The rate of growth in the dog

Abstract

Observations have been made on twenty-one litters. As soon after birth as possible, when the amniotic fluid had been dried off, each individual was weighed and at the same time it was earmarked and the sex determined. For the first three or four weeks the weights were taken daily, at the same hour (4 to 5 p.m.), and later every third day. From the figures obtained curves were plotted showing graphically the absolute weight increments and the rate of growth. The figures for the number of young, the proportion of the sexes, the birth mortality, and the body weights when born, are given in the following table.

The number of young in a litter varies from 2 to 12, families of 8 occurring most frequently. The proportion of the sexes is in favor of the female, the ratio being 100 males to 119 females.

This does not agree with the statistics for the human subject nor with Minot's results in the guinea-pig, but, of course, the number of individuals so far examined by me is too small to draw any general conclusion from. The birth mortality is highest in the males, as is also the average body weight when born.

Minot found that in male guinea-pigs, as in newborn children, there is an actual loss of weight for the first 3 or 4 days after birth. Such, however, is not the case in the dog. In almost all the litters there is some gain in 24 hours, and this is very decided at the end of the second day. There is a post-natal retardation of growth but it is of relatively short duration.