This study deals with the immunological quality of canine colostrum in relation to the different parturition modes in bitches. It included four groups of bitches, who underwent vaginal parturition (VP), emergency cesarean section (EM-CS), elective cesarean section (EL-CS), or elective cesarean section with aglepristone injection 24 h prior to surgery (EL-A). Colostrum samples from 40 bitches of 18 breeds were taken immediately after the birth of the first puppy or directly after surgery, and four hours later. The concentrations of immunoglobulin G (IgG) and IgA were measured using ELISA tests. The initial IgG concentration was 18.3 ± 10.2 g/L, and the IgA concentration was 13.7 ± 5.8 g/L, respectively. Significantly lower IgG and IgA concentrations were observed in the EL-CS group compared to other groups. The administration of aglepristone led to an increase in IgG and IgA concentrations. Despite the lower immunoglobulin levels with EL-CS, the survival rate of the puppies was not affected. The study shows that immunoglobulin concentrations in colostrum vary between bitches, with the type of birth significantly influencing the levels. Progesterone withdrawal before birth could play a decisive role in increasing IgG and IgA concentrations in the mammary glands of the bitches.