James Jensen

Plasma evaluation for ivermectin in llamas (Lama glama) after standard subcutaneous dosing.

Abstract Plasma levels of the parasiticide ivermectin were studied by high-performance liquid chromatography in five llamas (Lama glama) after single 200 μg/kg s.c. injections. Ivermectin levels were undetectable in plasma samples drawn up to 4 wk after injection, suggesting that the dosage used was insufficient to reach therapeutic concentrations in this species.

EVALUATION OF ANTHELMINTIC ACTIVITY IN CAPTIVE WILD RUMINANTS BY FECAL EGG REDUCTION TESTS AND A LARVAL DEVELOPMENT ASSAY

Abstract The effectiveness of anthelmintics was evaluated in four herds of captive ruminants, wapiti (Cervus elaphus), Armenian red sheep (Ovis orientalis), giraffe (Giraffa camelopardalis), and pronghorn (Antilocapra americana), by the use of fecal egg reduction tests (FERTs) and a commercial larval development assay (LDA) designed to evaluate susceptibility or resistance of nematodes to anthelmintics. Haemonchus sp. was the predominant nematode in the red sheep, giraffe, and pronghorn herds, whereas Ostertagia sp. and Trichostrongylus sp. were predominant in the wapiti. The LDA data indicated susceptibility by the worms to benzimidazoles except in the red sheep flock, which showed a high level of resistance. High levels of resistance to levamisole were seen in the worm populations from the wapiti and red sheep, moderate resistance in the pronghorn herd, and susceptibility in the giraffe herd. Worms were susceptible in all four herds to a combination of benzimidazole/levamisole. There was suspected avermectin resistance by Trichostrongylus sp. in the wapiti herd and by Haemonchus sp. in the giraffe. The FERTs agreed with the LDA in showing the Haemonchus in the giraffe was susceptible to fenbendazole and had suspected resistance to ivermectin, whereas Haemonchus in the red sheep and pronghorn were susceptible to ivermectin. There was correlation between the tests evaluating anthelmintics. The LDA is useful as a screening test in the selection of an anthelmintic for use in grazing ruminants, but the effectiveness of a drug in a host species may depend as much on the dose used, and the method of administration, as it does on the parasites sensitivity to the anthelmintic.

DISPOSITION OF SULFADIMETHOXINE IN MALE LLAMAS (LLAMA GLAMA) AFTER SINGLE INTRAVENOUS AND ORAL ADMINISTRATIONS

Abstract This study determined the disposition of sulfadimethoxine in six, healthy, adult, gelded male llamas (Llama glama) by using a nonrandomized crossover design with i.v. dosing (58.8 ± 3.0 mg/kg based on metabolic scaling) followed by oral dosing (59.3 mg/kg ± 8.3). Blood samples were collected intermittently for a 72-hr period, and serum sulfadimethoxine concentrations were quantified using high-performance liquid chromatography. Serum sulfadimethoxine concentrations across time were subjected to standard pharmacokinetic analysis based on linear regression. Mean maximum serum concentration after oral dosing was 23.6 ± 14.9 μg/ml, and extrapolated peak concentration after i.v. administration was 246.6 ± 15.8 μg/ml. Total clearance of sulfadimethoxine was 45.4 ± 13.9 L/kg. Half-lives after i.v. and oral administration were 541 ± 111 min and 642.4 ± 204.8 min, respectively. Oral bioavailability was 52.6 ± 15%. These data suggest that the oral dose administered to llamas in this study, based on metabolic scaling from cattle, may be inadequate when compared with the reported minimum inhibitory concentration (512 μg/ml) breakpoint for sulfadimethoxine.

CURRENT RATITE THERAPY

This article describes the use of drugs and therapeutic techniques in the treatment of ratite diseases. Effective routes of administration are documented. Appropriate selection and dose regimens are provided for bacterial and parasitic conditions. This article includes empirical formularies for antibiotics and anthelmintics. Metabolic drug dosage and nutrient scaling for ratites are outlined.

DISPOSITION OF SULFADIMETHOXINE IN CAMELS (CAMELUS DROMEDARIUS) FOLLOWING SINGLE INTRAVENOUS AND ORAL DOSES

Abstract Single-dose pharmacokinetics of sulfadimethoxine were determined in six adult camels (Camelus dromedarius) following administration of a mean dosage of 17.5 ± 2.7 mg/kg both i.v. and p.o. Serial blood samples were collected through an indwelling jugular catheter intermittently for 5 days for both routes. Sulfadimethoxine was assayed using high-performance liquid chromatography. Serum drug concentration versus time data for each animal was subjected to linear regression, with the best-fit model selected based on residual analysis. The data fit best into a two-compartment open model, with first-order input for oral administration. For orally administered drug, mean maximum serum concentration of 19.3 ± 1.7 μg/ml was reached at 11.41 ± 2.59 hr, with an elimination rate constant of 0.09/hr ± 0.05/hr and an elimination half-life of 11.7 ± 3 hr. Mean peak serum concentration following i.v. administration was 223 ± 48 μg/ml. Mean volume of distribution at steady state was 0.393 ± 0.049 L/kg. Elimination rate constants differed with i.v. and oral administration, suggesting a flip-flop model. Oral bioavailability was 103% ± 38%. Comparison of maximum serum concentrations to the microbial breakpoint concentration reported for sulfadimethoxine (512 μg/ml) suggests that the dose used in this study, 17.5 ± 2.7 mg/kg, is insufficient for achieving therapeutic serum levels.

The emerging exotic ungulate livestock industry: a survey of current producers.

Survey responses concerning the general aspects of current exotic operations and attitudes of current producers are presented. A wide diversity of exotic livestock operations was indicated by the respondents. Respondents were on average well educated and in high gross income brackets. Overall, the responses could be characterized as coming from producers involved in an industry in the introductory stage. Limited information and lack of knowledge concerning marketing issues were the major concerns indicated by the respondents concerning the development of the exotic venison industry.

DISPOSITION OF CEFTIOFUR AND ITS ACTIVE METABOLITES IN FALLOW DEER (DAMA DAMA) FOLLOWING SINGLE-DOSE INTRAVENOUS AND INTRAMUSCULAR ADMINISTRATION

Septicemia and foot infections associated with Fusobacterium necrophorum , Pasturella multocida, and Streptococcus suis in captive fallow deer (Dama dama) are reasonably treated with ceftiofur hydrochloride. This study describes the disposition of ceftiofur after single-dose intravenous and intramuscular administration of 3.65±0.1678 mg/kg in six female adult fallow deer using a nonrandomized crossover design and a 7-day washout period. Serial blood samples were collected for 12 hr postdrug administration. Ceftiofur bioactivity, including its active metabolite desfuroylceftiofur, was quantitated in serum using a microbiologic assay. After i.v. administration, the extrapolated serum drug concentration reported as median (range) was 52.83 (43.32-57.49) μg/ml and elimination half-life was 178.36 (19.75-217.22) min. The volume of distribution at steady-state was 0.171 (0.101-0.229) L/kg and serum clearance was 0.97 (0.48-4.3) ml/min per kg. After i.m. administration, median peak plasma concentration (Cmax) was 14.37 (9.00-32.00) μg/ml at 54.5 (11.00-95.00) min. The median elimination half-life and mean residence time were 128.32 (38.03-242.40) and 203.65 (62.48-347.15) min, respectively. The median absorption time after i.m. administration was 14.77 (-57.74 to 94.79) min. Bioavailability of ceftiofur following i.m. administration was 78.00 (58.00-137.00) percent. Based on this study, a mean i.m. dose of ceftiofur of 3.65±0.1678 mg/kg every 12 hr is recommended for maintaining serum concentrations above MIC90 levels for infections associated with F. necrophorum, P. multocida, and S. suis, in addition to other susceptible infectious bacteria.