The examination of the equine lacrimal gland. [German]Original Title Die Untersuchung der Tranendruse beim Pferd.

摘要

The clinical examination of the equine lacrimal gland is only poorly documented as yet. The goal of this paper was to develop a thorough and complete clinical minimal invasive examination protocol for examination of the equine lacrimal gland. This includes inspection of the dorsotemporal region of the upper eye lid, transconjunctival palpation and ultrasonographic examination of the lacrimal gland with a 7,5 MHz probe. As further imaging techniques for the evaluation of the lacrimal gland computed tomography (CT) and magnetic resonance tomography (MRT) are described. Finally, a minimal invasive biopsy technique for the lacrimal glands was developed. Forty horses of different age, gender and breeds were subjected to an ophthalmologic examination of both eyes, and were, when ophthalmologically normal, evaluated for lacrimal gland disorders, beginning with inspection and digital palpation in the standing horse. The texture of the anterior rim of the gland could be palpated and evaluated for possible pain, swelling, and foreign body. This was followed by a transpalpebral sonographic examination of both lacrimal glands with the ultrasound probe placed on the lower eye lid and directed dorso-temporally upward. This was well tolerated by the unsedated horses. Using this technique, the mean thickness of the gland was 3.2 mm in the left, and 3.3 mm in the right eye. In two patients with thickened lacrimal glands both were more than 10 mm thick. MRT was superior to CT examination of the gland tissue, as MRT showed more details of the soft tissue structure of the gland even in its position below the bony zygomatic arch of the frontal bone. Disadvantages are the need for general anesthesia for these examinations. Furthermore, a transconjunctival biopsy technique using an 18 G (1.2x152 mm) soft tissue biopsy needle that was manually curved to fit to the concave ventral contour of the lacrimal glandular fossa of the bony orbit and to enable the introduction of the needle between the globe and the bony orbit. Twenty eight biopsy specimens were taken from freshly euthanatized horses and were compared with specimens of the whole lacrimal gland. It was found that the results of the histological evaluation of the biopsy specimens were comparable to those of the specimens from the whole lacrimal gland. In two patients with severe swelling of the upper eye lid and severe chronic epiphora due to a swelling of the lacrimal gland needle biopsies could successfully be obtained transconjunctively under general anesthesia, rendering transpalpebral biopsy unnecessary. Since 2008, systematic histopathological examination results on the normal and diseased equine lacrimal gland are available (Medl 2008) which can serve as a reference for diagnostic evaluation of lacrimal gland biopsies. Using the here described modern examination techniques a complete examination protocol for cases of suspected lacrimal gland disorders exists.