Transdermal drug delivery (TDD) is a novel technique for drug administration and is an active area of research in human medicine. Although there is some precedent for use of TDD in veterinary species, most of this use is based on empirical information. There are limited reports of active research or controlled trials investigating this modality in the veterinary medical literature.
The skin is considered the largest organ system in the body. Due to its easy access and ability to maintain applied formulations for prolonged periods of time, the skin is a likely target for drug delivery techniques. The physical structure of the skin itself provides a basic barrier to the agents utilized in TDD techniques. The skin is divided into three layers: the epidermis, dermis, and subdermis. The epidermis is further divided into five layers: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. The barrier created...