Introduction

The nasolacrimal duct (NLD) system functions to drain the tear film and is present in most mammals.^1,2 The nasolacrimal system consists of the ocular puncta, lacrimal sac, NLD, and nasal puncta. The puncta serve as the openings of the system at the eye (ocular puncta) and in the nasal cavity (nasal puncta). There are 2 small, round ocular puncta per eye: 1 punctum located on the dorsal medial eyelid and 1 punctum located on the ventral medial eyelid. The ocular puncta are located approximately 4 to 6 mm along the dorsal and ventral eyelid from the medial canthus.⁶ The dorsal punctum is located on the dorsal eyelid, immediately within the mucocutaneous junction. The ventral punctum is located in a similar position along the ventral eyelid.³ The puncta connect to the dorsal and ventral canaliculi,⁴ which join to form the lacrimal sac. The lacrimal sac connects the canaliculi located in the subconjunctival tissue of the medial orbit to the NLD, which travels through the lacrimal bone, maxillary bone, and submucosal tissue of the nasal cavity. The NLD opens in the nasal cavity as the nasal puncta, also referred to as the nasolacrimal orifice.^1,4,5 In camelids, the nasal puncta are round-oval, slit-like openings located 1.5 to 2 cm interior to the wings of the nares (the junction of the cartilaginous nostril septum with the philtrum) along the ventral lateral wall of the nasal cavity.³ The total length of the NLD is approximately 11 to 15 cm long in adult llamas and has a potential diameter of 2 to 4 mm for the entirety of the duct.⁶

Disorders of the nasolacrimal system in camelids include obstruction of the duct, ocular puncta, or nasal puncta. These obstructions can be either congenital or acquired.⁴ Clinical signs include dacryocystitis, chronic discharge, inflammation of ocular adnexa, epiphora, crusting and matting of the hair, and conjunctivitis.^4,7 Case studies reporting on NLD obstruction in camelids have demonstrated successful treatment in alpacas.^4,7 In 1 case, a series of 4 alpacas with congenital atresia of the nasal puncta, surgical correction with cannulation resulted in patency in all 4 patients.⁷ In another, a cria with bilateral atresia of the nasal puncta had complete resolution of clinical signs after undergoing surgical correction of bilateral puncta atresia.⁴

Though NLD atresia and obstruction is anecdotally considered common in South American camelids,⁸ little research has been done on the topic. To the authors’ knowledge, no studies have been conducted to examine the prevalence in camelid populations. The goal of this study was to examine the prevalence of NLD obstruction in a referral hospital population as well as to examine the presentation and report on diagnostics and clinical approaches for correction of both NLD atresia and obstruction.

Methods

The medical record databases were searched at 2 veterinary teaching hospitals (Kansas State University and The Ohio State University) to identify records of camelids with diagnoses of NLD obstruction or undergoing NLD lavage during the period from January 1, 2000, to December 31, 2022. Initial search criteria included the following terms, along with all relevant permutations: nasolacrimal duct atresia, nasolacrimal duct hypoplasia, nasolacrimal duct obstruction, obstruction-nasolacrimal, conjunctivitis-follicular, or purulent eye discharge. Additionally, medical records containing any of the following keywords in invoiced items were reviewed: ophthalmology nasolacrimal, ophthalmology consult–in house, dacryoplasty, radiology large animal–dacryorhinocystogram, large animal implant–subconjunctival, conjunctival flap, large animal conjunctivectomy, nasolacrimal irrigation, and nasolacrimal duct lavage. Additionally, the total number of alpacas and llamas seen at each university between 2000 and 2023 was also obtained from the medical record database.

Animals were excluded from the study if they did not have any procedures related to the NLD or if there was not a definitive diagnosis of NLD obstruction made in the medical record. Inclusion criteria were llamas and alpacas, admitted between 2000 and 2023, for which medical records indicated a diagnosis of NLD obstruction. For each case reported in the study, the following information was obtained from the medical record when available: consult date, diagnosis, date of birth, age at presentation, sex, species, history, physical exam findings, additional diagnostics, concurrent morbidities, corrective therapy, sedation protocols, post-therapy treatment, complications, and follow-up.

Camelids were classified into 1 of 3 categories on the basis of diagnosis or procedure: NLD obstruction from atresia, mucoid obstruction of the NLD, or nondifferentiated obstruction. Diagnosis was recorded as obstruction from atresia if the diagnosis in the medical record indicated NLD atresia or surgical opening of either nasal or ocular puncta. Diagnosis was recorded as mucoid obstruction if NLD lavage was reported in the record and mucus expulsion or resolution of obstruction was established postlavage. Diagnosis was recorded as nondifferentiated obstruction if the diagnosis in the medical record indicated nasolacrimal obstruction but there was no specification in the record to obstruction due to either mucus or atresia.

The medical history was reviewed, and the client complaints and reason for presentation were recorded. Physical exam findings were also recorded. Ocular discharge was classified as mucoid, epiphora, or uncharacterized. Camelids were diagnosed with epiphora if physical exam findings indicated damp fiber around the eyes. Camelids were diagnosed with conjunctivitis if physical exam findings indicated reddened conjunctiva or conjunctival erythema. Camelids were diagnosed with chemosis if physical exam findings indicated swollen ocular adnexa and periorbital swelling.

Long-term follow-up was obtained by telephone or email questionnaire with owners. Owners were asked whether they recalled the animal, whether they still had the animal, and whether the ocular problems recurred. If recurrence was noted, owners were asked whether treatment was elected, and if so, where it was performed and what treatment was done. Treatment was considered successful if clinical signs did not recur.

Results

The medical records of 306 camelids met the initial search criteria. Animals that did not have procedures related to the NLD system were excluded. Thirty-one camelids met the inclusion criteria (Supplementary Table S1). Of the 31 camelids, 94% (29/31) were alpacas. The remaining 2 animals were llamas. A total of 8,027 alpacas and 1,998 llamas were seen between 2000 and 2022 (80% alpacas and 20% llamas) at 1 teaching institution. The total number of alpacas and llamas was not available for the second teaching institution. Excluding the 3 alpacas from this institution left the percentage of alpacas at 92%. The prevalence of NLD obstruction for this population of alpacas was 0.3% (26/8,027). Females comprised 61% (19/31) of the study population. Ages ranged from 1 month to 13 years of age, with 29% (9/31) of camelids presenting at < 6 months of age, 32% (10/31) presenting between 6 months and 1 year of age, 29% (9/31) presenting between 1 and 3 years of age, and 10% (3/31) camelids presenting at > 3 years old.

The most common diagnosis was obstruction from atresia (16/31 [52%]). Nine camelids were diagnosed with mucoid obstruction (29%), and 6 had nondifferentiated NLD obstruction (19%). Eighty-nine percent (8/9) of camelids with mucoid obstruction were noted to have bilateral obstruction. One patient had no mention of laterality within the record. Of those camelids with obstruction from atresia, 56% (9/16) were diagnosed with absent nasal puncta, 25% (4/16) with absent ocular puncta, and in 3 camelids the atresia was not classified. Additionally, 12 of the 16 camelids with obstruction from atresia had laterality noted within the medical record. The atresia was bilateral in 7 of these 12 (58%), left sided in 3, and right sided in 2 cases. The laterality of the remaining 4 atresia cases was not noted within the record.

When comparing diagnosis with age of onset of clinical signs, no animal was diagnosed with obstruction by atresia over the age of 3 years (Table 1). Mucoid obstruction was diagnosed through all age ranges (2 weeks to 13 years of age). In both the cases of mucoid obstruction and obstruction from atresia, most cases had an age of onset < 1 year (n = 6 and 9, respectively). There were 6 cases of nondifferentiated obstruction with at least 1 case in each age range (2 months to 9 years of age).

Of the 31 camelids in the study, 23 had history data available. The age of onset of clinical signs was determined on the basis of age at presentation and history. Thirty-five percent (8/23) of camelids first developed clinical signs at < 1 month of age, 35% (8/23) developed clinical signs between 2 months and 1 year of age, 4 of 23 developed clinical signs when older than 1 year of age, and the remaining 3 camelids did not have sufficient information available to determine the onset of clinical signs.

Ten cases within the study did not have a presenting complaint or history noted in the medical record. Of the remaining 21 cases, 19 presented for an ocular complaint. The 2 cases that did not present for ocular concerns were diagnosed with NLD obstruction while hospitalized. These 2 cases had lethargy and anorexia with a primary diagnosis of parasitism. Diagnostic data were available for a limited number of cases. The most common diagnostics that were reported included fluorescein staining (n = 7) of the eye and an aerobic culture of the conjunctiva (5). Only 2 cases explicitly stated that fluorescein staining was not noted to be observed within the nasal passage after a period of time. The remaining 5 cases did not comment on the presence of stain in the nostrils. Additional diagnostics on various cases included cytology (n = 2) and sinus CT with contrast (1).

Chemical restraint was employed in several cases, as the patients’ demeanor did not permit the clinician to perform the procedure safely. Chemical restraint protocols were mentioned in 16 cases. Two cases mentioned that chemical restraint was used, but the protocol was not recorded. An additional case mentioned the drugs utilized for restraint without dosages. Chemical restraint was used to facilitate lavage in 7 cases and for performing surgical procedures in 7 cases. The remaining 2 cases did not indicate the reason for chemical restraint. A ketamine, xylazine, and butorphanol combination was the most common protocol, used in 7 of 16 cases. This protocol was used for both opening of nasal and ocular puncta as well as NLD lavage. The most common dosages for this protocol were 0.3 mg/kg ketamine, 0.3 mg/kg xylazine, and 0.1 mg/kg butorphanol IV, which was used in 6 of 7 cases. The next most common protocol consisted of xylazine alone (5/16). The most common dosage utilized for xylazine when used alone was 0.3 mg/kg IV (3/5). Additional protocols included ketamine and xylazine (n = 1). Gas anesthesia was utilized in 2 cases when IV chemical restraint was not adequate to catheterize the NLD (n = 1) or surgical correction was more invasive (1).

Procedural data were variable between records. The type of flush used was recorded in 13 cases. In all 13 of these cases, sterile saline was used to irrigate and lavage the NLD. Catheter size used for catheterization of the NLD was specified in 8 cases. Of those 8 cases, 6 utilized a 3.5-Fr polypropylene catheter and 2 used a 5-Fr polypropylene catheter. This size catheter was utilized for both NLD lavage and surgical correction of NLD atresia. Direction of catheter insertion was reported in 13 cases. In 5 cases the catheter was passed retrograde, and in 8 cases the catheter was passed normograde. In cases of obstruction from atresia in which an opening was created, various methods were utilized to create the opening. The most utilized method was an incision with a No. 15 scalpel blade (n = 3). An additional method included a 14-gauge needle (n = 2), an 18-gauge needle (1), and 22-gauge orthopedic wire fed through the catheterized duct and advanced through the nasal punctum (1). One case had a secondary surgical procedure at the time of the correction of obstruction by atresia. This case was also diagnosed with stenotic nares and had an alar fold resection performed during the same anesthetic event.

After establishing patency in the NLD by creating an opening in either the nasal or ocular puncta, the clinician either sutured the catheter in place as a stent or lavaged the NLD and removed the catheter. In instances of surgical stenting, a variety of suture materials were utilized. Polypropylene suture and polydioxanone suture were utilized in an equal number of cases (n = 2 each). The most common suture size was 2-0. Stenting was utilized in 6 atresia cases, catheterization with no long-term stenting in 9 cases, and 1 case of NLD atresia had no data recorded indicating catheterization or stenting.

A variety of medications were prescribed to patients in the study population. The most prescribed medications were neomycin polymyxin dexamethasone ophthalmic ointment (n = 13 cases) and neomycin/polymyxin/bacitracin ophthalmic ointment (11 cases). Additional ocular medications included atropine ophthalmic drops, ciloxin ophthalmic drops, and lubricating eye drops. In several cases, the following systemic antibiotics were administered: ceftiofur sodium (n = 3), florfenicol (2), and tulathromycin (1).

Follow-up data were available for 15 camelids. At the time of follow-up, 4 animals were reported to still be living, 2 were deceased, 7 were reported as “sold,” and the status of 2 alpacas was unknown because the owners could not provide additional information or the owners did not respond to attempts to contact. Of these, 13 were alpacas and 2 were llamas. Six of the camelids with follow-up data were diagnosed with a mucoid obstruction, 7 with NLD atresia, and 2 with nondifferentiated obstruction. Follow-up ranged from 9 months to 23 years after discharge from the hospital. Owners reported no recurrence of clinical signs for 11 out of 15 (73%). Three (20%) cases were reported to have a negative outcome. One alpaca was reported to have mild clinical signs but overall improved from prior to treatment. One alpaca and 1 llama were reported to have no improvement or resolution of clinical signs. One alpaca was reported to have returned home after treatment and developed acute onset of neurologic disease and was re-presented to the hospital. This alpaca subsequently died and was suspected to have listeriosis or polioencephalomalacia; no definitive diagnosis was made. Of the 3 camelids with continued clinical signs, treatment was sought for 2 camelids after being discharged from the hospital. These cases were treated by their referring veterinarian with repeated NLD lavage and ocular medications. In both cases, clinical signs improved but did not completely resolve. Eighty-three percent (5/6) of the camelids with a mucoid obstruction had a documented positive outcome. The other case of mucoid obstruction did not have an outcome recorded, as the owner was not able to recall the patient. Diagnosis for cases with unsuccessful outcomes included obstruction by atresia (n = 2) and nondifferentiated obstruction (1). Eleven cases had both procedural information and reported outcomes. Of these 11 cases, 10 had positive outcomes. One of the cases treated with a stent had a negative outcome (Table 2).

Of the camelids with a successful outcome, 7 (47%) were diagnosed with obstruction by atresia, 6 (40%) with mucoid obstruction, and 2 (13%) with a nondifferentiated obstruction. Of the 5 camelids with obstruction by atresia, 3 had a cannula placed after surgery and 2 were opened with temporary catheterization without long-term (postsurgical) stenting.

Discussion

For the majority of camelids included in this case series, the onset of clinical signs and presentation to the veterinary hospital were under 1 year of age. This supports previous work indicating that NLD obstruction is often congenital.³ Clinical signs usually develop within days, weeks, or months of birth.⁹ Most commonly described clinical signs include ocular discharge that varies from serous to mucopurulent, and the condition may also be associated with conjunctivitis and dacrocystitis,³ which is consistent with the findings of this study. All cases in this series had an NLD obstruction and had a lavage of the NLD performed. Lavage can be used as both a diagnostic and therapeutic technique. After sedation, a catheter is fed either retrograde or normograde through the nasal puncta or ocular puncta, respectively.¹⁰ Saline is flushed, and patency is verified by accumulation of saline within the eye or drainage through the nose. Description of this procedure indicates the use of a 5-Fr polypropylene catheter for adults and 3.5-Fr for crias.¹⁰ Previous studies have also documented the use of fluorescein stain placed into the eye to diagnose patency by visualization of stain in the nasal passage.³ This lavage is therapeutic in cases of obstruction of the NLD with mucus or debris and diagnostic in cases of atresia. Visualization of stain in the nose has been inconsistent in normal camelids; therefore, the absence of stain in the nostrils should be interpreted with caution.¹¹

Of the camelids in the study population, 94% were alpacas. When removing the 3 alpacas from the institution where total case numbers were unavailable, the proportion of alpacas and llamas was 92% alpacas and 8% llamas. Although NLD atresia has previously been reported in llamas,¹² more information and case data appear to be available in alpacas.^4,7 This could potentially indicate a species effect for development of congenital NLD disease. This is supported by the difference in species proportion (92% alpacas and 8% llamas) compared to the total population seen in hospital, where total case numbers of camelids were available (80% alpacas and 20% llamas).

Nasolacrimal duct obstruction is also observed in other species. Punctal stenosis is seen in both dogs and cats and is more common in brachycephalic breeds.¹³ Atresia of the eyelid puncta is the most common site for punctal atresia in dogs.¹⁴ Nasolacrimal duct atresia is also a common finding in horses. In horses, the nasal punctum is the most likely site of atresia.¹⁵ Of those camelids with obstruction by atresia, 56% (9/16) were diagnosed with absent nasal puncta, 25% (4/16) with absent ocular puncta, and in 3 camelids the atresia was not classified. This is consistent with previous observations that most obstructions occur at the nasal punctum.⁹

The most prescribed medication was neomycin polymyxin dexamethasone ophthalmic ointment (n = 13 cases). Topical steroids are commonly used post–NLD surgery to reduce inflammation and prevent subsequent premature closure of the NLD while epithelialization occurs.^14,16 Limited follow-up data were available for the cases in the study. Due to this limited follow-up, it is difficult to draw conclusions based on the available data. Eleven of 15 (73%) cases were successful. The treatments and types of obstructions were variable, with no obvious differences in success or failure rates. In cases of atresia in which surgical correction was unsuccessful, utilizing dacryocystorhinography may be beneficial to determine the definitive site of obstruction of the NLD.¹⁷ Prospective or case-controlled studies focusing on standardized, short-term follow-up may prove to be more useful to associate outcomes with specific interventions.

The surgical technique described for treatment of NLD obstruction utilizes a polyethylene catheter to cannulate the duct before instilling with lidocaine followed by incision over the bleb.¹⁷ The current case population that had surgical opening of absent puncta either had the polyethylene tubing removed or left in place as a stent. Descriptions of the surgical procedure in previous literature indicate leaving the tubing or monofilament suture in place for 2 to 6 weeks to allow for epithelialization.¹⁷ This may account for some of the failures within the study population, but due to the limited nature of follow-up and lack of consistent data, it is difficult to draw conclusions.

Limitations of the study included those associated with retrospective evaluation of information like lack of medical record data and consistent follow-up information. Follow-up was subject to recall bias, as a number of owners either could not recall the camelids in the study or remembered very little about the specific animals. This may have impacted the quality of information obtained at follow-up. The overall case load may also have impacted case numbers, as the number of camelids seen over the study period decreased with time. Additionally, the significantly lower number of llamas in the hospital population precludes definitive conclusions regarding this species or accurate comparison between llamas and alpacas.

In conclusion, NLD obstruction is a possible cause of ocular disease in alpacas and llamas and should be considered as a differential for these species presenting to veterinary teaching hospitals for clinical signs associated with the eye. In this case series, most of the cases consisted of alpacas < 1 year of age. Treatment often resulted in positive outcomes with no recurrence of clinical signs, especially in cases of mucoid obstruction.

Supplementary Materials

Supplementary materials are posted online at the journal website: avmajournals.avma.org.

Disclosures

The authors have nothing to disclose. No AI-assisted technologies were used in the generation of this manuscript.

Funding

The authors have nothing to disclose.