Page 749 - Veterinary Immunology, 10th Edition

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FIG. 23.7 Clostridium perfringens antitoxin levels in serum,
colostrum, and milk of six pony mares and in the serum of their foals
from birth to 5 months. (Jeffcott LB: Studies on passive immunity in
the foal. 1. γ-globulin and antibody variations associated with the
maternal transfer of immunity and the onset of active immunity. J
Comp Pathol 84:93-101, 1974.)

Neonatal mammals develop proteinuria. This is due to intestinal
absorption of very small proteins such as β-lactoglobulin that can
be excreted in the urine. In addition, the glomeruli of newborn
mammals are permeable so that the urine of neonatal ruminants

contains intact immunoglobulin molecules. This proteinuria ceases
with the termination of intestinal absorption. Urine from puppies
collected 24 hours after birth contains relatively large amounts of
IgG, IgM, and IgA. The amount declines over time so that IgM is

undetectable by 14 days, although there may still be significant
amounts of IgG and IgA present. Over the first 2 weeks of life, the
puppy's glomeruli mature and acquire the ability to retain
macromolecules.

The secretions of the mammary gland gradually change from
colostrum to milk. Ruminant milk is rich in IgG1 and IgA.
Nonruminant milk is rich in IgA. For the first few weeks in life,
while protease activity is low, these immunoglobulins can be found

throughout the intestine and in the feces of young mammals. As the
digestive ability of the intestine increases, eventually only secretory
IgA molecules remain intact. The amount of IgA provided by milk
can be large; for instance, a 3-week-old piglet may receive 1.6 g

daily from sow's milk.
Although IgE is present in mare's milk and transmitted to the

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