Mycoplasma hyopneumoniae infection dynamics in naïve replacement gilts introduced to positive farms.

This study was designed to characterize the dynamics of infection of Mycoplasma hyopneumoniae in naïve replacement gilts after introduction to positive systems. Ninety-eight naïve gilts were monitored in three positive commercial farms (A, B, and C). The näive gilts were housed for 21 days in pens adjacently located to older gilt cohorts (named seeders), which have been naturally exposed to the positive farms. The infection dynamics was evaluated by PCR and ELISA, from laryngeal swabs and serum samples, respectively. Samples were collected at 150 (arrival), 165, 180, 210, 240, 270, 300 days of age (doa), and pre-farrowing. Infection occurred rapidly on farms A and B, taking 25.2 and 23.9 days for 95% of gilts to be PCR positive, respectively. There was no influence on the number of seeders at the time of exposure, but their absence (farm C) could explain the extended period it took for gilts to get infected (69.4 days). On average, it took 162.2 days after the first PCR detection for 85% of gilts to stop shedding the bacterium. The serology results were consistent with the herd infection curve. At pre-farrowing, 100% of gilts seroconverted and 36.7% remained PCR positive. A total of 1.33% of piglets were positive at weaning. Fifteen variants were detected among the three farms by MLVA. The acclimation protocol was efficient and easy to perform, and the presence of seeders was likely critical for early acclimation for M. hyopneumoniae.

Pasteurella multocida polyserositis in growing-finishing pigs.

Pasteurella multocida is the main secondary bacterium isolated from cases of swine pneumonia. Although highly pathogenic strains of P. multocida have been associated with primary septic lesions and polyserositis in pigs, studies on this pathological presentation in naturally occurring cases are limited. The aim of this work was to characterize the clinical, pathological and molecular findings in cases of P. multocida polyserositis in growing-finishing pigs in a commercial farm in Brazil. The mean age of 17 investigated pigs was 120 days. Clinically, the disease was acute (11/17), with clinical signs of dyspnoea and apathy. Sudden death occurred in some animals (6/17). The main gross findings included fibrinous serositis affecting the abdominal and thoracic cavities (17/17), fibrinous pericarditis (15/17), marked cranioventral pulmonary consolidation (17/17) and splenic infarcts (3/17). P. multocida was isolated in all cases from systemic sites, including the pericardial sac and abdominal exudate. Molecular typing of genus and species was performed on four isolates, and all were characterized as P. multocida type A. Another five isolates were positive for the pathogenicity marker gene pfhA by polymerase chain reaction. This study reinforces the role of P. multocida as a cause of polyserositis in growing-finishing pigs.

Non-ambulatory pigs in two Brazilian growing-finishing farms: a clinic, etiological and pathological perspective on 76 cases.

BACKGROUND: Non-ambulatory pigs, colloquially known as downers or downed pigs, are animals presented with limited to no mobility, usually as a result of pre-existing neurologic or musculoskeletal conditions. Impaired ambulation is a major cause of euthanasia in pigs, leading to economic losses and animal welfare concerns. Additionally, reaching the underlying diagnosis of impaired ambulation in pigs is commonly a challenging task for swine practitioners. The aim of this necropsy-based study was to report the clinical, etiological, and pathological findings of 76 non-ambulatory grower-finisher pigs, and to correlate tail-biting lesions with the causes of death/reason for euthanasia in non-ambulatory pigs. Necropsies of downed pigs were performed during on-site visits to two pig farms in southern Brazil. RESULTS: The diagnosis of the conditions was based on the clinical, macroscopic, histopathological, bacteriological, immunohistochemical, and molecular findings. The diseases diagnosed in non-ambulatory pigs in this study were suppurative arthritis (29/76), suppurative spondylitis (10/76), PVC-2 associated diseases (8/76), bone fracture (7/76), non-suppurative meningoencephalomyelitis (4/76), suppurative meningoencephalitis (6/76), fibrocartilaginous thromboembolism (3/76), epiphysiolysis (3/76), ascending bacterial myelitis (3/76), and other conditions (3/76). The frequency of suppurative arthritis, suppurative spondylitis, and ascending bacterial myelitis/meningitis was higher in pigs with tail biting lesions than controls (P < 0.001). CONCLUSIONS: Non-ambulatory pigs were observed during the entire rearing period, however, the occurrence of non-ambulatory pigs increased in animals aged ≥ 150 days. Infectious diseases were the most common cause of downed pigs, mainly associated with chronic bacterial infections. Tail biting lesions were an important predisposing factor to suppurative arthritis, suppurative spondylitis, and ascending bacterial myelitis/meningitis.

Mycoplasma hyopneumoniae detection by PCR in naturally infected finishing pigs.

The aim of this study was to compare the sensitivity of different in vivo and post-mortem samples collected from finishing pigs under field conditions on Mycoplasma hyopneumoniae detection by PCR. Results suggested that tracheobronchial secretions and bronchial swabs conferred the highest sensitivity in vivo and post-mortem, respectively.

Causes of death in growing-finishing pigs in two technified farms in southern Brazil / Causas de morte em suínos de crescimento e terminação em duas granjas tecnificadas no Sul do Brasil

The aim of this study was to investigate the main causes of death in growing-finishing pigs in southern Brazil. During a one-year period (from 2018 to 2019), two industrial pig herds (18 and 20 thousand pigs each farm) in southern Brazil were monitored along the four seasons of the year (12 days per season on each farm), in order to perform necropsies of all pigs that died in that period. The two farms had an average monthly mortality rate ranging from 0.94 to 3.93% in the evaluated months. At necropsy, tissues were collected, fixed in 10% formalin solution and processed routinely for histopathological examination. When necessary, samples were sent for bacterial culture and PCR to identify etiologic agents. A total of 601 necropsies were performed, with 94.9% of conclusive diagnoses. Infectious diseases corresponded to 64.4% of conclusive diagnosis and non-infectious diseases to 35.6%. The most prevalent causes of death were: pneumonia (33%), gastric ulcers (15.4%), circovirosis (9.9%), systemic bacterial embolism (5.4%), polyserositis (4.4%), dilated cardiomyopathy and torsion of abdominal organs (4.3% each), and bacterial pericarditis (3.4%). Regarding pneumonias (199/601), the main agents identified in these cases were Pasteurella multocida, Influenza A virus and Mycoplasma hyopneumoniae, mainly in associations.(AU)

O objetivo do presente trabalho foi investigar as principais causas de morte de suínos em fase de crescimento e terminação no Sul do Brasil. Durante o período de um ano (entre 2018 e 2019), duas granjas tecnificadas de suínos no Sul do Brasil foram acompanhadas nas quatro estações (12 dias por estação em cada granja), para realização de necropsias dos suínos que morreram nesse período. As duas propriedades apresentavam mortalidade mensal média entre 0,94 e 3,93% nos meses avaliados. Na necropsia, amostras de órgãos foram colhidas, fixadas em formol 10% e processadas rotineiramente para o exame histopatológico. Quando necessário, amostras foram enviadas para o cultivo bacteriano e PCR para identificação de agentes etiológicos. Foram realizadas um total de 601 necropsias, com 94,9% de diagnósticos conclusivos. As doenças infecciosas corresponderam a 64,4% dos diagnósticos conclusivos e as não infecciosas a 35,6%. As principais causas de morte foram: pneumonias (33%), úlcera gástrica (15,4%), circovirose (9,9%), embolia bacteriana sistêmica (5,4%), polisserosite (4,4%), cardiomiopatia dilatada e torção de órgãos abdominais (4,3% cada) e pericardite bacteriana (3,4%). Com relação às pneumonias (199/601), os principais agentes associadas as lesões foram Pasteurella multocida, vírus da Influenza A e Mycoplasma hyopneumoniae, principalmente associados entre si.(AU)