96 • Alternatives to Animal Use in Research, Testing, and Education 
riety of species that effective research on their 
control has been possible (19). Perhaps ironically, 
the same diverse mix of species that transmits dis- 
ease to humans forms the substrate for research 
to ameliorate human disease. 
Infection of multiple animal species has led to 
virtual control in industrial countries of the 
plagues just mentioned. Yet a paucity of animal 
vectors or models hampers control of certain 
other human infectious diseases. Leprosy, herpes, 
and gonorrhea (which are not zoonoses) have yet 
to be brought under control, owing partly to the 
lack of effective animal models. Recent discoveries 
of leprosy and herpes infections in primates, the 
culture of the leprosy bacillus in armadillos, and 
adaptation of the gonorrheal organisms to some 
species of laboratory animals offer promise that 
effective animal models will soon become avail- 
able for research (19). Yet research on other con- 
ditions of still-unknown etiology, such as Alz- 
heimer’s disease, remains impeded by the inability 
to identify an appropriate animal model. 
Additional impetus for employing a variety of 
species in the course of research comes from a 
consideration of the immune response, which rec- 
ognizes material that is foreign to the body. The 
immune system thus serves as an animal’s defense 
against infections due to viruses, fungi, or bacte- 
ria. When foreign proteins, or antigens, are in- 
troduced into an animal, the immune system re- 
sponds by manufacturing a protein of its own, 
an antibody, to counter the invader. This is the 
principle on which the development of vaccines 
is based: An antigen is injected, and it stimulates 
production of an antibody that combats the for- 
eign antigen. 
The strength of an immune response varies 
from species to species, and even within a spe- 
cies, according to the genetic constitution of the 
animal used. Researchers often cannot gain a full 
understanding of how to develop useful vaccines 
unless they test several species to examine sub- 
tle differences in immune responses. In this way, 
species differences in response to foreign antigens 
are found and can be exploited in the production 
of effective vaccines for humans and animals. It 
is this use of the immune system that has con- 
trolled most of the major infectious viral diseases, 
including smallpox, which was controlled through 
the use of the cowpox, or vaccinia, virus. 
No one animal species is the complete research 
model for the human. In general, nonhuman pri- 
mate species have the greatest anatomical, physio- 
logical, and metabolic similarities to humans. Yet, 
as table 5-2 indicates, much important biological 
information can be provided by using dissimilar 
organisms. (This table oversimplifies the use of 
various animals in studying human health and dis- 
ease because it does not rate the closeness of the 
similarity of the conditions between humans and 
animals (19).) 
It is important to establish any new biological 
principle or a new phase of understanding a dis- 
ease condition in as many species as possible in 
order to improve safely the extrapolation from 
one animal to another and to humans (19). Re- 
search results derived from multiple systems in 
varied species, such as those listed in table 5-2, 
complement each other to approximate human 
anatomy, physiology, and metabolism. 
Some biomedical research, collectively known 
as veterinary research, seeks to understand the 
life processes of animals and applies this knowl- 
edge to serve animals themselves, as well as hu- 
mans. Veterinary research addresses the normal 
structure and function of animals and the causes, 
diagnosis, prevention, and treatment of disease 
in experimental animals and clinical (i.e., patient) 
animals. Research on food- and fiber-producing 
domestic animals supports the utilization of plant 
and animal resources for human sustenance. 
Veterinary research plays a prominent role in 
controlling diseases of importance in food -produc- 
ing animals and, hence, of importance to humans. 
Veterinary research supports, and is closely al- 
lied with, veterinary medicine. Practitioners of 
veterinary medicine maintain and improve the 
health and well-being of animals. The profession 
concentrates on the health of animals important 
for food and fiber and on companion animals. 
Other species receiving veterinary attention in- 
clude laboratory animals, fish and aquatic ani- 
mals, and zoo and wild animals. Thus, the ma- 
jority of veterinary medicine addresses 30 to 40 
different species of economic, ecologic, and envi- 
ronmental importance. These include: 
• domestic animals (e.g., cats, cattle, chickens, 
dogs, donkeys, goats, horses, sheep, and 
turkeys); 
