Chapter 5 of our Managing Pig Health section reviews the various management and environmental factors that have an adverse affect on reproductive efficiency. Chapter 6 considers the effects disease can have on infertility. However, it is important to understand there is often an overlap between infectious and non infectious infertility and in many cases the two are interrelated.
It is necessary to determine if there is an infectious component to a problem in a herd because corrective measures may involve both treatment and management procedures.
This Problem Solver demonstrates a pathway that can be used to help identify the causes of an infectious infertility problem. It asks the question what diseases are present in the herd, because any one of these may have an occasional effect. For example, if a herd is infected long term with aujeszky's disease virus, porcine parvovirus (PPV), porcine reproductive and respiratory syndrome (PRRS) or swine influenza (SI) then at varying intervals following the initial herd outbreak there may be reproductive failures, albeit in many cases at individual sow levels.
If a herd is free from these infections and then become infected with one of them an acute episode of that disease will occur. This will be manifest by reproductive failure including increased numbers of abortions, repeats on a normal and abnormal cycle and in the case of those viruses that cross the placenta, there will be foetal death, mummified and stillborn piglets.
Diseases such as porcine parvovirus (PPV), PRRS and leptospirosis may infect the sow without causing other clinical signs. Usually in such cases the disease picture is sporadic (unless it appears for the first time) and a detailed examination of records helps to clarify this.