Samples of urine and serum from 45 newborn rottweiler puppies from six litters, and milk from their mothers, were taken 24, 48 and 72 hours and seven and 14 days after birth. Urine total protein and creatinine concentrations were determined and the ratios calculated. The immunoglobulin (Ig) concentrations of IgG, IgM and IgA in urine, serum and milk were determined with a commercially available ELISA kit. The concentration of total protein in urine decreased from 1·64 to 0·29 mg/ml, and it and the ratio of total protein to creatinine in the urine of the neonatal puppies exceeded the normal values for adult dogs, but all the puppies developed normally. The average concentration of IgG in urine decreased from 0·0035 to 0·0003 mg/ml, that of IgA from 0·0035 to 0·0002 mg/ml and that of IgM from 0·0006 mg/ml to undetectable levels after two weeks. After two weeks, 47 per cent of the puppies had measurable levels of IgA and 70·6 per cent had measurable levels of IgG, but none of them had measurable levels of IgM.