Good husbandry is an essential component of a quality animal care program. Husbandry factors not only greatly influence the health and well-being of the research guinea pig, but also have the potential to affect the outcome of current and future research studies. Environmental conditions play an important role in the husbandry practices for maintaining research guinea pigs. A good animal-care program involves the intertwined workings of housing, nutrition, environmental enrichment, healthy animals, and animal care personnel and practices. Record keeping with well-maintained documentation provides proof of acceptable animal care and use standards. The basis of a good record-keeping program relies on all needed information being in written form, easily understood and completed, and readily accessible to those needing the information. The backbone of proper record keeping is the identification of animals. Guinea pigs may be identified individually by subcutaneous transponders, ear tag, ear notch or punch, tattoo, or coloration of the fur with permanent dyes or a marking pen.