Contrast computed tomography dacryocystorhinography identifies nasolacrimal duct obstruction secondary to chronic dental disease in two chinchilla langeria

Abstract

Objective

To determine the impact of chronic dental disease on the nasolacrimal duct of chinchillas using contrast CT dacryocystorhinography.

Animals Studied

Two 12‐year‐old female chinchillas with uni‐ or bilateral ocular discharge and a history of chronic, moderate (Chinchilla 1, one‐year) or severe (Chinchilla 2, three‐years) dental disease.

Procedures

Contrast CT dacryocystorhinography was performed to identify abnormalities in the nasolacrimal duct and dentition, and to correlate those changes.

Results

Chinchilla 1 had a focal soft tissue attenuating expansion of the maxillary bone rostral to the first left premolar interpreted as possible abscessation causing deviation of the nasolacrimal duct over its dorsomedial margin. The right nasolacrimal duct appeared normal. Chinchilla 2 had periapical abscessation of a retained subgingival left maxillary incisor fragment which extended into the nasal cavity causing focal narrowing and distal dilation of the left nasolacrimal duct. Complete contrast infusion of the right nasolacrimal duct could not be completed on Chinchilla 2. A focal area of superficial corneal fibrosis ipsilateral to the obstructed nasolacrimal duct was also identified in Chinchilla 2. Treatment consisted of occlusal adjustments to correct the coronal elongation, systemic antibiotics (metronidazole and either marbofloxacin or azithromycin), and topical tear replacement therapy and diclofenac as needed. Ocular discharge decreased in both chinchillas but did not resolve long‐term in either animal.

Conclusions

Chronic dental disease including periapical abscessation in chinchillas can obstruct the nasolacrimal duct, leading to impaired tear drainage. Management of dental disease is crucial to maintain patency of the nasolacrimal duct.

1. INTRODUCTION

The development of dental disease is common in aged chinchillas (Chinchilla langeria), with diet and genetics as proposed predisposing factors. ¹ Chinchilla teeth are hypselodont, meaning that they grow continuously throughout their life, and aradicular, meaning that they lack an anatomic root. ¹ , ² , ³ The nasolacrimal duct courses in close approximation to the maxillary dental arcade, thus chronic apical dental disease can lead to nasolacrimal duct obstruction and the development of ocular discharge in chinchillas. ⁴ , ⁵ , ⁶ , ⁷ Contrast computed tomography (CT) dacryocystorhinography has been performed in other veterinary species to identify and localize nasolacrimal duct obstructions. ⁸ , ⁹ , ¹⁰ , ¹¹ However, to the authors' knowledge, there are no reports of this technique in chinchillas with nasolacrimal duct obstructions, and treatment options for nasolacrimal duct obstructions in chinchillas have not been reported. Most chinchillas are treated by managing their dental disease with occlusal adjustments to reduce the crown length and prevent the progression of apical overgrowth, ¹ which can help alleviate nasolacrimal duct obstruction. The present case series describes the use of contrast CT dacryocystorhinography to determine the impact of chronic apical dental disease on the nasolacrimal duct in two chinchillas.

2. CASE SERIES

2.1. Chinchilla 1

Chinchilla 1, a 9‐year‐old intact female Chinchilla langeria, initially presented for excessive tail barbering. At this visit, tenacious white ocular discharge OS, a mildly inflamed left naris, and firm ventral mandibular irregularities were palpated that were more prominent on the left, were identified. She was diagnosed with mild dental disease based on these physical exam findings. At this time, the owner was recommended to increase forage in the diet to encourage proper tooth growth, but no medical therapy was instituted. A year and a half after her initial presentation, no ocular discharge was identified, but her dental disease had advanced to all four quadrants based on intraoral examination. She returned for her first occlusal adjustment 1 month later at which time she had mild serous ocular discharge OS. At her second occlusal adjustment, several dental caries and pockets of purulent material were identified, thus treatment with oral metronidazole and marbofloxacin was initiated. The patient required occlusal adjustments with an interval of one to five months for the next 1.5 years. At these visits, mild serous ocular discharge was reported intermittently OS and OU once.

Three years after her initial presentation, Chinchilla 1 (then 12‐years‐old) presented for a contrast CT dacryocystorhinogram to assess the contribution of her dental disease to the intermittent ocular discharge. Slit lamp biomicroscopy (SL‐17, Kowa American Corp.) without pupillary dilation identified mild, serous ocular discharge OS, but no other anterior segment abnormalities were noted. Chinchilla 1 was placed under general anesthesia and an initial CT scan was performed. The superior nasolacrimal punctum was cannulated with at 30 gauge cannula attached to a 3 mL syringe and infused with about 1 mL of an iodinated contrast agent (Isovue 370, Bracco Diagnostics) diluted 1:3 with eyewash (Medi‐First, Medique Products). Two additional CT scans were performed after contrast infusion for each side. The initial scans identified that there is malocclusion of the check teeth which is more pronounced on the right. The right nasolacrimal duct was apparently normal with a consistent contrast column from the punctum to the naris and minimal tortuosity (Figure 1A). Additionally, the presence of contrast in the naris indicates that the nasolacrimal system was patent in the absence of a Jones test. Retrograde contrast flow to the right inferior nasolacrimal punctum was not identified, but during infusion of contrast into the left superior nasolacrimal punctum, white discharge was expressed from the ipsilateral inferior punctum. On the left, the imaging showed a focal soft tissue attenuating expansion of the maxillary bone rostral to the first maxillary premolar, which was interpreted as a possible abscess with an atypical presentation (Figure 1B). This soft tissue lesion partially enhanced with contrast, indicating that the nasolacrimal duct coursed adjacent to and communicated with the lesion. Additionally, the contrast column was deviated along the dorsomedial margin of the soft tissue lesion, increasing the tortuosity of this duct. However, contrast was present in the naris, indicating that this nasolacrimal duct was at least partially patent in the absence of a Jones test. The presence of a soft tissue opacity (a presumed dental abscess) which enhanced with contrast adjacent to a deviated nasolacrimal duct indicates that the nasolacrimal duct alterations were likely secondary to the dental disease. An occlusal adjustment was performed after imaging and the patient was maintained on oral antibiotics (marbofloxacin and metronidazole).

FIGURE 1.

Contrast dacryocystorhinography of Chinchilla 1. The right nasolacrimal duct in this animal appeared healthy and patent with an uninterrupted and relatively straight column of contrast from the punctum to the naris (A). A focal region of soft tissue attenuating expansion of the maxillary bone rostral to the first premolar interpreted as a possible periapical abscess was noted on the left side (B). This soft tissue lesion partially enhances with contrast due to communication between the nasolacrimal duct and the lesion (blue arrow). The presence of contrast within the soft tissue lesion and the narrowed and deviated course of the nasolacrimal duct (not shown but apparent in the orthologous views) indicate that these alterations are likely secondary to the dental disease in this region.

Chinchilla 1 has subsequently undergone seven additional occlusal adjustments over 2 years with mild serous to mild mucoid ocular discharge or tear staining of the periapical fur being present at a majority of these visits. After each procedure, there was a temporary reduction of the ocular discharge for a few weeks. However, it would return completely by approximately 3 months after the procedure.

2.2. Chinchilla 2

Chinchilla 2, a 9‐year‐old intact female Chinchilla langeria, initially presented for decreased appetite and weight loss. She had a history of intermittent ocular discharge OU of unknown character or duration but none was identified on examination at this visit. However, severe malocclusion of her incisors, premolars and molars was noted on physical exam, leading to her first occlusal adjustment days later. Due to the severity of her dental disease, regular occlusal adjustments were recommended to maintain her oral comfort. She received occlusal adjustments every one to four months for the following 3 years with mild mucoid ocular discharge OU being identified rarely at these visits. During this time, Chinchilla 2 was treated intermittently with oral antibiotics, including marbofloxacin, metronidazole, trimethoprim/sulfamethoxazole, azithromycin, based on the results of aerobic and anaerobic cultures of purulent material in her oral cavity.

Three years after her initial presentation, Chinchilla 2 presented with marked yellow, mucoid ocular discharge OS causing the eyelids to adhere together. Following hydration and rinsing of the discharge with saline solution, the palpebral fissure was gently opened with a cotton tipped applicator. On slit lamp examination, a focal region of central corneal fibrosis was identified OS without hyperemia or chemosis and white ocular discharge and periocular alopecia were identified OD (Figure 2). She was diagnosed with ocular discharge OS, suspected to be caused by a nasolacrimal duct obstruction, and treated with one drop of diclofenac (0.1%, Bausch + Lomb) twice daily and one drop of artificial tears (I‐drop Vet Plus, I‐Med Animal Health) three times daily to limit the discharge and intermittent blepharoconjunctivitis and/or dacryocystitis. One month later, a nasolacrimal duct flush was performed on the superior nasolacrimal punctum with a 30 gauge cannula and 3 mL eye wash (Medi‐First). However, over the next 2 months, the clinical signs did not completely resolve as white tenacious ocular discharge would recur OS after discontinuation of topical medications. She also developed bilateral serous nasal discharge during this period, which can suggest the progression of apical dental disease.

FIGURE 2.

Color photography of Chinchilla 2 depicting ocular discharge and a focal area of superficial corneal fibrosis. At this visit, periocular alopecia and white ocular discharge were identified at the right medial canthus (A, red arrow) of Chinchilla 2, consistent with nasolacrimal disease. She also had a focal opacity of the left cornea (B, blue arrow).

Three months after presenting for severe ocular discharge, a contrast CT dacryocystorhinogram was performed on Chinchilla 2 (then 12‐years‐old) to evaluate her dental disease and nasolacrimal duct. No ocular discharge was noted at the time. The contrast CT dacryocystorhinography was performed as described for Chinchilla 1. One scan was performed prior to contrast infusion, four scans were performed after attempted infusion on the right side and two scans were performed after contrast infusion on the left side. On the right side, there is malocclusion and apical overgrowth of the maxillary molars and premolars. A small amount of contrast could be seen in the proximal superior nasolacrimal punctum, but the entire drainage system could not be visualized in this study (Figure 3A). It is unclear if this was due to an obstruction or inadequate cannulation and infusion of contrast. However, this lack of a contrast column after four attempted cannulations suggests that the nasolacrimal duct was not patent in the absence of a Jones test, likely due to direct obstruction by the overgrown maxillary teeth. On the left side, the clinical crown of the maxillary incisor was absent with hyperdense fragments of the reserve crown contained within the alveolar bone and there is a periapical lucency surrounding the reserve crown of this retained incisor. There is expansion and lysis of the alveolar bone at this level that communicates with the left nasal cavity. Additionally, there is malocclusion of the incisors and cheek teeth. A focal region of contrast attenuation and proximal dilation of the nasolacrimal duct was identified adjacent to a periapical expansion of the left incisor and lysis of the alveolar bone, which communicated with the nasal cavity (Figure 3B). As a corneal opacity was present OS (Figure 2B), we suspect that obstruction of the nasolacrimal duct led to chronic ocular surface inflammation and the subsequent development of corneal fibrosis. Overall, these findings suggest that the right nasolacrimal duct is obstructed and support that chronic nasolacrimal duct obstruction on the left side have occurred secondary to periapical dental disease. An occlusal adjustment was performed after imaging and the patient was maintained on oral antibiotics (azithromycin and metronidazole).

FIGURE 3.

Contrast dacryocystorhinography of Chinchilla 2. The nasolacrimal punctum of the right eye could not be cannulated for contrast infusion (A). However, a small amount of contrast can be seen in the proximal duct (red arrow). Periapical abscessation of the retained left maxillary incisor extended into the nasal cavity and was associated with focal narrowing of the nasolacrimal duct (B), evident by the attenuation of the contrast column at this point (blue arrow) along with dilation of the nasolacrimal duct proximal to this point.

Due to the severity of dental disease and persistence of the ocular and nasal discharge, extraction of the tooth fragment to remove the source of oral inflammation and blockage of the normal drainage systems was discussed but not pursued due to the complexity involved with the removal of this retained incisor. The extraction of a retained incisor would have involved a maxillary osteotomy due to the limited accessibility of the tooth fragment and extensive post‐operative care. ¹² As the patient appeared comfortable on the oral antibiotics and the ocular discharge was partially responsive to topical therapies, the client elected to continue with medical management only. Thus, Chinchilla 2 was maintained with four occlusal adjustments, oral antibiotics, and topical therapies as necessary for the next year until she was euthanized for unrelated health issues.

3. DISCUSSION

Published anatomic and dacryocystorhinographic studies have been performed in other rodent species showing the effects of dental disease on the nasolacrimal duct, ¹³ , ¹⁴ but this is the first case series to identify nasolacrimal duct obstructions secondary to chronic apical dental disease using contrast CT dacryocystorhinography in chinchillas. Previous reports of chinchillas with chronic ocular discharge have suspected nasolacrimal duct obstructions due to dental disease, ⁴ , ⁷ however, this was not confirmed with advanced imaging. Importantly, this case series suggests that the normal course of the nasolacrimal duct of chinchillas courses directly adjacent to the maxillary dental arcade and highlights the pathologic attenuation of the contrast column due to chronic dental disease.

In this case series, the superior nasolacrimal puncta in three of four eyes of two chinchillas were successfully cannulated for contrast infusion and evaluation with CT. Additionally, purulent material was expressed from the left inferior nasolacrimal punctum after contrast infusion into the superior nasolacrimal punctum of Chinchilla 1. The ability to successfully infuse contrast into the superior nasolacrimal punctum and to perform a retrograde flush of the inferior nasolacrimal punctum indicate that both puncta are patent in chinchillas unlike rabbits which only have an inferior nasolacrimal puncta. ¹⁵ However, it was not possible to visualize contrast in the inferior nasolacrimal canaliculi in the CT studies performed on these cases. As the cannulas utilized were designed for larger species, they may have bypassed the union of the nasolacrimal canaliculi, and potentially entered the lacrimal sac, therefore preventing visualization of contrast in the inferior canaliculi.

Additionally, neither the Jones I nor II tests were performed in this study to assess for patency of the nasolacrimal duct prior to contrast infusion. The presence of fluorescein in the naris would have shown that the nasolacrimal duct is patent, but these authors are not aware of any established reference ranges for the transit time through the nasolacrimal apparatus of chinchillas, thus test would have been challenging to interpret if the fluorescein was not immediately apparent. However, contrast was visualized in the nares of three of the four eyes in this case series, indicating that the nasolacrimal system was patent in those eyes.

There are important differences in the dental disease of chinchillas compared with other rodents that could predispose them to the development of nasolacrimal duct abnormalities. Specifically, chinchillas are significantly more likely than guinea pigs or rabbits to have lesions of their maxillary premolars and to have elongated clinical crowns of their maxillary dental arcade. ⁵ Due to the close proximity of the nasolacrimal duct to the maxillary dental arcade, this could lead to an increased likelihood of nasolacrimal duct sequelae in this species.

Currently, coronal reduction via occlusal adjustments, antibiotics for bacterial dental abscesses, and non‐steroidal anti‐inflammatory medications are the most commonly utilized methods to treat dental disease and secondary nasolacrimal duct obstructions in chinchillas. ⁶ Extractions of severely affected dentition could also relieve the obstruction on the nasolacrimal duct, but patient‐specific factors, such as those described in Chinchilla 2, can make this approach challenging. Additionally, it is unknown if the nasolacrimal duct would reestablish patency after the tooth is extracted as the compression and inflammation associated with the dental disease could cause irreversible damage. ¹¹

Given that treatment of dental disease alone may not be sufficient to alleviate the ocular and nasolacrimal sequelae of dental disease, topical anti‐inflammatory agents and artificial tear replacement can be useful adjunct therapies. Ultimately, stenting of the nasolacrimal duct would be the preferred treatment option to reestablish patency. Stenting, or neocanalization, has been performed in dogs, horses, cats, and rabbits with nasolacrimal duct obstructions, ¹⁰ , ¹⁶ , ¹⁷ , ¹⁸ but the authors are not aware of any reports of this procedure being performed in chinchillas, likely due to the small size of their nasolacrimal puncta and duct. ⁶ Thus, the development of such a procedure would be challenging, but would represent a significant advancement to the management of nasolacrimal duct obstructions secondary to dental disease in chinchillas.

4. CONCLUSIONS

Based on the two patients described here, contrast CT dacryocystorhinography can be performed in anesthetized chinchillas to assess the nasolacrimal duct and to confirm and localize nasolacrimal duct obstructions. This technique is particularly useful in showing the spatial relationship between teeth affected by apical dental disease and the site of the nasolacrimal duct obstruction, thereby providing further evidence of the likely role of dental disease in the pathogenesis of nasolacrimal duct obstructions in this species. Occlusal adjustments and systemic antibiotics are commonly used to treat dental disease in chinchillas. In cases with suspected nasolacrimal duct obstruction, topical anti‐inflammatory medications and artificial tear replacement can be used as adjunct therapies to reduce the ocular signs. However, these treatments may be insufficient to permanently resolve the ocular sequelae. Thus, more intensive procedures, like tooth extractions, may be necessary to resolve the chronic ocular discharge in more severely affected patients. Additionally, the development of neocanalization procedures to reestablish patency in cases of chronic nasolacrimal duct obstruction are needed. This case series highlights the importance of early detection and treatment of dental disease in chinchillas to prevent the development of nasolacrimal duct obstructions.

AUTHOR CONTRIBUTIONS

Erin A. Hisey: Conceptualization; investigation; methodology; resources; visualization; writing – original draft; writing – review and editing. Paula Rodriguez: Investigation; writing – review and editing. Danielle K. Tarbert: Investigation; writing – review and editing. Joanne R. Paul‐Murphy: Investigation; writing – review and editing. Carli Hendrickson: Investigation; writing – review and editing. Kelsey Brust: Investigation; writing – review and editing. David J. Maggs: Investigation; writing – review and editing. Brian C. Leonard: Conceptualization; investigation; methodology; resources; writing – original draft; writing – review and editing.

CONFLICT OF INTEREST STATEMENT

The authors have no conflicts of interest to disclose.

ETHICS STATEMENT

This study complies with the Guidelines for Ethical Research in Veterinary Ophthalmology (GERVO) and is exempt from approval by an ethics committee. Animal owners or owners' representatives provided written consent for the treatment provided and for the publication of data and images.

Hisey EA, Rodriguez P, Tarbert DK, et al. Contrast computed tomography dacryocystorhinography identifies nasolacrimal duct obstruction secondary to chronic dental disease in two chinchilla langeria . Vet Ophthalmol. 2025;28:983‐989. doi: 10.1111/vop.13281

DATA AVAILABILITY STATEMENT

As this manuscript was a case report, there is no data associated with this study. Clinical images and information are available on reasonable request.