Dystocia
Text by Willem Schaftenaar
Obstructed labor, also known as labor dystocia, can be defined as the condition in which the fetus is unable to pass through the birth canal because the passage is physically blocked. As per definition, the birth process has already started, indicated by the drop of blood progesterone to base-line level. This hormonal change should be followed by labor activities within about 3 days. The longer this period takes, the higher the chances are that a dystocia will develop. Monitoring the birth process using transrectal ultrasonographic examination is of great importance, especially in older elephants. Click here to read more about the normal birth process.
In elephants, the main causes for dystocia are:
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Insufficient dilatation of the vaginal vestibulum due to lack of elasticity of the skin that covers the vaginal vestibulum;
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Malposition
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Intra-uterine fetal death
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Relatively too large fetus
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Uterine inertia (physical and psychological)
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Too small pelvis of the dam
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Intra-uterine death
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Retained fetus
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Tumors/cysts
1. Insufficient dilatation of the vaginal vestibulum due to lack of elasticity of the skin that covers the vaginal vestibulum. This is probably the major cause of dystocia and stillbirth in older elephants getting their first calf. Whether this is caused by insufficient production of estrogens, is unknown. Once the major part of the calf's body has entered the vertical part of the birth canal, the contractions of the uterus have very little (if any) influence on the propulsion of the calf. Gravity force has taken over the forces produced by uterine contractions. In this position, the umbilical cord may have ruptured already or might be compressed, as the calf is literally squeezed into a narrow space. The author has assisted in at least 5 dystocia cases caused by this phenomenon.
Too narrow birth canal in an aged nulliparous elephant resulted in the suffocation of the calf in the vertical part of the vaginal vestibulum. Courtesy: Dak Lak Elephant Conservation Center.
2. Malposition is another important cause of dystocia similar to other mammalian species. The malposition may be caused after the calf died in the uterus. This happened in a 29 yr-old Asian elephant when the umbilical cord was twisted twice around the first presenting leg of her calf. As a result, the calf got stuck in a horizontal position, unable to make the necessary longitudinal twist-movement when entering the vaginal vestibulum. Click here to read this case report.
3. Intra-uterine fetal death can be the result of a fatal infection, e.g. cowpox, salmonellosis or any other form of septicemia. Usually there has been a known episode of illness of the dam during her pregnancy.
4. A relatively too large fetus can result in stagnation of the parturition. In several zoos the birth weight of the calves is too high. The body weight of a newborn calf should not exceed 120 kg. Lack of movement and/or an unbalanced diet are the main reasons for overweight of the new born.
5. Uterine inertia can play an important role in stagnation of the birth process. Exhaustion of the uterine muscle is a form of physiological uterine inertia. It can be induced by repeated administration of (high) doses of oxytocin, which has been reported anecdotally several times. Like in horses, elephants may react on environmental disturbances during the birth process by ceasing labor activities. Hypocalcemia can result in a decrease of the uterine muscle contractions. The author has noticed at multiple occasions, that intravenous infusion of 1-2 liter calcium-magnesium borogluconate increased the strength of the contractions. This was confirmed by transrectal ultrasound examination: the position of the uterus in the abdomen was higher than before the infusion. Monitoring blood calcium levels, and more specifically the ionized calcium concentration, should be part of the monitoring of the birth process. The ionized calcium levels should be around 1.25–1.30 mmol/L (van der Kolk, 2008).
Finally, excessive body weight and/or lack of exercise of the dam can possibly play a negative role on the uterine fitness.
6. If the pelvis of the dam too small, the fetus may get stuck even before entering the birth canal. The author assisted a unsuccessful fetotomy in an Asian elephant with a relatively small pelvic diameter. The procedure failed, as the fetus's body could not be reached through the episiotomy -opening.
7. Intra-uterine death of the fetus can result in abnormal position of the fetus. Like in other mammalian species, the fetus should actively collaborate with the labor activities of the dam. If a leg or the head is not stretched at the right time, this may cause complete obstruction of the passage. The author has witnessed that rotation along the longitudinal axis of a dead calf (after creating access through episiotomy) resulted in the easy passage of the calf. Figure 1 shows that the calf rotated along its longitudinal axis on its way through the birth canal.
Figure 1. Natural rotation along the longitudinal axis facilitated the birth of this healthy Asian elephant calf.
8. Retained fetus
Retention of a dead fetus is not uncommon in elephants. It has been reported in African and Asian elephants kept in captivity. No study has been done on the mechanisms that lead to fetal retention. When the blood progesterone level drops to its baseline at the end of pregnancy, parturition should follow within a few days. The length of the period between baseline progesterone values and the actual birth of the calf is not known. However, following the expected physiological pattern of the birth process in other mammalians, birth should take place in about three days, though there are exceptions of calves being born alive after as long as 14 days. If the period of low progesterone levels exceeds 2 weeks, we can call it a prolonged pregnancy or fetal retention. The chances for the calf to survive a prolonged pregnancy are assumed to be low. To date, reported cases of prolonged pregnancies range from 3 to 60 months. Fetal membranes may or may not remain intact. In contrast to other mammalian species, the fetus is not always affected by microbial contamination. Sterile mummification can result in the conservation of the dead fetal carcass, due to the specific anatomy of the birth canal: the total length of the vaginal vestibulum ranges from 1-1,4 m, including a long vertical part and long horizontal part. In one case (Thitaram, 2006) the hind legs were macerated, while the anterior part of the calf (in anterior presentation!) was well conserved.
Labour activities occurring around the expected calving date may have been missed. In 1 case (zoo-born 37 yr-old Asian elephant, 6th calf), vague signs of a birth process, including colic-like symptoms were observed 1 day after progesterone blood levels returned to its baseline level (Schaftenaar, 2013). From that moment the birth canal was ultrasonographically monitored. No changes were noted until 13 days later, when ultrasound examination confirmed partial relaxation of the cervix (13.7 mm, figure 2). In the following days the cervix closed again and remained closed until the final birth process started 13 months later. The mummified calf was removed by total fetotomy. The cause of the stagnation of the birth process could be explained by the congenital arthrogryposis of the calf's legs. This dam survived in good health for another 15 years, when it was euthanized because of chronic degenerative joint disease. At necropsy, the wall of the uterus appeared very thick and there was a known fistula (1 mm diameter) in the skin covering the vaginal vestibulum. No other remnants of the fetotomy were observed.
Figure 2. Transrectal ultrasonographic examination of the Asian elephant shows the partial relaxation of the cervix uteri, with a 13.7 mm diameter of the cervix canal.
Interestingly, the mother of the previous elephant also suffered a fetal retention of her 5th calf at the age of 38 years. This fetus probably died around 18 months of gestation due to severe illness of the dam. A pyometra was suspected based on the white-yellowish vaginal discharge, which at times contained pieces of (assumed) macerated tissue. The dam was humanely euthanized. Post-mortem examination showed massive adhesions between the uterus and the abdominal wall and the spleen, which probably prevented the uterus from contracting and expelling the dead foetus. After its death the fetus remained in the uterus for another 33 months (Pers. comm. Carsten Gröhndal, 2005).
Repeated fetal retentions occurred in a herd of African elephants kept in one zoo. Over a period of 11 years, one female retained four female fetuses, sired by the same bull, while another female from the same herd, but sired by a different bull, retained one female fetus. The retention period ranged from 6-19 months. The calf on this photo was 6 months overdue. (Courtesy Colchester Zoo)
One episiotomy or vaginal vestibulotomy after fetal retention in a 32 yr-old nulliparous Asian elephant in Thailand has been published (Thitaram, 2006). Four months before the expected birth, loss of vaginal fluid with necrotic pieces of amnion tissue was noticed. Twelve months later, the animal showed clear signs of signs of labor. As the fetus got stuck in the birth canal, a successful episiotomy was performed.
Two cases of fetal retention that were successfully handled by episiotomy with manual traction in Nepal were mentioned in a short communication in the journal Gajah. No further details were provided (Mandal, 2013).
9. Tumors/cysts
Tumors in the reproductive organs of female elephants are not uncommon. Leiomyomas are the most frequently found tumors. As they are associated with the uterine muscles, large leiomyomas can reduce the power of the uterine contractions. Due to the space they may occupy in the uterus, these tumors usually reduce the chances for a pregnancy and may result in early stage abortion rather than palying a role in retention of the fetus.
In nulliparous cows >30 years of age, vaginal cysts can become so extensive that they fill the entire vaginal lumen, which may block the passage of the fetus.
A 26 kg lipoma, situated on the peritoneal side of the uterus in a 22 yr-old Asian elephant in a European zoo had restricted the intra-uterine movement of the hind legs of the fetus, which resulted in ankylosis of those legs. As a consequence, the fetus could not be delivered and remained stuck inside the uterus. During the birth process the uterus ruptured and the dam was humanely euthanized (Figure 3 and 4; the lipoma was located outside within the red circle; photos taken by the author).
Figure 3
Figure 4
No doubt that there are more conditions that are resulting in dystocia. Much is still unknown and many cases have not been reported. More information has been provided by Hermes et al. (Hermes, 2008).
Dealing with dystocia
Much depend on the degree of training of the elephant. If the animal is not trained for any medical intervention (e.g. blood collection, rectal examination), any diagnostic procedure or curative treatment must be done under standing sedation.
Elephants that are trained for rectal examination should be monitored by ultrasound examination on a daily base once the progesterone level has dropped to baseline value. Ultrasound examination is the most important diagnostic tool to get data of the phase of the birth process. Click here to read more about the parturition process and the options for treatment of dystocia.
References
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Hermes R, Saragusty J, Schaftenaar W, Göritz F, Schmitt DL, Hildebrandt TB. 2008. Obstetrics in elephants. Theriogenology 70 (2008) 131–144.
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van der Kolk JH, van Leeuwen JPTM, van den Belt AJM, van Schaik RHN, Schaftenaar W. Subclinical hypocalcaemia in captive Asian elephants (Elephas maximus). Vet Rec 2008;162(15):475–9.
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Madal RK, and Khadka KK. 2013. Health Status of Captive Asian Elephants in Chitwan National Park, Nepal. 2013. Rabindra Kumar Mandal et al. Gajah 39, page 38.
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Schaftenaar W. 2013. Delayed postpartum fetotomy in an Asian elephant (Elephas maximus). Journal of Zoo and Wildlife Medicine 44(1): 130–135, 2013.
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Thitaram C, Pongsopawijit P, Thongtip N, Angkavanich T, Chansittivej S, Wongkalasin W, Somgird C, Suwankong N, Prachsilpchai W, Suchit K, Clausen B, Boonthong P, Nimtrakul K, Niponkit C, Siritepsongklod S, Roongsri R, Mahasavankul S. 2006. Dystocia following prolonged retention of a dead fetus in an Asian elephant (Elephas maximus) Theriogenology 66 (2006) 1284–1291.