Clinical Findings
Behavioral aberrations range from frequent,
intermittent estrus with exaggerated monosexual drive to bull-like
behavior (bulling), including mounting, pawing the ground, and
bellowing. This behavior may be accompanied by masculinization of the
head and neck. Relaxation of the vulva, perineum, and the large pelvic
ligaments, which causes the tail head to be elevated, can occur in
chronic cases. Some affected cows show these signs, but others may be
sexually quiescent; anestrous cows are the most common presentation.
This variation is due to the duration of the condition and the nature of
the hormone signals or lack thereof from the diseased ovary.
The affected ovaries generally are enlarged and
rounded, but their size varies, depending on the number and size of
cysts. Their surface is smooth, elevated, and blister-like, particularly
when cysts exceed 2.5–3 cm in diameter. Cysts frequently are multiple
and may approach 4–6 cm in diameter.