animals Commentary Training Pigs for Oral Glucose Tolerance Test—Six Years’ Experience of a Refined Model Elin Manell * , Patricia Hedenqvist and Marianne Jensen-Waern   Citation: Manell, E.; Hedenqvist, P.; Jensen-Waern, M. Training Pigs for Oral Glucose Tolerance Test—Six Years’ Experience of a Refined Model. Animals 2021, 11, 1677. https:// doi.org/10.3390/ani11061677 Academic Editor: Augusta Zannoni Received: 4 May 2021 Accepted: 3 June 2021 Published: 4 June 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Department of Clinical Sciences, Swedish University of Agricultural Sciences, 75007 Uppsala, Sweden; patricia.hedenqvist@slu.se (P.H.); marianne.jensen-waern@slu.se (M.J.-W.) * Correspondence: elin.manell@slu.se Simple Summary: Animal models for human diseases are used in situations where studies cannot be carried out on humans. While animal models in biomedical research play a pivotal part in the development of new and safe treatments for humans, it is important that the animals are used in the best way and that possible refinements are considered. Pigs are often used to model humans since the two species share many anatomical and physiological characteristics. This publication describes refinements in the training technique of pigs prior to an oral glucose tolerance test, a test commonly used in diabetes research where the individual drinks a certain amount of glucose followed by blood sampling. Sharing these results with the research community will help other researchers to successfully train pigs in such studies. Abstract: Animal models of human diseases are important in biomedical research. When using animals for scientific purposes, the 3Rs (replace, reduce, refine) should be considered. Refinement of animal models is essential to ensure best use of animals, which is important for ethical reasons and to retrieve reliable research data. The present publication describes improvements to an oral glucose tolerance test (OGTT) model for pigs published in 2016. Historical data from 42 pigs were used to describe improvements in the training technique over six years. Pigs of various breeds and ages can be trained to bottle-feed glucose dissolved in water to undergo OGTT. This publication describes different tips and techniques to apply for successful training and will help researchers to minimize exclusions of pigs due to unsuccessful training. The improvements are an important contribution to the 3Rs. Keywords: pig; bottle-feeding; oral glucose tolerance test; training 1. Introduction In biomedical research, animal models for human diseases play a pivotal part in finding new or improved treatments. When using animals in research, the 3Rs, replace, reduce and refine, should be considered [1]. It is important to refine animal models and to disseminate results to ensure that all animals are used in the best possible way to minimise negative effects on the animals, reduce numbers of animals needed, and to acquire research data with high validity. Pigs are used as large animal models since they share many anatomical and physiological characteristics with humans [2]. Training the pigs before they are used in research studies is always important to minimise negative impact on animal welfare, since stressful situations can induce behavioural responses such as a flight response or vocalisations, which are indicators of fear [3]. Repeated negative experiences can induce chronic stress with a large impact on the physiology and welfare of the animals [4]. Furthermore, stress responses will affect a range of different physiological parameters, which could affect research results [3]. For example, blood glucose concentrations increase rapidly in response to acute stress [5] and can bias studies on diabetes and metabolism. Animals 2021, 11, 1677. https://doi.org/10.3390/ani11061677 https://www.mdpi.com/journal/animals