Evaluation of lung function in pigs either experimentally or naturally infected with Chlamydiaceae

This study evaluated the influence of chlamydial infections on lung function in conventionally raised pigs. Eight pigs aged 39-44 days were included in an aerogeneous challenge model (4 were exposed to Chlamydia suis; 4 served as controls). Nineteen pigs aged 5-27 weeks without clinical symptoms (but partly PCR-positive for chlamydial species) were examined over 6 months. For lung function testing, impulse oscillometry was used. In total, all 27 pigs underwent 465 lung function tests. Variables of ventilation (respiratory rate, tidal volume, minute volume), respiratory impedance (expressed as resistance and reactance within the frequency range 3-15 Hz), and model derived resistance of proximal and distal airways were measured. Experimental exposure to C. suis significantly affected lung function. Early distal airway obstruction (3-5 days after infection) was followed by an obstruction of proximal airways (7 days after infection). The breathing pattern was significantly changed (decreased tidal volume; increased respiratory rate). In symptom-free pigs having a naturally acquired presence of different chlamydial species in the respiratory system, no deterioration in lung function could be determined up to the age of 6 months. In conclusion, the consequences of respiratory chlamydial infections appear to vary from clinical inapparence to severe respiratory distress.     

Evaluation of lung function in pigs either experimentally or naturally infected with Chlamydiaceae

This study evaluated the influence of chlamydial infections on lung function in conventionally raised pigs. Eight pigs aged 39–44 days were included in an aerogeneous challenge model (4 were exposed to Chlamydia suis; 4 served as controls). Nineteen pigs aged 5–27 weeks without clinical symptoms (but partly PCR-positive for chlamydial species) were examined over 6 months. For lung function testing, impulse oscillometry was used. In total, all 27 pigs underwent 465 lung function tests. Variables of ventilation (respiratory rate, tidal volume, minute volume), respiratory impedance (expressed as resistance and reactance within the frequency range 3–15 Hz), and model derived resistance of proximal and distal airways were measured. Experimental exposure to C. suis significantly affected lung function. Early distal airway obstruction (3–5 days after infection) was followed by an obstruction of proximal airways (7 days after infection). The breathing pattern was significantly changed (decreased tidal volume; increased respiratory rate). In symptom-free pigs having a naturally acquired presence of different chlamydial species in the respiratory system, no deterioration in lung function could be determined up to the age of 6 months. In conclusion, the consequences of respiratory chlamydial infections appear to vary from clinical inapparence to severe respiratory distress.     

Non-infectious factors associated with macroscopic and microscopic lung lesions in slaughter pigs from farrow-to-finish herds

A cross-sectional epidemiological study was conducted in 150 randomly selected farrow-to-finish herds to investigate which non-infectious factors might act as risk indicators for the prevalence and severity of macroscopic and microscopic lung lesions in slaughter pigs. Data were collected during herd visits through inspections of the pigs and through interviews with the farmers. Macroscopic lung lesions of pneumonia and pleuritis were recorded at slaughter from 25 pigs per herd, and microscopic lung lesions of lymphohistiocytic infiltration were recorded from 10 pigs per herd. The median herd level prevalences were 24 per cent for pneumonia, 16 per cent for pleuritis and 60 per cent for lymphohistiocytic infiltration. Pneumonia lesions were negatively associated with pleuritis lesions and positively associated with lymphohistiocytic infiltration. Pleuritis lesions were negatively associated with lymphohistiocytic infiltration. The prevalence and the severity of pneumonia lesions were increased by a high frequency of purchasing gilts and by a slaughter date in January to February. The presence of a growing unit also increased the severity of pneumonia. The prevalence and the severity of pleuritis lesions were higher when there were more pig herds in the municipality, and when there were poor biosecurity measures, and their prevalence was increased by a slaughter date in January to February, and their severity by a slaughter date in March to April. An increase in the airspace stocking density in the finishing unit also increased the prevalence of pleuritis. The prevalence and the severity of lymphohistiocytic infiltration in the lung tissue were higher in herds purchasing gilts. Pigs raised in pens with slatted floors were also at higher risk of more severe lesions of lymphohistiocytic infiltration.     

Bacteriologic studies of the occurrence of Chlamydia psittaci in organs of swine and in aborted swine fetuses

By inoculation of embryonating chicken eggs via the yolk sac route Chlamydia psittaci was grown from 11 lungs of 45 pigs with pneumonia (24.4%). From the lungs of 55 pigs with other diseases the organism was isolated in five cases (9.1%). Chlamydiae were not detectable by cultural methods in the uterine mucosa of 87 sows, arthritic joints of 30 store pigs and in aborted fetuses. A commercial available enzyme amplified immunoassay indicated the presence of chlamydial antigen in mucosal scrapings from the uterus of two sows and in the fetal membranes as well as fetal organs in one case of porcine abortion.     

An experimentally induced Chlamydia suis infection in pigs results in severe lung function disorders and pulmonary inflammation

This study was aimed at evaluating the pathophysiology of pulmonary dysfunctions and inflammatory consequences of an acute respiratory chlamydial infection induced experimentally in conventionally raised pigs (aged 39-44 days). Eight animals were exposed to Chlamydia suis (C. suis) and four non-infected animals served as controls. The total observation period was from seven days before challenge to seven days post exposure. While non-infected control pigs did not exhibit any clinical symptoms, animals exposed to C. suis developed fever and were severely respiratory distressed within the first week after exposure. After C. suis infection, pulmonary dysfunctions were characterised by a significant decrease in the diffusion capacity of the lung (i.e. transfer factor of the lung for carbon monoxide; TL CO), a significant increase in the functional residual capacity (FRC), and significant changes in the pattern of ventilation (respiratory rate increased while the tidal volume decreased). In exhaled breath condensate (EBC), leukotriene B(4) (LTB(4)) and interleukin 6 (IL-6) showed a tendency to increase after infection. In the broncho-alveolar lavage fluid (BALF) of C. suis infected pigs, the activity of matrix metalloprotease 9 (MMP-9) was found to be increased compared to controls. BALF cytology was characterised by increased numbers of granulocytes and activated lymphocytes. Pulmonary inflammation in infected pigs was confirmed by post mortem histology. A prominent dissemination of chlamydial bodies in the lung was accompanied by an influx of macrophages, granulocytes and activated T-cells. Data obtained in this study provide new insight into the pathogenesis of acute respiratory chlamydial infections in pigs.     

Evaluation of tulathromycin for the treatment of pneumonia following experimental infection of swine with Mycoplasma hyopneumoniae

Tulathromycin was evaluated in the treatment of pneumonia in weaned pigs inoculated intranasally with Mycoplasma hyopneumoniae. Five days postchallenge, the pigs were randomized to treatment with a single IM administration of saline, a single IM administration of tulathromycin (2.5 mg/kg; day 0), or three IM administrations of enrofloxacin (5.0 mg/kg; days 0, 1, 2). Pigs were necropsied on day 12 or 13. Unchallenged controls remained healthy with no lung pathology. Compared with saline, coughing, mean lung lesion score, and proportional lung weight were significantly reduced and weight gain was significantly greater for tulathromycin-treated pigs (P < .05). Compared with enrofloxacin, there were no significant differences in proportional lung weight or weight gains, but coughing and lung lesion scores were greater for tulathromycin-treated pigs (P < .05). Tulathromycin was effective in the treatment of pneumonia following experimental infection with M. hyopneumoniae.     

Immunity to chlamydial infections in mice—I. Establishment of quantitative techniques

Some methods for quantitative measurement of immunity to chlamydial pneumonia in laboratory mice were evaluated. Death, and histopathological grading of lung changes were quantifiable responses, but lung impression smears stained for chlamydia were not     

IL‐12p40 gene expression in lung and hilar lymph nodes of MPS‐resistant pigs

Mycoplasma pneumonia of swine (MPS) is caused by Mycoplasma hyopneumoniae (M.hp) and is a common chronic respiratory disease of pigs. Recently, a genetically selected variant of the Landrace pig (Miyagino L2) has a lower incidence of pulmonary MPS lesions. We investigated the pathological and immunological characteristics of MPS resistance in these pigs (n = 24) by comparing with the normal landrace pig (control: n = 24). The pathological MPS lung lesion score in MPS‐selected landrace pigs was significantly lower than in the control. The gene expression of interleukin (IL)‐12p40, which acts as a chemoattractant and a component of the bioactive cytokines IL‐12 and IL‐23, was significantly higher at the hilar lymph nodes, lung, and spleen in MPS‐selected landrace pigs than in control landrace pigs, and these were negatively correlated with the macroscopic MPS lung lesion score. In summary, we demonstrate that resistance against MPS in Miyagino L2 pigs is associated with IL‐12p40 up‐regulation, in comparison with normal landrace pigs without the MPS vaccine. In addition, a comparative study of macroscopic MPS lung lesions and IL‐12p40 gene expression in lung and hilar lymph nodes may lead to beneficial selection traits for the genetic selection for MPS resistance in pigs.     

Bronchoalveolar lavage for the diagnosis and treatment of pneumonia associated with transport in Thoroughbred racehorses.

To evaluate a hypothese that use of bronchoalveolar lavage (BAL) for early treatment of pneumonia would improve their prognosis by reducing bacterial numbers and excessive numbers of neutrophils in the lung, initial experiences with BAL in the diagnosis and treatment of pneumonia were performed in 36 racehorses that became ill within 24 hr of long distance travel (1,200-1,600 km, 26-32 hr) by road. Comparisons were made of the outcomes of the 36 horses and those of 42 horses (81.0% recovered, 50.0% returned to racing) treated for transport associated pneumonia without BAL. The total amount of BAL fluid injected during hospitalization varied from 700 to 3,700 ml and the duration of antibiotic treatments ranged from 5 to 40 days. Clinical symptoms after lavages showed good results with no side effects. None of the horses required thoracic drainage. Horses treated with BAL required shorter period of antibiotic therapy, a greater percentage recovered (100%, 36/36) and a greater percentage returned to racing (77.8%, 28/36). Eight (22.2%) never raced because of lameness or other considerations.     

Performance measured in pigs with pneumonia and housed in different environments

During an investigation of poor growth performance, rate of weight gain and feed efficiency were studied in pigs with pneumonia. During the study, pigs either were housed in an improved environment or remained at their home farm. In both environments, rate of gain tended to decrease in association with increasing severity of pneumonia. When pigs with similar extent of lung lesions were compared, growth performance of pigs housed in the improved environment was better than that of pigs on the home farm. However, growth performance of pigs with pneumonia affecting greater than 20% of lung tissue was equally poor in either environment. When type of housing and extent of pneumonia were included in a model for analysis of variance, housing had a highly significant (P = 0.003) effect on rate of gain, and pneumonia had a nonsignificant effect.     

Pasteurella multocida and Bordetella bronchiseptica in atrophic rhinitis and pneumonia in swine.

A total of 163 pigs from nine farrow-to-finish herds representing various levels of atrophic rhinitis (AR) were selected for postslaughter examination of AR and pneumonia. Nasal swabs and lungs were cultured for detection of Bordetella bronchiseptica and Pasteurella multocida. Seventy-three pigs were examined at eight weeks of age and 90 contemporaries at six months of age. Mean AR scores were 1.21 and 1.11 for the eight week and six month old pigs, respectively (0 = normal, 3 = severe). In individual pigs increasing AR score was related to increasing pneumonia score in eight week old pigs but not in six month old hogs. In eight week old pigs, B. bronchiseptica and P. multocida were isolated more frequently from pigs with higher AR scores. From nasal swabs of six month old hogs, Bordetella was almost never recovered while Pasteurella was frequently isolated score. Toxigenic type DP. multocida was isolated from nasal cultures of only seven (4%) pigs and from lung cultures of only one pig. Pasteurella was never isolated from lungs of the eight week old pigs and Bordetella never from the six month old hogs. The isolation rate of P. multocida, predominantly type A, from lungs of six month old pigs increased from 11% in grossly normal lungs to 86% in lungs with severe pneumonia. Pigs from one herd free from lesions of AR and pneumonia were also examined; type AP. multocida was isolated from nasal cultures of one of six eight week old pigs. Somatic antigens of P. multocida were determined for 94 nasal and 20 lung isolates. Somatic serovar 3 was found in 93% of the nasal isolates and in all lung isolates.(ABSTRACT TRUNCATED AT 250 WORDS)     

种猪场猪支原体肺炎（气喘病）控制与净经技术研究

在一个气喘病流行已有数年的种猪场，结合种猪选育，实施了以免疫、消毒、隔离、淘汰并加速更换种猪建立和新种猪群等为主要技术措施的猪气喘病控制和净化技术后，取得了显著效果，气喘病临床病猪已经少见，肺部有气喘病病变的猪也从试验初期的１０．９％下降至后期的３％左右，仔猪活率和生长速度显著提高。     

Effects of intranasal inoculation of porcine reproductive and respiratory syndrome virus, Bordetella bronchiseptica, or a combination of both organisms in pigs

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.     

Pulmonary botryomycosis in a Scottish highland steer.

Pertinent necropsy findings in a 5 1/2-year-old Scottish Highland steer with chronic intractable pneumonia and cough were limited to the pulmonary system. The accessory lobe of the lung was collapsed, scarred, and multifocally adhered to parietal pleura. A polypoid mass almost completely obstructed the lobar bronchus and protruded into the trachea; mucopurulent exudate distended more distal bronchi. Botryomycosis was diagnosed when histologic examination revealed pyogranulomatous pneumonia with eosinophilic granules and "club" formation surrounding colonies of gram-positive cocci. Staphylococcus aureus was cultured from the lung. Botryomycosis is an unusual response to infection with common bacteria and is characterized by pyogranulomatous inflammation with formation of eosinophilic granules surrounding colonies of gram-positive cocci or gram-negative bacilli. Among domestic species, staphylococcal botryomycosis is most common as a wound infection in horses or as mastitis in cows and sows. Pulmonary botryomycosis is rare in horses, humans, and guinea pigs and apparently has not been reported in cattle.     

Chronological study of Mycoplasma hyopneumoniae infection, seroconversion and associated lung lesions in vaccinated and non-vaccinated pigs

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.     

Mycoplasma hyopneumoniae increases the susceptibility of pigs to experimental Pasteurella multocida pneumonia.

The interaction between Mycoplasma hyopneumoniae and Pasteurella multocida in experimental pneumonia was investigated in conventional pigs. The experimental animals were 49 days old when inoculated with M. hyopneumoniae; they were inoculated with P. multocida after 23 days, and killed 13 days later. In pigs inoculated only with P. multocida, clinical signs and lung lesions were not observed, and the agent was not recovered. Pigs inoculated with M. hyopneumoniae developed fever, moderate cough and dyspnea which tended to disappear, and small proliferative lung lesions from which M. hyopneumoniae was isolated. Pigs inoculated with both agents had higher fever, severe cough and dyspnea which tended to aggravate, and extensive exudative lung lesions from which organisms were isolated. All animals had similar growth rates, but the group infected with both agents consumed 60% more food. Therefore, M. hyopneumoniae causes mild pneumonia, whereas P. multocida is not pathogenic alone but aggravates the pneumonia initiated by M. hyopneumoniae.     

Association of growth performance with atrophic rhinitis and pneumonia detected at slaughter in a conventional pig herd in Hungary

The influence of atrophic rhinitis (AR) and pneumonia on growth performance was assessed in a conventional farrow-to-finish pig farm affected by both diseases. All tested pigs (n = 138) were individually weighed at birth, at weaning, at moving to the growing/finishing unit, and at slaughtering. The extent (grade) of turbinate atrophy and lung consolidation attributable to pneumonia was determined in each pig at slaughter. A negative correlation was found between birth weight and the prevalence of nasal lesions at slaughter, suggesting that pigs born with smaller weight may be more susceptible to AR. The growth performance of the pigs also showed a negative correlation with the degree of turbinate atrophy. In the nursery period, the average daily gain (ADG) of pigs with moderate/severe turbinate atrophy was 13.3% lower than that of animals with healthy snouts. In the finishing period, pigs with mild AR lesions had an ADG reduction of 6.2%, while pigs with severe AR lesions had a significant, 9.4% reduction in ADG as compared to the AR-free pigs. The extent of weight gain reduction over the whole life cycle was very similar (approximately 6%) in the pigs having either AR or pneumonia alone. In those pigs where both respiratory diseases were present, their effects seemed to be added up (11.5%); however, nasal lesion scores and percentage of lung consolidation did not show statistically apparent interactive effects on growth performance.     

In situ detection of apoptosis in regressing corpus luteum of pregnant sow: Evidence of an early presence of DNA fragmentation

Luteolysis has been shown to be correlated with apoptosis in rats, sheep, and cows. In pigs, apoptosis has already been demonstrated as regards atretic follicles. The present study has been conducted to evaluate whether apoptosis occurs during corpora lutea regression in the pregnant pig and to investigate the temporal relationship between apoptosis and functional luteolysis. The apoptotic process has been studied through the research of oligonucleosome fragmentation by means of classical electrophoresis methods and by in situ detection on histological luteal sections. The latter method allows the identification of apoptosis and the localization of apoptotic cells. Pregnant sows were cloprostenol (PGF_2α analog) treated and ovariectomized 0, 6, 12, 24, 48, and 72 hr after treatment. Corpora lutea were utilized for progesterone and DNA extraction and in situ evaluation of apoptosis. Clear evidence of apoptosis was seen earlier with the in situ technique (6 hr for stromal tissue, 12 hr for luteal cells) than with the classical method (24 hr). Apoptosis was, however, apparent after plasma and tissue progesterone had reached basal levels. In conclusion, these results are consistent with the hypothesis that apoptosis occurs during luteolysis in pigs. Moreover, the data obtained with the in situ technique made it possible to identify signs of structural regression in stromal tissue first than in parenchymal cells. A two-stage activation of apoptosis has been discussed to explain structural changes that occur during luteolysis after cloprostenol treatment in swine corpora lutea.     

Efficacy of in-feed medication with tylosin for the treatment and control of Mycoplasma hyopneumoniae infections

The efficacy of in-feed medication with tylosin for the treatment of enzootic pneumonia was examined in an experimental Mycoplasma hyopneumoniae infection model. One group of 10 conventional M. hyopneumoniae-free pigs was inoculated intratracheally with a highly virulent field isolate of M. hyopneumoniae; a second group of 10 pigs was inoculated in the same way and after 12 days was given tylosin at 100 mg/kg feed for 21 days; a third group of 10 pigs was inoculated with sterile culture medium, and these pigs were not given tylosin. The pigs were examined daily for clinical signs and each pig was given a respiratory disease score. Thirty-three days after they had been infected the pigs were euthanased, the lung lesions were quantified and samples of lung were processed for immunofluorescence testing for M. hyopneumoniae. The mean (sd) respiratory disease and lung lesion scores were significantly higher (P<0.05) in both the infected groups than in the uninfected group. Between 23 and 33 days after infection the mean respiratory disease score of the pigs treated with tylosin was 0.54 (0.22), significantly (P<0.05) lower than that of the infected pigs which were left untreated, 1.54 (0.46); similarly, their average lung lesion score, 1.72 (1.20), was significantly lower than that of the untreated pigs, 5.27 (3.85).     

Conjunctivitis caused by a swine Chlamydia trachomatis-like organism in gnotobiotic pigs.

The objective of this study was to determine whether a chlamydial strain recovered from growing and finishing swine with conjunctivitis or keratoconjunctivitis could cause the same infections in gnotobiotic pigs. The strain shares biological characteristics with Chlamydia trachomatis. After propagation in Vero cells and preparation of the inoculum (10(7) inclusion-forming units/ml), chlamydial strain H7 was instilled into the ventral conjunctival sac (0.15 ml/sac) of 12 anesthetized 3-day-old gnotobiotic piglets. Four age-matched gnotobiotic piglets were anesthetized and sham infected with uninfected cell culture lysates. None of the principal piglets developed clinical symptoms of conjunctivitis or keratoconjunctivitis. Principal piglets necropsied 7 days postinfection (DPI) had histologic lesions of mild or moderate conjunctivitis; immunohistochemical evaluation revealed chlamydial antigen in conjunctival epithelium. A majority of principal piglets necropsied at 14-28 DPI had histologic lesions of mild conjunctivitis, but chlamydial antigen was not detected by immunohistochemistry. The results indicated that chlamydial strain H7 can cause mild or occasionally moderate conjunctivitis in gnotobiotic pigs, but the conjunctival infection is asymptomatic.