Large animal models, a necessary and respected tool to study human pregnancies

By Agata Parsons Aubone, DVM

Animal models are often used to investigate basic biology, and importantly are necessary in experimental research to develop a better understanding of animal and human anatomy, physiology and pathology. They are of great utility because they provide the possibility of experimenting under controlled situations and mimicking physiological conditions of human and animal diseases.

To be used as a model, animal species must meet specific criteria in line with the final goal of the research. Many species are used in biomedical studies, such as insects, fish, frogs and mammals, like mice, rats, pigs, monkeys and sheep, due to their phylogenetic proximity to humans. Sometimes the model must be modified to meet specific characteristics. As an example, is the study of human pregnancy pathologies, such as intrauterine growth restriction (IUGR), using sheep as a model as we do in our laboratory.

For pregnancy to be successful in any mammal, a proper functioning placenta is absolutely critical. Even though placentation is not quite the same between human and sheep, the pregnant sheep has been used extensively to study maternal-fetal interaction during pregnancy for several reasons. First, the management of the sheep estrous cycle and pregnancy has been well studied and is easy to apply. Secondly, sheep carry one or two fetuses to term and pregnancy is long (similar to humans), and allows for repetitive sampling of both maternal and fetal blood to monitor placental transport and utilization of oxygen and nutrients. Finally, the relatively large size of the placenta and fetus allows for the collection of large numbers of samples for future analysis.

Animal models are very useful to study a large number of conditions, but we must not forget they are living beings, which is why their well-being must always be valued. Taking into consideration the correct handling, the use of large animals in biomedical studies is an invaluable tool in any field of biomedicine.

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Agata Parsons Aubone, DVM, is a 1st year PhD student at Colorado State University, studying the role of androgen receptor in placental physiology. She received her DVM degree from the University of Buenos Aires, Argentina, specializing in large animal medicine.