Showsight - November 2021

Form Follows FUNCTION



W hen one delves into the nuance of one part of a dog’s body, it is amazing how complex what seems to be a simple anatomical part can be. It seems there are as many differing types of tails as there are breeds. Bobtail, bushy, curled, gay, docked, otter, plumed, ringed, screwed, snap, squirrel, teapot handle, wheel, rat, saber, sickle, terrier, flag, tapered, rocker, bent, clamped, kinked, crooked, half moon, knotted, twist- ed—and these were just through the standards of the first four Groups! Luck- ily for us the normal mechanics are basically the same for any breed, so that is what we will discuss today. THE CROUP The three fused sacral vertebrae (see Figure 1. A–Sacrum) and the first four-to-five tail vertebrae (see Figure 1. B–Coccygeal Vertebrae) form the muscular area just above and around the set-on of the tail, which is defined as the croup. This group forms a slightly curved area, which is easily found upon physical examination (see Figure 2. Sacrum Side View). The structure of the sacrum (the three fused vertebrae) works as one unit, as there is no movement possible between them. The sacrum forms the anchor for the hind limb assembly where the transverse processes (the wings) of the sacrum join to the pelvis via a cartilaginous joint on both sides (see Figure 3). This very firm joining allows the direct transfer of the drive generated by the hind limbs to the spine (vertebral column). The function of the croup is to determine the set-on of the tail. The sacrum (sacral vertebrae) and the first several coccygeal (tail) vertebrae form the croup (see Figure 4 A). The angulation of the croup determines the tail set. If the croup is flat (horizontal) or level, the tail set will be high. If the croup is gently rounded, it becomes a continuation of the backline and the tail usually contin- ues on the level of the spine, carried horizontally to the ground. If the croup is angled downward, the tail set will be low. The steeper the downward angle, the lower the tail set will be on the dog. The angulation of the croup is entirely dependent upon the curvature of the individual sacral and tail vertebrae.

Figure 1. Pelvic Girdle. A–Sacrum, B–Coccygeal Vertebrae, C–Hip Socket (Acetabulum), D–Pin Bone (Ischial Tuberosity)

Figure 2. Sacrum Side View A–Sacral Wing, B–Crest, C–Intermediate Crest, D–First Tail (Caudal) Vertebra


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