Pulmonary and hematologic changes in swine with Mycoplasma hyopneumoniae pneumonia.

Studies were made of the physiologic changes in the lung of young growing pigs intratracheally inoculated at 5.5 to 6 weeks of age with Mycoplasma hyopneumoniae. Hematologic changes also were studied. Studies were performed at the 4th, 5th, and 6th weeks after inoculations were done. The inoculated pigs had a marked decrease in body weight gain. There were no significant changes in the heart rate, respiratory rate, and rectal temperature, even though at necropsy the apical, cardiac, and diaphragmatic lobes of the lungs of inoculated pigs had scattered, but well-demarcated, pneumonic lesions. The lungs were edematous and increased in weight, compared with those of control (noninoculated) pigs. There were several changes in respiratory functions in the inoculated animals, including significant increases in esophageal pressure negativity, expiratory flow rate, tidal and minute volumes, and work of breathing and significantly less oxygen consumption. Inspiratory flow rate and airway resistance were markedly increased. The elasticity of infected lungs was reduced, as shown by notable decreases of dynamic lung compliance. According to blood gas analyses, acid-base balance had changed in the inoculated pigs. Arterial blood pH, arterial partial pressures of O2 and CO2, and arterial concentration of HCO3- decreased. To some degree respiratory acidosis indicated by a significant decrease of base excess was evident in the blood of inoculated pigs. As a result, inoculated animals required hyperventilation (compensatory respiratory alkalosis) to maintain the pH of arterial blood near a physiologically normal value. The pigs with mycoplasmal pneumonia showed no drastic hematologic changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of a microtitration complement-fixation test and a tube latex agglutination test for diagnosis of Mycoplasma hyopneumoniae swine pneumonia.

Comparison of a tube latex agglutination (LA) test and a microtitration complement-fixation (CF) test for the diagnosis of Mycoplasma hyopneumoniae swine pneumonia was done. In a group of 107 pigs from Iowa, Texas, and California (survey A), correlation of data on microscopic pulmonary changes with the LA and CF titers indicated the LA test might be a better indicator of microscopic lesions than the CF test. In another field study involving lungs from 50 pigs from various herds (survey B), both LA and CF test results predicted gross lesions at a 0.01 significance level, using chi-square analysis. Data from 3 Nebraska swine herds (survey C) indicated good correlation of gross and microscopic pulmonic lesions with CF and LA test results in 2 of the 3 herds. In the 3rd herd, results of the CF test failed to agree with either gross and microscopic pulmonic lesions or culture results, whereas LA test results closely correlated with these variables. Chi-square analysis at 0.5 significance level of 106 pigs from 5 Iowa specific-pathogen-free herds (survey D) indicated a correlation of CF and LA test results with the microscopic pulmonic changes of penmates.

Parenteral vaccination of young swine against Bordetella bronchiseptica.

The efficacy of Bordetella bronchiseptica bacterins for the prevention of nasal turbinate atrophy caused by induced B bronchiseptica infection in young swine was evaluated. Vaccination of pigs at an early age (eg, at 1 and 4 weeks of age) with potent B bronchiseptica strain D-1 bacterins resulted in high concentrations of circulating antibody up to 12 weeks of age or longer and in a significant (P less than 0.01) reduction in the frequency of turbinate atrophy.

Efficacy of Bordetella bronchiseptica bacterin in controlling enzootic atrophic rhinitis in swine.

The efficacy of a Bordetella bronchiseptica bacterin was evaluated in 2 commercial swine herds affected with mild and severe enzootic atrophic rhinitis (AR). In the 1st herd study, (mild AR), the degree of clinical AR, nasal turbinate evaluation, blood serum titer to B bronchiseptica antigen, and adjusted days from birth to 100 kg were determined for individual pigs. Bacterin inoculation reduced the incidence and severity of gross turbinate atrophy 57% and reduced clinical AR over 93%. Inoculated swine had an average blood serum-agglutinating titer greater than 1:2,793 and noninoculated (control) swine had an average titer of 1:112. Increased serum titer significantly (P less than 0.05) correlated with decreased degree of nasal turbinate atrophy. Inoculated and control pigs reached 100 kg in an average of 171 and 178 days after birth, respectively. In the 2nd study (severe enzootic AR), inoculated and control pigs were individually evaluated for clinical AR and total average daily weight gain. Inoculation reduced clinical AR over 90%. The total average daily gain for the inoculated and control pits was 435.84 g and 340.50 g, respectively. Inoculated pigs and control pigs reached 100-kg market weight in 184 and 238 days, respectively.

Evaluation of nasal culturing procedures for the control of atrophic rhinitis caused by Bordetella bronchiseptica in swine.

Control of infectious atrophic rhinitis in swine breeding herds by culturing of 3 series of nasal swab specimens from each animal, with subsequent elimination of Bordetella bronchiseptica culture-positive animals, was evaluated. Thirteen of 17 (77%) B bronchiseptica-infected herds experiencing clinical atrophic rhinitis were feedic rhinitis were freed of clinical signs of the disease by the use of this nasal culturing procedure. In 15 of 23 (65%) B bronchiseptica-infected herds, pigs were cultured negative for this organism at 4 to 10 weeks of age.

A fluorescent antibody technique for identification of Mycoplasma hyopneumoniae colonies.

Fluorescent antibody staining of Mycoplasma hyopneumoniae colonies is difficult because the colonies wash from the agar. Airdrying of the colonies grown on solid medium-overlayed glass microscope slides fixed the colonies in place, so that fluorescent antibody stain could be readily accomplished. Apparent loss or alteration of antigenicity did not result from the air-drying process. The technique is useful for the identification of M hyopneumoniae isolates.

Electron microscopic evaluation of bone cells in pigs with experimentally induced Bordetella rhinitis (turbinate osteoporosis).

The development of osseous lesions in the nasal turbinates of pigs with experimentally induced Bordetella rhinitis, occurring 2 to 6 weeks after inoculation with Bordetella bronchiseptica strain B, was evaluated ultrastructurally, and comparisons were made with controls. Progressive degenerative changes were seen in osteoblasts and osteocytes of diseased pigs. These changes included swollen mitochondria, distention of cisternae of endoplasmic reticulum, and lysis of some cells. Bacterial organisms, believed to be B bronchiseptica, were observed in the cytoplasm of osteoblasts and inclose proximity to bone surfaces in diseased pigs. Although osteoclasts occasionally had degenerative changes in the brush border, most osteoclasts wer similar to those of control pigs. Resorption of bone adjacent to degenerative osteoblasts and osteocytes may have contributed to the development of turbinate osteoporosis when combined with the normal cellular resorptive processes. Thes ultrastructural changes were similar to those previously reported in bone cells of the nasal turbinates of pigs with experimentally induced and naturally occurring atrophic rhinitis.

A suggested mechanism for the pathogenesis of infectious atrophic rhinitis.

Boivin extracts of Bordetella bronchiseptica inhibited or uncoupled the energized processes of bovine heart and pig heart mitochondria. Energy-dependent accumulation of calcium phosphate by both types of mitochondria was markedly inhibited by the extracts. The thesis is advanced that Boivin extracts of B. bronchiseptica may contain the membrane-damaging component responsible for infectious atrophic rhinitis. The action of the extracts was decreased by heat but seemed rather insensitive to digestion by trypsin or extraction by lipid solvents. Attempts to resolve the active component from the extracts were unsuccessful.