A retrospective evaluation of systemic and/or topical pilocarpine treatment for canine neurogenic dry eye: 11 cases.

OBJECTIVE To assess the response to topical and/or systemic pilocarpine in dogs with neurogenic dry eye. METHOD Medical records of dogs diagnosed with dry eye between 2015 and 2018 were reviewed. Cases were excluded if STT values were decreased bilaterally, if dogs were lost to follow-up, or if surgical measures (parotid duct transposition) were undertaken within thirty days of presentation. Dogs were on treatment with topical pilocarpine (0.1%, every 6 hours) and/or oral pilocarpine (starting dose 2%, one drop per 10 kg every twelve hours). RESULTS Eleven cases were included in the study, seven females and four males with mean age of 10 years. Seven cases had xeromycteria, two cases had facial nerve paralysis, and one case had Horner's syndrome. Seven cases (63.6%) had successful outcome following pilocarpine treatment, return to normal STT (15-25mm/minute), in an average of 24 ± 5.1 days. Of these cases, five had both systemic and topical treatment, one had just topical treatment, and one had just systemic treatment. The average time to normal tear production on treatment with topical pilocarpine ± systemic was 23 days (range 9-48 days). The number of systemic drops until a positive response varied between individuals from 0.8drops/10kg to 7drops/10kg. CONCLUSION Pilocarpine treatment (topical ± systemic) is an effective therapy for unilateral dry eye disease in cases suspected to be neurogenic in origin. Most cases responded within 30 days. Side effects included topical irritation to the ophthalmic solution and systemic effects from oral pilocarpine, such as diarrhea and regurgitation.