Blood Platelets of the Cheetah (Acinonyx jubatus) L. du Plessis, 1 * A.J. Botha, 2 F. Reyers, 3 and K. Stevens 1 1 Department of Hematology, Institute of Pathology, University of Pretoria, Pretoria, South Africa 2 Laboratory for Microscopy and Microanalysis, University of Pretoria, Pretoria, South Africa 3 Department of Companion Animal Clinical Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa The blood platelet count and platelet morphology of 22 adult cheetahs was investigated. The platelet counts of the animals displayed a normal distribution, with a mean count of 344  10 9 /l and a mean platelet volume of 11 fl. Morphological and ultrastructural features of the cheetah platelets revealed the typical platelet morphology of anuclear cells, with granules scattered throughout the cytoplasm. The characteristic surface canalicular system and microtubules were present. True cross-sections of the platelets had a mean area of 2.146 mm 2 , circumference of 6.805 mm, and mean minimum and maximum projections of 1.000 mm and 2.933 mm, respectively. Zoo Biol 23:263–271, 2004.  c 2004 Wiley-Liss, Inc. Key words: cheetahs; platelets; morphology; ultrastructure INTRODUCTION Compared to the information available on domesticated and laboratory animals, little normal hematological information on healthy wild animals is available. This is probably due to logistical problems in obtaining fresh blood samples from adequate numbers of animals to be representative of a specific species. In recent years, a database [ISIS, 2002] of the medical records of zoological institutions has been created, and the hematology of such animals has been addressed; however, various other publications have made no mention of the *Correspondence to: L. du Plessis, Department of Hematology, Institute of Pathology, University of Pretoria, P.O. Box 2034, Pretoria 0001, South Africa. E-mail: ldupless@postillion.up.ac.za Received for publication May 5, 2003; Accepted September 29, 2003. DOI: 10.1002/zoo.20009 Published online in Wiley InterScience (www.interscience.wiley.com). Zoo Biology 23:263–271 (2004)  c 2004 Wiley-Liss, Inc.