Abstract: This study was performed to introduce the anatomical location (gross appearance) and radiographic views (dacryocystorhinography) of lacrimal duct in goats. The anatomy of the nasolacrimal duct of twenty goats (Capra hircus) studied grossly and radiographically. Dacryocystorhinography was performed on cadaver heads, using a radiographic contrast media. Anatomic casts of the nasolacrimal apparatus were obtained by cannulation of the duct and use of corrosion cast (Rodopas cast) material. Dacryocystorhinography accurately revealed the nasolacrimal apparatus and compared favorably with gross dissection and Rodopas casts. The present study on the lacrimal apparatus of the goat might be useful for differentiation of congenital or clinical cases affecting the lacrimal system area.
INTRODUCTION
The lacrimal apparatus system provides a passage for tear drainage from the eye to the nasal cavity. The system for each eye in most species consists of dorsal and ventral lacrimal puncta, paired canaliculi, lacrimal sac and the nasolacrimal duct (Prince et al., 1960). The nasolacrimal system of sheep has been studied previously by Gilanpour (1979). There are no reports on the lacrimal apparatus system in the goat. Dacryocystorhinography, the radiographic visualization of the lacrimal apparatus using radiographic contrast media, has been used to study normal anatomy (Gelatt et al., 1972; Shokry et al., 1987) as well as pathologic conditions of the nasolacrimal duct in human beings (Hurwitz and Welham, 1975), dogs (Fowler, 1989), horses (Latimer et al., 1984), sheep (Gilanpour, 1979), cattle (Heider et al., 1975; Wilkie and Rings, 1990), camels (Shokry et al., 1987), cats (Gelatt et al., 1972) and llamas (Sapienza et al., 1992; Mangan et al., 2008). The present study on the lacrimal apparatus of the goat might be useful for differentiation of congenital or clinical cases affecting the lacrimal system area.
MATERIALS AND METHODS
This study was performed in February 2008. Twenty heads (cut above the third cervical vertebra) of adult Lori breed goat were collected from a local slaughterhouse of Shahreh-Kord area of Chahar-Mahale Bakhtiari Province of Iran. In gross observation the dorsal and ventral puncta were found in the medial canthus of eyelids that were remarkably small and could not be probed, therefore the distal opening of nasolacrimal duct was found in nasal cavity and was cannulated with a 4-French cut down tube. One milliliters of a sodium and meglumine diatriozoate mixture (Urographin 76%, Schering Company, Germany) were injected into the lacrimal duct in retrograde fashion. Lateral and dorsoventral oblique radiographic views were taken (80 KV and 10 mAs) (Fig. 1). For gross anatomic studies, casting materials was also introduced in retrograde fashion from distal opening of lacrimal duct. Approximately 1-2 milliliter of casting material (Rodopas, Merck Company, Germany) was needed to fill the entire length of the nasolacrimal duct. When the casting materials had solidified, the lacrimal apparatus was examined grossly via exposure of the lateral aspect of the nasal cavity by removing a strip of bone from the lacrimal, zygomatic, maxillary and incisive bones. Medial dissection was facilitated by removal of the ethmoturbinates, ventral conchae and lacrimal bone. Descriptive statistics were done by computer program SPSS, Analytical soft ware, version 15.00.
RESULTS
Anatomic Studies
In gross anatomical studies, the lacrimal puncta were slit-like opening,
0.72±0.19 mm (mean±SD) in diameter, located approximately
1 mm from the margin and 2.36±0.41 mm (mean±SD) from the
medial canthus just within the mucocutaneous junction of the palpebral
margin. The paired ventral and dorsal canaliculi were 8±0.79 mm
(mean±SD) long and converged into a small dilatation, the lacrimal
sac, which was located in the orbit on the fossa of the lacrimal bone
outside the periorbita. The nasolacrimal duct extended from the lacrimal
sac to the nostril in the wall of the nasal cavity (Fig.
2). The proximal portion of the lacrimal duct was in the osseous lacrimal
canal and was 77.6±2.3 mm (mean±SD) long. The osseous lacrimal
canal ran rostrally, with a slight curve at its origin. It passed the
lacrimal, zygomatic and maxillary bones-first, lateral to the lacrimal
sinus and then, dorsal to the maxillary sinus. The middle portion of the
nasolacrimal duct was appeared through the osseous lacrimal canal after
crossing the ventral conchal crest. The duct then traversed the nasal
cavity in a straight fashion, covered only by nasal mucosa and a thin
connective tissue membrane (Fig. 2). The opening of the
nasolacrimal duct was 1.7±0.21 mm (mean±SD) in diameter
and was on the lateral wall of the nostril about 28.8±2.5 mm (mean±SD)
from the dorsal angle of the nostril. Casting material provided finely
tailed casts of the nasolacrimal duct (Fig. 2). Since
the Rodopas was fragile, we cannot draw any finding with this technique.
| Fig. 1: | Lateral contrast media radiographic views. (a) Middle portion of lacrimal duct (b) Distal opening of lacrimal duct |
| Fig. 2: | Lacrimal drainage system of goat exposed in the medial surfaces, white arrow shows the distal of lacrimal duct (a) and on the lateral surface of the nasal cavity, black arrow shows the middle portion of lacrimal duct (b ) |
Radiographic Study
Positive contrast Dacryocystorhinography provided detailed visualization
of the lacrimal apparatus. The nasolacrimal duct continues rostrally in
a straight fashion parallel to nasal bone from the orbit to the nasal
cavity (Fig. 1). The terminal portion of the nasolacrimal
duct tapered to a fine exit, rostral to the nasal processes of the incisive
bone. The lateral dacryocystorhinographic view was better than ventrodorsal
oblique view for detailed viewing of the course of the nasolacrimal duct
(Fig. 1).
DISCUSSION
The nasolacrimal system of various domestic species has been previously described (Abdalla et al., 1970; Gelatt et al., 1972; Gilanpour, 1979; Shokry et al., 1987; Sapienza et al., 1992; Aldana Marcos and Affanni, 2005; Rehorek et al., 2005). Radiographic and gross anatomic description of the lacrimal apparatus in sheep has been published (Gilanpour, 1979) but there is no report about the lacrimal apparatus in goat. Anatomic and radiographic findings in goat of our study were similar to those reported by Gilanpour (1979). The lacrimal apparatus consisted of an orbital part and a nasal cavity part. The orbital lacrimal apparatus consisted of a simple lacrimal sac, paired canaliculi with the dorsal and ventral puncta. The first part generally consists of two lacrimal puncta, two ducts and a lacrimal sac. In some animal such as the pig, a single punctum and a single duct are present (Prince et al., 1960). In the dog, the punctum of the ventral eyelid is occasionally absent; sometimes the duct is also (Gelatt et al., 1972). The nasolacrimal duct coursed rostrally in a straight fashion, quite similar to that observed in sheep (Gilanpour, 1979), however in llamas the nasolacrimal duct coursed rostrally in a sigmoid fashion (Sapienza et al., 1992). The nasolacrimal duct was regular in diameter throughout its entirety, unlike that in horses (Latimer et al., 1984). Dacryocystorhinography accurately revealed the lacrimal apparatus and compared favorably with gross dissections and Rodopas casts. The casts provided fine detail of the nasolacrimal duct, but were fragile and tended to break easily in situ (Sapienza et al., 1992). The lateral dacryocystorhinographic view was better than the dorsoventral view for visualization of duct over its entirety (Latimer et al., 1984; Shokry et al., 1987). A dorsoventral oblique view has provided more detailed view than dorsoventral view (Sapienza et al., 1992).
CONCLUSION
Radiography and cannulation via the puncta are techniques that may be useful for detection of obstructions and anomalies of the lacrimal apparatus in goat.