Causes of Sow Mortality and Risks to Post-Mortem Findings in a Brazilian Intensive Swine Production System

SIMPLE SUMMARY: Genetic selection increased sow productivity over the last decades, but also increased sow mortality. The impact of mortality includes financial losses, affects labor morale, and raises ethical and animal-welfare concerns. Despite the impact of mortality, the literature is still scarce regarding risk factors for post-mortem findings and bacterial agents involved. Therefore, the present study was conducted to investigate the cause and risk factors related to post-mortem findings in sow death by performing post-mortem examinations, bacteriological investigations, and evaluations of individual sow records. Spontaneous death occurred mainly in the peripartum period. Deaths in the peripartum period were associated with heart failures, genitourinary disorders, and prolapses. Euthanized sows had more locomotor disorders. Sow mortality had a multifactorial etiology including infectious and non-infectious agents; in 75% of the deaths, lesions affecting more than one system were observed. Infections were polymicrobial. The high index of secondary lesions such as gastric ulcers, cystitis, locomotor disorders, and lung pleurisy raise concerns about sow welfare. This study can be used to identify females with a higher risk of injuries and to guide management practices to reduce sow death and increase sow welfare in breeding herds. ABSTRACT: The present study was conducted to investigate the risk factors for post-mortem findings and causes of sow mortality. A post-mortem examination and microbiological investigation were conducted on 123 sows from a breeding herd with 15,000 dams. The mortality of spontaneous death in sows occurred mostly in the peripartum period (53%; p < 0.05). The spontaneous deaths were associated with heart failures, hemorrhagic and perforating gastric ulcers, and liver torsion, while in the euthanized sows, the post-mortem findings were associated with locomotor disorders. A higher body condition score (BCS ≥ 3.5) increased (p < 0.05) heart failure on the post-mortem examination. The excessive use of manual obstetric interventions increased sow deaths resulting from cervix/uterus ruptures and increased the odds of death (p < 0.05) due to metritis. Sow mortality had a multifactorial etiology. Infections were polymicrobial. The main microbial agents identified from a septic lesion in locomotor, genitourinary, and respiratory systems were Trueperella pyogenes, Escherichia coli, and Actinobacillus pleuropneumoniae, respectively. In conclusion, sow mortality involved multiple risk factors and several bacterial agents. These results indicate that better management practices can reduce sow mortality in swine production and increase sow welfare.