Spondylosis

painful!

Spondylosis is a type of arthritis of the vetebrae in the back. Spurs of bone grow, usually beneath the vertebra, and these will grow over the gap between vertebra until they fuse with the adjacent vertebra. When adjacent vetebra are involved, there come a time when the spurs are close to each other and pinching of the tissues or nerves can occur, causing acute, sharp pain and a frightened dog. (much rarer in cats). Dogs need painkiller/ant-inflammatories at this stage.

Eventually the spondylosis fuses with the neighbouring vetebra and then the pain goes, leaving a slightly stiffer back, but pain-free.

In the picture you can see anormal gao (1), then varying degrees of spondylosis (2-3) with 2 almost fused. You can see higher vertebrae also affected in the top Xray.
This Xray is of the lumbar spine (just above the pelvis).