Congenital nasolacrimal atresia in 4 alpacas

Abstract

Four alpacas, 2 wk to 1 y of age, were diagnosed with congenital atresia of the nasal puncta of the nasolacrimal duct. Dacryocystorhinography confirmed and localized the atresia. All animals were treated successfully by surgical creation of nasal puncta and patency was ensured by placement of a surgical stent for several weeks.

The function of the nasolacrimal duct system is to drain the tear film from the ocular surface into the nasal passages. Diseases of the nasolacrimal duct system may be congenital or acquired and are limited to inflammation or lack of patency (1). Although nasolacrimal disease is not uncommon in the South American camelid, there are few reports in the literature (2). In this paper we describe the clinical manifestations, diagnosis, and treatment of congenital nasolacrimal duct (nasal punctal atresia) in 4 alpacas.

Case descriptions

Ophthalmic examination and dacryocystorhinography

All animals were examined by a veterinary ophthalmologist at the Western College of Veterinary Medicine between September 2005 and December 2009. Ocular examinations included neuro-ophthalmic evaluations, Schirmer tear test (STT) measurements (Schirmer Tear Test Strips; Alcon Canada, Mississauga, Ontario) and fluorescein staining (Fluorets, Bausch & Lomb Canada, Markham, Ontario). The intraocular pressures were estimated with a rebound tonometer (Tonvet; Tiolat, Helsinki, Finland). Biomicroscopic (Osram 64222; Carl Zeiss Canada, Don Mills, Ontario) and indirect ophthalmoscopic (Heine Omega 200; Heine Instruments Canada, Kitchener, Ontario) examinations were completed following pharmacological mydriasis with 0.5% tropicamide (Mydriacyl; Alcon Canada, Mississauga, Ontario). Following applications of 0.5% pro-paracaine hydrochloride (Alcaine; Alcon Canada) nasolacrimal lavages were completed by cannulation of the upper and lower nasolacrimal puncta with a 24 gauge × 3/4 inch intravenous catheter (Surflo I.V. catheter; Terumo Medical Corporation, Elkton Maryland, USA) and flushing with 3 to 6 mL of sterile saline.

Dacryocystorhinography was completed in all animals following general anesthesia. For this procedure both superior (when present) and inferior nasolacrimal canaliculi were cannulated with a 22–24 gauge intravenous catheter. The catheters were secured to the facial skin with 5-0 monofilament nylon (Monosof; United States Surgical, Norwalk, Connecticut, USA) sutures. Approximately 3 mL of radiopaque contrast material (Omnipaque, Iohexal 52% GE Healthcare Canada, Mississauga, Ontario) were injected through the upper cannula and lateral and oblique radiographs were completed. Third eyelid flaps were placed and topical ocular lubricant (Refresh Lacrilube; Allergan, Markham, Ontario) was used to protect the cornea during the dacryocystorhinographies.

Case 1

A 3-month-old male alpaca was presented with a 1-month history of bilateral ocular discharge. The STT measurements were 25 mm/min and 22 mm/min in the right and left eye, respectively. Intraocular pressures were 15 mmHg bilaterally. Ocular examination revealed bilateral conjunctival hyperemia, marked epiphora, and mucopurulent punctal and conjunctival discharge. Both superior and inferior nasolacrimal puncta were present bilaterally. Following fluorescein application, dye did not pass to the nostril. Attempts at nasolacrimal lavage were unsuccessful; both superior and inferior puncta were patent but saline could not be flushed through the nose. Culture of the punctal discharge revealed 1+ Pseudomonas species and 1+ Micrococcus species but neither was considered significant due to the low numbers isolated. Dacryocystorhinography revealed a nasolacrimal duct structure that appeared normal except for non-patent distal openings bilaterally (Figure 1). The diagnosis was nasal punctal atresia.

Figure 1.

Dacryocystorhinography of the left side of an alpaca (Case 1) showing non-patent distal end of the nasolacrimal duct (arrow).

A 3.5 French × 31 cm polyethylene infant feeding tube (Argyle; Tyco Healthcare Group LP, Mansfield, Massachusetts, USA) was passed through the inferior canaliculus into the nasolacrimal duct. The end of the catheter was palpated beneath the nasal mucosa in the ventral floor or the distal nasal cavity. An incision was made in the nasal mucosa over the distal end of the catheter using a 6500 beaver blade (Becton Dickinson, Franklin Lakes, New Jersey, USA). The tubing was then passed through the incision and secured to the skin at the medial canthus and the lateral nostrils with 2-0 monofilament, non-absorbable sutures (Novafil; Tyco Healthcare Group LP). The tubing was left as a surgical stent for several weeks (Figure 2). Post-operative treatment included topical triple antibiotic solution (neomycin/polymyxin B/gramicidin, Optimyxin plus, Sandoz Canada, Boucherville, Quebec) and prednisolone acetate 1% (Sandoz Prednisolone, Sandoz Canada), q12h for 3 wk. The stents were removed 5 wk later and nasolacrimal patency was confirmed via nasolacrimal lavage. No recurrence of epiphora has been noted for 5 y.

Figure 2.

Post-operative photograph of the left side of the alpaca (Case 1) showing surgical stent placement.

Case 2

A 1-year-old female alpaca was presented with a history of epiphora from the left eye since birth. The discharge had become mucopurulent in the last few months and topical triple antibiotic ointment resulted in only temporary resolution. The STT measurements were 20 mm/min and 15 mm/min in the right and left eye, respectively. Intraocular pressures were 21 mmHg bilaterally. Ocular examination revealed conjunctival hyperemia, marked epiphora, and copious mucoid ocular discharge on the left side (Figure 3). Both superior and inferior nasolacrimal puncta were present bilaterally. Mucoid punctal discharge was present on the left. Following fluorescein application, dye passed to the right nostril but not the left. Attempts at nasolacrimal lavage were unsuccessful on the left side; both superior and inferior puncta were patent but saline could not be flushed through the nose. Dacryocystorhinography revealed a normal appearing nasolacrimal duct on the right and a non-patent distal opening on the left. The diagnosis was left nasal punctal atresia. Surgical correction was completed as described in Case 1 and the stent was left in place for 6 wk. Post-operative therapy was topical triple antibiotic eye drops q6h and corticosteroid eye drops (Dexamethasone 0.1%, Maxidex; Alcon Canada), q12h for 3 wk. Nasolacrimal patency was confirmed via nasolacrimal lavage at the time of stent removal. No recurrence has been noted at 4 y.

Figure 3.

Photograph of alpaca with unilateral epiphora and mucoid discharge secondary to congenital nasal punctal atresia.

Case 3

At 2-weeks of age, the female cria of Case 2 was presented with bilateral epiphora since birth. The STT measurements were 20 mm/min and 11 mm/min in the right and left eye, respectively. Intraocular pressures were 15 mmHg bilaterally. Ocular examination revealed moderate epiphora bilaterally. Both superior nasolacrimal puncta were absent while the inferior nasolacrimal puncta were present bilaterally. Following fluorescein application, dye did not pass to either nostril. Nasolacrimal atresia was suspected; however, due to the cria’s age, the owner elected to delay further assessment or treatment. She was presented at 1 year of age with a history of chronic intermittent bilateral mucopurulent discharge which would temporarily improve following triple antibiotic ointment application. Moderate conjunctival hyperemia, marked epiphora, and mucoid and conjunctival discharge were present bilaterally (Figure 4). Attempts at nasolacrimal lavage were unsuccessful on both sides; only the inferior puncta were patent and saline could not be flushed through the nose. Dacryocystorhinography revealed non-patent distal openings of the nasolacrimal duct on both sides. The diagnosis was bilateral superior punctal atresia and nasal puncta atresia. Surgical corrections were completed as described in Case 1 and the stents were left in place for 6 wk. The superior palpebral conjunctival punctal atresia was not corrected as the inferior puncta is primarily responsible for drainage of tears (1). Post-operative therapy was topical triple antibiotic eye drops q6h and corticosteroid (Dexamethasone 0.1%; Maxidex, Alcon Canada) eye drops q12h for 3 wk. Nasolacrimal patency was confirmed via nasolacrimal lavage at the time of stent removal. No recurrence has been noted at 2 y.

Figure 4.

Photograph of alpaca with bilateral epiphora secondary to congenital nasal punctal atresia.

Case 4

A 7-month-old female alpaca was presented for epiphora of the left side since birth. The discharge had become mucopurulent in the last few months. The purulent nature resolved temporarily with topical triple antibiotic ointment. The STT measurements were 15 mm/min and 20 mm/min in the right and left eye, respectively. Intraocular pressures were 11 and 9 mmHg in the right and left eye, respectively. Ocular examination revealed moderate conjunctival hyperemia, marked epiphora, and copious mucopurulent discharge from the left eye. Additional ocular abnormalities were noted in the left eye including miosis prior to mydriasis, mild aqueous flare, posterior lenticonus, and immature cataract. Both superior and inferior nasolacrimal puncta were present bilaterally. Following fluorescein application, dye passed to the right nostril but not the left. Attempts at nasolacrimal lavage were unsuccessful on the left side; both superior and inferior puncta were patent. Culture of the punctal discharge revealed 1+ Bacteroides species. Dacryocystorhinography revealed nasolacrimal duct that appeared normal on the right but had a non-patent distal opening on the left. The diagnoses were left nasal punctal atresia, congenital lenticonus, and cataract. Additionally, the miosis and aqueous flare were consistent with anterior uveitis, most likely secondary to the cataract in this eye. Surgical correction of the nasal punctal atresia was completed as described in Case 1 and the stent was left in place for 6 wk. Post-operative therapy was topical antibiotic/corticosteroid combination, (neomycin/polymyxin B/dexamethasone, Maxitrol; Alcon Canada), q12h for 3 wk, then q24h until stent removal. Nasolacrimal patency was confirmed via nasolacrimal lavage at the time of stent removal. The uveitis appeared to be controlled and the antibiotic/corticosteroid eye drops were discontinued. The alpaca continues to be monitored for recurrence of uveitis. No recurrence of nasolacrimal obstruction has been noted at 1 mo.

Discussion

Although there are no reports of specific anatomic structure of the nasolacrimal system in alpacas, it appears to be similar in most domestic species. It consists of the superior and inferior puncta which are oval to slit-like openings located in the palpebral conjunctiva along the edge of the upper and lower eyelids near the medial canthus. These open into canaliculi that extend through the orbicularis oculi muscle and join to form the lacrimal sac at the beginning of the nasolacrimal duct (1,2). The nasolacrimal duct passes through a canal in the maxillary bone and ends in the nasal puncta which is located in the ventral floor of the nasal vestibule (1,3).

The nasolacrimal duct system develops from surface ectoderm within a furrow that separates the lateral nasal fold and the maxillary process (4). Ectoderm cells form a cord as the maxillary process fuses with the lateral nasal fold. This cord grows toward the nasal cavity and the eye and later develops into a duct through the process of canalization (4).

Obstruction of the nasolacrimal system may involve any of its anatomic components. Acquired obstruction may occur due to trauma, dacryocystitis, foreign material, and invasion or compression by neoplasia or acquired cysts (5–18). Congenital anomalies may include nasolacrimal cysts, dysplastic or supranumary openings, and atresia of the proximal or distal components of the nasolacrimal system (19–28). Atresia is due to incomplete canalization of the embryologic cord of ectoderm. Eyelid punctal atresias are the most frequently diagnosed congenital anomaly of the nasolacrimal system in the dog (1). Conversely, atresia of the nasal punctum is the most common congenital anomaly in the horse (29,30). Congenital anomalies of the nasolacrimal system are rarely reported in the alpaca. Atresia involving the distal half of both nasolacrimal ducts was reported in a 2-month-old cria (31). All animals in our case series had nasal punctal atresia which was bilateral in 2 animals and unilateral in 2. One animal had concurrent bilateral superior punctal atresia.

One affected alpaca was also diagnosed with additional ipsilateral congenital anomalies of the lens. These were lenticonus and cataract. Cataracts are one of the most common congenital anomalies in camelids and are possibly inherited; however, the mode of inheritance is unknown (2,32). Other potential causes of congenital cataracts include in utero exposure to infection or toxic agents (2,32,33). The association of the lenticular and nasolacrimal anomalies in this case is unknown and probably coincidental. The inheritence of congenital nasolacrimal anomalies is not known. In this case series a dam and her offspring were affected and this suggests possible heritability of the trait.

The alpacas in this case series all had marked chronic epiphora with crusting and matting of the hair below the eye and variable degrees of mucoid to mucopurulent discharge associated with their nasal punctal atresia. The most common clinical manifestation of nasolacrimal duct atresia is epiphora which develops as the tear volume overwhelms the normal drainage. Chronic epiphora may lead to moist dermatitis, increased prevalence of flies and subsequent irritation, and poor physical appearance (23). Nasolacrimal obstruction often leads to secondary conjunctivitis and dacryocystitis due to collection of debris and bacterial overgrowth (1,30). Culture was completed on 2 cases which had a purulent component to the discharge, however, only small numbers of bacteria were isolated and their significance is questioned. Treatment with topical triple antibiotic in addition to surgery was adequate in these cases in resolving any clinical signs of dacryocystitis.

The alpacas in this series were presented between 2 wk and 1 y of age. Animals may not present with nasolacrimal system congenital defects until several months when the clinical signs become severe with copious mucoid and eventually mucopurulent discharge (34). The alpaca that was presented at 2 wk was the offspring of a previously affected female. Presumably, the cria’s owners were more aware of the clinical signs of the condition and sought veterinary care early.

Diagnosis of nasolacrimal duct obstruction is relatively straightforward. The fluorescein dye passage test is a primary test of patency; however, false negative results occur (1). This test was useful in all affected alpacas in this case series. The normograde nasolacrimal flush helped confirm a diagnosis of nasolacrimal obstruction in all cases. Dacryocystorhinography was then used to investigate the anatomy of the nasolacrimal duct system and to locate the cause of obstruction prior to surgical intervention (3,35,36).

Surgical treatment was effective in relieving the atresia and clinical signs in these alpacas. Treatment of nasolacrimal obstruction involves relieving the obstruction by creating a new opening (30). Nasal and eyelid punctal atresia are relatively simple to correct by incision in the nasal mucosa or eyelid conjunctiva. Tubing must be left in place for several weeks to allow epithelialization of the new puncta (34). When more extensive anomalies are present, surgical therapy may require conjunctivorhinostomy, conjunctival maxillary sinusotomy, or conjunctivobuccostomy. Such procedures by-pass the nasolacrimal system and create a fistulous tract from the conjunctiva into the nasal, maxillary, or oral cavity, respectively (7,23,31). Following surgery, treatment with topical antibiotics and corticosteroids is indicated to address bacterial overgrowth and inflammation associated with the obstruction (30).

Congenital nasal punctal atresia may be a common cause of nasolacrimal disease in alpacas. We diagnosed 4 alpacas with congenital nasal punctal atresia in a period of 4 y. Most animals were presented after 3 months of age and the most common reason for presentation was chronic epiphora. Chronic or periodic mucopurulent discharge and conjunctivitis were also common. The fluorescein dye passage test and nasolacrimal flush were useful for diagnosis of nasolacrimal obstruction, while dacryocystorhinography was needed to localize the cause. The condition was relatively simple to correct by incision in the nasal mucosa and placement of a surgical stent for several weeks.