In two-thirds of cases, whelping occurs at night, rather complicating matters for breeders, since it is inconvenient staying up at night waiting for puppies to be born. Therefore, several protocols are being examined to induce whelping during the day.

These protocols show promise, although to date they only have been validated in a few breeds. They involve inducing parturition through the use of "antiprogesterone" medications that mimic the drop in the level of this hormone, which always precedes full term. By introducing oxytocin the next day, it is possible to induce whelping on the following day.

In principle, these substances are without risk to the puppies. The survival rate of newborns is therefore not compromised (at least not in Beagles, the main breed on which such tests have been conducted so far). To the contrary, "antiprogesterone" drugs seem to promote fetal maturation and thus avoid the birth of premature puppies particularly by encouraging the secretion of surfactant in the pulmonary alveoli—a tensioactive product that helps newborn puppies to draw their first breath and take in enough oxygen.

Precursory Signs

It is useful to identify precursory signs so as to avoid being taken by surprise at the onset of whelping, but at the same time, it is also important to understand the signs’ reliability in order to avoid needless worry.

Clinical Signs

• Appearance of milk in the teats. Although this often occurs approximately one week before whelping, it is not a reliable criterion for the imminence of giving birth, since lactation can begin much earlier in bitches that have already produced litters or later if it is the first time.• Distension of vulva and pelvic ligaments. During the final week because of a slight increase in estrogen, the bitch’s vulva dilates and the pelvic ligaments become distended, which may considerably alter the bitch’s silhouette (her ribs may "spring").

• Discharge of cervical mucus plug. In the 24 hours before whelping, effacement of the cervix results in the appearance of a semi-transparent liquid from the vulval fold. This sign is not always easy to detect and therefore unreliable.

• Discharge of placental pigment. When the placentas begin detaching themselves, the placental pigment—uteroverdine—flows into the uterus and produces a dark green vulval discharge. This marks the onset of whelping.

Behavioral Signs

• Scratching at the ground. From one to seven days before term, the uterus begins to contract slightly. These contractions are imperceptible from the outside, but they generate a change in the bitch’s behavior. During these contractions, she begins to scratch at the ground energetically with her forepaws. Although this may look spectacular, it is nothing to worry about.

• Refusal to eat. Most bitches refuse to eat in the hours before whelping. This is a good indication of the imminence of parturition.

Hormonal Changes

A bitch on the verge of whelping undergoes considerable hormonal changes, essential in triggering contractions that otherwise cannot occur. Estrogen levels increase slightly, but above all, progesterone levels in the blood, having remained high until now, drop sharply. Veterinarians use this information to determine whether or not a bitch is at full term; if she is, her basal progesterone concentration will be less than 2 ng/ml. How to detect the imminence of whelping

• The rectal temperature. The sudden drop in blood progesterone levels during the 12 to 48 hours preceding the onset of labor disrupts the bitch’s body temperature regulation, causing a transient drop in rectal temperature that lasts for a few hours before returning to normal. Breeders are therefore accustomed to taking the bitch’s temperature three or four times daily in the week leading up to full term. The ideal method is to record each figure in a notebook.

In general—although, unfortunately, not always—the temperature will drop by 1.5 to 2.0 degrees Fahrenheit in the 12 to 48 hours before whelping, compared to the average for previous days.

• Measuring devices. There are devices for measuring uterine activity and fetal heartbeats. These are in the shape of a belt that can be fastened around the bitch. Breeders can rent these belts for use at whelping time.