Thoracic Region (Back/Chest)
The thoracic vertebrae are relatively slender and have tall dorsal spinous processes.
Despite this, it is a very stable region due to the ribs forming a strong rib cage.
The shoulder blades stabilize the front section. The spinous processes slope backward in the first thoracic vertebrae, gradually becoming more upright.
The 11th thoracic vertebra stands vertically, and the last two vertebrae tilt progressively forward — resembling the lumbar vertebrae.
Lumbar Region (Loins)
The lumbar vertebrae have low, forward-sloping spinous processes and no ribs.
They feature flat transverse processes extending outward and slightly forward on both sides in an almost horizontal plane.
Sacrum
The sacrum forms when the sacral vertebrae fuse at around 6 months of age, typically into three vertebrae.
The sacrum continues from the last lumbar vertebra with backward-pointing spinous processes.
At the lumbosacral junction, the spinous processes form a large “V”-shape, allowing significant vertical movement, enabling the dog to bring its hindquarters underneath its body.
On each side of the sacrum, there is a joint connecting it to the pelvis. These sacroiliac joints are crucial for transmitting power from the hindquarters forward through the spine.
Pelvis
The pelvis is a ring-shaped structure formed by three bones that fuse between 3 and 6 months of age.
However, secondary ossification centers — such as the point of the hip and the acetabulum (hip socket) — are not fully ossified until around 3 years of age.
Coccygeal (Tail) Vertebrae
These are small, simple vertebrae arranged like pearls on a string, extending from the end of the sacrum.