Complications of Intracanal Irrigation During Root Canal Therapy of a Maxillary Canine Tooth in a Cat

This case describes a previously unreported complication of maxillary canine root canal therapy in a cat. A 5-year-old Russian Blue cat was presented with a complicated crown fracture (pulp exposure) of its left maxillary canine tooth (204). To salvage the tooth, root canal therapy was initiated but not completed due to hemorrhage within the canal. The procedure was staged. On recovery from the procedure, unilateral facial swelling and corneal ulceration were observed. This was consistent with retrograde passage of sodium hypochlorite through the nasolacrimal duct, inducing chemical injury to the cornea. The patient was treated with topical antibiotics, ophthalmic lubrication and systemic analgesia. After seven days of treatment, vast improvements to the eye were noted, with a full recovery confirmed at subsequent follow-up. Rather than complete stage two of the root canal therapy, the affected tooth was extracted; due to progression of pathology affecting the periapical bone. Clinicians should be aware of retrograde chemical irrigation as a potential complication when undertaking root canal therapy of maxillary canine teeth in cats. The close association between the maxillary canine tooth root and the nasolacrimal duct in cats needs to be taken into consideration and may require further evaluation prior to undertaking endodontic treatment. Advanced imaging should be considered. Immediate management of chemical corneal injuries should include copious flushing of the corneal surface, followed by swift referral for ophthalmic assessment.