Unlike many veterinarians, I breed dogs, so I have experience in breeding and whelping puppies. I probably take a different
approach to breeders and discussing their concerns about dystocia because of my experience and encourage you to do so as well.
Try to keep in mind that breeders are experienced and usually knowledgeable; in fact, they may have whelped hundreds of litters.
So approach them with respect.
PREWHELPING POINTERS
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
- No puppy is born within four hours of the temperature readjusting to normal (> 100 F [37.7 C]).
- Active stage 2 labor lasts more than one hour without producing a pup.
- More than three hours pass between pups without active contractions.
- A black, green, or red discharge is present before any pups are born (indicating placental separation and fetal distress),
or a large amount of fresh blood is passed during labor.
- A pup is lodged in the birth canal.
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).
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