Abstract

Juvenile elephants may be affected by many conditions, including infectious diseases and nutritional imbalances, which can impact overall health and survivability. The strength of even very young elephants can prevent easy physical restraint, with the result that some ill animals may not receive diagnostic exams or treatments until they are too weak to resist handling. Our experiences with two young Asian elephants have shown that early intervention using operant conditioning or sedation, has allowed us to monitor, manage, and stabilize these animals. Ongoing communication and cooperation between the elephant management staff and the veterinary staff have allowed identification of training priorities for juvenile elephants which make diagnostic testing and therapeutic management less stressful for all involved parties. This document discusses several aspects of the management of critical juvenile Asian elephants in captivity: early calf training priorities, calf sedation, hand-rearing using milk replacement formulas, and monitoring and treating calves for elephant endotheliotropic herpesviral infection.

Discussion

The Saint Louis Zoo’s elephant training philosophy supports the introduction of training early in an elephant calf’s life. As soon as the bond between the mother and calf is secure and nursing is consistent, the calf is introduced to simple behaviors. The primary objective of the training program is, beginning within the first weeks of a calf’s life, to build a trusting and cooperative relationship between the calf and the keepers so that the calf will not only be consistently cooperative with all learned husbandry behaviors but will also be accepting of unexpected diagnostic evaluations and treatments that may be required during times of compromised health.

With consistent training and acclimation from the elephant care team in its first year of life, an elephant calf can be expected to present many of the same husbandry behaviors as the adult elephants. To give the best opportunity for day-to-day health care, nutritional monitoring, and husbandry, and to be reasonably prepared for a health crisis, it is ideal for an elephant calf to understand the training “bridge,” be proficient with target training, and allow the following as early as possible: present and position all parts of its body for physical examination and external ultrasonography; lie sternally and laterally upon request; present feet and limbs for radiographs; present ear for heart-rate monitoring; open mouth for oral exams; step on a platform scale for weighing; accept medications orally, rectally, and parenterally; stand for urine collection; and allow blood sample collection. Blood collection is one of the more challenging behaviors to introduce, but we feel that this behavior is vital for monitoring health and nutritional status in young elephants and its importance should not be underestimated.

Sedation has been a critical component of our medical management of juvenile elephants, allowing intervention while an elephant is still active and strong. Sedation dosages for adult African and Asian elephants have been published, but little work seems to have been done recently with juvenile animals. We routinely use detomidine-butorphanol combinations for standing sedation in our young elephants. The youngest age at which an elephant at our facility has been sedated is two months (body weight 144 kg). The dosages used produce a plane in which the animal is immobile but stable on its feet. An animal that has been taught to lie down on cue can be persuaded into lateral recumbency if necessary. Dosage ranges are as follows: butorphanol, 0.02–0.03 mg/kg IM; detomidine, 0.02–0.03 mg/kg IM; atipamezole, 0.1–0.16 mg/kg IM; and naltrexone, 2.0–3.5 mg/kg IM.

One multiparous cow showed evidence of decreased milk production in the first two months of lactation, possibly in association with retained placental tags. Dietary and social changes were implemented to encourage milk production. In addition, the cow was initially treated with metoclopramide 100 mg PO q 8 h for five days. No significant change was seen following the husbandry changes and treatment, so we changed to the dopamine antagonist, domperidone, administered orally (initially 500 mg q 24 h, increased over time to 3800 mg q 24 h) for 30 days. Evidence of increased milk production was appreciated after this treatment and the calf began to gain weight again. The calf was sedated for passage of a stomach tube and administration of milk replacer at 14–20 ml/kg daily for 10 days for nutritional support while waiting for the dam’s milk production to return.

As recommended by the AZA Elephant TAG Nutrition Advisory Committee, we have used Grober’s Asian elephant milk replacer formula to supplement one calf. This animal became dehydrated and constipated when this milk replacer was offered at the recommended concentration, requiring sedation and intravenous fluid therapy. When this milk replacer was diluted, the calf digested the formula well, gained weight, and maintained hydration. However, the diluted formula, in conjunction with the hay and grain the animal was consuming, did not offer adequate dietary calcium. To address this, we began adding calcium carbonate to the formula and no further concerns have been noted either with formula tolerance or systemic calcium status.

Use of serum calcium or blood-ionized calcium concentrations to monitor for calcium deficiency are relatively ineffective as blood calcium concentrations do not decrease until the animal reaches a critical state of hypocalcemia. Ionized calcium in our formula-supplemented calf was 1.36 mg/dl at the same time that radiographs and urine chemistry analyses strongly suggested nutritional hyperparathyroidism.

Monitoring urine for calcium and phosphorus excretion allowed us to document significant differences in our formula-supplemented calf before and after calcium was added to the formula. Urinary calcium and phosphorus values for a mother-reared calf and for adult animals suggest that excretion is relatively consistent for juveniles and adults (Table 1).

Table 1. Urinary calcium and phosphorus concentrations in Asian elephants

Radiographs were used to document signs of presumptive nutritional osteodystrophy in an 11-month-old calf. The formula-supplemented calf showed flaring at metaphyses and hypomineralization.

Radiology is a relatively insensitive tool for monitoring overall calcium status as significant changes may have occurred to the skeleton before they may be detected on radiographs.

Management of cases of elephant endotheliotropic herpesviral (EEHV) infection is challenging. Early detection and early intervention are key for a positive outcome. A 23-month-old elephant showed lameness of two-days duration, decreased appetite, and subdued behavior. Although other “classic” symptoms were not evident at the time, as a precaution a voluntary blood sample was collected and submitted to the EEHV lab for testing and oral famciclovir treatment was initiated (see dosages below). Two days later we received PCR-positive results from the EEHV lab and began aggressive management of the animal.

Hypotension is a significant concern in EEHV patients and maintenance of hydration is critical. Colloids may be beneficial, especially in animals with compromised vasculature. Intravenous catheters were very hard to maintain, especially with an ambulatory animal. We used a combination of intravenous and rectal fluid administration to help maintain hydration. Whole blood transfusions may be indicated if severe anemia or thrombocytopenia develop.

Monitoring of an EEHV infected calf include the following: blood pressure measurement, checking for retinal hemorrhages and hematuria, monitoring hematocrit and platelet count regularly, echocardiography for heart rate measurement, and monitoring for pericardial fluid accumulation and peripheral blood oxygen saturation.

Dosages used for oral famciclovir administration were as follows: for an asymptomatic PCR-positive 36-month-old calf in contact with the clinically affected calf, 7.8 mg/kg famciclovir was given PO BID; for the clinically affected PCR-positive 23-month-old calf, a 12 mg/kg loading dose of famciclovir was given PO, followed by 8 mg/kg PO TID.

Alternatively, ganciclovir was given instead of famciclovir. The dosage for intravenous use of ganciclovir in humans is 5 mg/kg BID. We used ganciclovir orally in elephant calves at the same dosage, 5 mg/kg BID. Preparation of ganciclovir for oral use was as follows: mix each vial of injectable ganciclovir (500 mg) with 3 ml sterile water, withdraw drug and place into beaker, add 50 ml oral sweetener, add 1 ml 3% hydrogen peroxide, mix well, and add sweetener to a final total volume of 100 ml.