The first step in dealing with any herd health challenge is diagnosing the problem. Without this critical step, launching into therapeutic or preventative responses is foolhardy and the chances of success will be severely limited.

But what happens when the initial diagnosis is wrong?

A misguided diagnosis could happen any number of ways:

• The presenting clinical signs might be confusing or misleading to the untrained eye;

• The presenting problem may be just one part of a disease complex;

• There may be several disease processes occurring within the population at the same time, and only one (perhaps the most innocuous) rises to the degree of clinical disease;

• The experience of the person making the diagnosis may be too limited when a “new” or different disease process occurs;

• The problem may be over-simplified;

• The diagnosis could be based on faulty information; or

• Lab tests are either not specific or sensitive enough for a particular disease.

No Simple Answers

The days of simple answers to challenging health problems, making a “drive-by diagnosis” or expecting an accurate diagnosis over the phone are gone forever. Even a veterinarian with a lifetime of experience diagnosing diseases will submit lab samples to confirm or deny their preliminary diagnosis.

Recently, I participated in a large mortality surveillance study that involved performing necropsies (postmortem exams) on a large number of grow-finish animals. The pigs were necropsied and the findings were compared to the “barn” diagnosis.

The barn diagnosis is typically made by the caretakers and is based on the outward appearance of the carcass and where it was found within the barn. As is commonly done, the caretakers were instructed to choose the diagnosis from an abbreviated list of mortality reasons, which for the most part was outdated and incomplete.

The results of this survey were quite disturbing. Of more than 1,000 pigs that were necropsied, the barn diagnosis was correct on only 40% of the cases.

The technicians who performed the necropsies checked their accuracy by submitting tissues to a state diagnostic laboratory. Results showed they were nearly 100% correct in their determination of reasons for death based on gross lesions.

The lesson learned from this survey was that “eyeballing” carcasses and “educated guessing” should be avoided.

What is the most concerning about the outcome of this study was that we had been making significant herd health-related decisions based on severely flawed information.

In response to the monthly death loss summaries, vaccination protocols and antibiotic therapy were instituted, but they were doomed to fail because they were attempting to attack the wrong enemy!

Why Are These Pigs Dying?

Finishing pig health has been defined many different ways, but often the first noticeable sign of problems in the finishing phase of production is a rise in the mortality rate.

Across the industry, mortality rates vary widely between systems and even between sites or groups of pigs within a system.

Two decades ago, it was uncommon for a producer to report more than 3% mortality in finishing; 1-2% was the target.

When mortality occurs, eventually someone asks: “Why?”

Perhaps the question doesn't come with the first few mortalities, but when the death rate for the group exceeds the interference level for that particular group or system, it is imperative that we try to understand what is going on.

Morbidity is the term used to describe the illness rate or the frequency of animals in the population that are sick. Mortality rate describes the number of deaths that occur in a given group or from a given cause.

You may hear veterinarians refer to a disease as having high morbidity, but low mortality. This means that many in the group got sick, but few died from the disease. This would describe how Mycoplasmal pneumonia.

On the other hand, a syndrome such as hemorrhagic bowel syndrome (HBS) may affect only a few pigs in the population (low morbidity), but it kills nearly every pig it affects (high mortality).

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