The static assessment - Part 1 - Posture and conformation

The aim of this three-part, weekly blog series is to show how a static exam can be a key tool in determining future athletic problems. Although postural changes are not always necessarily associated with lameness, maintenance assessments to track changes and work towards correcting them will improve your horse’s performance and welfare.

In the first part of the blog series, I will be defining what a static exam is, differentiating between posture and conformation and also discussing some other common findings which can also have long term detrimental effects.

What is a static exam?

This is the part of the assessment when the owner is asked to try to stand the horse square, on a flat and level surface. The position which the horse resorts to can be considered to be that within which the horse is most comfortable.

Image 1: Photos against a repeatable background can be an excellent tool in tracking how your horse is changing.

The way a horse stands is influenced by a number of factors. Its conformation (genetic predisposition) cannot be changed. Horses are bred to perform specific disciplines, and the genetic traits of both the stallion and mare are essential during the selection process. Conformation therefore refers to genetic characteristics involving bone length and shape, however, this can be influenced by some external factors (such as diet and turn out).

On the other hand, posture is determined by the soft tissue structures (muscles, fascia, ligaments and tendons). These structures can be changed, positively or negatively. Poor posture increases risk of musculoskeletal injury due to abnormal and unbalanced loading of limbs. Posture can also be influenced by other para-professionals, including correct saddle fit and routine, balanced farriery.

Changes in joint orientation and increase in fluid (effusion) in the joint can decrease blood supply to the bones forming the joint (1). As effusion results in elevated pressure within a joint, the damage to the articular cartilage is also increased (2). Inappropriate loading of the joint will therefore eventually result in degenerative (negative) changes.

The assessment

A familiar and confident handler can help to ensure that the horse is not consistently moving about. It should include examination of the conformation of the hooves, and limbs, thoracolumbar and pelvic region, including symmetrical and appropriate muscle development. Superficial and deep palpation of the back and gluteal muscles should be carried out, looking for signs of spasm or pain. Noting any signs of old scars (surgical or old wounds), external trauma, ectoparasites, body condition score and other asymmetries can also help to create a more thorough assessment. Recognizing initial signs of dermatological disease can help to improve animal welfare through early veterinary intervention.

Image 2: Note the mass on the third eyelid - potential a squamous cell carcinoma, early diagnosis removal will decrease risk of metastasis.

Horse owners and professionals are unable to consistently and accurately assess a horse’s body condition score (3). Obesity has been linked with an increased risk for suspensory desmitis (4), and therefore, having a good grasp of how to carry out accurate body condition scoring is vital (5). Although bodyweight is not directly linked with laminitis (6), recognizing a cresty neck which may be indicative of metabolic disease, such as Cushing's or Equine Metabolic Syndrome (EMS), may allow for early diagnosis and prevention of endocrinopathic laminitis.

Photography can be a great tracking tool between assessments.

Conformation

Horses have evolved to have a single toe over the last 58 million years (7), allowing for faster, energy efficient locomotion. Conformational traits are highly heritable (8).

A 2004 study (9) looked at the correlation between musculoskeletal problems and conformation. Due to the abnormal distribution of load present because of these changes, some of the main findings included:

• Longer bottomline of the neck resulting in increased forelimb fetlock problems (potentially due to increased weight of a longer neck).

• Increased fetlock effusion when the fetlock or carpal joints were offset from the centre.

• There was no link between musculoskeletal disease and the following variables in these young horses: neck topline, wither and croup height, scapular angles, hock angle, and length of humerus, radius, femur, tibia, metacarpal or metatarsal bones.

10-35% of thoroughbred foals in central Kentucky undergo surgery to change conformation (10), even though mild to moderate conformation deviations to forelimbs did not alter racing performance (11). The same study also showed that only 15% of the 292 horses were considered to be straight through both of their forelimb fetlocks and carpi. Therefore, although surgical intervention at a younger age may not be necessary for the horse to perform at the required level, what will the long term implications be after retiring from racing?

Conclusion

When assessing a horse, experience is essential in determining correlation between different variables. Experience is also key in compiling an appropriate conditioning and rehabilitation plan and then tracking progress of postural changes. This must be specific to each horse, depending on orthopedic history, temperament and the owner’s time and resources.

The next part of this blog series will look at the shape of the feet and splint bone injuries.

References

1. Arnoldi, C., Reimann, I., Mortensen, S., Christensen, S., Kristoffersen, J., Sønnichsen, H. and Smith, M., 1980. The Effect of Joint Position on Juxta-Articular Bone Marrow Pressure:Relation to Intra-articular Pressure and Joint Effusion—An Experimental Study on Horses. Acta Orthopaedica Scandinavica, 51, pp.893-897.

2. Vegter, J., 1987. The influence of joint posture on intra-articular pressure. A study of transient synovitis and Perthes' disease. The Journal of Bone and Joint Surgery., 69, pp.71-74.

3. Morrison, P., Harris, P., Maltin, C., Grove-White, D., Barfoot, C. and Argo, C., 2017. Perceptions of Obesity and Management Practices in a UK Population of Leisure-Horse Owners and Managers. Journal of Equine Veterinary Science, 53, pp.19-29.

4. Gruyaert, M., Pollard, D. and Dyson, S., 2020. An investigation into the occurrence of, and risk factors for, concurrent suspensory ligament injuries in horses with hindlimb proximal suspensory desmopathy. Equine Veterinary Education, 32(S10), pp.173-182.

5. Henneke, D., Potter, G., Kreider, J. and Yeates, B., 1983. Relationship between condition score, physical measurements and body fat percentage in mares. Equine Veterinary Journal, 15(4), pp.371-372.

6. Wylie, C., Collins, S., Verheyen, K. and Newton, J., 2012. Risk factors for equine laminitis: A systematic review with quality appraisal of published evidence. The Veterinary Journal, 193(1), pp.58-66.

7. MacFadden, B., 1994. Fossil horses: systematics, paleobiology, and evolution of the family Equidae.. Cambridge [England]: Cambridge University Press.

8. Love, S., Wyse, C., Stirk, A., Stear, M., Calver, P., Voute, L. and Mellor, D., 2006. Prevalence, heritability and significance of musculoskeletal conformational traits in Thoroughbred yearlings. Equine Veterinary Journal, 38(7), pp.597-603.

9. Anderson, T., McIlwraith, C. and Douay, P., 2004. The role of conformation in musculoskeletal problems in the racing Thoroughbred. Equine Veterinary Journal, 36(7), pp.571-575.

10. Hughes, A., 2012. A surgical assist to creating the perfect horse,. [online] Available at: <http://www.kentucky.com/2012/09/09/2329563/asurgical assist-to-creating.html;> [Accessed 19 April 2021].

11. Santschi, E., White, B., Peterson, E., Gotchey, M., Morgan, J. and Leibsle, S., 2017. Forelimb Conformation, Sales Results, and Lifetime Racing Performance of 2-Year-Old Thoroughbred Racing Prospects Sold at Auction. Journal of Equine Veterinary Science, 53, pp.74-80.