Lymphoid organ weights and organ:body weight ratios of growing beagles

Although dogs, especially beagles, are used extensively in biological and clinical investigations, the literature dealing with normal biological measurements of their lymphoid organs is scanty. This study was undertaken to provide the information on the weight of lymphoid organs of beagles. The thymus, spleen, and prescapular, popliteal, and mesenteric lymph nodes of 95 normal beagle dogs, from one day to 11 months of age, were weighed and compared with body weights. The weight of the thymus and spleen increased drastically at and after 2 months of age, although the organ:body weight ratios remained the same at 2 months of age and decreased afterward. Similar increases in the weight of the mesenteric lymph node complex, but with an increase in the organ:body weight ratio, occurred also at and after 2 months of age, reflecting the importance of the gut-associated lymphoid organs after weaning. The increases in the size of the cutaneous nodes, prescapular and popliteal, were less pronounced and their organ:body weight ratios remained the same from birth through 11 months of age.