many drug candidates as an offshoot of human drug development. Direct adver-
tising of products to pet owners in some countries enlarges this market segment.
The commonality of the underlying science, highlighted in the recent reemergence
of the “one medicine – one health” concept linking human and veterinary medicine,
further propels this synergy (Enserink 2007 ). This linkage is additionally supported
by the development of so-called “life-style” drugs for managing health and beha-
viour of companion animals. Therefore, together with their financial profitability,
novel drug development is facilitated by similarities in physiology. This is evi-
denced by the number of behaviour-modifying drugs currently being developed
from psychopharmacology research for the treatment of conditions including
aggressive behaviour, separation anxiety or obsessive–compulsive disorders, as
well as by the recent introduction of dirlotapide, a drug designed and introduced
to reduce obesity in dogs (Overall 2001 ; Wren et al. 2007 ).
A consequence of societal trends on animal health drug development is that the
companion animal market can bear a wider range of directed health products than is
possible for the food animal production market where physiological differences are
greater in many species (notably ruminants and birds), while profit margins remain
narrow amidst intense global competition for food. These financial considerations
do not exclude development of food animal drugs, delivery systems or diagnostic
screens, provided they are sufficiently economical on a per-unit basis and can
perform well in this much larger market segment. Technological breakthroughs
tend to promote such novel developments. One area, wherein the development of
food animal drugs may be potentially profitable, is non-hormonal growth regulating
agents, developed to increase the efficiency of feed conversion and to increase lean
body mass of food animals for consumption by health-conscious populations in
developed countries (Sillence 2004 ). Paradoxically, meat consumption in develop-
ing countries is also increasing (Nellemann et al. 2009 ), thereby further enlarging,
yet differentiating, the food animal market. For example, agents designed to reduce
environmental impact of animal agriculture in developing countries have a large
potential market. However, increased regulatory and safety issues concerning the
impact of animal agriculture on human food safety (such as antimicrobial resis-
tance, toxic drug and pesticide residues and bovine spongiform encephalopathy –
BSE) creates market entry barriers that are higher than those occurring in the
companion animal market. For the latter the only significant human safety issues
relate to the individual animal owner or veterinarian in handling or administering
animal products.
Regulatory policies and efforts to achieve global harmonisation in all major
animal health drug markets are major determinants of which products are profitable
for development. Should major changes occur in regulatory policies that either
increase the time required for product approval or increase the cost of meeting
regulatory demands, product submissions are likely to decrease, as both factors
increase development costs and subsequent profit margins are reduced. In con-
trast, should a major pandemic crisis occur, regulatory control could be eased to
allow the use of high-throughput technologies, as discussed later, to facilitate
rapid development of diagnostic and therapeutic responses to the emerging threat.
194 J.E. Riviere