Chapter 44 Neonatal Elephant Mortality
The mortality rate of captive elephant calves in North America and Europe has been discussed with growing concern in a number of publications. A survey conducted in 1996 revealed there were significantly higher stillbirths and infant mortality rates in Asian elephants (Elephas maximus) living in European and North American institutions than in Asian institutions.19 Evidence also indicates that the North American Asian elephant population is not self-sustaining.12 The North American African elephant (Loxodonta africana) population statistics are somewhat more encouraging, but this population is also not self-sustaining and will decrease rapidly over the next 50 years without improvements in infant survivability and improved reproduction rates.12
The most significant factors affecting captive elephant perinatal and juvenile calf mortality rates have been multifactorial dystocias and stillbirths, herpesvirus infections, maternal rejection, trauma, poor survivability in hand-reared calves, infections, and gastrointestinal disorders.
STILLBIRTHS AND DYSTOCIAS
An overview of the captive birth data reveals a distinct increase in the percentage of dystocias and stillbirths in the older age groups of both Asian and African elephants, primarily in older nulliparous females. Historically, a high percentage of stillbirths has been reported in African elephants, but since 2003, eight viable calves have been born of every nine pregnancies. Still, to date, pregnancies in captive nulliparous African elephants in North America over age 24 years have resulted only in dystocias or stillbirths; just one live viable calf was born to a captive 29-year-old multiparous African elephant.11 There have been no primiparous pregnancies resulting in a live calf in Asian elephants over age 31; however, there have been over seven viable calves born to multiparous members of that age group in North America.7
Since 1972, 11 cases of fatal elephant dystocia have been described in the literature.6 Eight of these animals were older than 25 years at the time of their dystocia, and all but two were nulliparous at the time of their conception.
The etiology of each dystocia was not always determined, although overweight and physically unfit cows may be at greater risk.19 Pelvic fusion in older females, uterine abnormalities, and hormonal fluctuations could also be contributing factors. Fetuses that are too large or malpositioned may also result in a dystocia. Fetal death could be either a cause or a result of the dystocia.
In some cases the cause of the dystocia or the stillbirth has been determined. Salmonellosis in two pregnant African elephants at one facility resulted in the death and expulsion of both full-term fetuses.3 Herpesvirus has been found in two stillborn Asian elephant fetuses, suggesting this virus could play a role in the etiology of other stillborn or dystocia cases.
There has been one confirmed case of arthrogryposis of an African elephant fetus causing stiffness and angular deformities in the limbs, which in turn was the likely etiology of that dystocia,5 as well as a second suspected case of an arthrogryposis-induced dystocia. Arthrogryposis is a growth deformity causing ankylosis of the limbs and has been described in cattle, sheep, and goats. Etiologies of arthrogryposis in other species include genetic predisposition, exposure to Akabane or bluetongue virus, or the ingestion of teratogens containing anagyrine or piperidine, found in plants in the Fabaceae family, which includes lupine. There was lupine growing near the elephant exhibit in the one confirmed case of fetal arthrogryposis, although it is not known if the elephant ingested lupine during its pregnancy.
Twinning has been another cause of stillbirths, and although most twins do not survive, one twin of a set was born alive and survived to adulthood.
A cowpox virus infection was responsible for one stillbirth of an Asian elephant.21
Congenital abnormalities have been described in newborn calves, with one Asian calf exhibiting multiple cardiac congenital anomalies.18 Umbilical hernias have been described in elephants, although they may not cause serious complications. A 2-week-old Asian elephant calf was diagnosed with an umbilical hernia that was successfully corrected surgically.1
To date, 22 cases of elephant endotheliotropic herpesvirus (EEHV) have been diagnosed in calves 5 years old or younger in Europe and North America.15 (see Chapter 42). Of those, six were treated with famciclovir, and three survived. Also, EEHV was found in two stillborn fetuses and a 1-day-old calf.
MATERNAL REJECTION AND AGGRESSION
Historically, there has been a high prevalence of maternal rejection, trauma, and infanticide in Western zoos and circuses, which has been correlated to a lack of close contact of the dam with an older female.19 The problem was created when elephants were first imported into Western facilities as juveniles and were placed together with other unrelated elephants, forming artificial herds of similarly aged young animals. In many cases the first calf born to these reproductively naive females was their first-ever encounter with a calf. They often responded to their first calf as if frightened by it. Now that captive breeding is meeting with greater success and herd experience with calves is more commonplace, maternal rejection or trauma is less frequent and is now generally seen only in inexperienced herds.
Because of the documented instances of maternal rejection or aggression toward newborn calves, most institutions have a policy of immediately pulling newborns from their dam. This allows a thorough veterinary examination to be conducted and allows for controlled introductions of the calf back to the dam.
The birth of the first calf at one institution caused the dam to become frantic, setting off the elephants in the barn to vocalize and trumpet, resulting in an excited environment. The calf was immediately pulled away from the dam. Each time the keepers tried to reintroduce the calf, the dam responded by becoming frightened and aggressive. With a rope and a harness attached, the calf was gradually introduced to the dam, which was secured with leg restraints. This system allowed trusted keepers to carefully bring the calf close to the dam, allowed them to approach her with the calf from both the side and the front of her body, and allowed the calf to nurse safely from the dam. Introductions were attempted numerous times each day. By the fourth day, the dam accepted the calf and successfully reared it. As more females at that facility gained experience observing and interacting with the calves and the birthing process, subsequent births have been quiet and uneventful.10
At another facility it took 12 days of steady encouragement to reunite a calf with its dam. During that time the cow was secured with leg restraints whenever the keepers brought in the calf to nurse. Nursing took place every 1 to 2 hours during the day, and the calf was offered a specialized formula at night. The calf was housed within view of the cow but kept at a safe distance. The cow finally accepted the calf, and the staff continued a 24-hour watch for another 2 weeks. Once accepted, this calf was also successfully mother-reared.13,14
As elephant herds grow and adult and juvenile females gain more experience with calves in their herd, some elephant managers may be more comfortable leaving their experienced dams alone during the birthing process. There is evidence that cows with experience around calves of other elephants have fewer tendencies toward rejecting or harming their own calves. Each case is different, and all options must be evaluated carefully.
Dams may be more relaxed if they are gradually habituated to more people and equipment in their birthing area in the weeks to months before the event. Likewise, calves may be rejected because the dam’s environment or routine has radically changed in the weeks and especially the days before parturition.