Which of the following diseases is often associated with reproductive issues in swine?

Leptospirosis is a bacterial infection that commonly affects swine and is particularly well-known for its association with reproductive issues. This disease can lead to various reproductive problems in pigs, such as low fertility rates, stillbirths, and abortion storms in pregnant sows. The causative agent, Leptospira, can be transmitted through contaminated water or feed, and it can establish itself in the reproductive tissues, ultimately leading to these negative outcomes.

In contrast, while other diseases listed might impact the overall health and productivity of swine, they are not primarily known for causing reproductive problems. For instance, atrophic rhinitis affects the respiratory system and can lead to decreased growth performance, but it isn’t directly connected to reproductive failure. Similarly, pneumonia and mycoplasmal pneumonia are respiratory diseases that can cause general poor health and reduced growth rates, yet they do not primarily affect reproductive functions in swine. Therefore, leptospirosis stands out as the disease with a direct link to reproductive challenges in pigs.