To investigate the science of animal welfare for zoo and wild animals in the period from 1966 to 2007, we conducted a bibliometric analysis of abstracts downloaded from The Web of Science((c)) database using the keyword combination "Animal welfare, Zoo* and wild" in the topic field. In total we downloaded 1,125 abstracts, which were classified into the following categories: year of publication; environment of the study (e.g., zoo) or theoretical; area of knowledge (e.g., conservation in situ); number of experimental animals used; species; addresses of authors; taxonomic classification; publication language; journal name; number of citations received. Since 1990, there has been a rapid increase in the number of articles published in this area of animal welfare. One worrying result was that published articles were predominately of a theoretical nature (58.65%, N=563). Most of the articles were published by authors either in Europe (47.43%, N=480) or North America (37.65%, N=381) and written in English (87.71%, N=971). The majority of experimental studies were conducted with mammals (75.92%, N=391), and had small sample sizes (N=7 for zoo-based studies). In terms of impact factor (IF), the journals in this study had a median factor equivalent to that for the area of biological sciences (median IF=1.013). Little knowledge cross-over from farm animal welfare was found (only four articles) in this study. In conclusion, zoo and wild animal welfare as a science may benefit from a greater interaction with farm animal welfare.