Q: Someone at the yard said that my horse’s pelvis is ‘out’. Is this possible?
A: A horse’s pelvis can’t be ‘out’; it’s held together by a huge mass of muscle and layers of strong fibrous ligaments. Having said this, there are many reasons that a horse’s pelvis may appear uneven, causing people to use the term ‘out’.
The most common reason a pelvis appears asymmetrical is muscle atrophy, meaning less muscle on one side or in one area of the body. This kind of muscle asymmetry can be due to an underlying lameness, previous muscle damage or inappropriate training.
The pelvis is made up of three large bones, the ilium, the ischium and the pubis. These bones fuse to form the acetabulum – the socket in which the head of the femur sits to create the hip joint. The pelvis has three prominent bony landmarks – the tuber coxae laterally as the point of the hip on either side, plus the tuber sacrale (or the hunter’s bump) – this is where the ilium from either side of the horse’s pelvis meet. Here one point may appear lower or further in front of another. Then the horse’s seat bones (the tuber ischium) can also create the appearance of the pelvis being asymmetrical. These asymmetries can be something the horse is born with or a consequence of old damage to the ligamental system in the region. In addition, any old fractures within the pelvis can heal, leaving a visual imbalance in the external landmarks.
So, while your horse’s pelvis can’t be ‘out’, it can have issues that cause asymmetry and need veterinary attention.