The pharmacokinetics of flunixin were studied in 6 adult lactating cattle after administration of single IV and IM doses at 1.1 mg/kg of body weight. A crossover design was used, with route of first administration in each cow determined randomly. Plasma and milk concentrations of total flunixin were determined by use of high-pressure liquid chromatography, using an assay with a lower limit of detection of 50 ng of flunixin/ml. The pharmacokinetics of flunixin were best described by a 2-compartment, open model. After IV administration, mean plasma flunixin concentrations rapidly decreased from initial concentrations of > 10 micrograms/ml to nondetectable concentrations at 12 hours after administration. The distribution phase was short (t1/2 alpha, harmonic mean = 0.16 hours) and the elimination phase was more prolonged (t1/2 beta, harmonic mean = 3.14 hours). Mean +/- SD clearance after IV administration was 2.51 +/- 0.96 ml/kg/min. After IM administration, the harmonic mean for the elimination phase (t1/2 beta) was prolonged at 5.20 hours. Bioavailability after IM dosing gave a mean +/- SD (n = 5) of 76.0 +/- 28.0%. Adult lactating cows (n = 6) were challenge inoculated with endotoxin as a model of acute coliform mastitis. After multiple administration (total of 7 doses; first IV, remainder IM) of 1.1 mg/kg doses of flunixin at 8-hour intervals, plasma flunixin concentrations were approximately 1 microgram/ml at 2 hours after each dosing and 0.5 microgram/ml just prior to each dosing. Flunixin was not detected in milk at any sampling during the study. Flunixin concentrations necessary to induce therapeutic effects in cattle are unknown. Results of our study indicate that administration of 1.1 mg/kg doses of flunixin meglumine at 8-hour intervals would produce plasma concentrations similar to those demonstrated to be effective clinically in treatment of equine musculoskeletal disorders and colic.

The disposition of doxycycline hyclate after IV administration of 20 mg/kg of body weight was studied in 6 pigs. Median elimination half-life, estimated in 4 pigs, was 3.92 hours. Mean (+/- SEM) total body clearance was 1.67 +/- 0.18 ml/min/kg, and mean apparent volume of distribution at steady state was 0.53 +/- 0.04 L/kg. In 2 pigs, secondary peaks in the logarithmic serum concentration-time profile suggested discontinuous enterohepatic cycling, and precluded using these pigs in the pharmacokinetic analysis. The extent of doxycycline binding to serum protein was 93.1 +/- 0.2%. Serum or urine from 3 of the pigs was analyzed by use of photodiode array detection and mass spectrometry of a high-performance liquid chromatographic column effluent. These procedures documented lack of doxycycline biotransformation in pigs. It is concluded that, despite an elimination half-life shorter than that reported in other species, doxycycline may be a valuable antimicrobial drug for use in swine practice, pending the development of appropriate formulations.

The effect of age and training status on the pharmacokinetics of flunixin meglumine was evaluated in 16 Thoroughbreds. Horses were assigned to 1 of 3 groups on the basis of age and training status: group A (n = 6), horses in active training and less than or equal 5 years old; group B (n = 5), horses out of training for a minimum of 6 weeks and less than or equal to 5 years old; and group C (n = 5), horses out of training for at least 2 years and greater than or equal to 9 years old. After administration of 500 mg of flunixin meglumine IV, multiple serum and urine samples were obtained over 24 hours and assayed for flunixin by high-performance liquid chromatography. Although the mean distribution rate constant and volume of distribution were similar for the 3 groups, mean total body clearance and elimination rate constant were significantly (P < 0.05) greater and half-life significantly (P < 0.01) less in groups A and B, compared with group C. Differences in pharmacokinetic values were not observed between the horses in groups A and B. In addition, the changes in clearance, elimination rate constant, and half-life of flunixin were found to significantly (P < 0.05) correlate with age. The results of this investigation indicated that age, but not training status, influences disposition of flunixin meglumine in Thoroughbreds.

Cytoplasmic proteins from unsporulated and sporulated Eimeria maxima oocysts were analyzed by gel-filtration column chromatography. Unsporulated oocysts were characterized as having 3 major cytoplasmic proteins and sporulated oocysts as having 5 major cytoplasmic proteins. Molecular weights ranged from 5 X 10(3) to 1.4 X 10(6). Larger molecular weight proteins were detected in sporulated and unsporulated oocysts, but were associated more with sporocysts of sporulated oocysts.

Bovine fibroblast interferon (BoF-IFN), produced in bovine embryonic kidney cell cultures by priming and infection with bluetongue virus, was partially purified by controlled pore glass chromatography. The partially purified B0F-IFN then was subjected to beaded agarose affinity chromatography. The IFN eluted by affinity chromatography in 2 distinct fractions-1 after the addition of 1M NaCl and the other one after the addition of 1.5M NaCl containing 50% ethylene glycol. Analysis of fractions by sodium dodecyl sulfate/polyacrylamide-gel electrophoresis revealed a broad molecular weight range (14,900 to 27,900) for the IFN eluted by 1M NaCl, and 2 discrete molecular weight ranges (16,000 to 19,500 and 28,300 to 34,000) for IFN eluted by 1.5M NaCl containing 50% ethylene glycol. The specific activity of the IFN eluted with 1.5M NaCl containing ethylene glycol was 2.85 X 10(6) U/mg of protein, compared with 5.7 X 10(5) U/mg of protein in the controlled pore glass-purified IFN.

Bovine fibroblast interferon (BoF-IFN), produced in primary bovine embryonic kidney cell cultures after priming and infection with bluetongue virus, was purified by controlled pore glass (CPG) chromatography to a specific activity of 10(6) U/mg of protein, with 40% recovery of the original activity. The crude IFN was concentrated more than sevenfold during purification. This proved to be a relatively simple, practical method of obtaining sufficient quantities of partially purified natural BoF-IFN for further studies. The CPG-purified BoF-IFN was further concentrated by sequential ultrafiltration and was analyzed by sodium dodecyl sulfate/polyacrylamide-gel electrophoresis (SDS-PAGE). Interferon, recovered from denaturing conditions either by dialysis against phosphate-buffered saline solution or by dilution in cell culture medium containing 10% fetal bovine serum, migrated as a single stainable protein with molecular weight of 21,000 on analytic SDS-PAGE gels. Recovered IFN activity from preparative SDS-PAGE totalled 8.7% of that applied. Attempts to further pruify CPG-purified BoF-IFN by zinc chelate affinity chromatography were unsuccessful.

The concentrations of dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindole-3-acetic acid (5-HIAA) in CSF obtained from the cisterna magna of 21 nonneurologically compromised dogs were determined by high-pressure liquid chromatography and electrochemical detection. A rapid method of sample preparation, which involved single filtration through a deproteinizing membrane, was used. Canine CSF obtained in this manner contained 5.78 +/- 0.78 ng of DOPAC/ml, 72.19 +/- 4.09 ng of HVA/ml, and 29.95 +/- 1.67 ng of 5-HIAA/ml. Linear regression analysis between HVA and 5-HIAA yielded a correlation coefficient of 0.4804. The neurotransmitter index, HVA/5-HIAA, was found to be more indicative of the dopaminergic metabolite HVA than the acid metabolite of serotonin, 5-HIAA (correlation coefficient with HVA = 0.5529 vs a correlation coefficient with 5-HIAA = -0.4462). A poor relationship (correlation coefficient = -0.1715) was found to exist between the 2 dopaminergic metabolites DOPAC and HVA in the CSF.

monoclonal antibodies derived from Trichinella spiralis-infected mice reacted with other swine parasites, one monoclonal antibody recognized antigenic determinant specific to T. spiralis, isolation of this antigen by monoclonal antibody-affinity chromatography, use of antigen in enzyme-linked immunosorbent assay eliminated false-positive reactions with serum of healthy swine and detected all pigs infected with T. spiralis

Objective: To evaluate 4 methods used to measure plasma insulin-like growth factor (IGF) 1 concentrations in healthy cats and cats with diabetes mellitus or other diseases. Animals: 39 healthy cats, 7 cats with diabetes mellitus, and 33 cats with other diseases. Procedures: 4 assays preceded by different sample preparation methods were evaluated, including acid chromatography followed by radioimmunoassay (AC-RIA), acid-ethanol extraction followed by immunoradiometry assay (AEE-IRMA), acidification followed by immunochemiluminescence assay (A-ICMA), and IGF-2 excess followed by RIA (IE-RIA). Validation of the methods included determination of precision, accuracy, and recovery. The concentration of IGF-1 was measured with all methods, and results were compared among cat groups. Results: The intra-assay coefficient of variation was < 10% for AC-RIA, A-ICMA, and AEE-IRMA and 14% to 22% for IE-RIA. The linearity of dilution was close to 1 for each method. Recovery rates ranged from 69% to 119%. Five healthy cats had IGF-1 concentrations > 1,000 ng/mLwith the AEE-IRMA, but < 1,000 ng/mL with the other methods. Compared with healthy cats, hyperthyroid cats had significantly higher concentrations of IGF-1 with the A-ICMA method, but lower concentrations with the IE-RIA method. Cats with lymphoma had lower IGF-1 concentrations than did healthy cats regardless of the method used. Conclusions and Clinical Relevance: Differences in the methodologies of assays for IGF-1 may explain, at least in part, the conflicting results previously reported in diabetic cats. Disorders such as hyperthyroidism and lymphoma affected IGF-1 concentrations, making interpretation of results more difficult if these conditions are present in cats with diabetes mellitus.

Objective-To determine the pharmacokinetic disposition of IV administered caffeine in healthy Lama spp camelids. Animals-4 adult male alpacas and 4 adult female llamas. Procedures-Caffeine (3 mg/kg) was administered as an IV bolus. Plasma caffeine concentrations were determined by use of high-performance liquid chromatography in 6 animals and by use of liquid chromatography-mass spectrometry in 2 llamas. Results-Median elimination half-life was 11 hours (range, 9.3 to 29.8 hours) in alpacas and 16 hours (range, 5.4 to 17 hours) in llamas. The volume of distribution at steady state was 0.60 L/kg (range, 0.45 to 0.93 L/kg) in alpacas and 0.75 L/kg (range, 0.68 to 1.15 L/kg) in llamas. Total plasma clearance was 44 mL/h/kg (range, 24 to 56 mL/h/kg) in alpacas and 42 mL/h/kg (range, 30 to 109 mL/h/kg) in llamas. Conclusions and Clinical Relevance-High-performance liquid chromatography and liquid chromatography-mass spectrometry were suitable methods for determination of plasma caffeine concentrations in alpacas and llamas. Plasma caffeine concentration-time curves were best described by a 2-compartment model. Elimination half-lives, plasma clearance, volume of distribution at steady state, and mean residence time were not significantly different between alpacas and llamas. Intravenous administration of caffeine at a dose of 3 mg/kg did not induce clinical signs of excitement.