Serum alpha 1-acid glycoprotein (AAG) levels were measured in healthy beagles of various ages (66 male and 74 female) by turbidimetric immunoassay (TIA), and then separately--in pregnant beagles--by single radial immunodiffusion (SRID). The first experiment revealed that serum AAG levels ranged from 40 to 960 microg/ml (mean of 322 +/- 202 microg/ml) in male dogs, and from 47 to 833 microg/ml--in female dogs (mean of 316 +/- 199 microg/ml), without any significant sex- or age-related variation. The second experiment, however, revealed that serum AAG levels increased in all pregnant beagles and peaked in the middle of gestation at 250-1,000 microg/ml (mean of 634 +/- 246 microg/ml). In 7 of 8 dogs the AAG levels peaked about 45 days after ovulation. Despite a high value of 1,210-1,360 microg/ml being observed for serum AAG levels in 3 pregnant beagles inoculated with Staphylococcus aureus, its levels in umbilical cord blood were below the detection limit of SRID (40 microg/ml).