Six primiparous Holstein cows were fed a Se-deficient diet, beginning at least 90 days before their first calving, and 6 other primiparous cows were given the same diet plus a supplement of 2 mg of Se/cow/d as sodium selenite. All cows were fed their diets for the duration of the experimental period. One uninfected quarter of each cow was injected with 25 microgram of Escherichia coli endotoxin at postpartum week 5. Leukocytes were isolated by centrifugation from milk collected at postinjection hour 16. Isolated cells were 92 +/- 3% neutrophils and were incubated with Staphylococcus aureus or E coli in a 1:300 ratio. Phagocytosis and intracellular killing by neutrophils were assessed after 0, 30, 60, and 90 minutes by a fluorochrome assay, using acridine orange. Viability of neutrophils was assessed by use of trypan blue. Superoxide anion production and hydrogen peroxide production by neutrophils also were determined. Cows fed Se-deficient diets had significantly (P < 0.05) lower blood Se concentration and blood glutathione peroxidase activity than cows fed Se-supplemented diets. Selenium status had no effect on the phagocytic capacity of neutrophils. Neutrophils obtained from cows fed Se-supplemented diets killed a significantly (P < 0.05) higher percentage of ingested bacteria than did neutrophils from cows fed the Se-deficient diet. Viability was significantly (P < 0.05) reduced by incubation with S aureus in neutrophils from both groups of cows, with neutrophils from Se-deficient cows having lower viability. Superoxide anion production did not differ significantly between neutrophils from the 2 groups, but extracellular hydrogen peroxide concentration was significantly (P < 0.05) higher in neutrophils harvested from milk of cows fed the Se-deficient diet.

The efficacy, safety, and compatibility of fenbendazole (FBZ) and clorsulon (CLN) were tested after oral administration of label recommended and of higher (5 x) dosage rates to calves naturally infected with gastrointestinal nematodes and Fasciola hepatica. Results for 42 calves allotted to 4 treatment groups indicated a similar efficacy against mature F hepatica by FBZ (5 mg/kg of body weight) and CLN (7 mg/kg) in a combined oral suspension, compared with CLN (7 mg/kg) alone (100 vs 99% reduction). A lesser efficacy was observed against immature flukes (88.6 and 84.9% reduction, respectively). Calves given 25 mg of FBZ/kg and 35 mg of CLN/kg had nearly complete reduction of both mature (99.6%) and immature flukes (99.1%). Fasciola egg counts were reduced by > 99.5% in all treated groups. Against Ostertagia ostertagi, the percentage of efficacy of the combined FBZ (5 mg/kg) and CLN (7 mg/kg) treatment was 94.3% against adults and 81.3% against inhibited larvae. Efficacy against all other nematodes was 100%, except against Cooperia spp adults (98.3%) and immature Oesaphagostomum radiatum (88.0%). At 5 x dosage rates for FBZ and CLN, percentage of removal of adults and inhibited larvae of O ostertagi was 99.3 and 99.0%, respectively, and 99 to 100% for other nematodes. Results indicate that FBZ and CLN are compatible when mixed together and administered as an oral suspension to cattle and that the efficacy is similar to that of the drugs individually. On the basis of further results, we suggest that summer treatment may be superior in preventive value for gastrointestinal nematodes and F hepatica, compared with spring treatment, because of seasonal infection dynamics of the major cattle parasites in Louisiana.

Using arthroscopic technique, identical diameter defects were created in the proximal articular surface of both intermediate carpal bones of 6 horses. One of each pair of defects was deepened to penetrate the subchondral plate. Removed cartilage was assayed for [35S] sulfate incorporation, total hexosamine content, and DNA content. Six weeks later, cartilage was harvested and similarly analyzed from the distolateral portion of the radius directly opposite the created lesions and the distomedial portion of the radius distant from the lesion. The repair tissue filling the full-thickness defect and the cartilage at the periphery of the partial-thickness lesion also were analyzed. There was a marked increase in synthetic activity (35S sulfate incorporation) opposite the full-thickness defect, compared with the cartilage opposite the partial-thickness defect. A marked decrease in glycosaminoglycan content in the cartilage opposite the full-thickness defect was found as compared with that opposite the partial-thickness defect. The repair tissue filling the full-thickness defect was highly cellular, high in synthetic activity, but low in glycosaminoglycan content. Insignificant changes occurred in the cartilage adjacent to the partial-thickness defect. On the basis of these results, we suggest that full-thickness defects at 6 weeks result in more detrimental change to the cartilage opposite it than do partial-thickness lesions of the same diameter.

A group of 48 crossbred steers (approx 250 kg each) were used to determine the effects of various diets and treatments on serum prolactin concentrations and rectal temperatures. The steers were randomly assigned to groups fed the following: (1) endophyte fungus-infested fescue hay; (2) ammoniated endophyte fungus-infested cattle industry hay; (3) endophyte fungus-infested fescue hay plus 1 g of thiabendazole (TBZ)/9.1 kg of body weight at 7-day intervals; (4) ammoniated endophyte fungus-infested fescue hay plus 1 g of TBZ/9.1 kg at 7-day intervals; (5) ground Bermuda grass hay; and (6) endophyte-fungus-free fescue hay. Blood samples for prolactin determinations and rectal temperatures were obtained biweekly beginning on week 3 and continuing through week 9. A significant correlation (P < 0.05) between low prolactin concentrations and high rectal temperatures in cattle eating endophyte-infested fescue hay was determined; however, as the prolactin concentrations approached normal (control animal) concentrations, this relationship between serum prolactin and rectal temperatures was not observed. Two antifungal agents used in this experiment (thiabendazole and ammonia) appeared to have different effects on the variables measured. Thiabendazole had no significant effect on prolactin concentrations or rectal temperatures of cattle ingesting endophyte-infested fescue hay, whereas ammoniation of this hay induced significantly higher (P<0.05) prolactin concentrations and lower rectal temperatures than in steers receiving only endophyte-infested fescue hay. Therefore, ammonia may be valuable not only as an aid in determining the cause of the fescue problem but also as a practical solution to some of the fescue-related economic problems in the cattleindustry. Also, prolactin concentrations may be valuable in diagnosing fescue-related problems.

Logistic regression was used to develop models predicting preweaning survival in 334 neonatal swine. Measured risk factors included birth weight, litter size (live born), dam parity, serum IgG concentration, serum ELISA titers recognizing common gram-negative core antigens, and serum concentrations of the third component of complement. Larger birth weights were associated with increased probability of preweaning survival. The highest mortality was observed in litters with more than 12 pigs. Pigs with serum concentration of the third component of complement (C3) in the lowest stratum, < 20% adult pooled C3 standard (APC3), had reduced mortality, compared with high (> 38% APC3) and middle (20 to 38% APC3) groups. Associations between all other variables, including total serum IgG concentration and preweaning survival were not significant. Few pigs had hypogammaglobulinemia, < 3% of the study population had serum IgG concentrations < 1 g/dl. Of all measured variables, only birth weight and dam parity were significant predictors of preweaning gain. Larger pigs and pigs born to third or greater parity dams had more preweaning gain than other pigs.

Effects of thyroid-stimulating hormone (TSH) and thyrotropin-releasing hormone (TRH) on plasma concentrations of thyroid hormones, and effects of ACTH and dexamethasone on plasma concentrations of cortisol, were studied in adult male ferrets. Thirteen ferrets were randomly assigned to test or control groups of eight and five animals, respectively. Combined (test + control groups) mean basal plasma thyroxine (T4) values were different between the TRH (1.81 +/- 0.41 microgram/dl, mean +/- SD) and TSH (2.69 +/- 0.87 microgram/dl) experiments, which were performed 2 months apart. Plasma T4 values significantly (P < 0.05) increased as early as 2 hours (3.37 +/- 1.10 microgram/dl) and remained high until 6 hours (3.45 +/- 0.86 microgram/dl) after IV injection of 1 IU of TSH/ferret. In contrast, IV injection of 500 microgram of TRH/ferret did not induce a significant increase until 6 hours (2.75 +/- 0.79) after injection, and induced side effects of hyperventilation, salivation, vomiting, and sedation. There was no significant increase in triiodothyronine (T3) values following TSH or TRH administration. Combined mean basal plasma cortisol values were not significantly different between ACTH stimulation (1.29 +/- 0.84 microgram/dl) and dexamethasone suppression test (0.74 +/- 0.56 microgram/dl) experiments. Intravenous injection of 0.5 IU of ACTH/ferret induced a significant increase in plasma cortisol concentrations by 30 minutes (5.26 +/- 1.21 microgram/dl), which persisted until 60 minutes (5.17 +/- 1.99 microgram/dl) after injection. Plasma cortisol values significantly decreased as early as 1 hour (0.41 +/- 0.13 microgram/dl), and had further decreased by 5 hours (0.26 +/- 0.15 microgram/dl) following IV injection of 0.2 mg of dexamethasone/ferret. These results indicate that IV injection of 1 IU of TSH/ferret is preferable to IV injection of 500 microgram of TRH/ferret for thyroid function testing in adult male ferrets. Results of this study also indicated that when TRH or TSH is used for the thyroid-stimulation test in male ferrets, plasma T4 concentrations, instead of T3, should be used as the indicator of thyroid response. Additionally, IV injection of 0.5 IU of ACTH and 0.2 mg of dexamethasone may be used in ferrets for the ACTH stimulation and dexamethasone-suppression tests, respectively.

Cytosolic assay was used to detect gonadal steroid receptors in brain tumor tissue from 6 dogs and 2 cats. For 4 samples, the maximal number of binding sites and the equilibrium dissociation constant were calculated, using Scatchard analysis. The concentration of receptor protein that was discovered was similar to that detected in hormone-sensitive tumors.

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.

Four virgin heifers were experimentally inoculated intravaginally with 7 X 10(6) Tritrichomonas foetus, and 2 heifers served as uninfected controls. The durations of infection were 13, 20, 21, and 28 weeks, respectively. An ELISA that used whole T foetus antigen was used to detect anti-T foetus immunoglobulins (IgA, IgG1, IgG2, and IgM) in vaginal, cervical, and uterine secretions, and sera during the course of infection. The vaginal and cervical antibody responses were characterized by significantly increased T foetus-specific IgA and IgG1 at 7 to 9 weeks of infection, whereas uterine IgA and IgG1 responses peaked at 10 to 12 weeks. The antibody response in serum was predominantly of the IgG1 and IgG2 subclasses. In all reproductive tract regions, IgA persisted at least until the time of T foetus clearance, and usually longer. The next most persistent isotype was IgG1, lasting longest in the vagina, then cervix, and for the shortest time in the uterus. In local secretions, IgG2 was seen only transiently, increasing at weeks 13 to 15 in the vagina, and at weeks 10 to 12 in the cervix. Little IgM, relative to that present before infection, was detected in any secretion or serum, although cervical secretions had the greatest amount. Eight to 12 weeks after clearance, the 4 experimental heifers were inoculated intravaginally with 1 x 10(5) T foetus, transient infections (2 to 3 weeks' duration) were established in only 2 of 4 heifers, as determined by culturing of reproductive tract secretions. The lag times of antibody responses during this reinfection were shorter than in the initial infection, and ELISA optical densities were at least as high as during the primary infection, suggesting an anamnestic response.

The effects of thyroid hormones on the serum and cutaneous fatty acid concentration profiles of dogs were evaluated. Thyroidectomized dogs had significant (P < 0.05) increases in serum oleic acid and linoleic acid concentrations, and decreases in concentration of dihomo-gamma-linolenic acid, arachidonic acid, and other elongation products of fatty acid metabolism. These changes were reversed in response to thyroid hormone replacement. Similar changes were found in cutaneous fatty acid concentration profiles. Thus, in dogs, thyroid hormones may be involved in the regulation of fatty acid delta-6-desaturase activity.