34th Annual Scientific Meeting proceedings

Retrobulbar disease can be categorised as primary or secondary, and the prevalence of either varies across the literature. One retrospective study in dogs with retrobulbar disease reported 62% had a primary cause and almost 38% secondary. The same study showed that of the primary retrobulbar disease approximately half were due to neoplasia and half were inflammatory, whilst of the secondary disease the majority were neoplastic (Winer et al 2018). Another study in dogs and cats reported inflammatory orbital disease was the most common aetiology in dogs (57%) and cats (62%), and within this category orbital cellulitis was the most common diagnosis (44% in dogs; 80% in cats) (Coall et al 2021).

Orbital neoplasia is commonly aggressive and malignant. In dogs and cats, 75% and 88% of orbital tumours are malignant respectively, and carry a guarded to poor prognosis (Attali-Soussay et al 2001). Exenteration may be required to attempt curative surgery or in palliation, and two main approaches have been described. The first via the anterior orbital rim and the second more extensive lateral approach (Berggren and Wallin Hakansson 2019).

Orbital foreign bodies may enter the retrobulbar space via a number of routes and are more commonly reported in dogs than cats. Exploration of the orbit is often required to retrieve these. Orbitotomy may also be employed for treatment of retrobulbar abscessation, zygomatic sialoadenitis and/or mucocoele or sialocoele, or resection of benign neoplasia, whilst retaining the globe.

The ventral transpalpebral anterior orbitotomy has been successfully employed in four cases with inflammatory conditions of the orbit and a benign neoplastic mass (lipoma). A curvilinear incision is made through the lower eyelid with sharp and blunt dissection to the ventral orbital rim, avoiding the dorsal and ventral branches of the palpebral nerve and arteries and zygomaticotemporal vein at the lateral canthus, as well as branches of the facial vein ventral to the orbital rim (McDonald et al 2016, Charnock et al 2020).

Dorsal and lateral approaches to the orbit have been described and numerous modifications have been published to tailor access to the orbital region required (Slatter and Abdelbaki 1979; Gilger et al 1994; Ramsey and Fox 1997, Bartoe et al 2007). A transfrontal approach has also been reported that includes a zygomatic arch osteotomy and zygomatic process osteotomy rostrodorsally giving wide surgical access to the orbit (Wallin Hakansson 2010). Three-dimensional printing of orbital and peri-orbital masses has been described utilising data from CT imaging and may provide useful insight for surgical planning (Dorbandt et al 2017).

A transoral approach to the orbit for access to the zygomatic salivary gland has more recently been described both in cadavers and a case series (Viitanen et al 2023). The maxillary artery and nerve that border the ventral orbit are significant hazards to bear in mind. Three other approaches to the zygomatic salivary gland have been described in  a cadaveric study: dorsal and ventral to the zygomatic arch and utilising a zygomatic osteotomy (Dorner et al 2021).

More extensive orbitectomies for resection of neoplasia have been described, with the use of cerclage wires, prolene mesh and collagen sheets to reconstruct the orbital support for the globe and normal facial contours (Wallin Hakansson and Berggren 2017).

References

• Winer JN, Verstraete FJM, Cissell DD, Le C, Vapniarsky N, Good KL, Gutierrez CJ and Arzi B (2018) Clinical Features and Computed Tomography Findings Are Utilized to Characterize Retrobulbar Disease in Dogs. Frontiers in Veterinary Science 5:186.
• Coall SM, Premont JE, Flatz K, Hindley K, Groth A, Billson FM (2022) Clinical, advanced imaging data and outcome of inflammatory and neoplastic orbital disease in 81 dogs and 16 cats in Australia (2010–2019). Veterinary Ophthalmology 25(s1):37–50.
• Attali-Soussay K, Jegou J-P, Clerc B (2001) Retrobulbar tumors in dogs and cats: 25 cases. Veterinary Ophthalmology 4:19-27.
• Berggren K, Wallin Hakansson N (2019) A surgical approach for extensive orbital exenteration in dogs; a description of technique and its application in 4 cases. Veterinary Ophthalmology 22:238–245.
• McDonald JE, Knollinger AM, Dees DD (2016) Ventral transpalpebral anterior orbitotomy: surgical description and report of 3 cases. Veterinary Ophthalmology 19(1): 81–89.
• Charnock L, Doran B, Milley E, Preston T (2020) Canine retrobulbar lipoma excision through a ventral transpalpebral anterior orbitotomy. Canadian Veterinary Journal 61:257–262.
• Slatter DH, Abdelbaki Y (1979) Lateral orbitotomy by zygomatic arch resection in the dog. Journal of American Veterinary Medicine Association 175:1179-1182.
• Gilger BC, Whitley RD, McLaughlin SA (1994) Modified lateral orbitotomy for removal of orbital neoplasms in two dogs. Veterinary Surgery 23:53-58.
• Ramsey DT, Fox DB. (1997) Surgery of the orbit. Veterinary Clinics of North America (Small Animal Practice) 27:1215-1264.
• Bartoe JT, Brightman AH, Davidson HJ (2007) Modified lateral orbitotomy for vision-sparing excision of a zygomatic mucocele in a dog. Veterinary Ophthalmology 10:127-131.
• Wallin Hakansson N,  Wallin Hakansson B (2010) Transfrontal orbitotomy in the dog: an adaptable three-step approach to the orbit. Veterinary Ophthalmology 13(6): 377–383
• Dorbandt DM, Joslyn SK, Hamor RE (2017) Three-dimensional printing of orbital and peri-orbital masses in three dogs and its potential applications in veterinary ophthalmology. Veterinary Ophthalmology 20(1): 58–64.
• Viitanen J,  de Rooster H, Kitshoff A, Arzi B,  Devriendt N (2023) Intraoral approach for zygomatic sialoadenectomy in dogs: An anatomical study and three clinical cases. Veterinary Surgery 52:257–265.
• Dörner J, Oberbacher S, Dupré G (2021) Comparison of three surgical approaches for zygomatic sialoadenectomy in canine cadavers. Veterinary Surgery 50:564–570.
• Wallin-Hakansson N, Berggren K (2017) Orbital reconstruction in the dog, cat, and horse. Veterinary Ophthalmology 20(4): 316–328.