Dystocia in the Bitch

Dystocia can be defined as inability to expel neonates through the birth canal from the uterus. Dystocia is not uncommon in the bitch and can have several causes. The diagnosis of dystocia should be made and treatment instituted in an expedient fashion. An incorrect diagnosis of dystocia may result in an unnecessary caesarian section, but failure to recognize or prioritize dystocia usually results in loss of puppies and perhaps even the dam. Dystocia can occur as a consequence of problems with the dam's uterus or birth canal or with the fetus. The diagnosis of dystocia should be based on the presence of any of the following criteria: 1. Failure of the dam to initiate labor at term. Bitches can be considered over term at more than 70 to 72 days from the first breeding, more than 58 to 60 days of diestrus, or more than 66 days from the luteinizing hormone (LH) surge or initial rise in progesterone during estrus. 2. Failure of the dam to enter stage] labor beyond 24 to 36 hours after a detectable drop in rectal temperature to less than 99 to 1000F or to proceed from stage 1 to stage 2 labor within 24 hours. 3. Failure of the dam to complete delivery of all fetuses in a timely fashion. Delivery should occur within 30 minutes to 1 hour of active labor (visible abdominal efforts) or 4 to 6 hours of intermittent labor. 4. Fetal distress (unborn puppies with slow heart rates, stillborns). 5. Maternal distress (excessive pain or systemic illness), green or copious vaginal bleeding. 6. Irreversible history of dystocia (pelvic canal abnormalities, mismatch between fetal and maternal size) or radio-graphic evidence of fetal malposition. Your veterinarian's diagnosis of dystocia is based on taking an accurate history, including reproductive history, ovulation timing, and breeding dates, and performing a careful physical examination including a digital pelvic examination for the presence of vaginal abnormalities and the presence of a fetus in the birth canal. A handheld Doppler device, abdominal ultrasonography, and x-rays can be helpful in assessing fetal viability, litter size, and fetal position. A blood test to measure calcium and glucose levels may be helpful in identifying metabolic disorders contributing to dystocia. Uterine abnormalities contributing to the development of dystocia include uterine inertia, abnormalities associated with fetal fluids, and herniation or torsion of a uterine horn. Uterine inertia, failure of the uterine muscle to contract in an effective manner, can be primary or secondary. Primary uterine inertia is multifactorial, with genetic, mechanical, hormonal, and physical components. Bitches exhibiting primary inertia fail to proceed into an effective labor pattern, and cesarian section is indicated. Bitches exhibiting secondary inertia fail to complete expulsion of all fetuses because of exhaustion of the uterine muscle. Medical management can be attempted, with adequate fetal monitoring, but cesarian section may be necessary. Intravenous glucose containing solutions and oxytocin ("pit") and calcium injections can be administered in appropriate doses. Generally, minute doses of oxytocin are adequate (0.25 to 4.0 units per dog). Spastic, uncoordinated contractions of the uterus occur if oxytocin is administered too rapidly or at too high a dose. Uterine contractions interfere with fetal oxygen supply by compressing placentas. Oxytocin should be administered only with veterinary guidance. Abnormalities of fetal or placental fluids include hydrops, an excessive accumulation of allantoic fluid associated with each fetus, causing the fetal unit to be markedly oversized. Rarely, underproduction of fetal fluids occurs, resulting in dystocia caused by lack of lubricating fluids. Disorders of the birth canal contributing to dystocia include pelvic abnormalities such as narrowing resulting from a healed fracture or congenital disorders and vaginovulvar abnormalities such as strictures. Successful natural breedings can occur despite the presence of septate (vertical) bands in the vaginal vault. Unfortunately, subsequent vaginal delivery of fetuses is usually impaired. Strictures should be detected by the veterinarian at the time of the soundness examination, before breeding. Anular (circular) strictures are often detected at the time of breeding, as they often interfere with the ability to attain a natural tie. These should be repaired before breeding. Bitches with unusually small vulvar openings may require a partial episiotomy to deliver puppies vaginally. Fetal causes of dystocia include fetal oversize; fetal anomalies; and abnormal fetal position, presentation, or posture. Fetal oversize can occur with prolonged gestation in abnormally small litters (especially if there is a single pup) and is the most common fetal cause of dystocia. Fetal anomalies such as anasarca and hydrocephalus (abnormalities of body fluid distribution) can cause a mismatch between the size of the birth canal and that of the fetus. Because both anterior (head-first) and posterior (breech) presentations are normal in the bitch, only a transverse (sideways) presentation is associated with dystocia and is rare. Puppies are normally positioned with the fetal backbone adjacent to the top surface of the uterus. Malpositioning can cause mild dystocia. Abnormalities of posture, normal being fully extended, are the second most frequent fetal cause of dystocia. Malpositioning of the head, forelimbs, or hindlimbs of the canine fetus is not readily corrected with the use of forceps, traction, or digital manipulation because of the limitations of the size of the birth canal of the bitch. The above is general veterinary information. Do not begin any course of treatment without consulting your regular veterinarian. All animals should be examined at least once every 12 months.