title: Subclinical hypocalcaemia in captive Asian elephants (Elephas maximus).
abstract: The hypothesis that hypocalcaemia may play a role in dystocia in captive Asian elephants (Elephas maximus) was investigated. The objectives of the study were to measure the total calcium concentration in elephant plasma; assess the changes in parameters of calcium metabolism during a feeding trial; investigate a possible relationship between calcium metabolism and dystocia; and assess bone mineralisation in captive Asian elephants in vivo. The following parameters were measured: total and ionised calcium, inorganic phosphorous and magnesium, the fractional excretions of these minerals, intact parathyroid hormone, 25-OH-D(3) and 1,25-OH-D(3). Radiographs were taken from tail vertebrae for assessment of bone mineralisation. The mean (sd) heparinised plasma total calcium concentration was 2.7 (0.33) mmol/l (n=43) ranging from 0.84 to 3.08 mmol/l in 11 Asian elephants. There was no significant correlation between plasma total calcium concentration and age. Following feeding of a calcium rich ration to four captive Asian elephant cows, plasma total and ionised calcium peaked at 3.6 (0.24) mmol/l (range 3.4 to 3.9 mmol/l) and 1.25 (0.07) mmol/l (range 1.17 to 1.32 mmol/l), respectively. Plasma ionised calcium concentrations around parturition in four Asian elephant cows ranged from 0.37 to 1.1 mmol/l only. The present study indicates that captive Asian elephants might be hypocalcaemic, and that, in captive Asian elephants, the normal plasma concentration of total calcium should actually be around 3.6 mmol/l and normal plasma concentration of ionised calcium around 1.25 mmol/l. Given the fact that elephants absorb dietary calcium mainly from the intestine, it could be concluded that elephants should be fed calcium-rich diets at all times, and particularly around parturition. In addition, normal values for ionised calcium in captive Asian elephants should be reassessed.
authors.affiliation: Department of Equine Sciences, Medicine Section, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: J H
authors.initials: JH
authors.lastname: van der Kolk
authors.forename: J P T M
authors.initials: JP
authors.lastname: van Leeuwen
authors.forename: A J M
authors.initials: AJ
authors.lastname: van den Belt
authors.forename: R H N
authors.initials: RH
authors.lastname: van Schaik
authors.forename: W
authors.initials: W
authors.lastname: Schaftenaar
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D000836:Animals, Zoo; D001774:Blood Chemical Analysis / Q000662:veterinary; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000378:metabolism*; D002118:Calcium / Q000097:blood / Q000172:deficiency / Q000378:metabolism*; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics; D004420:Dystocia / Q000378:metabolism / Q000662:veterinary; D004606:Elephants; D005260:Female; D006996:Hypocalcemia / Q000097:blood / Q000662:veterinary*; D016014:Linear Models; D008297:Male; D009426:Netherlands; D011247:Pregnancy; D011859:Radiography
chemical_list: D002136:Calcium, Dietary; D002118:Calcium