Preliminary findings on the effect of melatonin on the clinical outcome of cataract surgery in dogs

Objective Cataract is the most prevalent cause of blindness in dogs. Phacoemulsification (PE) is currently the surgical treatment of choice to remove the opaque lens; however, it is associated with varying degrees of postoperative inflammation. We assessed the effect of melatonin on postoperative complications of canine cataract surgery. Animal studied Eleven diabetic and thirteen healthy owned dogs with cataracts. Procedures All dogs underwent cataract surgery by PE. The anti-inflammatory effect of melatonin was compared with the reference treatments: nonsteroidal anti-inflammatory drugs (NSAIDs) for diabetic dogs, and dexamethasone for nondiabetic dogs. Eyes were examined by means of clinical evaluation and intraocular pressure (IOP). Results In diabetic dogs, melatonin was more effective than topical and systemic NSAIDs in reducing the clinical score at 2, 7, and 20 days postsurgery, while it showed a similar efficacy to topical dexamethasone in dogs with hereditary cataracts. IOP decreased in all groups at 2 days postsurgery, but this decrease reached statistical significance only in diabetic dogs treated with NSAIDs, and persisted at 7 days postsurgery in this group. Afterward, IOP returned to normal values in all groups. Melatonin decreased the occurrence of surgical sequelae in diabetic and nondiabetic dogs. Conclusions These results indicate that melatonin might constitute a useful tool for reducing postoperative PE complications in dogs.