Blood volume changes and production and destruction of erythrocytes in newborn dogs.

Erythrocyte, plasma, and total blood volumes were measured in dogs from birth to maturity. All of these volumes (per kilogram of body weight) were significantly greater in the dog at birth than at maturity. Erythrocyte volume decreased during neonatal and postnatal periods to less than that during adult period. Erythrocyte production and destruction were measured with a technique combining dilution method of T-1824 for blood volume measurement with uniform tagging of newly formed erythrocytes with 29Fe. Erythrocyte destruction was high during the first 2 weeks after birth.