Abstract
Risso's dolphin (Grampus griseus) is a cetacean species uncommonly kept under human care, and very little is known about medicine, physiology1 and hematology1,2 of this species.
The primary purpose of this study is to enhance medical care of this species through the establishment of haematological reference values for Risso's dolphins from different geographical area and the comparison with the parameters previously published.
For the present study, a total of 452 blood samples were considered: 6 blood samples were obtained from 3 Risso's dolphins stranded along the coast of the Adriatic Sea in Italy, 97 from two animals hosted in 2 different Japanese facilities, 74 samples from one animal kept in Taiwan and 275 blood samples were collected from the an animal kept under human care in Riccione, Italy. A young female of Risso's dolphin, rescued in 2005 from the Adriatic Sea (Mediterranean Sea-Italy) and estimated to be 8 years old, is in fact currently located in the Oltremare marine park in Riccione, Italy.
Only CBC values were considered (RBC, Hgb, Hct, MCV, MCH, MCHC, WBC and relative differential leukocyte count).The red blood cell count in Risso's dolphin (range 4.05–5.39 x106/microL, median 5.48 x106/microL) resulted to be higher than references values considered for bottlenose dolphins, beluga whales and false killer whales.3 Hematocrit values in Risso's dolphins resulted to be of 49.31% ± 4.68% (mean ± s.d.) and haemoglobin 17.23 ± 2.17g/dl. Of the 7 animals considered for the present study, 6 animals had WBC count (11.38 ± 2.02 x1000/microL) comparable with values reported by Natchtigall et al.,1 while only one animal (6.02 ± 1.46 x1000/microL) presented values comparable with those reported by Shirai and Sataki.2 The differential leukocyte count in all examined animals has shown a lower percentage of eosinophils than reference values for bottlenose dolphins.
The purpose of this study is to share information and knowledge about the haematology of this species thus generating a useful reference set aiding rehabilitation, recovery and hosting of a Risso's dolphin under human care.
Acknowledgments
The authors wish to thank Dr. I-Fan Jen from Farglory Ocean Park (Taiwan), Fondazione Cetacea (Italy), Dr. Hitoshi Nakano from Kujukushima Aquarium (Japan), Mrs. Natsuko Higa, Dr. Keiko Yamamoto and Dr. Shoko Kishima from Okinawa Marine Research Center (Japan) for the blood data provided.
References
1. Natchtigall PE, Pawloski JL, Schroeder JP, Sinclair S. Successful maintenance and research with a formerly stranded Risso's dolphin (Grampus griseus). Aquat Mamm. 1990;16(1):8–13.
2. Shirai K, Sataki T. Haematological findings in captive dolphins and whales. Aust Vet J. 1997;75(7):512–514.
3. Bossart GD, Reiderson TH, Dierauf LA, Duffield DA. Clinical pathology. In: Dieraf LA, Gulland FMD, eds. Handbook of Marine Mammal Medicine. CRC Press; 2001:383–395.