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.

Protein profiles of whole homogenates of anconeus (slow twitch) and biceps femoris (fast twitch) muscles of clinically normal dogs and of Labrador Retrievers with hereditary myopathy (HM) were resolved on flat bed polyacrylamide isoelectric-focusing gels. Three methods of sample solubilization were performed. The solubilization buffer, with high concentrations of urea, precipitated the zwitterionic detergent, but use of the buffer containing 3% NP-40, 9.2M urea, and 0.1M arginine resulted in better resolution and stability of pH gradient. Gels of anconeus muscle from clinically normal dogs contained 2 protein bands specific to anconeus muscle, whereas gels of biceps femoris muscle from clinically normal dogs contained 3 protein bands amplified in biceps femoris muscle that were barely detectable in anconeus muscle. The staining intensity of protein bands in biceps femoris muscles from Labrador Retrievers with HM was decreased, relative to controls. The quantitative analysis of peak height ratios of biceps femoris muscle revealed significant (P less than 0.05) differences between profiles of clinically normal dogs and Labrador Retrievers with HM.

Salivary glands from males of 3 Dermacentor species (D andersoni, D variabilis and D occidentalis) that were infected with either the Virginia or Idaho isolate of Anaplasma marginale as nymphs or adults were examined for colonies of A marginale by use of light and electron microscopy. Prior to dissection of salivary glands, exposed ticks were held at 25 C for 15 to 18 days, followed by a 3-day incubation at 37 C. Ticks of 2 species transmitted A marginale to calves; the third tick species was confirmed infected by demonstration of typical colonies in tick gut cells, but transmission was not attempted; Colonies of A marginale were seen with light microscopy in salivary glands of all 3 species of ticks; they were located in acinar cells that contained simple granules. Colonies varied morphologically from small, compact ones to larger structures that contained distinct organisms and often were adjacent to the host cell nucleus. Electron microscopy confirmed that the colonies were rickettsial organisms. Morphologic features of A marginale varied and included reticulated forms, forms with electron-dense centers, and small particles; these various forms were similar to those described previously in midgut epithelial cells of ticks. We believe that the organism seen within tick salivary glands may replicate in the glands before its transmission to the vertebrate host.

Bovine pulmonary artery cells in cell culture were exposed to lipopolysaccharide (LPS) purified from Pasteurella haemolytica serotype A1. This resulted in severe membrane damage, which caused a time- and dose-dependent release of lactate dehydrogenase that was first detected 4 hours after exposure and reached a maximal mean release of 67% after 24 hours of exposure to 1 microgram of LPS/ml. Mean release of 51chromium followed by a similar pattern and reached a maximum of 61% following 24 hours of exposure to 10 micrograms of LPS/ml. Morphologically, endothelial cells responded to LPS by marked cell membrane retraction, the formation of numerous cytoplasmic blebs, and ruffling of the cell membrane. Subsequently, the cells became round and detached. Cell detachment reached a mean of 95% following 8 hours of exposure to 1 microgram of LPS/ml. These studies demonstrated that P haemolytica LPS is capable of causing direct damage to bovine pulmonary arterial endothelial cells, which may be important in the pathogenesis of bovine pneumonic pasteurellosis.

Pilus-mediated adherence is a virulence attribute of Moraxella bovis. Several pilus types have been shown to exist among strains of this bacterium, but correlation between pilus type and specific field cases of the disease has not been done. During the summer of 1987, an epizootic of infectious bovine keratoconjunctivitis was reported in 7 Iowa counties. Eight isolates of M bovis were secured from 12 episodes studied. All 8 of the isolates were nearly homogeneous in biochemical properties and had the same plasmid biotype. Pilus typing performed by immunofluorescence and immunogold electron microscopy identified a single new pilus type among 5 of the 8 isolates. This pilus type was identified in field cases that developed within a narrow time frame and over large distances. The implication of these findings is that infectious bovine keratoconjunctivitis epizootics may be associated with emergence of a novel pilus type, and that rapid dissemination over wide distances can occur, presumably by transportation of carrier cattle.

An ELISA was used to detect IgG, IgM, and complement (C3) on the surface of canine erythrocytes. Erythrocytes were placed in wells of a microtitration plate and incubated with affinity purified, alkaline phosphatase-conjugated anti-canine IgG, IgM, or C3. Results of the ELISA were compared with the direct antiglobulin test (DAT) by preparing standard reference curves from canine blood type A erythrocytes that had been incubated with serial dilutions (1:2 to 1:8,192) of canine anti-A serum. The ELISA detected increased erythrocyte-bound immunoglobulin and complement at two- to fourfold dilutions greater than thoe required for positive results with the DAT. The ELISA required small sample and reagent volumes and detected lower concentrations of immune components than did the DAT.

Swine herds suspected to be infected with Leptospira interrogans serovar bratislava were vaccinated with bacterins containing 5 or 6 leptospiral serovars in which serovar bratislava was the unique component. The principal diagnostic feature indicating an infection by this organism was demonstration of antibody against serovar bratislava in sera from stillborn pigs. For 1 breeding cycle after vaccination of herds on 3 farms, 255 of 266 (95.9%) sows and gilts given the 6-serovar bacterin farrowed. In contrast, 233 of 311 (74.9%) sows and gilts given the 5-serovar bacterin farrowed. These results, as evaluated by analysis of variance techniques, showed a significant improvement (P less than 0.01) in reproductive performance for groups vaccinated against serovar bratislava.

Lectin binding of small intestinal goblet cells was examined in newborn, suckling, and weaned pigs. Sections of duodenum, proximal portion of the jejunum, distal portion of the jejunum, and ileum were embedded in a hydrophilic acrylic resin and treated with each of the following lectins: Canavalia ensiformis, Ricinus communis I, Glycine max, Ulex europaeus I, and Triticum vulgaris. Percentages of goblet cells binding each lectin were calculated within intestinal regions. Differences in lectin-binding affinity were detected among pigs of various ages and among various intestinal regions within pig age groups.

Neoplastic cells were isolated from 2 sibling Great Dane/Labrador Retriever mixed-breed dogs in which telangiectatic type osteosarcomas arose concurrently. Cells from various sites in the same osteosarcoma appeared similar in culture, but there were differences between the 2 osteosarcomas in growth characteristics and appearance of cells. Cells from 1 osteosarcoma had a small, but significant (P less than 0.05), cyclic adenosine monophosphate response to parathyroid hormone stimulation, indicating a low order of osteoblastic differentiation. Cells from the other osteosarcoma had no response to parathyroid hormone stimulation. Cells from both osteosarcomas and a concentrated cell-free filtrate from the osteosarcoma with osteoblastic differentiation were injected into nude mice, but osteosarcomas were not induced. Results of ultrastructural examination of osteosarcoma samples for viral particles were negative and supernatant fluids from cultured cells were considered negative for viral reverse transcriptase activity.