Elephants belong to the precocial species of mammals living in herds. The exact data related to the fetal presentation at birth are missing. The papers dealing with a larger number of elephant births failed to present the data pertinent to the fetal presentation (Dale 2010;
Flügger
et_al2001;
Kowalski et al., 2010) or simply stated, without referencing the source, that posterior presentation was much more common
(Hermes et al., 2008) or that anterior presentation occurred in about 30% of the cases (Von Lange
Hildebrandt et al., 1999). Since posterior presentation at birth of an elephant would be an opposite presentation to other herd mammals
(Holland et al., 1993; Vandeplassche 1987), it is necessary to conduct relevant research related to the incidence of anterior and posterior presentation of elephants at birth. Second, dystocia due to fetal malpresentation, is associated with increased perinatal mortality and morbidity of the newborn as well as mother
(Kaur et al., 2011; Katiyar et al., 2020; Khan et al., 2014). Finally, confirmation of the increased incidence of posterior presentation at birth would show the necessity of the investigation into the difference between elephants and other herd animals which might affect fetal presentation and thus provide insight into the aetiology of fetal presentation at birth.
The aim of this research is to establish the incidence of anterior and posterior presentation at birth in African (
Elephas maximus) and Asian elephants (
Loxodonta Africana).
The present experiment was carried out in the Department of Neurology, Medical Faculty Novi Sad, University of Novi Sad, Serbia. The research period was from 2015 to the 2018 year. The identification of papers describing elephant fetal presentation at birth was conducted by three investigators searching the free Medline database and SCOPUS using the keywords: elephant, birth, delivery, gestation from 2018 retrospectively. From the studies consequently identified, the search was extended to include their reference list. The World Wide Web was also used to search for video recordings of elephant births four times between April 2015 and September 2018. This search included the keywords: elephant, birth, delivery. Data about the presentation at birth, stillborn and dystocia were noted. An exclusion criterion was the publication of the case/birth because of fetal presentation. The differentiation between
Loxodonta africana and
Elephas maximus was done based on their external morphological characteristics. The
Loxodonta africana is characterized by a smoothly curved forehead, ears which cover the shoulders, back dips, they are tallest at the shoulder, with two lobes of flesh on the tip of the trunk.
Elephas maximus is characterized by a forehead with two humps, ears which do not cover the shoulders. They are tallest at the arch of the back and boast a single lobe of flesh on the tip of the trunk. The identification of fetal presentation, as well as the type of elephant in the footage, was conducted independently by three researchers and their results were compared to exclude any instance of subjectivity in the interpretation of the footages. In the case of births at zoos and in the presence of zoo staff, where the position could not be ascertained, contacting the person in charge was envisaged to obtain information about the presentation at birth.
Standard nonparametric methods of statistical research were used in processing the data. The statistical package SPSS (version 21) was used for all statistical analyses. Level of significance, p<0.05 was adopted.
The research identified 46 cases with the data about presentation at birth. Two cases of spontaneous birth with alive offspring were published in the literature. In the first case, it was anterior presentation in an Asian elephant from a circus (Chapman 1880). The other case was an African elephant from a zoo with posterior presentation (Lang 1967). In the literature available to the authors, 9 cases of dystocia were identified. In 8 cases the fetuses were stillborn and had to be extracted using fetotomy
(Chandrapuri et al., 2014; Dittrich 1985; Gage and Schmitt, 2003;
Merkt et al., 1985; Schaftenaar 1996; Schaftenaar 2013;
Thitaram et al., 2006; Von Lange Hildebrandt 1999). Only one case of an alive newborn was reported (Lang 1963). Anterior presentation was present in 6 cases
(Chandrapuri et al., 2014; Dittrich 1985; Gage and Schmitt D, 2003; Schaftenaar 2013;
Thitaram et al., 2006; Von Lange Hildebrandt 1999) while posterior presentation was present in 3 cases (Lang 1963;
Merkt et al., 1985; Schaftenaar 1996). The World Wide Web was searched between April 2015 and September 2018. Table 1 shows a summary of information obtained from the footages of elephants. The inter-observer agreement was 100%. Based on the footages available on the web, the fetal presentation was identified in 33 cases of spontaneous and unassisted births. The footages had to be reviewed several times by each researcher, since the birth occurs quickly and the first visible parts of the body are not clearly visible throughout the footage because of the amniotic sac. Curators of mammals were contacted in two cases to obtain the information about two additional cases of the fetal presentation, so the final number provided with www is 35 cases.
The data show that anterior presentation was present in 12 out of 46 cases. Posterior presentation was present in 34 cases. In 10 out of 34 cases related to the Asian elephant, the newborn was born in anterior presentation, while that number in case of the African elephant is 2 out of 12 cases. Rest of the cases were in posterior presentation. Incidence of posterior presentation was significantly more often presented compared to posterior presentation in Asian elephant (Chi-square test c
2 = 5.765 p=0.016 p<0.05) as well as in African elephant (Chi-square test c
2 = 5.333 p=0.021 p<0.05). The Fisher exact test (p=0.682) did not show a significant difference in the distribution of presentations between the African and Asian elephant.
When analyzing the difference in the distribution of fetal presentation in physiological delivery and labour with dystocia, a statistically significant difference was noted (Fisher exact test p=0.012). Namely, the ratio between anterior presentation 6 (18.51%) and posterior presentation 29 (81.49%) in delivery without knowing dystocia is statistically significantly different from the distribution of the fetal presentation ratio between anterior presentation 6 (66.7%) and posterior presentation 3 (33.3%) at delivery with dystocia (Fisher exact test p=0.012). Cases 29 and 35 from Table 1 were excluded from this comparison because of stillbirth.
The study shows that published anecdotal observations are correct about the increased incidence of posterior presentation at birth in elephants
(Hermes et al., 2008; Von Lange
Hildebrandt et al., 1999). The lack of information in the literature is possibly caused by the short duration of the final expulsion of the fetus with fetal membranes, which obstructs the view of the advanced part of the newborn. Furthermore, a female elephant often moves during labour, thus obstructing the view of the advanced part of the newborn. Following the expulsion, the newborn would usually hit the floor and be released of the membrane due to its rupture. Only then would it be possible to see the position of the anterior and posterior part of the body.
Anterior presentation has already been recognized as a major cause of dystocia in elephants
(Thitaram et al., 2006). Obstruction of delivery in AP occurs because of fetal neck flexion, which is accompanied by head impaction in the pelvic canal. To facilitate the delivery, it is necessary to place a hook between mandibles to elevate the head and extend the neck, after which the delivery progresses relatively easily
(Thitaram et al., 2006).
It seems that in case of all mammals, in early stages of pregnancy fetuses assume presentations at random, with equal probability of anterior and posterior presentation in longitudinal situs. This is the phase when altricial mammals give birth to sensorimotor immature offspring
(Sekulic et al., 2007). Unfortunately, despite the existence of studies which include ultrasound monitoring of elephant pregnancy, the data about the fetal presentation and situs during gestation are non-existent
(Drews et al., 2008; Hildebrandt et al., 2007; Lueders et al., 2012). In mammals which give birth to sensorimotor mature offspring, such as herd animals, there is a progressive increase of the anterior presentation during the second half of gestation which contradicts the results noted in elephants (Scanlon 1975; Scanlon 1976).
