Question

Immunoglobulin M (IgM) increases in which disease condition?

• A. Connective tissue disease
• B. Newborn animals before intake of colostrum
• C. Hereditary agammaglobulinemia
• D. Anaphylaxis

Hint:

In veterinary medicine, measuring IgM (or IgG) in a pre-colostral newborn is a valuable diagnostic test.
Since maternal antibodies cannot cross the placenta in livestock, any Ig present before colostrum must have been produced by the fetus itself in response to an in utero infection.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Newborn domestic animals (such as calves, foals, and piglets) with epitheliochorial placentation are born virtually immunologically naive and devoid of immunoglobulins because maternal antibodies cannot cross the thick placental barrier.
They rely entirely on absorbing immunoglobulins from the mother's first milk (colostrum) postnatally to establish passive immunity.

Step 2: Detailed Explanation:
Normally, the serum of a healthy newborn animal before colostrum intake contains almost undetectable levels of immunoglobulins.
However, if the fetus is exposed to an infectious pathogen (such as a virus or bacterium) in utero during late gestation, the fetal immune system is stimulated to mount an active immune response.
Because the immune system is primitive, the primary antibody produced by the fetus in response to an in utero infection is Immunoglobulin M (IgM).
Therefore, if a newborn animal is tested *before* it has ingested any colostrum, and its serum shows significantly elevated or increased levels of IgM, it serves as a diagnostic indicator of an in utero fetal infection or disease condition.
Under normal, non-infected conditions, IgM would be absent.
Hereditary agammaglobulinemia (C) is characterized by a complete absence of immunoglobulins, and anaphylaxis (D) is mediated primarily by IgE.

Step 3: Final Answer:
Thus, IgM increases in newborn animals before colostrum intake under disease (intrauterine infection) conditions, corresponding to option (B).