CVC Highlight: My approach to canine dystocia
It's important to know the bitch's expected whelping date. Ninety-nine percent of dogs whelp 63 days after ovulation (the day the serum progesterone concentration increases above 5 ng/dl as determined by a quantitative assay). You can determine the ovulation date by using vaginal cytology to identify the first day of diestrus, which occurs six days after ovulation, and the owner can use this information to prepare for whelping or an elective cesarean section. With an elective cesarean section, the whelping date is crucial. You don't want to deliver the puppies too early; even one or two days early can be problematic.Abdominal palpation is not a good method for detecting pregnancy unless you're very skilled. You'll feel discrete swellings at gestation days 20 to 25, but at day 30, they'll start to blend together. It's especially difficult to palpate the swellings in a large dog with few pups. You can radiograph the dog at day 45 and later to detect pregnancy. In fact, I recommend radiographing all pregnant dogs at day 50 to 60 so you have an idea of how many puppies to expect. You can generally detect the minimum number, but not the maximum. So it's important not to overinterpret the radiograph (e.g. it's better to tell the breeder "she's carrying at least five puppies").
As the expected whelping date nears, the owner should take the bitch's temperature once or twice daily. A decrease below 99 F (37.2 C) (or a serum progesterone concentration < 3 ng/dl) indicates that the bitch should begin labor within 24 hours.
It is not unusual for a bitch to be extremely uncomfortable the last week of gestation. This should not be confused with actual stage 2 labor, which is characterized by active uterine contraction.
DYSTOCIA AND FETAL DISTRESS DETECTION
Dystocia caused by failure of the uterus to push the fetus into the birth canal can be divided into primary and secondary uterine inertia. Primary inertia is characterized by lack of abdominal press. Secondary inertia follows a period of apparently normal labor that then ceases. This diagnosis is based on the lack of labor without problems involving the birth canal (e.g. no stuck puppies).
Once dystocia occurs, you have a small window of opportunity to save the unborn puppies, so it's important to recognize and address it quickly. You have dystocia when
To help determine the presence and cause of dystocia and evaluate the bitch's condition, the following procedures are indicated: Assess the bitch's vital signs, do a complete physical examination including abdominal palpation and a digital vaginal exam, and perform laboratory testing (check the packed cell volume and total protein concentration to help identify bleeding, and measure the blood glucose and serum calcium concentrations). I used to give calcium to every bitch with dystocia, but they generally don't need it; calcium deficiency is not a common cause of uterine inertia.
To assess fetal distress, radiographs are helpful. Take a ventrodorsal and a lateral view to assess the fetal number, relative size, and position. Keep in mind that many pups that look too large radiographically can fit through the birth canal. The ventrodorsal view doesn't generally help diagnose dystocia, but it does help identify pelvic trauma and narrowing. You can also use ultrasonography to assess fetal distress by evaluating fetal motion and heart rate. The fetal heart rate should be twice the maternal heart rate (< 150 beats/min is distress; < 100 beats/min is severe distress).