Surgical Treatment of Recurrent Dacryocystitis Secondary to Cystic Dilatation of the Nasolacrimal Duct in a Dog

Introduction

Dacryocystitis is an inflammation of the nasolacrimal sac, with possible extension to the nasolacrimal duct and canaliculi. Recurrent dacryocystitis can be associated with cystic dilatation of the nasolacrimal duct. The authors are aware of only two reports on the surgical treatment of this condition in dogs.¹² This case report briefly details the surgical treatment of recurrent dacryocystitis secondary to cystic dilatation of the nasolacrimal duct.

Case Report

A 3-year-old, castrated male golden retriever was referred for evaluation of chronic, recurrent purulent discharge from the left eye. This dog had been treated for 4 months, first with a topical antibiotic ointment^a and then with a combined antibiotic-corticosteroid suspension.^b Upon presentation to the Companion Animal Clinic of the University of Montreal, ophthalmic examination revealed unilateral, left-sided, mucopurulent discharge with mild conjunctivitis. Fluorescein^c applied topically in the left eye failed to appear in the left naris. The remainder of the ocular examination was unremarkable. Irrigation of the nasolacrimal system of the right eye was performed under local anesthesia^d and was unremarkable. Irrigation of the left nasolacrimal system was unsuccessful, because the procedure was too painful for the animal.

Under general anesthesia, the left inferior punctum was cannulated for nasolacrimal duct irrigation. Increased resistance to the irrigation was noted, but a significant quantity of thick, blood-tinged, mucopurulent discharge was expelled from the left naris. On lateral and dorsoventral intraoral skull radiographs, a soft-tissue density without any osseous changes was present in the left nasal cavity. The animal was discharged from the hospital with a neomycin-polymyxin B-dexamethasone ophthalmic suspension^e to be administered in the left eye q 8 hours.

Although the mucopurulent discharge resolved within days, it recurred after 2 weeks of treatment, at which time the animal was readmitted for nasolacrimal irrigation under topical anesthesia. A large quantity of purulent discharge was expelled through the palpebral punctum, but no drainage was observed via the nasal orifice. A sample of the discharge was submitted for aerobic and anaerobic cultures, which were subsequently negative for microbial growth. The animal was discharged with instructions for the topical antibiotic-corticosteroid suspension to be continued. The ocular discharge resolved for 1 month but then relapsed.

Reevaluation confirmed a persistent obstruction of the left nasolacrimal system. The nasolacrimal system was once again irrigated under general anesthesia, and increased resistance was noted with a moderate amount of mucopurulent discharge exiting from the left naris. Evaluation of the right nasolacrimal system was unremarkable. Lateral and dorsoventral intraoral skull radiographs revealed increased density at the mediodorsal aspect of the first molar tooth. Dacryocystorhinography was performed on the left side by catheterizing the left superior punctum and injecting 6 mL of a 1:1 dilution of iohexol^f and 0.9% saline.³⁴ The catheter was removed, and lateral and dorsoventral intraoral skull radiographs were repeated. Dacryocystorhinography of the left nasolacrimal system [Figure 1] outlined a 2 × 3 × 1.5-cm cystic dilatation in the left maxillary sinus, but no evidence of the nasolacrimal duct could be visualized distal to this cavity.

Surgical exploration of the left maxillary sinus was recommended and accepted by the owners. The animal was positioned in sternal recumbency, and a 4-cm linear skin incision was performed over the maxillary bone, halfway between the nasal midline and the infraorbital foramen. A 2 × 3 cm-diameter opening was created in the maxillary bone with the aid of a 5-mm, olive-shaped surgical burr^g and exposed a large, fluid-filled cavity. Aspirates of the cavity were submitted for aerobic, anaerobic, and fungal cultures and were subsequently negative. The left nasolacrimal duct was visualized by introducing 0-polypropylene^h suture material via the inferior palpebral punctum and entering the cavity at its most dorsolateral aspect. A thin layer of tissue lined the cavity. The entire cyst lining was removed with the aid of a periosteal elevator and was submitted for histopathology, which demonstrated pseudostratified ciliated epithelium. To establish drainage from the cyst cavity to the nasal cavity, the medial wall of the maxillary recess was removed with bone rongeurs, exposing the nasal turbinates [Figure 2]. Communication between the maxillary cavity and the nasal cavity was confirmed by fluid exiting from the left naris following irrigation of the cystic dilatation of the nasolacrimal duct.

Two sterile petroleum impregnated gauze stripsⁱ were packed within the cavity exiting dorsomedial to the skin incision and were sutured to the skin to control perioperative hemorrhage. Part of a 12-French, red-rubber tube^j was inserted into the nasal cavity via a separate hole through the frontal bone proximal to the sinusotomy. It was sutured to the skin using a Chinese finger trap with 4-0 nylon^k and left in place to prevent possible postoperative subcutaneous emphysema. The periosteum and levator nasolabialis muscle were apposed using 4-0 polyglyconate^l in a simple interrupted pattern. The subcutaneous tissues and skin were apposed in separate layers.

Topical ophthalmic bacitracin-neomycin-polymyxin B solution^m (one drop in the left eye q 8 hours for 10 days) was prescribed. The nasal packing strips were removed the day following surgery, the frontal sinus tube was removed on the second day postoperatively, and the animal was discharged 3 days after surgery.

At the time of suture removal, 14 days after surgery, the dog had no evidence of epiphora, conjunctivitis, or mucopurulent discharge from the left eye. A fluorescein test was performed at the referring veterinarian’s office, and fluorescence was observed at both nares. Regular examinations by the referring veterinarian and communication with the owners confirmed that the dog has had no abnormal ocular discharge for 36 months postoperatively.

Discussion

The nasolacrimal system is composed of two canaliculi (inferior and superior), a lacrimal sac (that rests in the lacrimal fossa of the lacrimal bone), and a nasolacrimal duct. The nasolacrimal duct leaves the lacrimal sac, passes through a tunnel in the lacrimal bone, then extends rostrally within a bony tunnel inside the maxillary recess of the maxillary sinus, and opens in the nasal cavity.

Dacryocystitis is an inflammation and/or infection of the lacrimal sac associated with a partial or complete obstruction of the nasolacrimal duct. Alteration of lacrimal flow may result in tear stagnation and secondary infection.⁵ Clinical signs that may be associated with dacryocystitis are epiphora, mild conjunctivitis, mucopurulent exudate at the medial canthus, pain at the medial canthus, recurrent unilateral conjunctivitis with temporary response to medical therapy, and occasional abcessation of the lacrimal sac. Recommended treatments include nasolacrimal flushes with topical medical therapy, semipermanent catheterization of the nasolacrimal duct, and surgical therapies such as conjunctivorhinostomy, conjunctivobuccostomy, or an intraosseous approach to perform dacryocystotomy or removal of a foreign body from the nasolacrimal duct.^6–8

Cystic dilatation of components of the nasolacrimal system has been reported.^9–11 In one report, cystic dilatation of the lacrimal gland ducts (i.e., dacryops) caused a fluctuant swelling at the medial canthus of a basset hound with secondary nasolacrimal duct obstruction.¹⁰ In two other reports, three basset hounds and a Shetland sheepdog were presented with a medial canthal subconjunctival cyst.⁹¹¹ Clinical signs resolved with surgical excision of the dacryops in these five dogs. Cystic dilatation of the canaliculi (i.e., canaliculops) causing epiphora has been treated successfully by surgical excision.¹²

Clinical manifestations of cystic dilatation of the nasolacrimal duct include epiphora, conjunctivitis, mucopurulent ocular discharge, and soft-tissue swelling of the maxillary area cranioventral to the medial canthus. Such dilatations may be either congenital or acquired. Suspected congenital dilatation of the nasolacrimal duct has been reported in dogs and infants.^1213–15 Causes of acquired obstruction of the nasolacrimal duct are numerous. Extraluminal compression of the nasolacrimal system secondary to trauma, inflammation, fibrosis, or neoplasia may cause physical impairment to drainage. Intraluminal foreign material (such as grass awns), cellular debris, and inflammation of the mucosa can result in narrowing or complete obstruction of the nasolacrimal duct. Acquired obstruction of the nasolacrimal duct may also arise secondary to chronic dacryocystitis.⁵⁶ In kittens, obstruction of the nasolacrimal duct can result from fibrosis secondary to upper respiratory viral infections such as feline rhinotracheitis. In the animal presented in this report, the authors hypothesized that cystic dilatation was probably acquired because of the age at which the clinical signs appeared. Although the precise cause was unknown, the dilatation may have been secondary to chronic inflammation of the nasolacrimal duct. A congenital lesion, with obstruction from secondary infection at a later age, could not be ruled out.

Dacryocystorhinography was critical in determining the presence of cystic dilatation nasolacrimal duct. The absence of contrast agent distal to the dilatation, but the presence of fluid at the left naris after irrigation of the nasolacrimal system, suggested a partial obstruction of the nasolacrimal duct distal to the cystic cavity.

Cystic dilatation of the nasolacrimal duct has seldom been reported in veterinary medicine. In a report by van der Woerdt, only one of the three dogs had a cyst originating from the nasolacrimal duct.¹ That dog was treated surgically with a nasal bone flap to reestablish drainage into the nasal cavity. White reported a case in which intranasal marsupialization was successfully performed under endoscopic visualization.²

In humans, dacryocystitis associated with nasolacrimal duct obstruction is a rare neonatal condition. The human neonatal nasolacrimal apparatus is often not patent at birth.¹⁶ Despite the apparent high incidence (73%) of an incomplete nasolacrimal duct, the incidence of obstruction varies from 6% to 30%.^17–18 Many affected children are treated with combined nasolacrimal duct probing and intranasal endoscopic marsupialization.¹³¹⁴

Conclusion

In the case reported here, cystic dilatation of the nasolacrimal duct was surgically corrected by extirpation of the cystic structure and creation of a communicating hole between the maxillary recess and the nasal cavity. The authors opted for surgical exploration of the paranasal sinus over endoscopic marsupialization because of lack of experience with the latter technique. In light of the excellent results in children, and after developing appropriate skills with the technique, the authors would strongly consider using intranasal endoscopic marsupialization in the next dog afflicted with cystic dilatation of the nasolacrimal duct.

Acknowledgments

The authors thank Mr. Marco Langlois for his photographic contribution.