SINGLE DOSE PHARMACOKINETICS OF AZITHROMYCIN IN BALL PYTHONS (Python regius) Rob L. Coke, DVM,1* Robert P. Hunter, MS, PhD,2 Ramiro Isaza, MS, DVM,1 James W. Carpenter, MS, DVM,1 David Koch, MS,2 and Marie Goatley, BS2 1Department of Clinical Sciences and the 2Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506 USA Abstract Azithromycin is a new sub-class of macrolide antibiotics classified as an azalide. This antimicrobial has a similar mechanism of action to the other macrolides (i.e., erythromycin) by binding to the 50S ribosomal subunit.2 Azithromycin provides broad-spectrum antibiosis against gram-positive and gram-negative bacteria.2 It also has the ability to obtain sustained drug concentrations in tissues much greater than the corresponding plasma concentration.1,3 This study determined the pharmacokinetics of azithromycin (Zithromax®, Pfizer Inc., New York, NY 10017 USA) in ball pythons (Python regius), a species that is representative of the Boidae family. Snakes were administered azithromycin intravenously (i.v.) to determine distribution and orally (p.o.) to determine bioavailability and absorption. Seven ball pythons (two males, five females), weighing approximately 0.67-0.96 kg, were used in this experiment. Using a crossover design, each snake was given a single 10 mg/kg i.v. dose of azithromycin via cardiocentesis. For the oral study, each snake was dosed at 10 mg/kg using the same i.v. azithromycin preparation. Blood samples were collected prior to dosing and at 1, 3, 6, 12, 24, 48, 72, and 96 hr post-azithromycin administration. Plasma t½ for i.v. and p.o. dosing was 17 hr and 51 hr, respectively, and the average oral bioavailability (F) was 77% (± 27%). The recommended dose for azithromycin in ball pythons is 10 mg/kg at 48-72 hr intervals. LITERATURE CITED 1. Hunter, R.P., M.J. Lynch, J.F. Ericson, et al. 1995. Pharmacokinetics, oral bioavailability, and tissue distribution of azithromycin in cats. J. Vet. Pharmacol. Therap. 18: 38-46. 2. Retsema, J., A. Girard, W. Schelkly, et al. 1987. Spectrum and mode of action of azithromycin (CP-62, 993), a new 15-membered-ring macrolide with improved potency against gram-negative organisms. Antimicrob. Agents Chemother. 31: 1939-1947. 3. Schentag, J.J. and C.H. Ballow. 1991. Tissue-directed pharmacokinetics. Am. J. Med. 91(Suppl. 3A): 5-11. 2001 PROCEEDINGS AAZV, AAWV, ARAV, NAZWV JOINT CONFERENCE 1 EVALUATION OF REPTILE THERMOREGULATION AND ENCLOSURE DESIGN USING DIGITAL THERMOGRAPHY Gregory J. Fleming, DVM,1†* Ramiro Isaza, DVM, MS,1 and Mark F. Spire, DVM, PhD2 1Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506 USA; 2Food Animal Health and Management Center, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506 USA †Present address: Department of Small Animal Clinical Sciences, Zoological Medicine Service, College of Veterinary Medicine, University of Florida Box 100125, Gainesville, FL 32610 USA Abstract One of the most important factors in successfully maintaining healthy captive reptiles is providing them a proper thermal environment. Most reptile species regulate their body temperatures by using external environmental heat sources such as the sun. Many people commonly refer to this as “cold- blooded”. In reality reptiles operate at a preferred optimum body temperature (POBT) similar or higher than internal body temperatures of mammals.5 The correct term for this behavior is poikilothermic. Reptiles have POBT’s that must be reached to maintain normal digestion and immune function.2,3 In the past, body temperatures of reptiles have been difficult to assess without multiple thermometers, invasive probes, and less accurate spot-point heat detectors. The study of thermoregulation has now been made easier with the development of digital thermography. Infrared thermography has been used widely in human and veterinary medicine to diagnosis inflammation, nerve, and musculoskeletal injury.1,3,4,6-8 Thermography is the study of infrared radiation that is emitted from all objects both inanimate and living. This energy is released as photons from objects and is translated in images by the Inframetrics PM280 hand-held, high- resolution (65,000 pixels) thermography camera (Flir Inc., 16 Esquire Rd, North Billerica, MA 01862 USA). Images are then displayed as both black and white and color still images, as well as real time video. These images can then be analysis with the thermography software and used to evaluate the thermal gradient of reptile enclosures. Arboreal, terrestrial, and sub-terrestrial reptiles all have different thermal requirements, which have been difficult to replicate in the past. This technology allows for accurate thermal imaging of the entire enclosure, as well as the animals that live within them. An enclosures “thermal” design can then be altered to be suite individual species resulting in optimal husbandry and health. LITERATURE CITED 1. Barnes, R.B. 1967. Determination of body temperature by infrared emission. J. Appl. Phsiol. 22:1143-1146. 2. Coulson, R.A. and T. Hernandez. 1983. Alligator Metabolism: Studies on Chemical Reactions In Vivo. London, Pergamon Press. 3. Glassman, A.B. and C.E. Bennet. 1978. Response of the alligator to infection and thermal stress. In: Throp J.H., and J.W. Gibbons (eds). Energy and environmental stress in aquatic systems. Washington, DC, Technical Information Center, U.S. Department of Energy. 2 2001 PROCEEDINGS AAZV, AAWV, ARAV, NAZWV JOINT CONFERENCE 4. Hamilton, B.L. 1986. An overview of proposed mechanisms underlying thermal dysfunction. In: Abernathy, M., and S. Uematsu (eds). Medical Thermography. American Academy of Thermology, Washington D.C. Pp. 6-18. 5. Lane, T.J. 1996. Crocodilians. In: Mader, D.R. (ed). Reptile Medicine and Surgery. Philadelphia, WB Saunders. Pp. 78-94. 6. Purohit, R.C., W.A. Bergfeld., M.D. McCoy, et al. 1977. Value of clinical thermography in veterinary medicine. Auburn Vet. 33:104-108. 7. Purohit, R.C. and M.D. McCoy. 1980. Thermography in the diagnosis of inflammatory processes in the horse. Am. J. Vet. Res. 41:1167-1174. 8. Spire, M.F., J.S. Drouillared, and J.C. Galland. 1999. Use of infrared thermography to detect inflammation caused by contaminated growth promotant ear implants in cattle. J. Am. Vet. Med. Assoc. 9:1320-1324. 2001 PROCEEDINGS AAZV, AAWV, ARAV, NAZWV JOINT CONFERENCE 3 CLINICAL APPLICATIONS OF A SUPRAVERTEBRAL (SUBCARAPACIAL) VEIN IN CHELONIA Stephen J. Hernandez-Divers, BSc (Hons), BVetMed, DzooMed (Reptilian), CBiol MIBiol, MRCVS,1* Sonia M . Hernandez-Divers, DVM,2 and Jeanette Wyneken, PhD3 1Royal College of Veterinary Surgeons Consultant in Zoo & Wildlife Medicine (Reptiles), 1105 Ellis Hollow Road, Ithaca, NY 14850 USA; 2Postdoctoral Fellow, Division of Wildlife Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853 USA; 3Department of Biological Sciences, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991 USA Abstract A variety of sites have been described for the purposes of blood collection and intravenous drug administration in chelonians, including the heart, jugular vein, brachial vein, ventral coccygeal vein, dorsal coccygeal vein, and the post-occipital sinus.1,2 However, another large vessel that is positioned in a supravertebral position, just below the carapace, is available for blood collection and injection.3 This vertebral vessel may be approached with either the head extended from, or retracted into, the coelom. For example, in the red-eared slider (Trachemys scripta elegans) a 22-ga, 1-inch needle is positioned dorsal to the head and neck, on the midline close to where the skin attaches to the cranial rim of the carapace. The needle is advanced caudally at an angle (to the horizontal) of 0° to 60° incline and the vessel is located just dorsal to the spine. This vein is particularly useful for blood collection from, or intravenous injection in: 1. Small or dehydrated individuals where peripheral vessels may be very small. 2. Those species that possess a front plastron hinge (e.g., Terrapene spp.). 3. Strong individuals that are capable of resisting head extraction for jugular sampling. 4. Individuals where the jugular or associated areas have been damaged or diseased. 5. Individuals where the jugular vessel is catheterized or is being reserved for catheterization. 6. Blood donor chelonians, where large volumes of blood are required quickly and easily. Contrast radiography was performed by injecting iohexol (Omnipaque, Sanofi Winthrop Pharmaceuticals, New York, NY 10016 USA) at 500-580 mg/kg i.v. into the aforementioned vessel of two red-eared sliders (Trachemys scripta elegans) via the previously described technique. A distinct line of radio-opaque material was noted coursing along the midline in both cases. Iohexol was also injected into the equivalent vessel of an eastern box turtle (Terrapene carolina) and fluoroscopic radiography performed. Within 10 sec, the contrast material was identified in the heart. This suggests that the contrast material drained from a vertebral vessel to the junction of the external jugular vein into the heart. Anatomic dissections to further describe the position and utility of this vessel are underway. 4 2001 PROCEEDINGS AAZV, AAWV, ARAV, NAZWV JOINT CONFERENCE This vessel has been utilized by the veterinary coauthors for blood collection and injection of anesthetic drugs, such as propofol, without any untoward effects. Therefore it is recommended as a potentially valuable i.v. access site in chelonians. LITERATURE CITED 1. Murray, M. 2000. Reptilian blood sampling and artifact considerations. In: Fudge, A.M. (ed.). Laboratory Medicine: Avian and Exotic Pets. WB Saunders Co., Philadelphia, Pennsylvania. Pp. 185-192. 2. Olson, G.A., J.R. Hessler, and R.E. Faith. 1975. Techniques for blood collection and intravascular infusion in reptiles. Lab. Anim. Sci. 25:783-786. 3. Divers, S.J. 2000. Diagnostic techniques in reptiles. Proceedings of the North American Veterinary Conference, Vol 14, Orlando, Florida, Pp.