Normal Ovary(left) Abnormal Ovary(right)
The large abnormal ovary is called a “cystic ovary”.
This sow returned to estrus 7 days post- weaning and was inseminated.
For some reason the follicles did not rupture normally and they continued to grow and became cystic (fluid filled).
A failure of LH (Luteinizing Hormone) release from the pituitary gland is the probable cause.
Sometimes this condition will cause the female to remain in estrus for several days.