Birth Trauma Incidence in Foals

Birth Trauma in Foals and its Links to Musculoskeletal Dysfunction in Adult Horses

In humans, birth trauma is well recognised by medical practitioners, osteopaths, physiotherapists, and chiropractors. Dr. Ian Bidstrup, a Veterinarian and Veterinary Chiropractic and Acupuncture Practitioner, has gathered his findings after treating over 10,000 horses and analysed related birth trauma research. Bidstrup hypothesised that not only is birth trauma a very common and a major cause of pain, discomfort, performance, and behavioral problems but that it also causes long term dysfunction of the right side of the upper thoracic vertebral column that he attributes to causing abnormal girth sensitivity in upward of 80% of adult horses.

In human babies, the biggest part to pass through the birth canal is the baby’s head. Baby skulls are quite maliable; the many plates of the skull are able to flex and contort as the head is delivered through the birth canal. The widest part of the foal as it passes through the birth canal is the chest, across the withers and the shoulders, and the second widest is the pelvis. These structure are much less mailable.

It is hard to imagine when watching a newborn foal find its feet and start to frisk around its paddock, that it may be carrying a degree of pain/dysfunction/asymmetry/discomfort. Typically, unless there was something obviously wrong with them (contracted tendons, badly broken ribs, sickness), we just tend to assume that they have nothing wrong. In a study by Jean, et al, where 263 foals were examined within 3 days of birth, 55 of them (20%) were found to have major ribcage injuries including ribcage fractures in at least 5% of these cases.

Rib fractures and costochondral contusions have been implicated as a common complication of the birth of the foal. The pelvis undergoes diagonal compression that could very well cause stress to the sacroiliac joints and the attachment of the abdominal muscles to the pelvis, and these structures can appear to be badly strained in some foals (Bistrup, 2005).

It is possible that another contributing factor to birth trauma is that the caecum (part of the large intestine) of the mare which occupies the right side of the mares’ abdomen is squashing onto the left side of the foal when the uterus contracts and the foal moves forward. This would cause the foals left side of the lower rib cage to wedge into the bony bottom right side of the mares’ pelvis. The foals’ right spinous processes of the withers would be then crushed up on the top side of the pelvis.

If the incidence of major birth trauma has been demonstrated to be present in 20% of foals, then the incidence of strain patterns and restrictions that are much less obvious but can still lead to musculoskeletal dysfunction would be much higher. Bidstrup reports that over 70% of foals he has treated are seen with right-sided wither damage, right pelvic depression, and damage to the left side of the cranial ribs (ribs closest to the shoulder blades). As in humans, these strain patterns typically do not go away on their own.

To solve these issues, horses need a collaborative team-based approach involving their veterinarian, osteopath/physio/chiropractor, farrier, and trainer (when it comes to the older horses). As osteopaths, we can work to unwind the strain patterns that occur during birth and help foals develop in a way that is free from unnecessary dysfunction

Musculoskeletal dysfunction/crookedness/asymmetry in adult horses

Birth trauma when left untreated can cause chronic long-term dysfunction and can lead to a multitude of problems for the horse, such as high-low heel syndrome, one-sidedness, girth region sensitivity, and musculoskeletal asymmetry.

Birth-related trauma/damage to the spinal column and ribcage at birth is likely to have a lasting effect on the “ neurological programming” of the developing nervous system. In the early stages of healing upper thoracic vertebral column (wither) damage in a foal, the multifidus muscles surrounding the damaged vertebrae tighten in order to protect the vertebrae and spinal cord while the vertebral joints and ligaments are healing (Bidstrup 2005). The rapidly learning, young nervous system of the foal is very likely to accept this tightened pattern as normal, and thus maintain it, even when healing of the physical damage is complete. Such changes could distort the afferent (nerve pathway) feedback from the muscles and sensory nerves, with the resultant abnormal sensitivity, abnormal muscle tone, and abnormal myofascial trigger point induction that is commonly found in girthy foals and horses (Bidstrup 2005). Treatment of the thoracic region is effective in correcting dysfunctional neurological pathways and reducing girthyness that can often be incorrectly diagnosed as other disorders (i.e. ulcers).

Bidstrup has observed that around 80% of horses he has treated, have trouble with their transitions from trot to canter on the right circle. This difficulty with transitions usually disappears with successful treatment of the abnormal girth sensitivity (Bidstrup 2005). It has been established in training circles that a sizeable majority of horses have a weakness in one of the hind legs, most commonly the right hind. Essentially, these horses have trouble with their transitions from trot to canter on the right circle. Further, many equestrians observe that around 80% of horses are better on their left lead than their right (Kilmartin, R).

High-low heel syndrome is most commonly caused by altered weight bearing through the front hooves. Pain/discomfort places the muscles of one limb in tension and can functionally shorten that limb, leading to a functionally different limb on the affected side. When there is dysfunction in one side of the horse (i.e. right sided girth region sensitivity), the horse will stand with the right leg back and the left leg forward, placing more weight into the left hoof and considerably less weight into the right. The left hoof undertaking the most weight stress will develop to be bigger and the right hoof consistently taking less weight will develop as an upright, high heeled, more 'boxy' hoof.

The trauma that caused the pain/discomfort may exist from birth or from later-acquired trauma; but either way, it leads to a habituated muscle shortening. This is an aspect that can often be addressed by appropriate bodywork in many forms: including acupuncture, chiropractic, deep massage, myofascial release work, stretching, and corrective riding exercise. Correct saddle fitting is also a key part of the equation (Ridgeway, K).

Signs and symptoms of a 'crooked' horse (all of which could be caused by a multitude of other problems that are just as important to identify and fix)

High-low heel syndrome

Dishes or flares on toes or quarters

Run under heels due to heavy heel strike of a horse on the forehand

Sheared heels

One high over-muscled shoulder and one side flattened and smaller

One shoulder or one side of the pelvis carried ahead of the other appearing rotated

One hip appears higher than the other

Chronic stifle catching or rear-end stumbling

Difficulty taking on canter lead or disuniting

Pulls heavily on one rein

Stiffness on one side

Bridle lameness

Mild but persistent lameness that thorough veterinary examination cannot precisely locate

Drifting to one side over jumps or whilst approaching fences

Saddle continually slipping to one side

One stirrup always feels longer

Saddle constantly requires re-fitting

Think about just how many horses have these problems and how preventable they could be if they were identified earlier and treated by the appropriate professionals throughout the development from foal to adult horse.

Birth related trauma is by all means not the only reason that the problems mentioned above can occur, but it certainly seems like it is a contributing factor to asymmetry and one-sidedness in horses. There are plenty of other issues that can happen to foals through to adult horses that cause musculoskeletal dysfunction. All of which are important to diagnose and treat using the appropriate team of professionals.

References

Bidstrup, I. The Impact of Birth Trauma on Horse Welfare and Performance. 2021.

Bidstrup, I. Is There a Link Between Birth Trauma and Abnormal Wither and Ribcage Sensitivity in Horses? Could this also relate to one-sidedness?. 2005.

Kilmartin, R. Equine Orthopaedic Balance: The Influence of foot balance on the biomechanics of the upper body - equineoptions.com.au

Jean, D. Laverty, S. Halley, J. Hannigan, D. Léveillé, R. Thoracic trauma in newborn foals. Equine Veterinary Journal, 31 (1999), pp. 149-152

Ridgway, K. Low Heel / High Heel Syndrome - http://www.drkerryridgway.com/