Abstract

In December 2006 all the dolphins from L’Oceanogràfic were removed from their exhibit and separated into several other minor enclosures during pool remodeling. When the work was finished 3 months later, all the animals were placed back in the dolphinarium. During the previous week one young male dolphin (body weight was 126 kg) was already experiencing a social stress situation in his own small group. According to the unstable blood work, some relevant rake marks and the concern this animal was potentially immunocompromised, antibiotic treatment with amoxicillin + clavulanic acid (Augmentine®, Glaxo Smith Kline, Tres Cantos, Madrid, Spain) at 10 mg/kg PO BID was initiated and this animal was separated from the aggressive pool mate.

Once in the dolphinarium, after 5 days of controlled regrouping of the entire original group, trauma from conspecifics resulted in new injuries, group isolation, and eventually shock of this juvenile dolphin.

The day of the crisis, although the animal was performing a show in the morning, at noon the dolphin was completely stuporous with tremors, became unable to swim and eventually unable to keep position in the water. Emergency support treatment was applied to stabilize the animal. Six hours later, he was able to swim without assistance, especially under the effect of pain relievers such as metamizole (Nolotil®, Boehringer Ingelheim España, Sant Cugat del Vallés, Barcelona, Spain) at a total dose of 1 g IM. The initial total leukocyte count was 2100 cells/µl with 94% neutrophils and 2% band cells (absolute leukopenia). Although there was an evident drop in ALKP, albumin, and iron, other relevant markers of inflammation such as ESR and fibrinogen were within normal ranges. A decision was made to institute among others, a more aggressive antibiotic therapy including amikacin (Biclin®, Bristol-Myers Squibb, Madrid, Spain) at 14 mg/kg IM SID) to cover the potential septic shock or septicemia.

Twelve hours after the initiation of the stabilizing therapy the WBC increased slightly up to 2720 cells/µl. Six hours later another blood sample showed a decrease to 1400 WBC/µl and another 6 hours later it fell to 1040 WBC/µl. At this point the animal had greatly improved in attitude, was swimming almost normally and was eating on its own. A decision was made to remove the clavulanic component of the antibiotic therapy and to decrease as much as possible, the metamizole as these two drugs have been previously described to potentially cause granulocytopenia and leukopenia in humans.^4,6 Additionally, dexamethasone (Fortecortín®, Merck Farma y Química, S.A., Mollet del Vallés, Barcelona, Spain) was used at a total dose of 30 mg IM to revert the shock. It was then substituted by progressive decreasing dosages of prednisone (Dacortín®, Merck Farma y Química, S.A., Polígono Merck, Barcelona, Spain). Finally, a recombinant human granulocyte colony-stimulating factor, G-CSF, the filgrastim (Neupogen®, Amgen Europe B.V., Breda, Holland) was administered at a total dose of 30 MU (0,0025 mg/kg) IM in an attempt to increase neutrophil production in this animal.

Twelve hours after the first filgrastim injection the WBC dramatically increased to 5160 cells/µl with 96,9% neutrophils and a band and proleukocite count of 76%. A second dose of the same amount of Neupogen® was administered 24 hours after the first one.

After these two filgrastim doses, the WBC kept gradually increasing during the next few days up to a maximum of 16400 cells/µl on the sixth day after the first administration. Meanwhile band cell counts kept decreasing, reaching normal values for this individual (1,7%) on the tenth day. The hemogram and blood chemistry was completely normal regarding baselines for this individual 19 days after the first filgrastim injection.

The viability of this initial increase of highly immature leukocytes to combat bacterial infection could be controversial. Furthermore, the potential host antibody production could inactivate the filgrastim in case of prolonged or successive treatments in allospecific patients. In this case there was no decline in the WBC series suppression after the treatment as described by other authors in other species.^1,2,5 In fact, they kept increasing during the 5 days following the second filgrastim dose. Additionally, in this particular case, filgrastim seemed to increase proliferation much faster than the previously reported experience in a killer whale (Orcinus orca),³ rising up not only granulocytes but all other leukocyte populations and even red blood cell precursors.

In the authors’ opinion, this case suggests that filgrastim is potentially useful to treat neutropenic bottlenose dolphins at a dose of 0,0025 mg/kg IM SID for 2 days, aiding to overcome infection especially in the event the bone marrow is not properly responding.

Acknowledgments

The authors would like to particularly acknowledge Mr. Pedro Malabia and Mr. Ezequiel Martí of the Central Hospital of Valencia for the support provided to this case, providing the Neupogen® when we required it. We wish to thank as well all the Marine Mammal team of L’Oceanogràfic and all the students involved in the animal care for their daily efforts to save this dolphin. Finally, thanks to Dr. James McBain, Dr. Géraldine Lacàve, and Dr. Andrew Greenwood for their expertise.

Literature Cited

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4.  Product Information: Reviewed May 2005. Nolotil® cápsulas, Metamizol Magnésico. Boehringer Ingelheim España, S.A. Sector Turó de Can Matas, 08173 Sant Cugat del Vallés, Barcelona, Spain.

5.  Rhinehart HL, Manire CA, Byrd L, Garner MM. Use of Neupogen (Filgrastim) in a green sea turtle (Chelonia mydas). In: Proceedings of the 33rd International Association for Aquatic Animal Medicine Conference. 2002:62.

6.  Salvo F, Polimeni G, Moretti U, Conforti A, Leone R, Leoni O, et al. Adverse drug reactions related to amoxicillin alone and in association with clavulanic acid: data from spontaneous reporting in Italy. J Antimicrob Chemother. 2007;60(1):121–126.