology revealed the mass to be a sinus cyst. We concluded that a bilateral sinus bone flap can be used in adult regular-sized horses to access the left and right paranasal sinuses simultaneously. Regional nerve blocks should be performed in order to increase analgesia. A temporary tracheotomy prevents any airway obstruction during the procedure. The post-operative cosmesis is excellent.
frontonasal bone flap; sinus cyst; computed tomography; standing surgery; horse.
Bilateral paranasal sinus diseases are rarely reported in horses. In previous studies reporting on large numbers of horses with sinonasal diseases, only 3.0% – 4.5% of cases had bilateral sinus involvement (Dixon et al.
The owner of the horse gave written consent for the surgery to be performed. The Research Ethics Committee of the university approved this case report (project REC054-18).
A 13-year-old Thoroughbred gelding was presented to the Onderstepoort Veterinary Academic Hospital with a 1-month history of unilateral, mucopurulent nasal discharge that progressed to a bilateral nasal discharge 1 week prior to presentation. Upon clinical examination, all vital parameters were within normal limits. A moderate bilateral facial swelling was noted over the caudal maxillary sinuses as well as a bilateral purulent nasal discharge. Shallow infundibular caries were observed on teeth 109, 110, 209 and 210.
Radiographic examination showed a round, well-circumscribed soft tissue opacity situated in the left ethmoid region extending rostrally into the nasal passages as well as towards the right side. Fluid was present within both caudal maxillary sinuses. The left ventral conchal sinus appeared enlarged with increased radio-opacity. Additional masses were visible in the dorsal conchal sinuses (
Initial ancillary diagnostic examinations of a 13-year-old Thoroughbred gelding presented with a bilateral nasal discharge. (a) Lateral head radiographs. Note the well-circumscribed soft tissue masses situated in the dorsal conchal sinuses and the fluid lines present within the caudal maxillary sinuses. Additional soft tissue opacities are visible in the ethmoidal region. (b) Endoscopic view of the left middle meatus. Note the red round mass extending from the left ethmoid region rostrally into the nasal cavity.
Upper respiratory endoscopy revealed a reddish globulous mass, compatible with an ethmoid hematoma, extending from the left ethmoid region rostrally into the nasal cavity, occluding the left sinus drainage angle (sinonasal drainage aperture) (
Computed tomography (CT) performed under standing sedation (Siemens Somatom Emotion Duo, Siemens, Erlangen, Germany) revealed extensive bilateral fluid accumulation in the rostral and caudal maxillary sinuses, ventral and dorsal conchal sinuses, sphenopalatine sinuses as well as the left ethmoidal sinus, sometimes contained by mineralised walls. Discrete masses were obvious in the left dorsal conchal sinus. These findings were consistent with widespread bilateral ethmoid haematomata (
Computed tomography study of the affected horse’s head. (a) Transverse image at the level of teeth 110 and 210. (b) Frontal image, parallel to the dorsal surface of the frontal bones, at the level of the ventral orbit. (c) Transverse close-up view of the sphenoidal sinus. Note the extensive bilateral fluid accumulation in the rostral and caudal maxillary sinuses, ventral and dorsal conchal sinuses, left sphenopalatine and left ethmoidal sinuses, with some fluid accumulations contained in partially mineralised walls.
Three days after presentation, the horse underwent surgery under standing sedation using detomidine (Domosedan, Zoetis, Sandton, South Africa; 10
Intraoperative photographs during creation of a large bilateral frontonasal bone flap on a standing horse. (a) Skin incision performed according to the described boundaries. (b) Image taken after extirpation of the abnormal sinonasal tissues and before packing. Note the excellent surgical exposure gained through this flap.
Masses consistent with ethmoid haematomata were removed from both frontal and caudal maxillary sinuses using traction with sponge forceps and digital separation, and specimens thereof were submitted for histopathology. Maxillary septal bullae were digitally perforated and these communications enlarged with arthroscopic rongeurs (Dixon et al.
The sinus packings were removed 48 h post-operatively through the nostrils with the horse sedated. Because a piece of stockinette was left behind, the right caudal maxillary sinus had to be trephined to extract the latter using arthroscopic rongeurs and sinoscopic guidance (Nickels
Histopathological examination revealed the mass to be a sinus cyst with its wall being lined on both sides by a layer of pseudostratified respiratory epithelium. The connective tissue subjacent to the epithelium displayed various degrees of oedema and haemorrhage, both acute and chronic, granulation tissue formation and chronic inflammation. All cyst walls contained bony plates centrally that were made up of bony spicules that showed varying degrees of remodelling.
Four weeks after surgery the horse was re-evaluated because of a mild left unilateral mucopurulent nasal discharge. The cosmesis of the surgical site was deemed excellent (
Photographs of the horse’s face 4 weeks after a large bilateral frontonasal bone flap was performed (a, b). Note the excellent cosmetic result.
Nine months after initial surgery, no recurrence of the nasal discharge was observed. Satisfaction of the client was excellent.
We described the successful surgical management of a bilateral sinus cyst using a large bilateral frontonasal bone flap on a standing adult Thoroughbred gelding.
The frontonasal bone flap was previously reported as being the ideal approach to the paranasal sinuses because it allows access to the conchofrontal sinus, the caudal maxillary sinus and the ventral conchal and rostral maxillary sinuses after perforation of the maxillary septal bulla (Easley & Freeman
The patient experienced discomfort when we sectioned the dorsal nasal septum in order to lift the bone flap caudally, and we had to inject local anaesthetic onto the sinus mucosa and into the dorsal septum. Previous authors also injected local anaesthetic into the sinus before making bone flaps (Easley & Freeman
Although it was stated that because of the minimal blood loss occurring in standing sinus flap procedures, sinus packing may not be required (Easley & Freeman
Sequestration is a well-known complication of sinus surgeries. It can occur on the margins of the flap or into the sinuses. We did not experience any healing complication, compared to other cases (Easley & Freeman
No post-operative sinus lavage was performed in our case. This could have prevented dehiscence from occurring because early aggressive lavage could lead to fluid leakage into the peri-incisional tissues (Barakzai & Dixon
Even if radiographs and endoscopy were useful in confirming the bilateral nature of the affection, CT allowed a thorough three-dimensional evaluation of all the sinus cavities and permitted elaboration of the surgical plan, as previously reported (Barakzai & Dixon
Our initial diagnosis based on endoscopic and surgical findings was an ethmoid haematoma. However, histopathology revealed the mass to be a cyst. Sinus cysts generally carry an excellent prognosis, with only a single treatment usually required (Dixon et al.
The aesthetic result of this large bilateral frontonasal bone flap was considered excellent and similar to what has been reported for unilateral maxillary and frontonasal bone flaps (Dixon et al.
In conclusion, it appears that a large bilateral sinus bone flap can be used successfully to access left and right paranasal sinuses simultaneously without jeopardising the horse’s cosmesis. A temporary tracheotomy should be considered if substantial intraoperative bleeding is expected. Regional nerve blocks should be considered to ensure adequate analgesia.
The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.
M.R., G.S. and Y.S. treated this patient; M.R. drafted the manuscript and all authors approved the final version to be published.
The South African Veterinary Association (SAVA) contributed financially towards the article processing fee.
The views expressed in this article are the authors’ own opinions and not an official position of the University of Pretoria.