The Golden Retriever Lifetime Study enrolled dogs from all around the continental United States. The animals are distributed roughly evenly around the country, so it is possible to learn about regional differences in diagnoses, treatments and outcomes.
The environmental exposures and lifestyle differences between dogs that live in rural areas vs those that live in urban areas can be dramatic. The Golden Retriever Lifetime Study collects this information on each dog, with neighborhoods classified as either urban, suburban or rural.
At enrollment, dogs needed to be between six months and two years of age. The enrollment period last about 2.5 years, so at any point in time the dogs span a range of about four years, as shown in the graph below.
At enrollment, 49% of the dogs were female and 51% male. Roughly one-third of each group were intact. Over the course of the study, some of those dogs have been spayed or neutered.