Surgery
The horse was prepared for a standing removal of the PEH under sedation and local anesthesia. Prior to surgery, the gelding was administered procaine penicillin (Propercillin 22 mg/kg bwt i.m. q. 12 h)4 and gentamicin (Gentam 6.6 mg/kg bwt i.v. q. 24 h)1 and intravenous phenylbutazone. Antimicrobial administration continued with the same regimen for 5 days, phenylbutazone (Nabudone 2.2 mg/kg bwt i.v q 12 h)1was administered orally every 24 hours for 5 days post-operatively.
The surgical area was clipped and surgically prepared. Mepivacaine (Vetacaine 0.07 mg/kg bwt s.c to effect)1 was infiltrated around the proposed surgical site. A combined fronto nasal and maxillary bone flap incision approach was performed. The rostral perpendicular incision was made from midline to the rostral end of the facial crest 1 cm dorsal to the infraorbital foramen, a ventral parallel incision was made 0.5 cm dorsal to the facial crest to the caudal aspect of the facial crest, a perpendicular caudal incision was made from the caudal aspect of the facial crest to approximately 0.5 cm abaxial to the incisive notch, then a short 5 cm parallel incision starting approximately 2 cm medial to the medial canthus of oculus dexter and finally a caudal perpendicular line from dorsal midline to join the last incision. The periosteum was incised to expose the underlying bone and 0.5 cm of periosteum was reflected using periosteal elevators. A Jacobs chuck with a 2mm Steinman pin was used to create equidistant holes along the flap edges. The exposed bone was then cut with an oscillating saw along the outlines of the flap.
The opening created in this way allowed direct access to the conchofrontal sinus, sphenopalatine and the maxillary sinuses, ethmoid labyrinth and the frontomaxillary opening. A large smooth oval, mottled, to dark green tinged mass occupying the frontal, sphenopalatine, maxillary and choncal sinuses was visualized (Figure 3 and 4). The hematoma was isolated from the ethmoid turbinates and surrounded mucosa by digital dissection and removed by careful traction. The sinuses were lavaged with sterile fluids and packed with sterile gauze bandage. Hemorrhage was considered minor during the procedure.
The fronto-nasal maxillary bone flap was replaced. The periosteum, and subcutaneous layers were closed with number 0-2 Glycomer 631(Byosin)5 in a simple continues pattern and the skin was then closed using a number 1 polydioxanone (MonoPlus)6 in a simple interrupted pattern. An elastic, self-adhesive bandage was applied to protect the surgical incision.
Post-operatively the horse was maintained on a 5-day course of Phenylbutazone, procaine penicillin and gentamicin sulphate as labeled above. The tracheotomy tube was removed 24 hours post-operatively.