Plasma glucocorticoid concentrations and blood gas values were determined for 6 days in 47 newborn calves that had been subjected to various obstetrical procedures at term. Concentrations of glucocorticoids were uniformly high at birth (70 to 103 ng/ml). Increasing degrees of acidosis were accompanied by increasing glucocorticoid concentrations in plasma. Plasma glucocorticoid concentrations decreased sharply during the first 6 hours after delivery and reached a plateau at 48 hours after birth (14 to 21 ng/ml). The latter was taken as an indication that adaptation had been achieved. Calves subjected to severe pulling had higher glucocorticoid concentrations at birth (110.4 ng/ml) than calves requiring no assistance (88.3 ng/ml), calves requiring only slight assistance (83.8 ng/ml), or calves that had been delivered by cesarean section (82.9 ng/ml).

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 directional (chemotactic) and random migration activities of neutrophils from cows and newborn and 2-week-old calves were determined by use of the chemotaxis-under-agarose assay. Blood samples were stored for 2, 24, or 48 hours and at 4 or 25 C before testing. During the assay, cells were incubated at 17, 27, or 37 C. The assay was found suitable for testing the directional and random migration activities of neutrophils from cattle. Directional migration of neutrophils was diminished (P < 0.05) when cells were incubated at 17 or 27 C, compared with data from incubation at 37 C. Random migration of neutrophils was unaffected by test incubation temperature. Significant (P < 0.05) differences were found between cows and calves regarding the percentage number and viability and the directional and random migration activities of neutrophils. Neutrophils from cows were adversely affected to a greater extent by prolonged sample storage times or low storage temperature than were neutrophils from calves. Results indicate that a sample storage time of up to 24 hours, a sample storage temperature of 25 C, and a test incubation temperature of 37 C provided optimal conditions for testing the migratory activities of neutrophils from cattle.

The reactivity of bovine lymphocytes to 4 species of Brucella was tested in thymidine-uptake assays, using long-term cultured lymphocytes and freshly obtained blood mononuclear cells. Lymphocytes were taken from cows that had been challenge exposed with a virulent strain of B abortus at midgestation. The cows were classified retrospectively as being naturally resistant or susceptible to brucellosis. Lymphocytes taken from these cows had 3 patterns of reactivity with species of Brucella: pattern 1 was defined by reactivity with 4 species (B abortus, B canis, B suis, and B melitensis); pattern 2 was defined by reactivity with all these species, except B melitensis; pattern 3 was defined by reactivity with B abortus and B canis, but not with B suis or B melitensis. There was a statistically significant correlation between susceptibility to brucellosis and expression of lymphocyte cross-reactivity with B suis (P < 0.01) and with B melitensis (P < 0.001).

The influence of cortisol on estrogen synthesis by the bovine placenta and the importance of the delta 4 and delta 5 pathway for estrogen production were investigated. For experiment 1, portions of fetal villi (200 mg) were incubated for 48 hours with 0, 10, 100, and 1,000 ng of cortisol/ml with [3H]androstenedione (3H-A) or [3H]pregnenolone (3H-P5). Villi were also incubated for 4, 28, and 52 hours with or without cortisol (500 ng/ml) and with 3H-A or 3H-P5 (experiment 2). The conversion of various [3H]steroid metabolites such as A, P5, 17 alpha-OH-pregnenolone (17 alpha-OH-P5), progesterone (P4), 17 alpha-OH-P4, cholesterol (chol), and chol plus lipoprotein (500 micrograms/ml) into estrogen was measured during a 4-hour incubation (experiment 3). In experiment 1, cortisol increased conversion of 3H-A and 3H-P5 into estrogen by 3 to 41% and 7 to 34%, respectively, in a dose-dependent manner (P < 0.05). In experiment 2, times of incubation did not influence conversion of 3H-A into estrogen, which, however, was increased significantly (P < 0.05) over all times of incubation by administration of 500 ng of cortisol/ml. Conversion of 3H-P5 into estrogen increased over time of incubation and was stimulated by cortisol (P < 0.05). However, there was no interaction between cortisol treatment and time of incubation. In experiment 3, conversion of 3H-A, 3H-P5, and 3H-17 alpha-OH-P5 into estrogen was greater than the conversion of the other precursors tested. Mean conversion of 3H-A, 3H-P5, 3H-17 alpha-OH-P5, 3H-P, 3H-17 alpha-OH-P4, 3H-chol, and 3H-chol plus lipoprotein was 23%, 10.6%, 11.0%, 1.8%, 1.8%, 0.3% and 0.7%, respectively. Our results suggest that, in cows, the delta 5 pathway is the preferred pathway for placental estrogen synthesis and that cortisol directly stimulates estrogen production, probably by activating enzymes involved in this pathway.

A successful attempt was made to mechanically transmit bovine leukosis virus (BLV) from a BLV-infected cow with a normal lymphocyte count to sheep by inoculation with horse fly (Tabanus abactor) mouthparts. After interrupted natural feeding, horse flies were anesthetized with CO2. Mouthparts were severed and pooled into a tissue grinder containing medium. Five inocula containing the mouthparts of 10 flies each, and 5 inocula containing the mouthparts of 20 flies each, were prepared and inoculated SC in the right axilla of 10 BLV antibody-negative sheep. Five additional sheep served as controls. Serum samples were collected at 2-week intervals and tested by agar gel immunodiffusion for BLV antibodies. One sheep injected with 20 mouthparts developed antibodies to BLV at 10 weeks after inoculation. Six months after inoculation with fly mouthparts, 1 BLV antibody-negative sheep was randomly selected from each treatment group and injected, in the left axilla, with 3 ml of blood from the donor cow to confirm susceptibility of the sheep. All 3 sheep developed antibodies to BLV within 4 weeks.

Genital tracts from 15 cows with catarrhal and purulent inflammation of the uterus and uterine tubes, cystic hyperplasia of the endometrium, or hydrosalpinx were evaluated by use of scanning electron microscopy to determine epithelial changes associated with these conditions. Uterine epithelium was revealed to be easily damaged, even in the course of mild inflammation, whereas epithelium of the uterine tube was more resistant.

Eight adult female cattle (6 Holstein, 1 Jersey, 1 Brown Swiss) were used to determine the antagonistic effects of tolazoline, an alpha 2-adrenoceptor antagonist, on xylazine-induced (via caudal epidural administration) depression of CNS, respiratory, and cardiovascular activity and rumen motility. A 2% solution of xylazine HCl was injected into the epidural space at the first coccygeal interspace, using a dosage of 0.05 mg/kg of body weight, diluted to a 5-ml volume with sterile water, and administered at a rate of approximately 1 ml/30 s. Eight minutes after xylazine injection, either tolazoline (0.3 mg/kg) or saline solution (4 ml) was administered IV. All 8 cattle were treated, using both regimens in a random sequence; at least 1 week elapsed between treatments. Epidurally administered xylazine induced caudal analgesia (S3 to coccyx), as evaluated by no response to superficial and deep muscular pinprick, and induced sedation, cardiopulmonary depression, and inhibition of rumen motility, but all cattle remained standing. Tolazoline effectively reversed xylazine-induced rumen hypomotility, and partially antagonized xylazine-induced cardiopulmonary depression without affecting sedation and desirable local (S3 to coccyx) analgesic effects.

The size of the liver, as well as the situation and diameter of vessels in cattle were determined by use of ultrasonography. Ultrasonographic examinations of the liver were performed on 10 cows 10 times within 2 weeks, using a 3.5-MHz linear transducer on the right side in the 12th, 11th, and 10th intercostal spaces. Dorsal and ventral margin of the liver as well as localization and diameter of the caudal vena cava and the portal vein were determined in each intercostal space. Furthermore, the angle of the liver in the ventral area between the visceral surface and the diaphragmatic surface, the dorsal margin, and the circumference of the gall bladder were determined. The ultrasonographic values of liver size and localization in healthy cows can be used as reference values for the diagnosis of changes in liver size attributable to illness.

The effect Of bovine mammary secretion during the nonlactating period and of antibiotic preparations on bovine polymorphonuclear neutrophil (PMN) phagocytic function and morphology were evaluated in a series of in vitro multifactorial experiments. Benzathine cloxacillin (CL), benzathine cephapirin (CE), sodium novobiocin (NO), and a combination of dihydrostreptomycin with procaine penicillin G (DP) were prepared in the presence and absence of a peanut oil aluminum monostearate vehicle. The PMN were isolated from bovine blood, and the effect of each antibiotic preparation on PMN function and morphology was evaluated in a buffer, fat, skim, and a combination of fat with skim from bovine mammary secretion during the nonlactating period. The fat and skim were diluted with buffer to approximate their concentration in mammary secretion. Phagocytic functions of PMN were monitored by fluorescent microscopy, which made it possible to estimate both ingestion and intracellular killing of bacteria by PMN. Changes in PMN morphology were monitored by transmission electron microscopy. The ability of PMN to ingest and kill Staphylococcus aureus ATCC 25923 was significantly decreased by fat, skim, CL, CE, NO, and DP. Effects of some antibiotics on ingestion and killing of bacteria by PMN were influenced by the addition of vehicle and by interactions with mammary secretion. Neutrophil morphology was altered by fat, skim, CL, CE, NO, and DP. The detrimental effects of CL, CE, NO, and DP on PMN morphology were influenced (some significantly) by the presence of vehicle and interactions with mammary secretion. There were significant correlations among secretion- and antibiotic-induced changes in PMN ingestion of bacteria, PMN killing of bacteria, and PMN morphology.