The lungs of 32 guinea-pigs inoculated intratracheally with Rhodococcus equi were examined histopathologically in order to study the pathogenesis of R. equi-pneumonia. The most characteristic lesion was suppurative bronchopneumonia, which developed as follows: Congestion, serous exudation and mild infiltration of macrophages carrying Gram-positive bacteria and multinucleate giant cells 1 day postinoculation (pi), infiltration of numerous neutrophils and macrophages in the alveoli 2-5 days pi, focal accumulation of necrotic cells and infiltration of mononuclear cells phagocytizing degenerative neutrophils with a few multinucleate giant cells 6-10 days pi, small accumulation of mononuclear cells surrounded by normal alveolar tissues 12-16 days pi. The lung lesions in R. equi-infected guinea-pigs healed more easily as compared with those in the foals.

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The pathological characteristics of salmonid herpesviruses (strain H-83, and OO-7812 strain of Oncorhynchus masou virus (OMV)) to three species of salmonid fish and the antibody production of the fish to the viruses were investigated. The strain H-83 was pathogenic to masu salmon (O. masou) and rainbow trout (Salmo gairdneri) fry. OMV was also pathogenic in masu salmon and coho salmon (Oncorhynchus kisutch) fry. Coho salmon developed tumors in the eyes and in and around the oral cavity. From the results of virus re-isolation, the liver seemed to be the target organ of OMV infection. In vitro passages of both herpesviruses resulted in the decrease of pathogenicity to masu salmon. Yearling masu salmon and rainbow trout appeared not to be sensitive to the infection with the strain H-83. The fish produced virus-neutralizing antibody but the antibody titers were relatively low. The expression of seconday immune response was observed.

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A two-year-old Holstein-Friesian dairy cow affected with skin leukosis was pathologically studied. The initial skin lesion was urticaria-like plaques appearing on the neck, shoulder, back, and abdomen. The plaque gradually increased in number on the whole body surface where more than 500 were noted. The plaques were then sloughed off regressed naturally. At autopsy, many of the internal organs and lymph nodes were infiltrated with neoplastic tissues. Microscopically neoplastic cells had proliferated in the dermis and infiltrated into the epidermis, and were finally discharged outwards through the epidermis. Macrophages infiltrated and phagocytized neoplastic cells in the lesions. Perivascular lymphocytic cell infiltration was observed in the regressing lesions. Electron microscopy revealed a clustered dense body in many of the neoplastic cells. The cow died with lymphosarcoma of the heart on the 94th day following the first medical examination.

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The ontogeny of the thyroid-stimulating activity of the pituitary gland associated with or dissociated from the hypothalamic control was studied in fetal rats based on electron microscopic observations of the thyroid follicular cells. The day following overnight mating was regarded as day 0 of gestation. Fetal hypophysectomy or encephalectomy (pituitary gland left intact) was performed on day 16, 17, 18 or 19, and operated fetuses were autopsied 2 days later and compared with intact littermate controls. In hypophysectomized fetuses, the weight of thyroid gland was reduced, the area ratio of "nucleus/cell" was increased and that of "rER/cytoplasm" was decreased, as compared with controls in all age groups. These changes were accompanied by shortening of microvilli on the apical surface of follicular cells, flattening of cells and shrinkage of the rER. In encephalectomized fetuses, no changes were found in all the parameters tested as compared with the controls. These electron microscopical observations support the view that the pituitary-thyroid axis in fetal rats develops independently of hypothalamic control.

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A total of 212 strains of Staphylococcus hyicus subsp. hyicus isolated from pigs affected with exudative epidermitis and healthy pigs, cattle and chickens were tested for antibiotic susceptibility and detection of penicillinase. One hundred and five strains (49.5%) were resistant to one or more of the 21 antibiotics tested. Drug resistance was found in 92 (74.2%) of 124 swine strains, and 27.2% and 72.8% of the resistant strains were single and multiple drug resistant types, respectively. The most frequent patterns (80.6%) of the multiple drug resistance were PCG TC OL LCM KM, OL LCM, PCG TC and TC OL LCM. Of 34 bovine strains, 14.7% were resistant strains including 2 single and 3 multiple drug resistant types. Seven single and 1 multiple drug resistant types were also found in 14.8% of 54 chicken strains. Compared to the bovine and chicken strains, in consequence, the resistant strains were frequent among swine strains with a tendency toward multiple drug resistance. The penicillinase production was found only in 47 swine strains (37.9%).

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BALB/c spleen cells, immunized with bovine thymocytes were fused with mouse myeloma cells. The resultant hybridomas were screened for reactivity with bovine thymocytes as measured by indirect immunofluorescence microscopy. Three monoclonal antibodies (MoAbs; BLMo-1, 2 and 3) which react with about 70% of adult cattle thymocytes were obtained. All three MoAbs were found to react with cortical cells but not with medullary thymic cells. They did not react with peripheral blood mononuclear cells or with the lymphocyte populations in the lymph node, spleen and bone marrow. All three hybridomas produced IgG₁ k immunoglobulin. None of the MoAbs reacted with tumor cells from thymic or calf sporadic bovine leukosis or with cells from enzootic bovine leukosis.

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To establish a recommended dose and prophylactic program of ivermectin for preventing D. immitis infection, antilarval activity of ivermectin at 3 or 6μg/kg against one day, 30 and 60 days old larvae was evaluated. The worms were recovered from all dogs given ivermectin at 3μg/kg one day after inoculation with an average infection ratio of 21.9%. One male worm was recovered from one of 6 dogs given ivermectin at 3μg/kg 30 days after inoculation with an extremely low average infection ratio of 0.1%. Out of 6 dogs given ivermectin at 3μg/kg 60 days after inoculation, 3 animals yielded worms with a low infection ratio of 4.0%. The results suggest that ivermectin at 3μg/kg demonstrates incomplete antilarval activity against D. immitis larvae of one day, 30 and 60 days old and is not suitable to monthly or bimonthly interval mdication for preventing D. immitis infection. Small numbers of the worms were recovered from 5 of 6 dogs given ivermectin at 6μg/kg one day after inoculation with an average infection ratio of 5.7%. No worms were recovered from all dogs given ivermectin at 6μg/kg 30 and 60 days after inoculation. The results show that a single oral dose of ivermectin at 6μg/kg, though the dose demonstrates incomplete antilarval activity against one day old larvae, would be a recommended dose which can completely kill the larvae which are naturally infected at any time when the dose is given once a month at one month interval during the period from one month after the first infection to one month after the last infection of D. immitis.

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Infectivity of Eimeria tenella sporozoites which contained various amounts of amylopectin after incubation at different temperatures was investigated. When sporozoites were incubated at 41°C for 16hr in phosphate buffer solution, almost no amylopectin granules were seen in their bodies and no vivid movements were noted. After sporozoites were incubated at 0, 29, 37 or 41°C for 16hr, both amylopectin contents of sporozoites and rates of their invasion into cultured chicken kidney cells decreased as the temperature of incubation increased. There was a high value of the coefficient of correlation between amylopectin contents and invasion rates of the sporozoites. Lower mortality rates and smaller production of oocysts were observed in chicken embryos inoculated with sporozoites incubated at 41°C for 16hr than those in embryos inoculated with fresh sporozoites. The present results suggest that amylopectin of E. tenella sporozoites plays an important role in establishing infection, i. e. amylopectin is probably a source of energy to survive and to access, invade, and develop in their host cells.

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Chicken thrombolytic function was observed in vivo, and the activation of chicken plasminogen by tissue plasminogen activator (t-PA) extracted roughly from chicken heart was studied. The chicken blood clot embedded subcutaneously or the thrombus clotted by thrombin injection in the brachial vein were removed promptly. The t-PA could be extracted when the fresh heart was homogenized with 2M KSCN, O.3M CH₃COOK, 5M (NH₂)₂CO, 3.9-62.5mM and 0.5-2 M MgSO₄ solution. The reactivity of t-PA extracted with 62.5mM MgSO₄ solution was remarkably enhanced by the addition of CaCl₂ in chicken plasminogen (Plg) and t-PA mixture after incubation at 37°C for 4hours. Human urokinase (UK) activation under the same conditions reached to the maximum in one hour. Changing the additional order and the addition of CaCl₂ beyond the range of 31.3-125mM were weakened the reaction. Epsilonaminocaproic acid (EACA) inhibited these activation system, being especially effective in activation of Plg. These findings suggest that chicken has a thrombolytic mechanism and a t-PA activation system in fibrinolysis.

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Single radial immunodiffusion (SRID) using convalescent cattle sera was developed to evaluate the potency of foot-and-mouth disease inactivated vaccine. The complete virion (140S antigen) was collected by sucrose-gradient centrifugation of inactivated virus. The 12S subunit antigen was prepared by heat treatment of purified 140S antigen. Convalescent cattle sera produced diffusion ring with 140S antigen alone, while hyperimmunized guinea pig sera produced with both 140S and 12S antigens. In SRID of mixed viral antigen (140S and 12S) tested against hyperimmunized guinea pig sera, diffusion rings of the former was affected by contamnination of the latter. When the same samples were tested in SRID using convalescent cattle sera, 12S antigen did not affect the quantitation of 140S antigen. Area of diffusion rings of purified 140S antigen clearly correlated with concentration of proteins measured by optical density, as well as by complement fixation tests using hyperimmunized guinea pig sera. SRID using convalescent cattle sera is more practical than conventional SRID using immunized guinea pig sera, because cattle sera react with effective component (140S antigen) alone, and not with ineffective 12S antigen, in the vaccine, and because infected cattle is more suitable to make large amount of pooled sera for the routine assay.

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The changes in lymphocyte transformation rate and proportion of E-rosette forming cells (ERFC), in addition with serum concentration of IgG and cortisol were examined on dairy cows in the perinatal period. The cows were bled at the various stages of pregnancy, parturition and post-parturient period. Also in calves, the lymphocyte transformation rate and proportion of ERFC were examined on the blood samples collected at weekly interval from birth to 5 weeks of age. The blastogenic response of lymphocytes to concanavalin A and pokeweed mitogen decreased beginning from the 3rd trimester and reached a minimum at parturition. The proportion of ERFC and serum IgG concentration also decreased with parturition. The high serum cortisol level at parturition may influence lymphocyte activity in cows. In neonatal calves, the number of ERFC and responsiveness of peripheral lymphocytes to mitogen corresponded to adult level immediately after birth.

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The present study was carried out to compare the effects of the injection of 1α-hydroxyvitamin D₃ (1αOHD₃) on the plasma 1α, 25-dihydroxyvitamin D (1, 25(OH)₂D) and calcium (Ca) concentrations in lactating cows, and to determine the efficacy of 1αOHD₃ as prophylactic of parturient hypocalcemia. The cows were divided into two groups, a control group consisting of 6 cows and treatment (1αOHD₃) group consisting of 5 cows. Each cow in the treatment group once received intramuscularly 500μg of 1αOHD₃ resolved in 3ml ethanol. The plasma 1, 25 (OH)₂D concentration in the 1αOHD₃ group was significantly higher than that in the control group from 6hr to 5 days after injection, and became significantly lower than that in the control group at 10 days after injection. The plasma total Ca concentration was significantly higher in the 1αOHD₃ group than that in the control group during 2 to 7 days after injection, while the plasma ionic Ca concentration in the former was significantly higher than that in the latter at 1, 2, 3, and 7 days after injection but lower than that at 14 days. Therefore, it is suggested to be appropriate for the prevention of the parturient hypocalcemia to inject 500μg of 1αOHD₃ intramuscularly within 2 to 5 days before parturition. However, if 1αOHD₃ was injected earlier than 10 days before parturition, this might produce a contrary result because the injection of 1αOHD₃ caused the decrease of plasma 1, 25 (OH)₂D and ionic Ca concentration at 10 and 14 days, respectively, after injection.

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In ordef to examine the changes in hemodynamics inducing heartworm migration from the pulmonary artery, the pressures of the right ventricle and pulmonary artery and right cardiac output were measured after administration of 1.5mg/kg body weight of milbemycin D (Milbe) in 6 heartworm-infected dogs under general anesthesia. The heartworms migrated from the pulmonary artery to the tricuspid valve orifice and right atrium from 50 to 105 min after Milbe administration in 4 of the dogs. After Milbe administration, heart rate increased transiently, then subsequently decreased. Systolic right ventricular and mean pulmonary pressures did not show uniform changes in heartworm-migration cases. The right cardiac output decreased clearly before heartworm migration in all such cases. Stroke volume (right cardiac output/heart rate), cardiac index (right cardiac output/kg body weight) and stroke index (stroke volume/kg body weight) also decreased in heartworm-migration cases. The heartworm migration from the pulmonary artery towards the right atrium may be associated with the decreases of blood flow volume and velocity in the right heart.

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Enzyme-linked immunosorbent assay (ELISA) using B42 strain of infectious bronchitis virus (IBV) as an antigen was developed for detection of antibodies against IBV. Purified IBV solubilized with Triton X-100 served as the antigen. Although there was little cross-reactivity in the serum neutralization (SN) test, cross-reactivity was observed among IBV strains B42, Gray, and A5968 (Massachusetts, Delaware, and Connecticut serotypes, respectively). In addition, B42 strain reacted also with antisera against three other serotype strains (Iowa97, Iowa609, and M41) and those against six strains isolated in Japan (distinguishable from each other by the SN test) in ELISA. Thus a wide range of cross-reaction was observed with B42 strain of IBV. Corrected ELISA (cELISA) values of serum samples of chickens naturally infected with IBV in the field did not correlate with thier SN titers. Those of chikens experimentally infected with a single strain of IBV (B42), however, increased with the rise of the SN titer. Therefore, our ELISA system seems to show an IBV-specific reaction. These results suggest that antibodies to several subtypes of IBV can be detected with only one type of virus as an ELISA antigen. The ELISA technique appears to be suitable for large-scale serological surveys and rapid and simple to perform.

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A total of 593 cats consisting of 144 adults and 449 kittens obtained from Animal Protection Center, Prefecture of Kanagawa, were examined. Of these, 51 (8.6%) had Campylobacter, 12 (2.1%) had Yersinia, and 8 (1.4%) had Salmonella. In adult cats, the respective recovery rates of the 3 bacteria were 9.0, 5.8, and 2.1% and in kittens, 8.5, 0.9, and 1.1%. Of 64 Campylobacter strains, 48 from 36 cats were identified as C. jejuni and 16 from 16 cats were as C. coli. Of 12 Yersinia strains, 6 were identified as Y. enterocolitica, 5 were as Y. frederiksenii, and 1 was as Y. pseudotuberculosis. Biovars (Wauters) of the 6 Y. enterocolitica strains were biovar 1 (5 strains) and biovar 2 (1 strain) and their serovars were 06 (1 strain), 07 (1 strain), 014 (1 strain), and ungroupable other than 01 to 033 (3 strains). Eight Salmonella strains were all identified as S. choleraesuis subsp. choleraesuis and belonged to 4 serovars, agona (3 strains), blockley (3 strains), braenderup (1 strain), and typhimurium (1 strain). These results indicate that Campylobacter is carried in the healthy pet cats more frequently than Yersinia and Salmonella.

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