Norepinephrine (NE) and epinephrine (EPI) collected from dogs were sequentially and temporally measured in blood and plasma at 24 C. Heparin and EDTA anticoagulants, in combination with reduced glutathione and EDTA as a preservative, were also compared. Norepinephrine and EPI concentrations were measured by high-pressure liquid chromatography with electrochemical detection. In heparinized plasma, NE and EPI concentrations were relatively stable in the absence or presence of preservative after 24 hours at 24 C. In EDTA plasma, NE and EPI values were less stable when compared with those in heparinized samples. Norepinephrine concentrations in EDTA plasma without preservative decreased by 163.2 +/- 8.88 pg over 24 hours, compared with an 86.6 +/- 7.92 pg loss of NE in heparinized plasma. The degradation of EPI in EDTA plasma without preservative was also twofold greater, compared with that in heparinized plasma. Addition of preservative had no stabilizing effect on NE or EPI in heparinized or EDTA plasma. During long-term storage at -70 C, plasma NE and EPI values decreased < 0.6 and < 0.1 pg/d, respectively. Norepinephrine and EPI values were stable in heparinized blood for 6 hours but decreased to < 25% and < 6% of initial base line values, respectively, when plasma separation was delayed 24 hours.

Healthy mature roosters (n = 10) were given gentamicin (5 mg/kg of body weight, IV) and, 30 days later, another dose IM. Serum concentrations of gentamicin were determined over 60 hours after each drug dosing, using a radioimmunoassay. Using nonlinear least-square regression methods, the combined data of IV and IM treatments were best fitted by a 2-compartment open model. The mean distribution phase half-life was 0.203 +/- 0.075 hours (mean +/- SD) and the terminal half-life was 3.38 +/- 0.62 hours. The volume of the central compartment was 0.0993 +/- 0.0097 L/kg, volume of distribution at steady state was 0.209 +/- 0.013 L/kg, and the total body clearance was 46.5 +/- 7.9 ml/h/kg. Intramuscular absorption was rapid, with a half-life for absorption of 0.281 +/- 0.081 hours. The extent of im absorption was 95 +/- 18%. Maximal serum concentration of 20.68 +/- 2.10 microgram/ml was detected at 0.62 +/- 0.18 hours after the dose. Kinetic calculations predicted that IM injection of gentamicin at a dosage of 4 mg/kg, q 12 h, and 1.5 mg/kg, q 8 h, would provide average steady-state serum concentrations of 6.82 and 3.83 microgram/ml, with minimal steady-state serum concentrations of 1.54 and 1.50 microgram/ml and maximal steady-state serum concentrations of 18.34 and 7.70 microgram/ml, respectively.

The cytotoxic effect of Moraxella bovis 118F on bovine neutrophils was evaluated and characterized by use of a 51Cr release assay. Neutrophils harvested from healthy adult cattle were labeled with 51Cr. The leukocidic activity produced by M bovis 118F, a hemolytic strain of M bovis, was heat-labile. A live culture of strain 118F, at a ratio of 100 bacteria/neutrophil, released 97.7% of the 51Cr from labeled neutrophils. Neither a heat-killed preparation of M bovis 118F nor a live or heat-killed preparation of M bovis IBH63 (a nonhemolytic and nonpathogenic strain) induced significant (P > 0.05) release of 51Cr. Moraxella bovis 118F broth culture filtrates prepared for evaluation of leukocidic activity also were evaluated for hemolytic activity. These 2 toxic activities had several characteristics in common. Both were filterable, heat-labile, produced by a hemolytic strain, and were released during early logarithmic phase growth from broth cultures. Leukocidic and hemolytic activities were protected from degradation by phenylmethyl sulfonyl fluoride, a serine protease inhibitor. Leukocidic and hemolytic activities were dependent on calcium ions. Filtrate resulted in 54.1% 51Cr release from labeled neutrophils and contained 646.7 hemolytic U/ml, respectively, when saline (0.85% NaCl) + 10 mM CaCl2 solution was used as diluent. Neither saline solution nor saline + 10 mM MgCl2 solution supported leukocidic or hemolytic activity. Serum, obtained from several calves 10 to 38 days after M bovis inoculation, substantially neutralized leukocidic and hemolytic activities, compared with paired preinoculation serum samples. In addition, no significant difference (P > 0.05) was detected when the ability of each calf's postinfection serum to neutralize leukocidic activity was compared with the ability of the serum to neutralize hemolytic activity.

Hybridomas secreting monoclonal antibodies (MAB) to transmissible gastroenteritis virus (TGEV) were produced by fusion of SP2/0 myeloma cells and splenic lymphocytes of BALB/c mice immunized with the virulent cell-passaged Miller strain of TGEV. The MAB secreted by these hybridomas were partially characterized; 4 of them (MA4, MA5, MH11, MB2) had high-neutralization titer for TGEV. The remaining 7 (MC6, MD9, ME5, MG5, MF2, ME9, MG7) did not neutralize TGEV at 1:25 dilution. All 4 neutralizing and 2 of the nonneutralizing MAB reacted with the E2 protein of TGEV in a radioimmunoprecipitation assay. The remaining 5 MAB reacted with the E1 protein of TGEV. Reactivity of the MAB was tested in an indirect immunofluorescent assay with 3 cell culture-adapted strains of TGEV (Miller, Purdue, and Illinois) and 13 wild-type isolates of TGEV. Neutralizing MAB reacted with all 13 wild-type isolates and the 3 cell culture-adapted strains of TGEV. In contrast, nonneutralizing MAB that reacted with the Miller strain of TGEV varied in their reactivity with the wild-type TGEV isolates. Reactivity of neutralizing MAB was also tested, using plaque-reduction neutralization assays with Miller, Purdue, and Illinois strains and 5 wild-type isolates. All 4 neutralizing MAB neutralized the 8 virus isolates, but the neutralization titer was higher with the homologous virus than with the heterologous virus isolates. However, neutralization titers of the 4 neutralizing MAB were 4 to 16 times higher for the homologous Miller strain of TGEV than for the heterologous Illinois and Purdue strains, and were 4 to 1,000 times higher than for the wild-type isolates. Extensive antigenic heterogeneity was observed among TGEV isolates on epitopes recognized by the nonneutralizing MAB directed against either E1 or E2 protein.

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).

A single dose of digoxin was injected, IV, into 5 mature male turkeys (0.066 mg/kg of body weight), 8 male ducks (0.066 mg/kg), and 6 roosters (0.33 mg/kg). Twenty-three serial venous blood samples were collected before (baseline) and after the administration of digoxin to turkeys, ducks, and roosters. Plasma concentrations of digoxin were determined in duplicate by a radioimmunoassay that was validated for avian species. The plasma concentrations were best fitted by a 3 (turkeys, ducks)- and 2 (roosters)-compartment open model, with first-order elimination from the central compartment. Significant (P < 0.05) kinetic differences were determined among species. Mean half-life (t1/2) for ducks, roosters, and turkeys were 8.30 +/- 2.70 (mean +/- SD), 6.67 +/- 3.50, and 23.7 +/- 4.8 hours, respectively. The volume of distribution at steady state (V(SS)) was 14.7 +/- 2.9, 3.13 +/- 0.49, and 2.27 +/- 0.36 L/kg, and total body clearance (CL) of drug was 1.54 +/- 0.43, 0.461 +/- 0.187, and 0.136 +/- 0.022 L/h/kg for ducks, roosters, and turkeys, respectively. The mean residence time was 10.3 +/- 3.9, 8.37 +/- 4.97, and 16.8 +/- 2.2 hours, respectively. Volume of distribution at steady state and CL in ducks were several fold higher than that in turkeys. The terminal half-life of digoxin determined for ducks and roosters in this study was considerably shorter than those previously reported for several mammalian species.

One hundred fifty Se-deficient, pregnant, crossbred beef cows were assigned to 1 of 4 treatment groups: group A, Se-deficient control; group B, 1 Se bolus at 0 and 119 days; group C, 1 Se bolus at 0 days; and group D, 2 Se pellets at 0 days. The Se bolus is an osmotic pump designed to release 3 mg of Se/d into the reticulorumen. The Se pellets weigh approximately 30 g and contain 10% elemental Se, which is liberated in the reticulorumen. The Se bolus is designed to provide Se supplementation for 120 days and the Se pellets provide supplementation for up to 18 months. Cattle were maintained on Se-deficient pasture or forages prepared from these pastures for the duration of the experiment. Blood samples were collected from cows prior to treatment (time 0) and at 28, 52, 119, and 220 days thereafter and analyzed for blood Se (BSe) concentration. Body weights were recorded at each sampling time. Blood Se concentration of cows from all supplemented groups were significantly (P < 0.01) higher than control values at all sample dates after treatments began. By the end of the 220-day study, treatment group-B cattle had significantly (P < 0.01) higher BSe concentrations than any other group. Body weights of treatment groups fluctuated throughout the study, but did not differ (P > 0.05) between groups. One cow and 6 calves born to cows during the experimental period died. Necropsy of 5 calves provided no evidence linking these deaths to treatments. A difference (P > 0.05) in mortality between groups was not detected. Blood samples were collected from calves prior to suckling, and were analyzed for BSe concentration. Colostrum samples were collected from dams and analyzed for total Se concentration. Additional blood samples were collected from calves 24 to 48 hours after suckling and analyzed for BSe concentration and serum creatine kinase activity. Birth weight, gender, and health were recorded for all calves. Calves from cows in Se-supplemented groups had significantly (P < 0.001) higher BSe concentrations, both before and after suckling, than did controls. Postsuckle BSe concentrations within the groups of calves were not significantly (P > 0.05) different than presuckle BSe concentrations for any of the groups. Selenium concentrations in colostrum from Se-supplemented cows were significantly (P < 0.001) higher than from control cows. A difference (P > 0.05) was not determined in serum creatine kinase activities or birth weights between groups.

Canine gastric dilatation-volvulus (GDV) is a naturally acquired condition of large-breed dogs primarily and is associated with high mortality. The clinical course suggests that reperfusion injury may be important in the pathogenesis of GDV. To evaluate the role of xanthine oxidase and iron-dependent lipid peroxidation (which are purported mechanisms of reperfusion injury) in the pathogenesis of GDV-related mortality, we created experimental GDV in 21 dogs. These dogs were then treated with either allopurinol (a xanthine oxidase inhibitor), U74006F (an experimental lipid peroxidation inhibitor), or saline solution (NaCl, 0.85%). Three of 8 dogs died in the allopurinol-treated group, none of 5 died in the U74006F-treated group, and 4 of 8 died in the saline solution-treated group. Tissue malondialdehyde concentration, a nonspecific indicator of lipid peroxidation, was significantly (P < 0.05) greater in the duodenum, jejunum, colon, liver, and pancreas of the saline-solution treated and allopurinol-treated dogs than in the same tissues of the U74006F-treated dogs after surgical correction of the GDV (ie, during reperfusion), compared with malondialdehyde concentrations determined before inducing GDV. The results of this study support the concept that lipid peroxidation associated with reperfusion injury is important in the pathogenesis and high mortality of canine GDV. Furthermore, this lipid peroxidation and mortality may be preventable by appropriate and timely treatment.

A sublethal dose of ethylene glycol was administered orally to 3 groups of dogs; dogs of a control group were given distilled water instead. Renal cortical biopsy samples were obtained from dogs of experimental and control groups at various times after treatment. Tissue was examined by use of light microscopy and transmission electron microscopy. In dogs of the control group, the light and electron microscopic appearances of tissue were within normal limits at all sample collection hours. In dogs of the experimental groups, renal corpuscular structure remained within normal limits by use of light and electron microscopy throughout the study, though morphologic change was seen in other structures of the cortex. Light microscopic lesions first appeared at 12 hours, and were similar to those reported in the literature. Ultrastructural lesions were first observed in the 5-hour samples, and similar to the light microscopic lesions, were most common in the proximal convoluted tubules (PCT). Initial PCT cellular changes included vacuolization of cells and distention of the parabasal extracellular spaces; PCT cellular lesions seen in later-hour samples included formation of apical buds and cellular rupture. Internalization or sloughing of the PCT brush border was not observed. Distal convoluted tubules (DCT) were frequently dilated and/or packed with cellular debris. A few DCT cells had degenerative or necrotic changes. In PCT and DCT, abnormal cells were frequently flanked by normal or nearly normal cells. During later hours, a few cells with types of changes first observed in early hours continued to be observed, implying ongoing response of cells to the toxin.

The vascular patterns to pelvic limb muscles were studied in 6 dogs (12 limbs) to identify muscles most suitable for transposition in the treatment of large wounds. Gross dissection of injected specimens and angiography were used to identify the vascular pedicles. The vascular pedicles to several muscles were generally consistent, and any variations would not interfere with most muscle transfers. The cranial part of the sartorius, gracillis, semitendinosus, and rectus femoris muscles were identified as suitable candidates for transfer. The caudal part of the sartorius, cranial tibial, and long digital extensor muscles have segmentalized vascular patterns that would limit its arc of rotation.