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1.
Cyclooxygenase-2 (COX-2) was detected and localized in 15 pigs with naturally occurring pleuropneumonia using a 437-base pair digoxigenin-labeled cDNA probe in an in situ hybridization protocol. Histopathologic changes in the acute stage were characterized by coagulative necrosis of lung parenchyma, hemorrhage, vascular thrombosis, edema, fibrin deposition, and infiltration of lung parenchyma by neutrophils and alveolar macrophages in nine pigs. In chronic lesions, a thick layer of granulation tissue surrounded foci of pulmonary necrosis in six pigs. All 15 pigs infected with Actinobacillus pleuropneumoniae, confirmed by bacterial isolation, had distinct positive hybridization signals for COX-2 in bronchial, bronchiolar epithelial cells, alveolar macrophages, neutrophils, and type I pneumocytes. COX-2 expression was detected primarily in neutrophils from pigs with acute lesions and primarily in alveolar macrophages from pigs with chronic lesions. The results suggest that a prostanoid product of COX-2 is an important component of the inflammatory response to acute and chronic A. pleuropneumoniae infection.  相似文献   

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3.
Contact transmission of vesicular stomatitis virus New Jersey in pigs   总被引：4，自引：0，他引：4  
OBJECTIVE: To determine how viral shedding and development or lack of clinical disease relate to contact transmission of vesicular stomatitis virus New Jersey (VSV-NJ) in pigs and determine whether pigs infected by contact could infect other pigs by contact. ANIMALS: 63 pigs. PROCEDURE: Serologically naive pigs were housed in direct contact with pigs that were experimentally inoculated with VSV-NJ via ID inoculation of the apex of the snout, application to a scarified area of the oral mucosa, application to intact oral mucosa, or ID inoculation of the ear. In a second experiment, pigs infected with VSV-NJ by contact were moved and housed with additional naive pigs. Pigs were monitored and sampled daily for clinical disease and virus isolation and were serologically tested before and after infection or contact. RESULTS: Contact transmission developed only when vesicular lesions were evident. Transmission developed rapidly; contact pigs shed virus as early as 1 day after contact. In pens in which contact transmission was detected, 2 of 3 or 3 of 3 contact pigs were infected. CONCLUSIONS AND CLINICAL RELEVANCE: Transmission was lesion-dependent; however, vesicular lesions often were subtle with few or no clinical signs of infection. Contact transmission was efficient, with resulting infections ranging from subclinical (detected only by seroconversion) to clinical (development of vesicular lesions). Long-term maintenance of VSV-NJ via contact transmission alone appears unlikely. Pigs represent an efficient large-animal system for further study of VSV-NJ pathogenesis and transmission.  相似文献   

4.
Fourteen of 24 pigs were immunised with repeated injections of killed cultures of Leptospira serotype pomona administered over a three-week period. The remaining 10 pigs served as controls.

Five days after immunisation all pigs were exposed to the same natural infection by being housed together for 12 weeks in a pen which received effluent from other pens containing infected pigs.

Neither leptospiruria nor kidney lesions were detected in any of the immunised pigs. In contrast, leptospiruria and kidney lesions occurred in all the controls.

The development of serum agglutinins after immunisation and before exposure suggested that this could be used as an index of adequate antigenic stimulation.  相似文献   

5.
A cohort of 57 pigs in a farrow-to-finish swine herd with mild clinical mycoplasmal disease was followed to determine patterns of seroconversion to Mycoplasma hyopneumoniae (MH), detected with an enzyme-linked immunosorbent assay (ELISA). Survival analysis was used to evaluate the relationship between time to seroconversion and possible risk factors for MH infection (or enzootic pneumonia).

Pigs were housed in outdoor pens at approximately 9 weeks of age, when passively acquired MH antibodies had decayed. From 9 to 11 weeks of age and during a 5 week period, pigs were exposed by direct (nose-to-nose) or indirect contact to older seropositive gilts. Blood samples were collected from each pig at 3 week intervals until market age, when they were either slaughtered or selected for breeding. Antibody concentration was measured as the ratio of optical densities of the serum sample to the positive control (S/P). Based on the sample distribution of S/P ratios from pigs in an MH-free herd, pigs were considered positive when S/P ratios were greater than 0.34. At the beginning of the study, all pigs were seronegative to MH. Seroconversion was first detected after 21 days, and was most frequent about 11 weeks after exposure to older seropositive gilts. By the end of the study, 11 pigs (19%) had seroconverted, with S/P ratios ranging from 0.40 to 1.11. The presence of gross lung lesions showed a moderate to good agreement with ELISA results (K = 0.62). Histologic lesions were evident in virtually all slaughtered pigs, ranging from mild, non MH-specific lesions to severe lesions typical of MH infection. No secondary respiratory pathogens were isolated. Clinical signs were mild and there was no significant difference (P > 0.4) in weight gain between seropositive and seronegative pigs, or between pigs with and without lung lesions. A Cox regression model was fitted to the seroconversion data, and opportunity of contact (direct or indirect) was the only significant variable. After adjustment for breed and antibody S/P ratio prior to exposure, pigs in direct contact with seropositive gilts were seven times more likely to seroconvert than those in only indirect contact.  相似文献   


6.
Abattoir data collected from three British pig health monitoring schemes were combined to investigate the associations between Salmonella infection and the presence of gross lesions detected in slaughtered pigs. Each set of results was linked back to the farm from which the pigs were submitted, and the Salmonella results and lesions reports were connected at farm level. Salmonella infection was determined through meat juice ELISA (MJE), and the health conditions were assessed by postmortem inspection. The final dataset contained 873 slapmarks, with an average of 215 samples tested by MJE, and 355 pigs that were assessed for health conditions, per slapmark. Each of the health assessment conditions was individually analysed by regression models to investigate associations with the MJE results, accounting for clustering at the slapmark level and also for seasonality. A multivariable model was also used to estimate the strength of association with MJE results when all the health conditions were entered into the model. The results showed positive associations between Salmonella and enzootic pneumonia-like lesions, milk spots, peritonitis and pericarditis.  相似文献   

7.
A field trial was conducted to study Mycoplasma hyopneumoniae (Mh) infection dynamics by nested polymerase chain reaction (nPCR) and serology in pigs of a farm affected by enzootic pneumonia (EP). Moreover, correlation of Mh detection at different respiratory tract sites with presence of EP gross and microscopic lung lesions was assessed. These parameters were studied and compared between vaccinated (two doses at 1 and 3 weeks of age versus one dose at 6 weeks of age) and non-vaccinated pigs. Animals were monitored from birth to slaughter by nPCR from nasal swabs and by serology. From 3 to 22 weeks of age, an average of three pigs per treatment and per batch were necropsied (n = 302). The remaining pigs were sent to the slaughter (n = 103). Nasal, bronchial and tonsillar swabs were taken from the necropsied/slaughtered pigs; gross and microscopic EP-suggestive lung lesions were also assessed. Single and double vaccination resulted in earlier seroconversion and higher percentage of Mh seropositive pigs compared to control group. At slaughter, double vaccinated pigs showed lower percentage of EP-compatible gross lung lesions and lower Mh prevalence at upper respiratory tract sites (nasal cavity and tonsil) than control pigs.  相似文献   

8.
An outbreak of fibrinous pleuropneumonia was observed in October 1971 in Saskatchewan on a farm of 900 feeder pigs. Morbidity and mortality were low. Pathologic-anatomic findings included fibrinous pleuritis, pulmonary vascular thrombosis and necrotizing fibrinous pneumonia. Hemophilus parahemolyticus was isolated from the lungs of affected animals. In addition pulmonary lesions were found which suggested an adenovirus infection. It was speculated that the viral infection possibly predisposed the pigs to the Hemophilus infection. The H. parahemolyticus isolate was sensitive to common antibiotics.  相似文献   

9.
The purpose of the study was to investigate the prevalence of gastric lesions and to provide diagnostic values for serum pepsinogen in non-infected pigs and in pigs with gastric disease. In an abattoir survey, the pepsinogen concentrations were measured in the serum from 62 non-infected pigs, 33 pigs with gastric lesions and 17 pigs infected with Hyostrongylus rubidus, using a specific radioimmunoassay (RIA). The mean (±SE) pepsinogen concentrations in the serum of non-infected pigs, in pigs with gastric ulcers, and in pigs with a heavy H. rubidus infection were 630.8±39.2 ng/ml, 1084.5±166.2 ng/ml and 1095.2±102.3 ng/ml, respectively (p<0.05). Because of the higher concentrations of pepsinogen in the blood of pigs with gastric ulcers or parasitic infections, it is suggested that the measurement of serum pepsinogen by RIA may be an effective biochemical approach to the diagnosis of chronic gastric disorders in pigs.  相似文献   

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11.
Forty gnotobiotic pigs from six litters were exposed orally to Escherichia coli 083:K·:NM at 69 to 148 hours of age, while 17 pigs from the same litters served as unexposed controls. Clinical signs of infection included fever, anorexia, diarrhea, lameness, and reluctance to move.

Eighty-four percent of the exposed pigs in four litters died, while only 13% in two litters died. Gross and microscopic lesions included serofibrinous to fibrinopurulent polyserositis in 96% of the exposed pigs in four litters and 33% of the exposed pigs in two litters. A few pigs had gross and/or microscopic lesions of arthritis. Escherichia coli was routinely isolated from the serous and synovial cavities of infected pigs.

Anti-hog cholera serum administered orally as a colostrum substitute gave partial protection against E. coli infection.

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12.
Pigs exposed to swine vesicular disease virus developed vesicular lesions by postinoculation day 2. Lesions first appeared on the coronary band and then on the dewclaw, tongue, snout, lips, and bulbs of the heels. The onset of viremia coincided with febrile response and the appearance of vesicles. Virus was isolated from the nasal discharge, esophageal-pharyngeal fluid, and feces as early as postinoculation day 1. Greater amounts of virus were isolated from samples collected during the first week of infection, and lesser amounts from samples collected during the second week. The appearance and the distribution of specific fluorescence in various tissues indicated that during the development of swine vesicular disease virus infection, the epithelial tissues were initially involved, followed by a generalized infection of lymph tissues, and subsequently, a primary viremia. Seroconversion was detectable as early as postinoculation day 4. A mild nonsuppurative meningoencephalomyelitis throughout the CNS was observed in both inoculated and contact-exposed pigs. The olfactory bulbs were most severely and were frequently affected, particularly in contact pigs. The most severe brain lesions were found in pigs 3 to 4 days after the onset of viremia; contact pigs showed more severe brain lesions than inoculated pigs. Microscopic changes were also found in the coronary band, snout, tongue, and heart.  相似文献   

13.
The aim of the study was to determine the presence of swine hepatitis E virus (HEV) RNA and antibodies in postweaning multisystemic wasting syndrome-affected (n=114) and non-affected (n=46) pigs and the possible association with hepatitis lesions. Forty-four pigs were RT-PCR positive (28.2%); 25 of them were PMWS cases, while 19 were non-PMWS pigs. In both groups, HEV RT-PCR results were associated with hepatitis (OR=5.61 for PMWS-affected pigs and OR=5.17 for non-PMWS affected pigs; p=0.01). No interaction was detected in a logistic regression between PMWS occurrence and HEV infection for the development of hepatitis lesions. Seropositivity to HEV was more likely to occur in pigs with hepatitis (51.9%) compared to pigs without hepatitis (36.1%; p=0.03). Significant differences in optical densities were notices comparing the lesional stage of pigs (p=0.009). While pigs with slight or moderate hepatitis were seropositive, pigs with more severe lesions were seronegative to HEV. These results indicate that swine HEV infection can be a significant contributor to the development of moderate hepatitis in pigs regardless of the PMWS status.  相似文献   

14.
Dual infection of pigs with swine influenza virus (SIV) and Mycoplasma hyopneumoniae was carried out to compare the clinical and pathological effects of dual infection in caesarian derived and colostrums deprived (CDCD) pigs, with that of a single infection with M. hyopneumoniae. In Experiment 1, 40-day-old CDCD pigs were inoculated only with SIV (A/Sw/Hok/2/81, H1N1). The virus was isolated from nasal swabs for 5-6 days. None of these pigs showed clinical signs of infection throughout the experimental period. These results suggested that this strain can infect pigs but is only slightly pathogenic when it is inoculated singly to a CDCD pig. In Experiment 2, 60-day-old CDCD pigs were inoculated with M. hyopneumoniae and then were inoculated with SIV (A/Sw/Hok/2/81) at 1 week (MHYO-7d-SIV-7d group) or 3 weeks (MHYO-21d-SIV-7d group) after M. hyopneumoniae inoculation. Macroscopically, dark red-to-purple lung lesions were observed in all of pigs at 14 or 28 days post-inoculation. Percentages of dark red-to-purple lung lesions in dual infection groups (MHYO-7d-SIV-7d group: 18.7 +/- 4.2%, MHYO-21d-SIV-7d group: 23.0 +/- 8.0%) were significantly (P < 0.05) increased compared to those of each control group in which pigs were inoculated only with M. hyopneumoniae (MHYO-14d group: 4.7 +/- 2.9%, MHYO-28 group: 3.3 +/- 2.4%). Microscopically, bronchial epithelial lesions (epithelial disruption, degeneration, hyperplasia and formation of microabscess) were frequently observed in dark red-to-purple lung lesions of only the dual infection groups. These results demonstrate that the lung lesion of pigs inoculated with M. hyopneumoniae and SIV is more severe than that of pigs inoculated only with M. hyopneumoniae.  相似文献   

15.
Porcine enteroviruses were isolated from weaner pigs that had nervous signs and mild non-suppurative meningoencephalomyelitis and ganglioneuritis. The clinical signs and lesions were not typical of enterovirus infection and it is believed that an organic arsenical present in feed enhanced pathogenicity of enteroviruses. Severe non-suppurative polioencephalomyelitis and ganglioneuritis were produced in gnotobiotic pigs by oral inoculation of the viruses.  相似文献   

16.
A total of 100 liver samples from pigs with postweaning multisystemic wasting syndrome (PMWS) were studied. All livers were evaluated microscopically and were staged based on the severity and localization of lesions. Presence of porcine circovirus type 2 (PCV-2) was evaluated using an in situ hybridization technique. Eighty-eight of 100 livers (88%) had a variable degree of lymphohistiocytic hepatitis, with apoptotic bodies, disorganization of hepatic plates, and/or perilobular fibrosis. Twelve pigs did not have microscopic liver lesions. Four stages of hepatic damage were established based on intensity and distribution of the lesions. Viral nucleic acid was detected in 70 of 100 livers (70%). Target cells for PCV-2 infection included Kupffer cells, hepatocytes, and inflammatory infiltrates. According to distribution of PCV-2 nucleic acid, four basic labeling patterns were identified. This study shows that liver damage is a frequent microscopic finding in cases of PMWS and hepatocytes are a target cell for PCV-2 infection and replication. Therefore, PCV-2 should be considered a new hepatitis-inducing viral agent in pigs.  相似文献   

17.
In a survey of 2500 market weight pigs in a Saskatchewan abattoir, 37% were infected with adult Ascaris suum and in 46% there were milkspot hepatic lesions. A total of 60% of the pigs examined had some evidence of A. suum infection. Most infected pigs contained less than 50 adult ascarids.

In a second abattoir survey of a further 2500 market weight pigs, 44% of the animals had milk-spot hepatic lesions. In approximately 12% of the affected pigs these lesions were very severe and a very similar proportion of pigs' livers were condemned or sent for use as animal feed.

The results of these surveys are discussed with particular reference to the significance of A. suum infection in growing pigs in Saskatchewan.

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18.
The prevalence of gastric Helicobacter infection in finishing pigs and the influence of this infection on gastric lesions was studied. Stomachs of 89 finishing pigs from 27 randomly selected herds were sampled at the slaughterhouse. Forty cases (Group A) were selected based upon the presence of gross pathological lesions in the pars oesophagea, and further 49 cases were obtained at random (Group B). Three samples of gastric tissue (junction of pars oesophagea and pars cardiaca, fundic area, and pyloric area) were collected from each stomach for histological and immunohistochemical examination. Helicobacter antigen was detected in 76 cases (85.4%). No association was found between the presence of Helicobacter in the stomach and the occurrence of gross pathological lesions in the pars oesophagea or gastritis detected on histological examination. However, a significant association was found between the occurrence of Helicobacter in the pyloric area and the presence of erosions/ulcers in the pars oesophagea (OR: 7.01, p = 0.022) in Group B. A significant association was also evident between the presence of Helicobacter and glandular lesions (dilatation of the glands + glandular abscess + degeneration of glandular epithelial cells). In conclusion, Helicobacter infection seems to be a contributing factor to pathological changes in the stomach of finishing pigs.  相似文献   

19.
A commercially manufactured leptospirosis vaccine containing serovars pomona and hardjo and licensed for use in cattle and sheep was investigated to determine if it would prevent leptospiruria in pigs exposed to serovar pomona. Twenty piglets were each vaccinated twice at an interval of three weeks. Twenty other piglets were unvaccinated and served as controls. Three weeks after the second dose of vaccine all animals were exposed for 64 to 89 days to a natural infection with pomona. During the investigation blood samples were examined serologically and urine samples were examined by dark ground microscopy and cultured for the presence of leptospirae. Attempts were made to culture leptospirae from kidneys at slaughter. Kidneys were also examined histologically for evidence of leptospira infection. One vaccinated animal developed a respiratory disease. It was treated with antibiotics and removed from the trial. Leptosphuria was demonstrated in six of the remaining 19 vaccinated pigs and leptospirae were found in nine of 578 (1.5%) urine samples examined from these animals during the period of exposure. In contrast leptospiruria occurred in 19 of 20 unvaccinated pigs and leptospirae were found in 253 of 642 (39.4%) urine samples examined from these animals. Histopathological lesions consistent with leptospirosis were found in kidneys examined from two of 16 vaccinates and 17 of 18 non-vaccinates. Antibodies to serovar pomona were detected in 12 of 19 vaccinated pigs examined three weeks after the second dose of vaccine and before exposure to infection, and in all of 18 unvaccinated pigs examined after exposure to infection. It was concluded that use of this vaccine in pigs resulted in a significant degree of protection against leptospiruria.  相似文献   

20.
OBJECTIVE: To examine effects of co-infection with porcine reproductive and respiratory syndrome virus (PRRSV) and Bordetella bronchiseptica in pigs. ANIMALS: Forty 3-week-old pigs. Procedure-30 pigs (10 pigs/group) were inoculated with PRRSV, B bronchiseptica, or both. Ten noninoculated pigs were control animals. RESULTS: Clinical signs, febrile response, and decreased weight gain were most severe in the group inoculated with both organisms. The PRRSV was isolated from all pigs in both groups inoculated with virus. All pigs in both groups that received PRRSV had gross and microscopic lesions consistent with interstitial pneumonia. Bordetella bronchiseptica was cultured from all pigs in both groups inoculated with that bacterium. Colonization of anatomic sites by B bronchiseptica was comparable between both groups. Pigs in the group that received only B bronchiseptica lacked gross or microscopic lung lesions, and B bronchiseptica was not isolated from lung tissue. In the group inoculated with B bronchiseptica and PRRSV, 3 of 5 pigs 10 days after inoculation and 5 of 5 pigs 21 days after inoculation had gross and microscopic lesions consistent with bacterial bronchopneumonia, and B bronchiseptica was isolated from the lungs of 7 of those 10 pigs. CONCLUSIONS AND CLINICAL RELEVANCE: Clinical disease was exacerbated in co-infected pigs, including an increased febrile response, decreased weight gain, and B bronchiseptica-induced pneumonia. Bordetella bronchiseptica and PRRSV may circulate in a herd and cause subclinical infections. Therefore, co-infection with these organisms may cause clinical respiratory tract disease and leave pigs more susceptible to subsequent infection with opportunistic bacteria.  相似文献   

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