Population pharmacokinetics of ceftazidime after a single intramuscular injection in wild turtles.

Ceftazidime, a third-generation cephalosporin, is important for treating opportunistic bacterial infections in turtles. Antibacterial dosage regimens are not well established for wild turtles and are often extrapolated from other reptiles or mammals. This investigation used a population pharmacokinetic approach to study ceftazidime in wild turtles presented for rehabilitation. Ceftazidime was administered to 24 wild turtles presented to the Turtle Rescue Team at North Carolina State University. A sparse blood sampling protocol was used to collect samples from 0 to 120 hr with three samples per individual after injection. Plasma samples were analyzed by high-pressure liquid chromatography (HPLC). A nonlinear mixed-effects model (NLME) was fitted to the data to determine typical values for population parameters. We identified a long half-life (T½) of approximately 35 hr and volume of distribution (VSS ) of 0.26 L/kg. We concluded that this long T½ will allow for a dose of 20 mg/kg injected IM to maintain concentrations above the MIC of most wild-type bacteria for 5 days. Because of long intervals between injections, stability of stored formulations was measured and showed that 90% strength was maintained for 120 hr when stored in the refrigerator and for 25 days when stored in the freezer.

Pharmacokinetics of enrofloxacin and ciprofloxacin in Atlantic horseshoe crabs (Limulus polyphemus) after single injection.

The pharmacokinetics of enrofloxacin and the metabolite ciprofloxacin were studied in horseshoe crabs after a single injection of 5 mg/kg. Twelve Atlantic horseshoe crabs (Limulus polyphemus) of undetermined age were injected with enrofloxacin into the dorsal cardiac sinus. Hemolymph samples were collected by syringe and needle at regular intervals for 120 hr. Samples were analyzed by high-pressure liquid chromatography and compartmental analysis performed on the results. Following injection, the elimination half-life (T½), peak concentration, area under the curve (AUC), and volume of distribution (VD) for enrofloxacin were 27.9 (29.13) hr, 8.98 (18.09) µg/ml, 367.38 (35.41) hr µg/ml, and 0.575 (20.48) L/kg, respectively (mean value, CV%). For ciprofloxacin, the elimination T½, peak concentration, and AUC were 61.36 (34.55) hr, 2.34 (24.11) µg/ml, and 304.46 (24.69) µg hr/ml. In these animals, the ciprofloxacin concentrations comprised an average of 45.8% of the total fluoroquinolone concentrations, which is substantial compared to other marine invertebrates. The total AUC produced (sum of enrofloxacin and ciprofloxacin) was 682.69 ± 180.61 µg hr/ml. Concentrations that were achieved after a single dose of 5 mg/kg horseshoe crabs were sufficient to treat bacteria susceptible to enrofloxacin and ciprofloxacin.

Microsurgery in liver research: end-to-side portocaval microanastomoses in dogfish.

BACKGROUND: The use of an operating microscope in animal liver surgery has made it possible to obtain new experimental models. The goal of this prospective animal study is to present our experience with dogfish portocaval microanastomoses. METHODS: Nineteen portocaval microanastomoses were performed in dogfish. The end-to-side anastomoses were accomplished using continuous 11-0 sutures. The diameter of the vessels and time required for the anastomoses were measured. A patency test and its outcome were also prospectively evaluated at the time of anastomoses and then 3 and 6 months after. RESULTS: The mean vessel diameter was 2.5 ± 0.2mm. The mean anastomosis time was 14 ± 1.5 min. The anastomoses patency rate was 100% at the time of surgery. A postoperative control performed after 3 and 6 months showed a partial stenosis in three animals. CONCLUSION: The dogfish appears to be a reliable experimental model in liver research. Moreover, this technique could be used for microsurgical training.

Phylogenetic analysis of spring virema of carp virus reveals distinct subgroups with common origins for recent isolates in North America and the UK.

Genetic relationships between 35 spring viremia of carp virus (SVCV) genogroup Ia isolates were determined based on the nucleotide sequences of the phosphoprotein (P) gene and glycoprotein (G) genes. Phylogenetic analysis based on P gene sequences revealed 2 distinct subgroups within SVCV genogroup Ia, designated SVCV Iai and Iaii, and suggests at least 2 independent introductions of the virus into the USA in 2002. Combined P- and G-sequence data support the emergence of SVCV in Illinois, USA, and in Lake Ontario, Canada, from the initial outbreak in Wisconsin, USA, and demonstrate a close genetic link to viruses isolated during routine import checks on fish brought into the UK from Asia. The data also showed a genetic link between SVCV isolations made in Missouri and Washington, USA, in 2004 and the earlier isolation made in North Carolina, USA, in 2002. However, based on the close relationship to a 2004 UK isolate, the data suggest than the Washington isolate represents a third introduction into the US from a common source, rather than a reemergence from the 2002 isolate. There was strong phylogenetic support for an Asian origin for 9 of 16 UK viruses isolated either from imported fish, or shown to have been in direct contact with fish imported from Asia. In one case, there was 100% nucleotide identity in the G-gene with a virus isolated in China.

Enrofloxacin pharmacokinetics in the European cuttlefish, Sepia officinalis, after a single i.v. injection and bath administration.

Enrofloxacin pharmacokinetics were studied in European cuttlefish, Sepia officinalis, after a single 5 mg/kg i.v. injection or a 2.5 mg/L 5 h bath. A pilot study with two animals was also performed following a 10 mg/kg p.o. administration. The concentration of enrofloxacin in hemolymph was assayed using high-performance liquid chromatography (HPLC) and pharmacokinetic parameters were derived from compartmental methods. In the i.v. study, the terminal half-life (t(1/2)), apparent volume of distribution, and systemic clearance were respectively 1.81 h, 385 mL/kg, and 4.71 mL/min/kg. Following bath administration the t(1/2), peak hemolymph concentration (C(max)), and area under the curve to infinity (AUC(0-infinity)) were 1.01 h, 0.5 +/- 0.12 mug/mL, and 0.98 microg.h/mL, respectively. After oral administration, the t(1/2), C(max), and AUC(0-infinity) were 1.01 h, 10.95 microg/mL, 26.71 mug.h/mL, respectively. The active metabolite of enrofloxacin, ciprofloxacin, was not detected in any samples tested. The hemolymph concentration was still above minimum inhibitory concentration (MIC) values for shrimp and fish bacterial isolates at 6 h after i.v. administration, therefore, a dose of 5 mg/kg i.v. every 8-12 h is suggested for additional studies of efficacy. The C(max) value for the water bath was lower than for the i.v. study, but a bath of 2.5 mg/L for 5 h once to twice daily is suggested for additional studies to test efficacy against highly susceptible organisms. Although only two animals were used for the oral study, a dose of 10 mg/kg produced hemolymph concentrations of enrofloxacin that were in a range consistent with therapeutic efficacy in other species.

Phacoemulsification of bilateral cataracts in a loggerhead sea turtle (Caretta caretta).

An immature free-living loggerhead sea turtle (Caretta caretta) of unknown sex was found moribund off the coast of Wise Point, Virginia. It was suffering from cachexia and had bilateral hypermature cataracts which were treated by phacoemulsification under general anaesthesia. The surgery restored the turtle's vision and it was returned to the wild.

Stabilisation of scoliosis in two koi (Cyprinus carpio).

Two koi (Cyprinus carpio) from the same pond developed similar lesions of scoliosis. Radiographic examinations showed that their spines had become malaligned as a result of vertebral compression fractures involving T14 to T16. The vertebrae in both fish were stabilised with screws, k-wire and polymethylmethacrylate. They both appeared to improve after surgery, but they began to decline and died within three months. A postmortem examination revealed multi-organ inflammation that was not associated with the surgical implants.

Evaluation of the tissue reactions in the skin and body wall of koi (Cyprinus carpio) to five suture materials.

Five different suture materials (silk, monofilament nylon, polyglyconate, polyglactin 910, and chromic gut) were placed in the skin and body wall of 10 Doitsu (scaleless) koi (Cyprinus carpio). After seven days the sutures were retrieved from five of the fish in 5 mm and 6 mm punch biopsies, and after 14 days they were retrieved in the same way from the other five. The tissue reactions were evaluated by gross visual inspection and by histological examination. The total inflammatory reaction was graded on a scale from 0 (no inflammation) to 5 (severe inflammation). The synthetic suture materials generally induced a moderate inflammatory reaction that decreased after seven days. After 14 days the superficial reaction to monofilament nylon was substantial, and the tissue reactions to the organic suture materials were slightly greater than the reactions to the synthetics. The inflammatory response to silk was greater after 14 days than after seven, and chromic gut induced a moderately severe inflammatory response after seven days; the chromic gut sutures fell out before the biopsies were taken after 14 days. The organic materials induced intense inflammatory reactions which did not subside if the suture remained in the tissue.

Comparative efficacy of tricaine methanesulfonate and clove oil for use as anesthetics in red pacu (Piaractus brachypomus).

OBJECTIVE: To compare the anesthetic efficacy and physiologic changes associated with exposure to tricaine methanesulfonate and clove oil (100% eugenol). ANIMALS: 15 adult cultured red pacu (Piaractus brachypomus). PROCEDURE: Fish were exposed to each of 6 anesthetic concentrations in a within-subjects complete crossover design. Stages of anesthesia and recovery were measured, and physiologic data were collected before and during anesthesia. RESULTS: Interval to induction was more rapid and recovery more prolonged in fish exposed to eugenol, compared with those exposed to tricaine methanesulfonate. The margin of safety for eugenol was narrow, because at the highest concentration, most fish required resuscitation. Mixed venous-arterial PO2 consistently decreased with anesthesia, while PCO2 consistently increased with anesthesia in all fish regardless of anesthetic agent. The increase in PCO2 was accompanied by a decrease in pH, presumably secondary to respiratory acidosis. Anesthesia was associated with increased blood glucose, potassium, and sodium concentrations as well as Hct and hemoglobin. Fish anesthetized with eugenol were more likely to react to a hypodermic needle puncture than fish anesthetized with tricaine methanesulfonate. CONCLUSIONS AND CLINICAL RELEVANCE: Anesthesia induced with tricaine methanesulfonate or eugenol contributes to hypoxemia, hypercapnia, respiratory acidosis, and hyperglycemia in red pacu. Similar to tricaine methanesulfonate, eugenol appears to be an effective immobilization compound, but eugenol is characterized by more rapid induction, prolonged recovery, and a narrow margin of safety. Care must be taken when using high concentrations of eugenol for induction, because ventilatory failure may occur rapidly. In addition, analgesic properties of eugenol are unknown.