nasal mass and injecting 2 mL of 60%diatrizoate meglumine (Renografm-76, Squibb Diagnostics, Montreal,. Quebec) into each. Both the ventral canaliculus and.
Incomplete nasomaxillary dysplasia in a foal Christine L. Theoret, Bruce H. Grahn, Peter B. Fretz Abstract Atresia of the nasal punctum is the most common congenital anomaly for the equine nasolacrimal system. Nasomaxillary dysplasia has not been previously documented in foals, is of unknown etiology, and appears to be a rare condition. Conjunctivomaxillary sinostomy was successful in resolving the epiphora.
Resume - Dysplasie nasomaxillaire incomplete chez un poulain. L'atresie du point nasal est l'anormalite congenitale la plus frequente au niveau du systeme nasolacrymal du cheval. La dysplasie nasomaxillaire n'a pas ete encore decrite chez le poulain, l'etiologie demeure inconnue et la condition semble rare. La sinusotomie conjonctivomaxillaire s'est averee efficace pour resoudre l'epiphora. (Traduit par docteur Andre Blouin) Can Vet J 1997; 38: 445-447
A4-month-old, 150-kg, Peruvian Paso filly was referred to the Western College of Veterinary Medicine for evaluation of a congenital anomaly of the left palpebral fissure and nostril. The owner reported that the filly was born to a healthy multiparous dam with a normal breeding history. The referring veterinarian noted an elongated left palpebral fissure, a fleshy mass at the left medial canthus, unilateral left mucopurulent ocular discharge, and an elongated left nostril. The filly was of normal size for her age and had received
therapy. On physical examination, the foal was in good body condition and abnormalities were limited to the left side of the face. The alar cartilage was drawn caudodorsad resulting in an elongated nostril. The medical canthus of the left eye was displaced rostroventrad, creating an enlarged palpebral fissure (48 mm long versus 40 mm for the right eye). A soft cylindrical mass, measuring 3 cm in length by 1 cm in diameter and covered by normal skin and hair, originated from the medioventral aspect of the medial canthus. A 1 cm by 1 cm ulcerated area was present on the skin of the face underlying the distal extremity of the mass (Figure 1). The soft tissue mass was nonpainful to palpation, had a lumen, had cilia at its distal extremity, and was pulled proximad when the filly blinked. A mucopurulent ocular discharge was present and the nasal punctum could not be identified. A neuro-ophthalmic examination revealed no abnormalities. The filly was sedated with xylazine hydrochloride (0.5 mg/kg body weight (BW), IV) (Rompun, Bayer, Etobicoke, Ontario) and restrained in stocks. A bilateral auriculopalpebral nerve block was performed by injecting 1.5 mL of 2% lidocaine hydrochloride (Lidocaine Neat, Langford, Guelph, Ontario). Schirmer tear tests were normal in both eyes. Corneal anesthesia was achieved by applying 0.5% proparacaine hydrochloride (Ophthetic, Allergan, Markham, Ontario). Applano
Department of Veterinary Anesthesiology, Radiology and Surgery (Theoret, Fretz); Department of Internal Medicine (Grahn), Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4. Reprints will not be available. 1997 July 1997 Can Vet J Volume 38, 38, July
Figure 1. A cylindrical mass was adherent to the medial can-
thus, contained a lumen, and had cilia at its distal extremity
(arrow).
nation tonometry confirmed normal intraocular pressures. Biomicroscopic examination revealed that the left dorsal palpebral punctum was absent. No additional abnormalities were noted on biomicroscopic or indirect ophthalmoscopic examination of either eye. Dacry-
ocystography (1) was performed by placing 20-gauge,
IV catheters (Abbott, St. Laurent, Quebec) into both the left ventral palpebral punctum and the duct of the nasal mass and injecting 2 mL of 60% diatrizoate
meglumine (Renografm-76, Squibb Diagnostics, Montreal, Quebec) into each. Both the ventral canaliculus and 445
445
Figure 2. Dacryocystography revealed 2 blind-ended canaliculi. The ventral canaliculus was normally located (black arrowhead), whereas the dorsal one (white arrow) was ectopically located within the cylindrical mass at the medial canthus.
the presumptive ectopic dorsal canaliculus located within the polypous mass at the medial canthus ended in blind pouches. The lacrimal duct could not be visualized (Figure 2). The diagnoses were left incomplete nasomaxillary dysplasia, including ectopic dorsal palpebral punctum and canaliculus, elongated and displaced medial palpebral fissure, left nasolacrimal duct and nasal punctum aplasia, and an elongated left nasal orifice. Surgical reconstruction of the palpebrae and the nasolacrimal system was performed with the animal restrained in right lateral recumbency. General anesthesia was induced with xylazine hydrochloride (1.1 mg/kg BW, IV) and ketamine hydrochloride (2.2 mg/kg BW, IV) (Rogarsetic, rogar STB, Montreal, Quebec) and maintained with halothane and oxygen in a semiclosed circle system. The polypous mass was amputated and preserved in 10% formalin for histologic examination. The medial canthoplasty was completed by removing the medial caruncle, moving the medial canthus dorsad and narrowing the palpebral fissure to 43 mm, by closing the conjunctival mucosa with a layer of simple interrupted sutures of size 7-0 polyglactin 910 (Vicryl, Ethicon, Somerville, New Jersey, USA) and the skin with a similar pattern of size 5-0 nylon (Dermalon, Davis & Geck, Markham, Ontario). A 3.12 mm Steinmann pin was placed through the ventral palpebral punctum and driven medially and rostroventrad into the left caudal maxillary sinus, using a Jacob's chuck. A 10 cm long segment of 2 mm outer diameter polyethylene tubing was threaded through the newly formed canal, and the fluted external orifice was anchored to the conjunctiva and the margin of the eyelid with 2 horizontal mattress sutures of size 5-0 nylon. Postoperative injection of contrast material into the polyethylene tubing confirmed a conjunctivomaxillary fistula. The filly was discharged from the Western College of Veterinary Medicine the following day with instructions to the owner to flush the conjunctival fornix with an eyewash (Eyestream, Alcon Canada, Mississauga, Ontario), and apply an antibiotic-steroid ointment (Maxitrol, Alcon Canada), q8h for 4 to 6 wk. Tissue from the amputated mass was embedded and sectioned routinely, stained with hematoxylin and eosin, AA,& 440
and examined by light microscopy. The mass was covered by epithelium and had an abundant connective tissue core. The central lumen was lined by pseudostratified columnar ciliated epithelium. The filly was re-evaluated 3 wk later, at which time the owner reported having observed a mild mucopurulent discharge. Ophthalmic examination confirmed that the polyethylene tubing was still present and showed that the conjunctivomaxillary fistula was patent. The filly was sedated with xylazine hydrochloride, and the polyethylene tube and sutures were removed. Seven weeks postoperatively, the filly was re-examined for persistent, moderate, mucopurulent ocular discharge, which had developed after the tube was removed. Following sedation with xylazine hydrochloride, an ophthalmic examination was performed. Topical fluroscein was applied to the left eye. The stain failed to appear at the left nostril and overflowed from the shallow medial canthus. The external orifice of the conjunctivomaxillary fistula was visible at the medial canthus. Attempts to cannulate the conjunctivomaxillary fistula with multiple sizes of IV catheters were unsuccessful. The obstruction was approximately 15 mm distal to the orifice of the fistula. A stricture was tentatively diagnosed. Local anesthesia by infiltration of 1 mL of 2% lidocaine hydrochloride at the medial canthus was performed and the conjunctivomaxillary "sinostomy" was repeated. As previously described, polyethylene tubing was inserted into the tract to maintain patency. Postoperative care consisted of topical application of antibiotic-steroid ointment (Maxitrol), q8h for 2 wk. The filly was re-examined at 17 wk. At that time, a mild epiphora was present. The filly was sedated with xylazine hydrochloride and received 2 mL of 2% lidocaine hydrochloride, SC, at the medial canthus. Examination revealed that the tubing was no longer present within the orifice at the medial conjunctival sac, but flushing of the conjunctivomaxillary fistula resulted in fluid at the left nostril. Diatrizoate meglumine (60%) was injected into the external aspect of the conjunctivomaxillary fistula, and a lateral radiograph of the head was obtained. The previously implanted tubing was lodged within the left maxillary sinus and nasal cavity, and was subsequently removed from the left nostril using a sponge forcep. One month later the filly was presented for persistent, moderate, mucopurulent discharge. Ophthalmic examination and contrast radiographs were performed and nonpatent fistula was evident. As before, the conjunctivomaxillary sinostomy was repeated under standing sedation and local anesthesia. This time a larger diameter tubing (3 mm) was inserted. The filly was discharged with recommendations to leave the tube in for several months. The tube was replaced twice by the referring veterinarian and was removed permanently after 3 mo. One year after discharge, the owner reported occasional mucoid discharge but was very satisfied with the appearance of the filly. The medial canthus had apparently gained a normal shape, and there was no discernable difference between the right and left palpebral fissures. Congenital anomalies of the equine nasolacrimal system have been reported, the most common of which is atresia of the nasal punctum (2). Abnormally Can Vet J Volume 38, July 1997
positioned or atretic palpebral puncta (either dorsal or ventral) have also been reported (2). However, to the authors' knowledge, nasomaxillary dysplasia with an elongation of the ipsilateral palpebral orifice and nostril, and displacement of the dorsal canaliculus in a polypous mass has not been previously described. The unilateral facial deformity observed in this foal resembled oblique facial clefts described in human infants (3). These congenital anomalies have their origin at the junction of facial processes and are much rarer than are clefts, such as harelip. Oblique facial clefts have been classified according to the orientation (naso-ocular or oro-ocular), the position around the orbit (Tessier classification), and the area in which the malformations have their origin (nasomaxillary or maxillary dysplasia) (3). An incomplete nasomaxillary dysplasia (or naso-ocular cleft) runs from the alar base, which is drawn upward, to the inferiorly dislocated medial canthus. The lip is intact and there may be a fistula of the lacrimal canal (3). One report in the literature describes a left unilateral oblique facial cleft associated with a lateral nasal proboscis attached to the medial canthus by a narrow pedicle (4). The tubular mass appeared to contain the dorsal palpebral punctum, which, it was determined with dacryocystography, ended blindly in a dilated sac (4). The baby in that report also had a cleft medial canthus; an incomplete hair lip; complete absence of the ipsilateral half of the nose; and coloboma of the iris, choroid, and retina (4). Although the abnormalities of the filly in this report were limited to the palpebral fissure, nostril, and nasolacrimal system, they closely resembled those described as incomplete nasomaxillary dysplasia. Histologic examination of the lumen of the mass originating at the medial canthus was of interest. Equine lacrimal sacs and ducts are normally lined by squamous or columnar epithelium (5). Although the lumen of the nasal mass of the filly in this report was comprised of pseudostratified columnar ciliated epithelium, the authors feel that it nonetheless represented an ectopically located dorsal canaliculus, based on its gross and radiographic appearance. The etiology of oblique facial clefts in humans is unknown. These defects are thought to occur sporadically with no familial tendency (3). The dam of the filly in this report had no history of bearing young with any congenital defects. Embryologically, oblique facial clefts have been explained by a failure of closure of the nasooptic groove between the frontonasal and the maxillary processes (6). The nasolacrimal duct forms in the groove between the lateral nasal and maxillary processes (7), hence a disturbance along this groove could result in aplasia of the duct. Disturbance of these cell populations have been reported to result from teratogenic factors (drugs, toxins, radiation, nutrition) or the physical environment of the fetus (8). The dam in this case had no known history of drug, toxin, or radiation exposure during this pregnancy. If a teratogen was indeed responsible for the observed defects, one would expect that such an insult would affect other fetal systems developing simultaneously (8), and would cause symmetrical defects. In human infants, amnion rupture, amniocentesis, or maternal trauma are know to produce malformations of the craniofacial complex (encephaloceles, hydrocephalus, Can Vet J Volume 38, July 1997
palatal clefts), the vertebrae (spina bifida), or the limb (constriction ring anomalies, acrosyndactyly) (9). In utero malposition has been implicated as a cause of wry nose in the foal (10). An amniogenic mechanism could not be confirmed in this filly. Obstruction of the nasolacrimal system can be congenital or acquired, and has been reported in numerous species (1,11-13). Surgical techniques for correction include conjunctivoralostomy (14), conjunctivobuccostomy (15), and conjunctivorhinostomy (15). These procedures create a permanent epithelium-lined fistula from the medioventral conjunctival cul-de-sac to the oral or nasal cavity, but are not applicable to the horse because the caudal maxillary sinus is interposed between the rostroventral portion of the orbit and the nasal passages (16). A surgical technique whereby a communication is created between the medial canthus and the maxillary sinus has been successful in resolving epiphora in 2 horses with a disrupted nasolacrimal system (16). We attempted a similar procedure in this filly. The time required for establishment of a permanent fistula varies with the individual case, but previous authors have suggested 3 wk (16) to 2 mo (13). Postoperative obstruction is not an uncommon complication and leads to recurrence of epiphora, as noted in this filly. In an attempt to prevent this complication, the 2nd stent was left in place for 10 wk and the subsequent stents were of larger diameter. With growth and surgery, the medial canthus eventually attained a normal shape, and replacement of the tube resulted in a permanent conjunctivomaxillary fistula. CVJ
References 1. Latimer CA, Wyman M, Diesem CD, Burt JK. Radiographic and gross anatomy of the nasolacrimal dust of the horse. Am J Vet Res 1984; 45: 451-458. 2. Lavach JD. Large Animal Ophthalmology, vol. 1. Philadelphia: CV Mosby, 1990: 85-100. 3. Van der Meulen JCH. Oblique facial clefts: Pathology, etiology, and reconstruction. Plast Reconstr Surg 1985; 76: 212-224. 4. Mahindra S, Daljit R, Jamwal N, Mathew M. Lateral nasal proboscis. J Laryngol Otol 1973; 87: 177-18 1. 5. Banks WJ. Applied Veterinary Histology, 3rd ed. Philadelphia: CV Mosby, 1993: 485. 6. Schlenker JD, Ricketson G, Lynch JB. Classification of oblique facial clefts with microphthalmia. Plast Reconstr Surg 1979; 63: 680-688. 7. Arey LB. Developmental Anatomy. Philadelphia: WB Saunders, 1965: 199-207. 8. Szabo KT. Congenital Malformations in Laboratory and Farm Animals. San Diego: Academic Pr, 1989: 33-79. 9. Poswillo D. Observations of fetal posture and causal mechanism of congenital deformity of palate, mandible and limbs. J Dent Res 1966; 45: 584-596. 10. Gaughan EM, DeBowes RM. Congenital diseases of the equine head. Vet Clin North Am Equine Pract 1993; 9: 93-110. 11. McLaughlin SA, Brightman AH, Nelson DR. Nasolacrimal duct anomaly in a Holstein calf. Agri Pract 1985; 6: 30-31. 12. Latimer CA, Wyman M. Atresia of the nasolacrimal duct in three horses. J Am Vet Med Assoc 1984; 184: 989-992. 13. Wilkie DA, Rings DM. Repair of anomalous nasolacrimal duct in a bull by use of conjunctivorhinostomy. J Am Vet Med Assoc 1990; 196: 1647-1650. 14. Gelatt KN, Gwin RM. Canine lacrimal and nasolacrimal systems. In: Gelatt KN, ed. Textbook of Veterinary Ophthalmology. Philadelphia: Lea & Febiger, 1981: 309-329. 15. Lavach JD. The lacrimal system. In: Slatter DA, ed. Textbook of Veterinary Surgery, vol. 2. Philadelphia: WB Saunders, 1985: 1483-1501. 16. Wilson DG, Levine SA. Surgical reconstruction of the nasolacrimal system in the horse. Equine Vet Sci 1991; 11: 232-234. 447
