The use of the anti-Müllerian hormone (AMH) serum concentration as a fertility marker has been shown in cows, sheep and mares and has been indicated in one study in female dogs. The aim of this study was to investigate the connection between the AMH serum concentration, taken at two defined time points during the bitch`s heat, and the litter size to investigate whether AMH can be used as a practical measurement for the individual breeding bitch to predict litter size. The study was carried out on 27 healthy female dogs presented for pre-breeding examination, considering all previously known influencing factors on AMH in the bitch such as age, body weight and estrous cycle phase at the time the sample was taken. Due to the AMH increase in early proestrus and its drop around ovulation, AMH was measured in blood samples taken within the first three days of heat (AMH1) and near ovulation (AMH2) with AMH1 being significantly higher than AMH 2 (p <
0.001). There was a highly significant negative correlation of body weight and AMH at both sampling times (p <
0.001). There were no significant results when the dogs were paired and grouped according to high or low AMH concentrations, but a significant effect of AMH serum concentration on litter size was found in the multifactorial analysis when the dogs were matched according to their body weight (AMH1: p = 0.022
AMH2: p = 0.030). In conclusion, a significant effect of the AMH concentration and the litter size among female dogs with matching body weight could be found, but a much larger sample collection is needed to evaluate reference intervals for AMH for bitches of different weight to predict the fertility of an individual bitch in the future.