Drug Delivery Devices

Spacers that can be used with metered dose inhalers that are currently on the market for use in horses include the Aerohippus (Trudell, Ontario,Canada) and the EquineHaler (Equine HealthCare, Horsholm, Denmark). The choice as to which to use is largely determined by cost and which device will best suit the particular horse in question. Although a recent study showed a trend for there to be a larger decrease in pulmonary resistance after treatment with albuterol using the Aerohippus, there were no statistical differences between the two devices. Regardless of the type of mask/spacer device used, actual delivery of particles to the lower airways is poor in the horse, as indeed it is even in humans, and the least efficacious means of delivering aerosolized drugs is by nebulization. (Bertin) An alternative to the MDI is the jet nebulizer, such as the Flexineb (Flexineb, Inc, Union City TN). Unfortunately, strategies that we know improve lung deposition of aerosolized drugs in humans, such as slow deep breathing and breath holding, are not practical in the horse. However, keeping the horse calm and the respiratory rate low may help