Problems of pregnancy and parturition (Proceedings) - Veterinary Healthcare


Problems of pregnancy and parturition (Proceedings)


If stage I has not progressed to stage II within 12 hours, the dam should be examined. Exercise often stimulates abdominal contractions. For that reason, some have recommended that the owners walk the bitch up and down the stairs or around the house before loading her in the car for the drive to the veterinary hospital. The onset of stage II of labor is recognized by the return of rectal temperature to normal, the presence of strong abdominal contractions, and the passage of amnionic fluid. The passage of amnionic fluid is an indication of stage II labor, irrespective of obvious abdominal contractions. The first pup should be born within 2 to 3 hours of amnionic fluid. Other findings of concern are the presence of a vulvar discharge, fetal membranes, or a partially delivered fetus. A dark green discharge in bitches or red-brown discharge in queens originates from the placenta. Its presence indicates that at least one placenta has begun to separate. If a pup or kitten has not been delivered within 2 to 4 hours, the dam should be examined. A bright yellow vulvar discharge is meconium. Passage of meconium is indicative of severe fetal stress. It is often associated with fetal aspiration of amnionic fluid and a grave prognosis for neonatal survival. A purulent discharge may be found if uterine infection or fetal maceration exists. Viable fetuses may also still be present.

In dogs neonatal mortality is directly correlated to duration of labor. If delivery is complete within 1 to 4.5 hours of the onset of stage II labor, puppy mortality is about 6%; whereas, neonatal mortality is about 14% after 5 to 24 hours of stage II labor. The outcome for the bitch and the puppies is favorable when the dam is healthy, the fetal heart rates are normal (>200 bpm), when stage I is less than 6 hours in duration, and the duration of stage II is less than 12 hours. When stage II lasts longer than 12 hours but less than 24 hours, the prognosis for puppy survival is poor, although the prognosis for the bitch is still fine. If stage II lasts longer than 24 hours, the puppies are likely to die and morbidity for the bitch is increased. Fetal heart rates less than 150 to 160 bpm or illness in the bitch is also associated with worsening prognosis.

The first step is to examine the perineum for evidence of a partially delivered fetus, which requires immediate attention. There may be a bulge in the perineum dorsal to the vulva, or there may be fetal limbs or tail protruding from the vulva. When it is determined that no partially delivered fetus is present, the complete physical examination of the dam proceeds as usual. Systemic illness in the dam should be pursued as usual for any ill animal. In bitches of adequate size, a digital vaginal exam should be performed to assess for the presence of a fetus in the birth canal. If none is found, the dorsal wall of the vagina should be stroked, because doing so often stimulates abdominal contractions. This procedure has been referred to as "feathering." The cervix is not palpable per vaginum. After assessing maternal health by physical examination, the fetuses are assessed by radiology and ultrasonography. The number, size, shape, location, posture, and presentation of any remaining fetuses are often best determined by radiographs. Ultrasonography is ideal for assessment of fetal viability on the basis of heart rate and fetal movement.

Fetal movement and heart rates are decreased as a result of stress and hypoxemia. In fetal pups, heart rates below normal (>180 bpm) are associated with poor neonatal survival. It has been shown that heart rates <150 to 160 bpm indicate fetal stress. When heart rates are less than 130 bpm, there is poor survival unless pups are delivered within 1 to 2 hours. There is high neonatal mortality among pups with fetal heart rates less than 100 bpm unless they are immediately delivered. Lack of fetal movement, irrespective of heart rate, is also a poor prognostic indicator.

When it has been determined that an "overdue" bitch is healthy and the fetuses are healthy (as determined by the presence of fetal movement and normal heart rates), serum concentrations of progesterone could be determined. This would be especially helpful in situations where information by which the actual length of gestation might be calculated is lacking. The finding of progesterone that is greater than 3 ng/ml (9 nmol/L) in a bitch would indicate that the pregnancy has not yet reached full term. Intervention should be delayed and watchful waiting should continue for several hours. If 24 hours pass with no progression of labor, all parameters should be reassessed. Animals in stage I of labor are expected to progress to stage II in less than 12 hours. When that does not happen, watchful waiting no longer applies, nor does it apply to dams already in stage II of labor.


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