This term defines failure of udder development and is relatively uncommon.
It can occasionally be seen in gilts because the hormones that are responsible for the development of the udder have not been produced in sufficient quantity. Such animals should be culled.
Occasionally herd problems are seen where poor nutrition, heavy worm burdens, chronic disease or mycotoxins may be implicated. The most likely mycotoxin to cause it is from ERGOT poisoning in pregnant gilts running in grass paddocks. Shortage of water is a common cause.
Rarely, hypoplasia may be due to a genetic mutation in the affected gilts ancestors.