Species” and “Drug Delivery Systems in Domestic Animal Species” of this text).
There is now a need to determine which factors increase activity and decrease
inter-individual variability. The adoption of population models has become com-
monplace in human medicine and their adoption in veterinary medicine will be
increasingly forthcoming as more user-friendly software continues to be developed
(see chapter, “Species Differences in Pharmacokinetics and Pharmacodynamics”
for further discussion).
5 Microfluidics
Computer processor miniaturisation and continuing advances in micro-scale engi-
neering have led to the development of so-called microfluidic devices, which
enable complete analytical chemistry platforms to be created on the size of a
postage stamp, described as the “lab on a chip” (Manz et al. 1990 ; McClain et al.
2003 ). In addition to the markedly reduced material costs, these systems, which are
also referred to as micro Total Analysis Systems (microTAS) devices, reduce
considerably reagent volumes and sample sizes required for both detection and
quantitation. Moreover, micro electromechanical systems (MEMS) have opened up
possibilities of implantable feed-back controlled drug delivery devices on a scale
much smaller than that which is currently available. One major advantage of
miniaturisation is reduction in power requirements, permitting battery technology
not to be rate-limiting. Indeed, it is likely that the future will witness the develop-
ment of devices powered by absorbing ionic substances from the animal in which
the device is implanted to energise internal batteries!
There are many applications for such devices, which were in the realm of science
fiction a mere decade ago. These devices can miniaturise traditional wet chemistry
assays, thereby greatly reducing required sample sizes, volumes of reagents and,
most importantly, the generation of hazardous waste. Microfluidic cell culture
systems are currently being developed and utilised (Rhee et al. 2005 ; Kim et al.
2006 ). In veterinary medicine, microfluidic analytical devices might be used for the
determination of biomarkers of disease or adverse drug effects in individual
animals, allowing true individualisation of drug therapy. Moreover, their small
size would reduce the cost of expensive species-specific reagents. The veterinarian
could have a clinical chemistry laboratory contained within a unit of the size of a
match-box! This could greatly increase the accuracy of diagnosis, and in turn
increase the efficacy and safety of drug therapy. Tests for chemicals and drug
residues in food animals could also be readily created to provide accurate and
sophisticated analytical capabilities to the range or the feedlot. These approaches
could be accomplished with current technology.
More advanced devices could be created with incremental improvements.
Real-time microbiological devices searching for specific genetic determinants of
drug resistance could allow selection of the appropriate antimicrobial drug for each
patient, thus enhancing significantly the use of drugs in a rational manner. All that is
200 J.E. Riviere