Evaluation of the sterility and clinical use of a disposable spray cap for ophthalmic medication delivery in equine patients

Objective: To evaluate the sterility of a commercially available disposable spray cap in an equine barn environment and assess its clinical use. Methods: This pilot study included an ex vivo microbiological study and an in vivo usability study. Ex vivo study: diclofenac 0.1% ophthalmic solution and neomycin-polymyxin B-dexamethasone 0.1% ophthalmic suspension were evaluated using either a traditional dropper or spray cap treatment method. Bottles were stored in an equine veterinary hospital barn and dispensed every 12 hours. Samples collected on day 0 and the final study day were analyzed for microbial contamination with next-generation DNA sequencing. In vivo usability study: client-owned horses were enrolled, and owners administered ophthalmic medications with the spray cap. A client survey evaluated owner satisfaction with the spray cap method. Results: Next-generation DNA sequencing detected no microbial contamination in any of the ophthalmic samples. Five horses were enrolled in the in vivo usability study, and 3 horses seemed to tolerate the spray cap very well, with the highest mean score for a horse of 4.9/5. Two horses did not seem to tolerate the spray cap, with the lowest mean score of 2.0/5. Audible spraying sound produced during activation of the device was reported as the biggest problem. Conclusions: The spray cap remained sterile in a barn environment and demonstrated favorable clinical use for some horses. Horse tolerance was variable depending on their temperament. Clinical Relevance: Disposable spray cap devices may represent a practical alternative for topical ophthalmic medication administration in selected equine patients and may also have applications for other species in veterinary medicine.