Pharmacologic Evaluation of Ceftazidime in Cownose Rays (Rhinoptera bonasus)
IAAAM 2014
Debbie A. Myers1*; Elizabeth A. Galvenek2; Johann F. Coetzee3
1Debbie Myers Inc., Pittsburgh, PA, USA; 2Pittsburgh Zoo and PPG Aquarium, Pittsburgh, PA, USA; 3Veterinary Diagnostic and Production Animal Medicine Department, Iowa State University, Ames, IA, USA


Antibacterial dosage recommendations are poorly studied in elasmobranchs. Most dose regimens are based on extrapolation from mammals or reptiles. Ceftazidime is a third-generation cephalosporin that is active against bacteria such as Vibrio sp., Aeromonas sp., and Pseudomonas sp. that have been linked to disease in elasmobranchs.1-3 The pharmacokinetics of ceftazidime in twenty-five juvenile cownose rays (Rhinoptera bonasus) following a single intramuscular (i.m.) injection was studied. Ceftazidime (Fortaz, GlaxoSmithKline, NC, 27709, USA) was given at 20 mg/kg intramuscularly at time 0 to all rays. Blood samples were taken prior to administration of drug and at predefined intervals thereafter (24, 48, 72, 96 and 120 hours post-administration). All serum samples were assayed using a sensitive, high-performance liquid chromatography. The drug is best described by a two-compartment model with a rapid rise in drug concentration and decline followed by a slower subsequent elimination. Minimum inhibitory concentration (MIC) data for bacterial isolates from elasmobranchs are not well established. MIC values were estimated at between 4,000 to 16,000 ng/ml based on studies in other species.4-6 For MIC values of 4000 ng/ml a single dose of ceftazidime at 20 mg/kg provides adequate serum concentrations for at least 52 hours and at a MIC of 16,000 the concentration is present for 39 hours. Based on these data, a dose of 20 mg/kg every 2 days is recommended for cownose rays.


The authors want to thank Amy Parker, Jennifer Dancico, Josianne Romasco, Mike Stephan, Bob Snowden and Paul Moylette for their assistance with sample collection for this project. The authors thank the Iowa State University Racing Chemistry Laboratory staff for their assistance with sample processing.

* Presenting author

Literature Cited

1.  Garner MM. A retrospective study of disease in elasmobranchs. Vet Pathol. 2013;50(3):377–389.

2.  Leibovitz L, Tamse CT. A newly reported disease of elasmobranchs: Aeromonas salmonicida infection of the little skate, Raja erinacea. Biol Bull. 1985;169:562.

3.  Terrell SP. An introduction to viral, bacterial and fungal diseases of elasmobranchs. In: Smith M, Warmolts D, Thoney D, Hueter R, eds. The Elasmobranch Husbandry Manual: Captive Care of Sharks, Rays and their Relatives. Columbus, OH: Ohio Biological Survey, Inc.; 2004: 427–432.

4.  Albarellos GA, Ambros LA, Landoni MF. Pharmacokinetics of ceftazidime after intravenous and intramuscular administration to domestic cats. Vet J. 2008;178(2):238–243.

5.  Chow D, Stoskopf MK, Vedros N, Aucoin D. Ceftazidime pharmacokinetics after intramuscular administration in healthy bottlenose dolphin (Tursiops aduncas). In: Proceedings from the 23rd Annual IAAAM Conference; May 10–14, 1992; San Leandro, CA, USA; pp. 43–45.

6.  Stamper MA, Papich MG, Lewbart GA, May SB, Plummer DD, Stoskopf MK. Pharmacokinetics of ceftazidime in loggerhead sea turtles (Caretta caretta) after single intravenous and intramuscular injections. J Zoo Wildl Med. 1999;30(1):32–35.


Speaker Information
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Debbie A. Myers
Debbie Myers Inc.
Pittsburgh, PA, USA

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