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Wat is ECVM?


ECVM stands for Equine Complex Vertebral Malformation - formerly known as The Congenital Malformation of the 6th and 7th Cervical Vertebrae in Horses. The name change was the result of ongoing research showing that the complexity of this malformation wasn’t justified by the simplicity of its term. Its effects reach far further than just the neck which makes this condition extremely complex in nature.

ECVM is an abnormality of the 6th / 7th cervical vertebra - it also involves the first and second ribs, thoracic and lumbar vertebrae. The consequences of ECVM can vary - from minor to quite extensive.

ECVM was first discovered by Australian ''bone lady'' Sharon May-Davis. Click here to read her original scientific research paper written in 2013.  You can find all this research on the article section on this website. 

In this article, we would like to inform you about what ECVM entails and what possible clinical symptoms could be present in affected horses. 


Since 2013, more research has been done on the development of ECVM in horses. Click here to watch a webinar with Sharon on what we know on the origins of ECVM.


ECVM is a genetic abnormality that is already present at birth.

The genetic / hereditary component means that a trait can be passed on from generation to generation, whether or not skipping a generation. 
It is not yet known which part of the DNA is responsible. We would love to do more research on this, so that you can make good choices in breeding. 

ECVM comes in a few variations: 

         - Unilateral malformation of C6
         - Unilateral malformation of both C6 & C7          
         - Bilateral malformation of C6
         - Bilateral malformation of C6 & C7




                                                                                                              Above:   Left: normal C6 - right: unilaterally malformed C6

                                                                                              Below: Left: normal C7 - right: transposed C7 

Within the malformation, the caudal ventral tubercle (CVT) of C6 and in some cases also C7 is absent. In other words, the bony attachment side
of the M. Longus Colli muscle is absent. In case of a bilateral malformation on C6 & C7, a transposition - or displacement - of the CVT appears on C7. That is, the point of  muscle attachment that is normally on C6, is now on C7. This significantly changes the anatomy & biomechanics of the lower neck. The forces on the vertebrae change and the stabilization / coordination in the low neck is significantly affected. The consequences of this can be major. Think of vertebral instability, joint degeneration, asymmetrical forces and modified movement patterns. 


The M. Longus Colli also plays an important role in informing the brain of muscle tone, length and health. With abnormal muscle tension, this information transfer is disrupted. As a result, the horse will make adjustments and compensate in other muscles. This can result in a chain reaction of adjustments and problems. 



The discovery of ECVM and its associated symptoms has led to a heated debate world-wide as to how to perceive this phenomenon.
It is often claimed that ECVM is not a condition, but a form variation with no adverse consequences. In other words: it is something that occurs naturally and can therefore be seen as normal.


And indeed, this is true, variations and deviations do occur in nature. However, if you look at this, some deviations have consequences, others don't. This is also the case with ECVM. In the words of Sharon, "logic dictates that an asymmetric shape is accompanied by asymmetric forces." ''


After research in many museums worldwide where many cervical vertebrae have been examined, we have come to the conclusion that for domestication

deviations can be found. Therefore, we believe that ECVM should be considered a condition. The asymmetry, abnormal movement patterns and reduced lower neck stability associated with ECVM have major implications for the usability and life expectancy of these horses.


However, many factors play a role such as the severity of the condition, the character of the horse, the management, the quality of the training and the extent to which the horse is able to meet our expectations. ECVM horses are often misunderstood - it's not that they don't want to, but they literally can't! This makes the situation complex quickly.


In general we can say that in ECVM horses, the result of the training often does not correspond to expectations. Sometimes those horses just seem to be difficult, or their character seems ugly. And sometimes there is just no progression in the training - you feel 'stuck' on the same level - not because they don't want to, but because they can't.



If you suspect a horse has this condition, the quickest and easiest way to diagnose is to take X-rays of the low neck. Click here to download
an X-ray protocol for ECVM.


Horses with ECVM show a variety of symptoms - making it an extremely complex condition, as each horse can have a different combination of problems. As an owner, it is therefore very important to keep a critical eye on your horse. The clinical symptoms we encounter in ECVM horses can be divided into physical and mental categories.


Physical symptoms

It is important for every animal to feel safe and comfortable in its own body. ECVM causes an asymmetry in the entire spine, which causes the necessary imbalance. Symptoms manifest themselves in different ways - depending on the horse. This is due to the many variations and the involvement of other structures. We have tried to list the most common complaints:


             - Loss of coordination and / or proprioception

             - Asymmetry of thoracic inlet & spine

             - (Unexplained) lameness

             - Sensitivity to palpation

             - Contact problems 

             - Imbalance in the feet

             - Dental problems

             - Hormonal and internal problems


          Left & center: ECVM horse Armando shows uneven feet, a lot of asymmetry and a loss of balance and proprioception. Right: asymmetry in an ECVM horse.


Mental & behavioral symptoms 

Describing mental symptoms related to ECVM is a subjective matter as every horse and situation is different. The associated symptoms are
based on empirical evidence of horse owners - ourselves included - who noted behavioral abnormalities in affected horses. These symptoms
may be caused by the neurological complications of ECVM, as well as internal stress due to asymmetry and compensation patterns.

For example, horses can experience pain due to overloading of muscles and/or other soft tissues as well as nerve compression reduced blood flow, osteoarthritis and so on. 


Much research has been done on pain in horses and how they express it. In 2014, dr. Katrina Gleerup presented a model of the Equine Pain
Face which could be very useful in establishing whether your horse might be dealing with pain. 


                                      Left: the Equine Pain Face by K. Gleerup                                                                                     Right: picture of Armando - a horse with ECVM

Below you can download a full useful scientific studies on pain in horses: 
1. An Equine Pain Face by Dr. Karina Gleerup 
2. ''The Equine Pain Face Explained'' with Karina Gleerup 
3. ''Development of an ethogram for a pain scoring system in ridden horses'' by Dyson et al. 
4. ''Development of the horse grimace scale as a pain assessment tool in horse undergoing routine castration'' by Costa et al

In addition to pain, horses can also exhibit other behavior because they, for example, feel less safe. It is very important that the horse can trust
its body so that it can flee quickly if needed. If you know that this is not possible due to physical problems, it causes stress. Instability causes stress and stress manifests itself in different ways in different horses. Horses with ECVM generally seem to be under more stress - something
that in itself also has a physical effect on the body. 

It is important to understand that horses with ECVM do not necessarily show pain all the time. It could be an 'on-off' situation.

In addition to facial expressions, there are other mental and behavioral symptoms that have been observed empirically in ECVM horses:


              • Less forward / willing to work

              • Not willing or difficulty with canter

              • Hitting / shaking the head

              • Looking at the shoulder / biting (himself)

              • General resistance

              • Rebellious in behavior

              • Unpredictability

              • Internally uncertain (inner fatter)

              • Sudden startled behavior

              • Rapidly build up inexplicable tension

              • More temperament as the horse gets older


It is important to ensure that management matches the horse's needs as closely as possible and adapt training expectations to the horse's capabilities. The prognosis differs from horse to horse and this is what makes it so difficult - it is important to recognize that you need to adapt your management and training to the possibilities for that particular horse every day.

Having said this, despite all the differences in each individual case there are also some similarities. The basis of all problems lie in asymmetry and instability. For this we can make management adjustments to improve these aspects.


In management, extra attention must be paid to stability training -  not only in the neck but throughout the horse's body. The trunk muscles (thoracic sling) are extremely important in stabilizing the horse and as such must be well taken care for.

The things below are important for every horse. However, with ECVM horses, more attention will have to be paid to these management routines and the frequency of any treatments increased: 

               - Passive physio (browsing)

               - Stability training

               - Proprioception training

               - Good hoof care with short intervals

               - Therapy / bodywork
               - Regular dentistry treatments

               - Removing other stressors (think of nutrition, isolation, too heavy training)         
               - In-hand training before riding the horse
               - Adapted and customized training schedules 

For advice or guidance on any of these elements, please reach out to one of our specialists listed on this website. 


As with many disorders, the expressions you can see in horses are not black and white. That means that not every horse shows the same symptoms. As an owner it therefore remains very important to keep looking at your horse. The moment you see a change or abnormality, it always has an underlying cause. The question is which one...

So keep looking at your horse, trust your gut feeling and don't hesitate to reach out if you think your horse might have ECVM. 


The aim of this website is 4-fold: 
                - Providing an informative platform 
                - Furthering research through creating a world-wide database 
                - Connecting experts and professionals world wide 
                - To promote careful breeding practises and improve horse well-fare. 

On this website you can find numerous scientific articles, webinars & podcasts on ECVM. 

To further research efforts, you can also register your horse with ECVM into a world wide data base. We hope that by building this data base we can raise even more:

                  - Awareness

                  - Improve diagnostic methods

                  - Update the gene pool in order to be able to make even more careful choices in breeding

Finally, you can also find a list of world wide professionals and experts you can reach out to once
your horse is diagnosed with ECVM. These experts can assist you in providing information, management, therapy, and training solutions in order to manage your horse with ECVM in the best possible way. We hope wecan expand the list of experts and professionals on a regular bases! 

Fig 1 - Can you recognise pain in your h
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