Dealing with dystocia (Proceedings)
Many of the reproductive abnormalities that present as emergencies are straight- forward and relatively easy to resolve. Treatment of these diseases, however, requires knowledge of the underlying pathophysiology as well as the options available for dealing with such emergencies. Many breeders are well informed about the latest developments and expect their veterinarians to be as well. This chapter will discuss the most common reproductive diseases that present to the emergency veterinarian and provide treatment options and recommendations for each.
Appropriate management of dystocia requires that the client be well educated and able to recognize signs of impending problems. Once dystocia does occur, there is typically a small window of opportunity in order to save the unborn puppies and kittens.The first question you need to be able to answer is "What is the bitches expected whelping date". Ninety-nine percent of dogs whelp 63 days after ovulation (the day progesterone rises above 5 ng/dl). By establishing this date, the owner can be appropriately prepared for whelping and the timing of an elective C-section, if desired, can be established. As the expected whelping date nears, the owner should take the bitch's temperature once to twice daily. A fall in temperature below 99°F indicates that the bitch will begin labor in within 24 hours. Owners, particularly first time breeders, should be instructed how to properly prepare a whelping area and how to deal with a normal uncomplicated whelping.
Signs of Fetal Distress
Vaginal discharge: Off-colored discharge (green, red, or brown) from the vagina prior to whelping is a sign of fetal distress. If discharge is seen an emergency C-section should be performed if the goal is to have as many alive puppies as possible.
More than 2 hours between stage 1 and 2 labor: If a bitch takes longer than two hours between the initiation of labor and the birth of the first puppy a C-section should be considered.
A puppy becomes lodged in the birth canal: A small birth canal can result from healed pelvic fractures, vaginal strictures, vaginal prolapse, etc. The puppies may be too big to pass through a normal-sized canal. In some breeds, such as the bulldog, the conformation of the breed is such that the wide-bodied, wide-headed pups frequently cannot pass through the pelvis. Bulldogs also have poor uterine contractility. Caesarian section is routinely done in these breeds. When litters are very small (1 or 2 pups) the pups may become too large to pass easily through the canal. Fetal monsters and anasarcous fetuses may also cause problems.
More than one hour passes between puppies: If a bitch is in active labor and more than one hour passes between puppies the bitch should be examined to determine if a puppy is malpositioned or any other problems exist.
A physical examination of the bitch should be performed in order to identify any systemic illness that might contribute to a difficult birthing such as anemia from torn uterine vessels or sepsis from a uterine rupture. A digital vaginal exam should then be performed in order to detect obstructions or the presence of a wedged fetus. Radiographs may be helpful to evaluate fetal size and number, and any possible abnormalities of the pelvic canal. Although an uncommon cause of dystocia, serum calcium and glucose should be measured to detect low concentrations which may prevent adequate contractions.
Dystocia due to failure of the uterus to push the fetus into the birth canal can be divided into primary uterine inertia and secondary uterine inertia. Primary uterine inertia is recognized by lack of abdominal press. In some instances when the litter is small, parturition does not occur normally. It is hypothesized that there is not enough hormonal stimulation from the small number of fetuses to induce the normal process of parturition. Diagnosis of primary uterine inertia is based on the failure of parturition to occur within the expected period, or better, on the failure of labor to follow a drop in temperature within 24 hours. Secondary uterine inertia follows a period of apparently normal labor, which then ceases. Diagnosis is based on the lack of labor, without problems involving the birth canal (no impingements, no stuck puppies).
If there is absolute fetal oversize or inadequate pelvic diameter, a C-section should be performed. If there is only one large pup or fetal monster wedged in the canal, one can try to manipulate it. In some case gentle traction and the addition of lubrication will allow the fetus to pass. However, in many cases this approach is unsuccessful.
Bitches with primary uterine inertia are usually healthy with normal calcium concentrations. Oxytocin (see protocol below) is the first line of treatment, however most bitches with primary uterine inertia will not respond to oxytocin. Caesarian section is indicated and is usually successful if done within 24 hours of the drop in rectal temperature.
In cases of secondary uterine inertia plasma glucose and calcium should be measured, if possible, to find whether there is a deficiency. Supplementation should only be given in cases with a documented deficiency. Treatment is administration of oxytocin. If no active contraction is seen within 20 minutes the dose can be repeated. If no puppy is born after two doses of oxytocin then a C-section is indicated. Oxytocin should not be used in cases in cases or narrowed birth canal, fetal malpositioning, and fetal oversize.
Reference: Available upon request