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31.
Abstract: A 14‐year‐old spayed American Paint mare was evaluated for mild colic, anorexia, pyrexia, and pancytopenia. Physical examination revealed mild tachycardia, tachypnea, and pale mucous membranes. Serial laboratory analyses revealed progressive pancytopenia, hyperfibrinogenemia, and hyperglobulinemia. A few large atypical cells were observed in peripheral blood smears. Results of tests for equine infectious anemia and antipenicillin antibody were negative. Serum protein electrophoresis indicated a polyclonal gammopathy. Smears of bone marrow aspirates contained hypercellular particles, but cell lines could not be identified because the cells were karyolytic, with pale basophilic smudged nuclei and lack of cellular detail. A diagnosis of bone marrow necrosis was made. Treatment consisted of antimicrobials, nonsteroidal anti‐inflammatory drugs, and corticosteroids. The pyrexia resolved; however, the pancytopenia progressively worsened and petechiation and epistaxis developed. The horse was humanely euthanized. Postmortem examination revealed a diffuse round cell neoplasm infiltrating the kidneys, spleen, lymph nodes, lungs, and bone marrow. Immunophenotyping results (CD3+, CD79α−) indicated the neoplastic cells were of T‐cell lineage. Infiltration of lymphoma cells into the bone marrow appeared to have resulted in severe myelophthisis and bone marrow necrosis. Bone marrow necrosis has been associated previously with lymphoma in humans and dogs. To our knowledge, this is the first reported case of lymphoma resulting in bone marrow necrosis in a horse.  相似文献   
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Remote rumen temperature monitoring is a potential method for early disease detection in beef cattle. This experiment was conducted to determine if remotely monitored rumen temperature boluses could detect a temperature change in steers exposed to bovine viral diarrhea virus (BVDV) and challenged with a common bovine respiratory disease pathogen, Mannheimia haemolytica (MH). Twenty-four Angus crossbred steers (BW = 313 ± 31 kg) were allotted to 1 of 4 treatments: 1) no challenge (control); 2) challenge by a 72-h exposure to 2 steers persistently infected with BVDV; 3) bacterial challenge with MH; and 4) viral challenge by a 72-h exposure to 2 steers persistently infected with BVDV followed by bacterial challenge with MH (BVDV + MH). Remotely monitored rumen temperature boluses programmed to transmit temperature every minute were placed in the rumen before the time of exposure to steers persistently infected with BVDV. Rectal temperatures were taken before MH challenge (0) and at 2, 4, 6, 12, 18, 24, 36, 48, 72, and 96 h after MH challenge. Rumen temperatures were recorded 3 d before (-72 h; period of BVDV exposure) through 14 d after (336 h) MH challenge. Rumen temperatures were analyzed as a randomized complete block design with a 2 × 2 factorial arrangement of treatments and a first-order autoregressive covariance structure for repeated measures. A treatment × day interaction was observed for average daily rumen temperature (P < 0.01). A treatment difference (P < 0.01) was observed on d 0, when MH-challenged steers had greater rumen temperatures than steers not challenged with MH. There was no BVDV × day interaction (P > 0.01). Rumen temperatures averaged every 2 h resulted in a BVDV × hour interaction (P < 0.01) and an MH × hour interaction (P < 0.01). The BVDV × hour differences occurred at h -18 to -14, 40 to 46, 110, 122, and 144 to 146 (P < 0.01). The MH × hour difference occurred at h 4 to 24 (P < 0.01). Maximum rumen temperature was increased (P < 0.01) for BVDV (0.8 °C), MH (1.2 °C), and BVDV + MH (1.3 °C) compared with the control. On average, rumen temperatures measured by the boluses at the same time points as the rectal temperatures were 0.13 °C less than rectal temperatures, and the 2 body temperatures were highly correlated (r = 0.89). Rumen temperature boluses appear to have potential as a tool for detecting temperature changes associated with adverse health events such as exposure to bovine respiratory disease and BVDV.  相似文献   
35.
Chlamydia psittaci was detected by PCR in the lung and equine foetal membranes of two aborted equine foetuses and one weak foal from two different studs in Victoria, Australia. The abortions occurred in September 2019 in two mares sharing a paddock northeast of Melbourne. The weak foal was born in October 2019 in a similar geographical region and died soon after birth despite receiving veterinary care. The detection of C. psittaci DNA in the lung and equine foetal membranes of the aborted or weak foals and the absence of any other factors that are commonly associated with abortion or neonatal death suggest that this pathogen may be the cause of the reproductive loss. The detection of C. psittaci in these cases is consistent with the recent detection of C. psittaci in association with equine abortion in New South Wales. These cases in Victoria show that C. psittaci, and the zoonotic risk it poses, should be considered in association with equine reproductive loss in other areas of Australia.  相似文献   
36.
Single strains of 5 different P. haemolytica serotypes (1, 2, 5, 6 and 9) and an untypable strain were compared in an attempt to detect differences which might be related to virulence. All but the untypable strain caused extensive lesions when injected into the lungs of healthy cattle. Each strain was found to be encapsulated and to be toxic in vitro for bovine leukocytes. Each strain also produced leukotoxin in vitro. The toxins varied, however, in total toxic activity and in the kinetics of leukotoxin production. Vaccination of cattle with each of the serotype strains elicited antibodies to organism somatic antigens and, to various degrees, the production of leukotoxin-neutralizing antibodies which showed no strain specificity in cross-neutralization studies. Although each of the serotype strains appeared to be a potential bovine pathogen, subtle differences were observed which may explain the importance of Serotype 1 strains in bovine pneumonic pasteurellosis.  相似文献   
37.
The evolution of vaccines for bovine pneumonic pasteurellosis   总被引:4,自引:0,他引:4  
Since the early 1900s bovine pneumonic pasteurellosis has been recognised as a major economic problem to European and North American cattle industries. Initial attempts to prevent the disease were complicated by incomplete knowledge of the causative organisms. Despite some early reports of vaccine-induced protection against disease, initial vaccines were of questionable protective value. From the late 1950s to the 1970s Pasteurella haemolytica and P multocida bacterins were the primary type of vaccine used commercially and experimentally. When viruses, most notably bovine herpesvirus 1 (infectious bovine rhinotracheitis virus) and parainfluenza-3 virus, were found to be associated with bovine respiratory disease, viral vaccines were used in attempts to prevent pneumonic pasteurellosis. Combinations of bacterins and viral vaccines were also developed and evaluated. Collectively, bacterins, viral vaccines and bacterin-virus combinations did not consistently reduce disease in experimental trials or field use. By the 1980s some studies using live vaccines were reportedly successful in reducing the incidence of pneumonic pasteurellosis. Current experimental studies revolve around the identification and incorporation of specific Pasteurella species antigen extracts into vaccines. The efficacy of these new extract vaccines is yet to be determined.  相似文献   
38.
The immunoglobulins (IgG1, IgG2, IgM, and IgA) of the Brucella-specific antibody response of 69 crossbred beef heifers were studied after Brucella abortus strain 19 vaccination and strain 2308 challenge exposure. The immunoglobulin isotype responses in serum and vaginal mucus were measured by use of fluorescent immunoassay. Serum antibody responses were detected also by 3 standard serologic tests (complement fixation [CF], Rivanol precipitation, and the CARD test] and 2 primary bindings assays that detect IgG antibodies. One month after vaccination, mean antibody titers for all immunoglobulin isotypes were higher for vaccinated cattle (n = 46) than for nonvaccinated controls (n = 23). After vaccination, IgA antibody responses in vaccinated cattle were only 2-fold higher than those for controls, whereas IgG1, IgG2, and IgM antibody responses were 3- to 90-fold greater than those for controls. Measurement of IgA antibody responses classified 21 of 39 vaccinates as seropositive after vaccination, whereas the other isotypes classified 28 or 34 cattle as seropositive. Three months after challenge exposure, the mean antibody responses for each isotype were higher in cattle that aborted or were culture positive than in cattle that did not abort and were culture negative. Although IgG1, IgG2, and IgM antibody titers were each of benefit in identifying B abortus-infected cattle, it did not appear that the magnitude of the antibody responses provided sufficient discrimination between S19-vaccinated cattle and S2308 challenge-exposed cattle. Serum IgA antibody responses were 10-fold higher after challenge exposure than after vaccination and may be a response to mucosal infection with the virulent organism.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
39.
Leukotoxin activity from culture supernatants of Pasteurella haemolytica serotype 1 in logarithmic growth phase caused rapid (less than 5 min) release of intracellular K+, uptake of extracellular Ca2+, and swelling of cultured bovine lymphoma cells (BL3 cells). Release of 51CrO4(2-) and lactate dehydrogenase (LDH) from BL3 cells began after 15 minutes of incubation with leukotoxin at 37 C and was completed between 60 and 120 minutes of incubation. In addition, leukotoxin exposure of BL3 cells resulted in cell aggregation and adherence to glass surfaces. Scanning electron microscopy indicated that after 10 minutes of leukotoxin exposure, BL3 cells increased in size, and large membrane defects developed between 20 and 60 minutes of exposure. The rate of release of LDH from leukotoxin-exposed BL3 cells was proportional to the amount of leukotoxin added. At high cell concentrations, the activity of LDH released at completion was directly proportional to the amount of leukotoxin added. Leukotoxin-induced release of LDH required a divalent cation, whereas K+ release and cell swelling did not. The addition of Ca2+, Mn2+, and Ba2+ resulted in increased leukotoxin-induced release of LDH. Divalent cation concentrations of 0.5 to 2.5 mM resulted in 50% of maximal stimulation. Ethylene glycol-bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid blocked increased release of LDH caused by Ca2+ addition, but had no effect on K+ release or cell swelling. Leukotoxin action on BL3 cells (K+ release, cell swelling, Ca2+ uptake, and release of LDH) was prevented by incubation at 4 C.  相似文献   
40.
To determine whether antigenic differences exist in Pasteurella haemolytica serotype 1 grown in different culture conditions, the bacteria was grown on solid enriched medium, in broth culture, and in tissue chambers subcutaneously implanted in the flanks of calves. The organisms obtained by each culture method were comparable with respect to encapsulation and lipopolysaccharide content. In the bacteria grown in vivo, several unique high molecular-mass (greater than 150 kDa) protein antigens were found by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and protein immunoblotting. Bacteria grown in vitro had higher concentrations of a 49- and a 26-kDa protein than the organisms grown in vivo. The concentration of several major proteins (30, 42, 55, 71, and 100 kDa) were similar among the organisms grown by the three cultural conditions. Although the high molecular-mass antigens were unique for the chamber-grown bacteria, they were recognized by serum from a calf that had been vaccinated with formalin-killed, solid medium-grown P haemolytica and were resistant to challenge exposure with the live organism. This recognition of antigens by serum from the P haemolytica-resistant calf that had been vaccinated with solid-medium-grown bacterium, indicates that the high molecular-mass antigens from chamber-grown P haemolytica may be precursors of or share antigenic determinants with other P haemolytica proteins and may not be important for consideration in vaccine formulation.  相似文献   
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