Inbreeding and genetic diversity in dogs: results from DNA analysis.

This review assesses evidence from DNA analysis to determine whether there is sufficient genetic diversity within breeds to ensure that populations are sustainable in the absence of cross breeding and to determine whether genetic diversity is declining. On average, dog breeds currently retain approximately 87% of the available domestic canine genetic diversity. Requirements that breeding stock must be 'clear' for all genetic disorders may firstly place undue genetic pressure on animals tested as being 'clear' of known genetic disorders, secondly may contribute to loss of diversity and thirdly may result in the dissemination of new recessive disorders for which no genetic tests are available. Global exchange of genetic material may hasten the loss of alleles and this practice should be discussed in relation to the current effective population size of a breed and its expected future popularity. Genomic data do not always support the results from pedigree analysis and possible reasons for this are discussed.