Hemodynamic effects of spontaneous ventilation, intermittent positive-pressure ventilation (IPPV), and high-frequency oscillatory ventilation (HFOV) were compared in 6 dogs during halothane anesthesia. Anesthesia was induced with IV thiamylal Na and was maintained with halothane (end-tidal concentration, 1.09%). During placement of catheters, dogs breathed spontaneously through a conventional semiclosed anesthesia circuit. Data were collected, and dogs were mechanically ventilated, using IPPV or HFOV in random order. Ventilation was adjusted to maintain PaCO2 between 38 and 43 mm of Hg during IPPV and HFOV. Cardiac index, aortic blood pressure, and maximum rate of increase of left ventricular pressure were significantly (P less than 0.05) less during HFOV than during spontaneous ventilation, whereas right atrial and pulmonary artery pressure were significantly greater during HFOV than during spontaneous ventilation. During IPPV, only the maximum rate of increase of left ventricular pressure was significantly less than that during spontaneous ventilation.

The 51Cr-labeled EDTA was validated as a suitable permeability probe in dogs for measurement of passive, unmediated diffusion across intestinal mucosa via intercellular pathways. The 51Cr-labeled EDTA was stable in aqueous solution and did not bind to biologic tissue and fluids. After incubation of 51Cr-labeled EDTA in isolated jejunal loops, analytic subcellular fractionation of jejunal mucosa on reorientating sucrose-density gradients was performed, and no association of 51Cr-labeled EDTA with particulate intracellular organelles was detected. Intravenously administered 51Cr-labeled EDTA was rapidly and completely excreted in urine. Intestinal permeability to 51Cr-labeled EDTA after oral administration was assessed in healthy dogs. The percentage of the administered dose of 51Cr-labeled EDTA excreted in the urine in 24 hours ranged from 2.3 to 17.6% (median, 13%).

Serum biochemical indicators of liver function were determined in healthy, age-matched foals during the first 270 days of life. Values were compared with those of healthy adult horses and with those determined on the day of birth (< 12 hours old). Serum alkaline phosphatase, gamma-glutamyl transferase, and L-iditol dehydrogenase activities were increased during the first 2 weeks of life. Serum cholesterol, triglyceride, and total and unconjugated bilirubin concentrations peaked during this same period. During the early neonatal period (<12 hours old), globulin concentrations (mainly beta 2 and gamma fractions) were low and albumin/globulin ratios were high. However, individual values for all analytes were varied.

Factors that influenced the in vitro bactericidal activity of bovine neutrophils against Actinomyces pyogenes were investigated. Neutrophils and serum from 2 clinically normal donor cows were incubated with bacteria for 2 hours. To determine bactericidal activity, colony-forming units were counted after a 48-hour incubation on blood agar plates. Microscopic examination indicated that in the presence of serum, bacteria were cell associated after incubation, whereas when serum was replaced by medium, bacteria were not cell associated. Bactericidal activity of neutrophils was similar whether the sera were heat-treated at 56 C for 30 minutes or were not heated. Heating the serum at 65 C for 30 minutes significantly (P less than 0.001) reduced bactericidal activity. Bactericidal activity decreased (P less than 0.001) as serum concentration (greater than 10%) decreased. More than 80% of the bacteria were killed within the 40 minutes of incubation. The opsonizing capacity of serum varied significantly (P less than 0.01) among 12 cows. Similarly, neutrophil bactericidal activity (by cow) was affected significantly (P less than 0.001). Preincubation of serum with A pyogenes significantly (P less than 0.001) reduced the opsonizing ability of the serum. Culture filtrate of A pyogenes was not chemotactic for neutrophils in vitro.

Diacetoxyscirpenol (DAS) was given IV to pigs (0, 0.5, and 1.0 mg/kg of body weight), cattle (0 and 0.5 mg/kg), and dogs (0 and 0.5 mg/kg). Blood was collected and hemograms were done at 0.5-hour intervals for 8 hours. The animals were euthanatized at 8 hours after treatment, and bone marrow samples were taken and examined by light microscopy. Moderate to severe necrosis of bone marrow hematopoietic elements was found in animals given DAS. The sequential increase in the type and number of abnormal cells in the blood suggested a successive destruction of the hematopoietic elements. A marked left shift in the neutrophil population was found in animals given DAS. Metarubricytes and large platelets were found in the blood of animals given DAS. Lymphocytes were replaced with immature cells. Pathologic changes were most severe in the pigs given a dosage of 1.0 mg of DAS/kg. The order of species sensitivity to DAS was pigs greater than dogs much greater than cattle.

Serum immunoglobulins of the IgG isotype recognizing common gram-negative cell core epitopes were serially measured, using a direct ELISA, on samples obtained from 20 neonatal Holstein calves. An R-mutant Escherichia coli (strain J5) was used as a plate antigen in this assay. Total serum IgG concentration was measured using radial immunodiffusion. Half-lives of core antigen-specific IgG (7.56 days) and total serum IgG (22.66 days) were dramatically different (P less than 0.0005). This may be an indication of cross-reactive consumption of core antigen-specific immunoglobulins.

Continous electromyographic recordings of pharyngeal muscle activity were made in 5 clinically normal control dogs and in 7 dogs 3 years after partial denervation of the pharyngeal muscles. Electromyographic recordings were made of the sequence of actions of each muscle and of the combined muscle activity, at rest and during swallowing of food. During 30-second periods, the recordings were digitalized and stored on diskette for further analysis. All control dogs had a distinct pattern of muscle activity during swallowing, the onset being in a constant order (hyopharyngeal, thyropharyngeal, and cricopharyngeal) and bilaterally synchronous. While eating, each dog had about 5 to 12 short periods of synchronous activity in each muscle, between the swallowing actions. During the resting period, there were longer periods of activity, which were synchronous with respiration. In each denervated dog, there were normal and irregular swallowing actions. Swallowing activity was recognized, but the sequence of hyopharyngeal, thyropharyngeal, and cricopharyngeal muscle activity was irregular and different from that in control dogs. Partial denervation of the pharyngeal muscles does not seriously impair motor activity of the muscles, but does alter the sequence of activity in the pharyngeal muscles during swallowing.

Fecal samples from 131 cattle clinically suspect for paratuberculosis were cultured bacteriologically, using the traditional sedimentation processing method and a processing method that included a centrifugation step. Of 16 samples that were contaminated, 6 were culture-positive on at least 1 medium and by 1 processing method. Ten of 131 (7.6%) fecal samples processed by both methods were lost because of contamination. The number of culture-positive samples (using both processing methods) were 65 of 121 (53.7%) on media without miconazole and 60 of 121 (49.6%) on media with miconazole. Seven of the 121 (5.8%) samples were culture-positive, using centrifugation, after 16 weeks' incubation at 37 C. Thirteen of 60 (21.7%) isolates were obtained only with centrifugation, and 10 of these had low colony counts, suggesting that a centrifugation step may have concentrated microorganisms that would have gone undetected without centrifugation. Six of 60 (10%) isolates positive for M paratuberculosis on the sedimentation method were negative on the centrifugation method. Contamination rates were significantly (P less than 0.001) increased when centrifugation was used. The miconazole significantly (P less 0.001) decreased contamination rates when centrifugation was used.

Bovine blood mononuclear cells were separated into 2 fractions by use of centrifugl elutriation. Total recovery, as well as recovery of each fraction, was greater than that obtained by use of Ficoll-sodium diatrizoate separation. The lymphocyte fraction contained less than 1% granulocytes, and the granulocyte fraction contained only 7% lymphocyte contamination. The technique was reproducible and results proved to be comparable with those of Ficoll-sodium diatrizoate density-gradient centrifugation; furthermore, the method is considerably cheaper and less time-consuming for processing large volumes of blood. Viability of cells separated by elutriation always was greater than 98%, whereas viability of cells separated by Ficoll-sodium diatrizoate was greater than 95%. Also, mitogen activation of lymphocytes separated by elutriation was superior to that of lymphocytes separated by Ficoll-sodium diatrizoate centrifugation.

We studied the antibody responses to transmissible gastroenteritis (TGE) in serum, colostrum, and milk from sows vaccinated with 2 attenuated (1 IM and 1 oral-IM) and 1 nonattenuated live vaccines and the relationship of these responses with the survivability of the sow's suckling pigs after challenge exposure with virulent TGE virus. Contrary to previous studies, the anti-TGE virus-neutralizing geometric mean titers (GMT) in the milk of sows vaccinated with attenuated vaccines at 3 and 5 days of lactation were similar to that found in the colostrum. Colostral and serum antibody titers were highest in sows given 2 injections of the IM attenuated vaccine. Half of the sows given the oral-IM attenuated vaccine did not seroconvert after 2 oral doses. Only sows vaccinated with the nonattenuated live vaccine had milk GMT that remained high for 21 days after farrowing. The linear relationship between colostral GMT and percentage of survivability of suckling pigs challenge exposed at 3 days of age was significant (P less than 0.05), although the relationship between serum GMT and percentage of survivability and the relationship between milk GMT and percentage of survivability were not significant (P greater than 0.10). The linear relationship between colostral (P less than 0.10) or pre-challenge exposure milk (P less than 0.05) GMT and percentage of survivability of suckling pigs challenge exposed at 5 days of age was significant. We have no adequate explanation for the relatively low colostral GMT, the relatively high milk GMT at 3 and 5 days of lactation in vaccinated sows, or the lack of significant linear relationship between milk GMT and survivability of pigs challenge exposed at 3 days of age.