Telomere lengths in dogs decrease with increasing donor age.

In vitro and in vivo studies of human tissues have demonstrated telomeric attrition with age and have linked this attrition to cellular senescence and aging. Telomere studies in canine subjects have not thus far consistently uncovered the same pattern of telomere attrition that would be expected because of the end replication problem. In this report we describe the investigation of telomere lengths in a broad age range of dogs from three different breeds: the Labrador Retriever, Miniature Schnauzer and Beagle. Peripheral blood mononuclear cell-derived DNA samples were subjected to terminal restriction fragment (TRF) analysis and demonstrated a range of mean TRFs from 9.7 to 22.3 kbp. Telomeric attrition tended to be associated with increasing donor age (P = 0.06). Interbreed differences in mean TRF values were also noted (P = 0.006). These results warrant further investigation of possible interbreed differences, given that shorter telomeres may contribute to differing life expectancy between breeds.