The bitch should be checked for pregnancy signs by abdominal palpation of the uterus at 28 days, or even better, an ultrasound performed using either a linear array or sector scan. The advantages of ultrasound are more than just accurately diagnosing pregnancy, but also identifying fetal status. The fetal heartbeats are detectable as early as 24-28 days after breeding and it is easy to determine by size, shape and the presence of the heartbeat the age of the fetuses. Radiography is also an important pregnancy monitor performed at approximately 50-55 days. The most common time for this reabsorption to occur is between the 32nd and 44th day.
Uterine disease is the second most common cause of reabsorption.
There may be areas of the uterus that have begun to undergo a hormonally driven hyperplastic condition that is aggravated by the presence of low numbers of bacteria in the uterine tissue. E. coli is the most common bacterial contaminate of the uterine wall that is responsible for reabsorption. For bitches that you are going to put in your breeding program, Eva, it is important that you know the thyroid status as well. One more category of agents that might produce an early embryonic death or a reabsorption are agents called teratogens. Teratogen is an agent that can induce a congenital defect when administered to a pregnant animal.