Age relationships of postmortem observations in Portuguese Water Dogs

Abstract

A dog model has been used to evaluate histological changes arising from senescence. Autopsies of 145 Portuguese Water Dogs have been used to evaluate the individual and group "state of health" at time of death. For each dog, weights or dimensions of organs or tissues were obtained, together with histological evaluation of tissues. Twenty-three morphological metrics correlated significantly to age at death. Many of these involved muscles; others were associated with derivatives of embryonic foregut. The latter included lengths of the small intestine and trachea as well as weights of the stomach and some lung lobes. Nearly all of the dogs examined had histological changes in multiple tissues, ranging from two to 12 per dog. Associations among pathologies included inflammatory bowel disease with osteoporosis and dental calculus/periodontitis with atherosclerosis and amyloidosis. In addition, two clusters of histological changes were correlated to aging: hyperplasia, frequency of adenomas, and hemosiderosis constituted one group; inflammation, plasmacytic and lymphocytic infiltration, fibrosis, and atrophy, another. Heritability analysis indicated that many of the changes in tissue/organ morphology or histology could be heritable and possibly associated with IGF1, but more autopsies will be required to substantiate these genetic relationships.

Fig. 1

Age at death of PW dogs received for autopsy. Dogs are ranked in order of increasing age

Fig. 2

Non-neoplastic histological changes in multiple organs. The frequency of dogs in which two or more organs/tissues affected by non-neoplastic histological changes were found is shown. The number of dogs (y axis) with 2, 3, 4, etc. organ/tissues affected (x axis) are shown. Data are from histological score sheets as in supplemental Table 1

Fig. 3

Clusters of histological changes correlated with age of death. Histological changes clustered such that as age of death increases the probability of finding multiple changes also increases. Cluster one: inflammation; plasmacytic infiltration, lymphocytic infiltration, fibrosis, and/or atrophy are histological changes that occur together at autopsy in increasing frequency with age of death. The animals with 0, 1, 2, 3, 4, or 5 of these pathologies are graphed on the x axis as a function of their age at time of death (y-axis). Cluster two: Animals showing adenomas, hyperplasia, and/or hemosiderosis at autopsy are histological changes that occur together at autopsy in increasing frequency with age of death. The animals with 0, 1, 2, or 3 of these pathologies are graphed on the x axis as a function of their age at time of death (y-axis)