Dacryocystography in rabbits

Marko Jumake MITROVIĆ et al.: Dacryocystography in rabbits Veterinarski Glasnik 2023, 77(2), 87-96 UDC: 636.92.09:617.764.1-008.8-073 Mini Review https://doi.org/10.2298/VETGL230115002M DACRYOCYSTOGRAPHY IN RABBITS Marko Jumake MITROVIĆ1*, Anastasija TODOROVIĆ1, Nikola TATALOVIĆ2, Aleksandar JANEVSKI3, Mirjana LAZAREVIĆ MACANOVIĆ1 University of Belgrade, Faculty of Veterinary Medicine, Department of Radiology and Radiation Hygiene, Belgrade, Serbia 1 University of Belgrade, Siniša Stanković Institute for Biological Research – National Institute of Republic of Serbia, Department of Physiology, Belgrade, Serbia 2 Saints Cyril and Methodius University, Faculty of Veterinary Medicine, Department for Visual Diagnostics, Skopje, North Macedonia 3 Received 15 January 2023; Accepted 05 April 2023 Published online: 10 May 2023 Copyright © 2023 Mitrović et al. This is an open-access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited How to cite: Marko Jumake Mitrović, Anastasija Todorović, Nikola Tatalović, Aleksandar Janevski, Mirjana Lazarević Macanović. Dacryocystography in rabbits. Veterinarski Glasnik, 2023. 77(2): 87-96. https://doi.org/10.2298/VETGL230115002M Abstract Dacryocystography is a specific method of radiological examination of the nasolacrimal apparatus based on the use of a positive contrast agent, which allows the assessment of morphology and patency. Pathological conditions of the nasolacrimal apparatus in rabbits are very common in clinical practice, and the disturbance of this apparatus’ patency is usually a consequence of dental diseases or respiratory infections. The aim of this article is to present the most common pathological conditions that can affect the patency of the nasolacrimal apparatus in rabbits, a detailed anatomical description of the nasolacrimal apparatus in these animals, and the technique for performing dacryocystography. Key Words: rabbit, dacryocystography, radiology, nasolacrimal apparatus INTRODUCTION Rabbits are increasingly kept as pets, and various pathological conditions of the nasolacrimal apparatus are very common in daily clinical practice (Van Caelenberg, 2008; *Corresponding author – e-mail: 87 Veterinarski Glasnik 2023, 77(2), 87-96 Artiles et al., 2020; Hedley et al., 2022). According to Saunders (2013), dacryocystitis is strictly defined as inflammation of the lacrimal sac, although in common usage the term involves other regions of the nasolacrimal apparatus, and usually involves bacterial infection as well as inflammation. The clinical signs of dacryocystitis depend mostly on the primary cause but are usually manifested by epiphora, serous and purulent ocular discharge, conjunctivitis, nasal dysrargia, blepharitis, periocular dermatitis and alopecia, and secondary keratitis (Morera and Martorell, 2005; Williams, 2007; Florin et al., 2009). Acute conjunctivitis-induced dacryocystitis can lead to transient obstruction of the lacrimal sac, compromising outflow and creating conditions favorable for secondary bacterial infections to occur (Knott, 2014). Cooper (2011) also points out the possibility of spreading infections from the nose to the nasolacrimal apparatus. In particular, some authors emphasize the importance of Pasteurella multocida bacteria in the development of lacrimal sac infection and the resulting obstruction of the nasolacrimal apparatus (Marini et al., 1996; Brown, 2006). On the other hand, chronic dacryocystitis usually develops secondary to apical elongation of the reserve crown and periductal osteomyelitis (Varga, 2014). Nasolacrimal apparatus obstruction usually results from apical elongation of the reserve crowns of the maxillary incisors and the first buccal tooth (Saunders, 2013). Less commonly, dacryocystitis may occur due to foreign bodies, polyps, tumors, or traumatic injury (Marini et al., 1996). In a study conducted by Hedley et al. (2022) on a total of 821 rabbits with dacryocystitis, dental problems were observed in 45% of them, while 38% had respiratory infections. The importance of dental disease in the development of dacryocystitis is pointed out by Florin et al. (2009), in whose study dacryocystitis was caused by dental disease in 53% of rabbits, while it was due to rhinitis in 23%. The anatomical conformation of the head may influence the morphology of the nasolacrimal apparatus, and therefore, brachiocephalic breeds have been found to have a greater tendency to develop nasolacrimal apparatus disease (Harvey et al., 2019). According to Schlueter et al. (2009), the greater the degree of brachiocephaly, the steeper the nasolacrimal apparatus, making it more difficult to drain and creating favorable conditions for the development of infections. Dacryocystitis is particularly common in brachiocephalic rabbit breeds such as Lionheads, Mini-Lops, Lops, and Dwarf Lops (Johnson and Burn, 2019; Hendley et al., 2022). Dacryocystography is a specific radiological examination method that is inexpensive and easy to perform while providing insight into the morphology of the nasolacrimal apparatus, its diameter, and degree of patency. In this paper, a brief description of the anatomical features of the lacrimal glands and nasolacrimal apparatus in rabbits is given, as well as a detailed description of the dacryocystography technique. 88 Marko Jumake MITROVIĆ et al.: Dacryocystography in rabbits ANATOMY OF THE LACRIMAL GLANDS AND NASOLACRIMAL APPARATUS Lacrimal glands The lacrimal gland is an organ that produces and secretes tears, and disruption of the composition, production or release of lacrimal fluid results in a feeling of discomfort and damage to the ocular surface (Bannier-Hélaouët et al., 2021). The lacrimal gland is composed of acini, ducts, nerves, myoepithelial and plasma cells (Hodges and Dartt, 2003; Klećkowska-Nawrot et al., 2016). Acinar cells make up 80% of the gland and secrete a primary fluid consisting of water, electrolytes and proteins. As the primary fluid passes through the ductal systems, its composition changes in the form of increased or decreased amounts of electrolytes (Hu et al., 2021). Fehr (2016) divided the lacrimal glands of rabbits into orbital, accessory and third eyelid lacrimal glands (Figure 1). Although most mammals appear to have at least one major large orbital gland, adult rabbits have four (Janssens et al., 1999) or five different glandular masses (Kittel, 1962; Kühnel, 1992). The orbital lacrimal gland is located dorsolaterally in the orbit and caudodorsally from the eyeball. The accessory lacrimal glands are divided into retroorbital, retrobulbar and intraorbital lobes and are located along the caudal and ventral margins of the orbit. Inside the third eyelid, there is a superficial gland (nictitans gland) and a deep gland (Harderian gland). All of these glands contribute to tear production, and their s (...truncated)