Swayback

Swayback, also known clinically as lordosis,[1] refers to abnormally bent postures in the backs of humans and of quadrupeds, especially horses.

Extreme lordosis can cause physical damage to the spinal cord and associated ligaments and tendons[1] which can lead to severe pain.

Most sway-back exhibits a posteriorly tilted pelvis; the lumbar region is usually flat (too flexed) and not hyperlordotic (too extended).

[1] Research into the genetics underlying the condition has several values beyond just the Saddlebred breed as it may "serve as a model for investigating congenital skeletal deformities in horses and other species.

"[4] In small ruminants (sheep, goats, deers), swayback is the common term for the enzootic ataxia, a disease in young animals due to copper deficiency in fetal and early postnatal development.