Hypermobility in horses
"Because decades of breeding have focused on flexibility, we are now increasingly seeing horses that are hypermobile."
What is hypermobility?
Hypermobility is defined as increased joint range of motion. This occurs because of a hereditary defect in the connective tissue, making it overly elastic. This increased elasticity results in less effective joint stabilization. While some flexibility is naturally beneficial for a sport horse, if it becomes excessive, the horse will experience difficulty stabilizing its body. This can affect the spine and trunk, as well as the joints in the legs.
What are the consequences for the horse?
Hypermobile horses are more susceptible to injuries in their tendons, joints, neck, back, and pelvic region. The lower neck is a particularly vulnerable area. Hypermobility is often associated with anatomical abnormalities of the 6th and/or 7th cervical vertebrae (ECVM).
In addition, modern sport horses lack the lamellae (connective tissue structures) that run from the nuchal ligament to the 6th and 7th vertebrae, or these are thinner. This, combined with hypermobility, leads to reduced stability of the lower neck. Because the weight has shifted more towards the forehand, greater forces are placed on the lower neck.
How do you recognize a hypermobile horse?
Hypermobile horses often have relatively long legs. The cannon bone and pastern bone, in particular, can be elongated. They are often slender and long-lined, with an elegant head. Because there is a strong influence from the English Thoroughbred, we see the characteristics of the racing skeleton.
- A deep chest (like a greyhound) which places the horse's balance point between the front legs rather than behind them
- A high withers that is pronounced
- Smaller angles in the foreleg, making the foreleg relatively short
- Larger angles in the hind leg making the hind leg relatively long with steep angles
- The pelvis is often tilted too much downwards
In motion, hypermobile horses generally have spectacular movements, unless they are too hypermobile. In that case, they don't bounce off the ground enough and instead move short and quickly. They have a lot of movement in the spine and pelvis.
Viewed from the front and from behind, we often see these horses landing close to the ground and the hind leg, because it is so long, has more driving power.
What else does a hypermobile horse experience?
Hypermobility isn't limited to increased joint mobility and increased tendon elasticity. It affects the entire body. Connective tissue is woven throughout the body, including the skin, organs, nervous system, and blood vessels. In hypermobile horses, we therefore more often see gastrointestinal complaints, reduced overall health, delayed wound healing, and increased inflammation. The immune system is also more often compromised, leading to increased susceptibility to colds and slower recovery. Allergies and autoimmune disorders are also common.
The nervous system of these horses also functions differently. They are often very sensitive to stimuli, whether it's touch, sound, or visual cues. They are often nervous or very calm, but with a kind of all-or-nothing reaction when the stimulus becomes too strong.
We often observe neurological abnormalities such as ataxia, hypermetria, convulsions and cocky gait.
Owners often say their horse is "a bit clumsy." They bump their heads more often, don't know where to put their feet, or do all sorts of awkward things in the paddock or pasture.
It's striking that these horses are highly intelligent and incredibly friendly and people-oriented. That's why owners often become very attached to them. And this was often one of the reasons for buying them; "He looked so friendly and made contact right away." "He's such an incredibly sweet animal."
Hypermobile horses also more often have metabolic complaints such as PSSM I or II or insulin resistance.
The hypermobile horse is often not taken seriously!
In recent years there has been increasing recognition for hypermobile horses, but it is not yet a generally accepted picture.
Hypermobility itself is easily detectable if you know what to look for. However, horses are very good at compensating, so it can sometimes remain somewhat hidden. The symptoms are also usually vague to begin with;
- Alternating lameness in alternating legs sometimes without any apparent cause
- Falls from one injury to another which seems to be “bad luck”
- Showing “difficult” behavior, especially under saddle
- “Just don't do it quite right”
- Varying fitness without clear cause
- Changing behavior without a clear cause
- Have a longer recovery time
- Don't build muscle very well
In many cases, owners end up in a veterinary process where small "things" are found in the horse's body, but which cannot really be the explanation for the complaints.
That's because hypermobility itself can cause a great deal of discomfort, but that can't be captured on an x-ray, ultrasound, or CT scan. These horses struggle to carry a rider because they can barely stabilize themselves. This causes stress. They are often hypersensitive, so every stimulus hits them much harder than with a "healthy" horse. They often experience aches and pains throughout their bodies, which aren't so severe that they're immediately noticeable to us, and often no real injury can be found. Simply put, everything is wrong in the horse, from the neck, back, pelvis, and legs to the muscle structure, organs, and nervous system.
What now?
Many owners experience enormous relief when they receive the knowledge and information relevant to their hypermobile horse. It's not pleasant, but SO much sense has fallen into place! Unfortunately, they've often been told to "just ride their horse through it." But there's actually more to it than that. So what now? With proper management and training, many hypermobile horses can live perfectly well and remain functional.
We do need to carefully adjust the load to their capacity. Hypermobile horses need more time to become strong enough. They also remain vulnerable to awkward accidents in the pasture or paddock, but on the other hand, they do need sufficient exercise to keep their bodies healthy.
On the page “Training the hypermobile horse” we go into more detail about what these horses need in training.
