The association “Aide aux Vieux Animaux” (AVA/Helping Aged Animals) provides a shelter to more than 400 individuals from different domestic mammal species on a 185 acres estate, in the North West of France, 100 km from Paris. Every year in France, a significant number of healthy domestic animals are euthanized. Aging animals show physiological and/or behavioral changes which some owners cannot deal with. Then owners request that their animal is euthanized. Younger animals, unable to cope with an inappropriate environment can display unwanted behavior. This also leads to owner’s request of euthanasia. The main goal of AVA is to offer an alternative to euthanasia in these cases. Around 130 pet dogs are housed in 75 large outdoor pens, mainly in small groups. About 100 domestic cats are housed in 3 outdoor enclosures of 0.62 acres each. Forty aged horses are living in enclosed pastures and half of them live with minimal human contacts. AVA provides also a shelter to 15 cows and 15 rabbits. In addition 50 fallow deer are kept outdoors with appropriate shelters and feeding resources. Veterinarians, vet nurses, animal keepers and dog trainers take care daily of this population. Last year, ethologists and students in ethology joined this team in order to evaluate the welfare of these domestic animals. As animal welfare is a complex multidimensional issue, we decided to investigate some specific related topics. Indeed, the behavior of pet animals at AVA shelter could be different from that of pets living under interspecific conditions with a human owner. Therefore, it seems to be important to understanding what is relevant and/or stressful in this particular environment, where pet animals live with intraspecifics and outdoor conditions. These data should be taken into account, for assessing welfare more specifically and attempting to improve it wherever necessary. Rehabilitation is an alternative to euthanasia for pet animals. As this process can be very long for some dogs, we decided to investigate this issue scientifically. Veterinarians and ethologists from various universities have already completed several studies on dogs, cats and fallow deer. These studies dealt with intra- and inter-specific communication, social learning and social and spatial organization. In order to extend our knowledge about domestic animals, especially pet animals, and because facilities that offer this opportunity are quite rare, AVA seems to be an important place to develop these studies, along with national and international exchanges and sharing experience with other research teams.