The objective of this study was to detect the frequency of antibodies against Neospora spp. in samples of presuckle foal, as weel as determine the best dilution of serum to be used in indirect fluorescent antibody test. We analyzed serum samples from 203 presuckle foals, by indirect fluorescent antibody test in different titrations. The titrations of 16 and 50 showed 25.1% and 9.9% of presuckle foals positive, respectively. Thus, in serum samples from presuckle foals the titration 16 can be considered more appropriate to detect the occurrence of infection by the protozoan and therefore the transplacental transmission of Neospora spp. in horses.
diagnosis; horse; indirect fluorescent antibody test; Neospora spp.; transplacental transmission.