The Thoracic Sling is a group of muscles, tendons, ligaments & fascia that connect the forelimbs to the thorax (chest) and supports the horse's weight between the front legs. It is a crucial component of a horse's muscular system, playing a vital role in its overall movement and well-being. Composed of specific muscles and other tissues that connect the front limbs to the thorax, the Thoracic Sling contributes significantly to a horse's balance, coordination, and strength. 

A major anatomical difference between horses and ourselves is that horses do not have a clavicle. The lack of a clavicle means there are no bones connecting the forelimbs to the ribcage & the rest of the body. Instead the shoulders are connected to the body by fascia, ligaments and muscles. The lack of a clavicle means the shoulder has a much greater range of motion. The Thoracic Sling lifts the thorax & holds the chest between the front limbs.

The Thoracic Sling allows for the majority of the horse’s movement giving it the ability to move in multiple directions such as forward and turning, bending & jumping. Because of its function, ensuring a well conditioned & functioning Thoracic Sling is essential for a horse's overall body soundness & performance.

Muscles Involved In The Thoracic Sling.

The group of pectoral muscles situated between the forelimbs and under the chest form an important aspect of the thoracic sling. Those muscles help to support the weight of the thorax during movement.

The Serratus Ventralis Thoracis, the Pectorals which are: Transverse Pectorals, Ascending Pectorals, Descending Pectorals & the Subclavius all make up the Thoracic Sling.

Recognising The Signs of a Weak Thoracic Sling.

A weak Thoracic Sling can have a profound impact on your horse's entire body & the way in which it functions. It can cause poor gait, which can then lead to dysfunction within the limbs. The risk of lameness can also be increased. 

Riding style, not enough free movement, and tense, consistent high head carriage will create dysfunction in the body and weakness in the thoracic sling.

Signs of a Weak Thoracic Sling May Include:

1. Difficulty in Turning.

2. Lack of Engagement and push from the hind end.

3. Tendency to "Fall In" on corners/turns.

4. Soreness through other areas of the body.

5. Falling onto the forehand.

6. Girthiness can also indicate soreness cause by a weak Thoracic Sling.

7. Struggling to navigate hilly or uneven ground.

8. Performance issues such a tiring more quickly during exercise.

9. A reduction in flexibility.

10. Shortening in length of stride.

11. Cross cantering and/or difficulty in picking up the correct lead.

12. Hollow posture when exercising.

13. Poor balance.

Whilst the above could indicate a weak Thoracic Sling, they could also be related to other possible issues. See a Massage Therapist or consult your Veterinarian.

Exercises to Help Strengthen the Thoracic Sling

1. Pole Work

Pole work is fantastic for improving the thoracic sling. It can be done in hand during the early stages of rehabilitation and increase in complexity as there are improvements and you move to ridden work.

2. Raised cavaletti work

Setting up raised cavaletti encourages the horse to lift its legs and stretch its head down and out, engaging the thoracic sling muscles.

3. Hill work

Riding the horse uphill prompts the engagement of the thoracic sling. This does not need to be fast work to get results. Plenty of slow work in hand and undersaddle at the walk will slowly build the thoracic sling

4. Backing up

Backing up a few times in hand on a daily basis encourages the horse to use its thoracic sling muscles more correctly. The horse should be allowed/encouraged to lower its head during this exercise, or they will hollow. A raised head also inhibits their ability to step backwards.

3. Lateral Work

Incorporating lateral exercises such as leg-yields and shoulder-in when the horse is ready can further strengthen the thoracic sling and connected muscles.

Taking time to work through beneficial exercises, such as above will help the horse develop correct muscle function, better posture and reduce wear on the anatomy of the lower limbs.

Finally

Understanding and addressing the importance of the thoracic sling in a horse's musculature is essential for promoting optimal performance and preventing injuries. Regular, targeted exercises can contribute to the development of a strong and resilient thoracic sling, ensuring a horse's overall well-being.

Illustrations by Alexa McKenna BVM & S from the book Horse Movement, Structure, Function and Rehabilitation by Gail Williams PhD