Stringhalt In Horses: Everything You Need To Know

As a horse owner, it can be more than a little unsettling for you to find that your horse isn’t able to walk or move around comfortably. One of the most common reasons for this is that your horse may have stringhalt, which is primarily a neurological condition that can cause them to kick or jerk their back leg (or legs) as they move.

Before you begin to panic, it’s important to understand what stringhalt is, what can cause the condition, and how it’s treated. Of course, learning more about the condition is just the first step. You’ll also need to contact your local equine vet for them to assess and diagnose your beloved riding companion.

But let’s take a closer look at the condition and what to look out for if you suspect that your horse is sick.

What is Stringhalt in Horses?

Stringhalt, or equine reflex hypertonia, is a neuromuscular condition observed in horses which leads to a gait abnormality in the hind legs. Usually, the condition can affect one hind limb or both and can vary in its degree of severity.

Typically, mild cases of stringhalt in horses cause sporadic lifting and lowering of the hind leg while the horse is walking. However, more severe cases can cause full spasms of the hind legs, where the horse will raise its foot towards its stomach before stomping it onto the ground.

When a horse develops stringhalt, the abnormal gait is most obvious when it’s walking. But when the horse is trotting or cantering, it may be less obvious to riders and owners.

Stringhalt can appear in horses of all ages and breeds, and the exact cause is usually difficult to determine. In some cases, it may be a direct result of ingesting toxic plants, while in other cases, it seems to develop out of nowhere.

Clinical Signs of Stringhalt in Horses

The clinical signs of stringhalt can vary in their severity and presentation. However, there are a few things to look out for that may help you to identify the signs early on. The clinical signs include:

• Involuntary or exaggerated upward movement of the hind legs: Horses affected by stringhalt usually exhibit a sudden or exaggerated flexion of the hind limbs. This is particularly noticeable when they are walking at a steady pace.
• Hopping or jerking: The movement of the horse’s hind leg may be a momentary movement that can be characterized as a jerk, hop, or jump. The hind limb is also usually pulled up high, toward the stomach area.
• Kicking upwards: In some cases, a horse with stringhalt may accidentally kick their stomach as a result of the movement. However, this is more common in severe cases.
• Incoordination or dragging of the hind hooves: Stringhalt may cause a lack of coordination in the back legs, which can lead to the horse dragging or having difficulty lifting or lowering their hooves as they step.
• Muscle atrophy in the lower leg: In more severe instances where peripheral neuropathy has occurred, there may be neurogenic muscle degeneration and atrophy of the hindlimb muscles, particularly the gaskin or the rump.
• Inability to stand: When the condition is left untreated, your horse may struggle to stand on their own. This can limit their mobility and cause discomfort in the horse.

Classic Stringhalt

Classic stringhalt, also known as true or idiopathic stringhalt, usually occurs in older horses and has uncertain causes and progression. It also typically only affects one hind leg, making it a unilateral condition.

Unlike some other conditions that are seen in horses, idiopathic stringhalt doesn’t seem to affect any specific breed or be linked to specific activities, which makes it even trickier to discern a root cause. However, one of the possible causes of idiopathic stringhalt seems to be evidence that links to an injury to the lateral digital extensor tendon or dorsum of the metatarsus.

In horses with classic stringhalt, the nerves that are responsible for transmitting impulses and triggering certain muscle contractions in the back legs are affected. The damage to the peripheral nervous system is what leads to abnormal muscle contractions, which results in the clinical signs that lead to a diagnosis.

This type of stringhalt can be difficult to treat, and affected horses aren’t able to recover without intervention. So, if you notice your horse exhibiting any stringhalt symptoms, you’ll need to consult with your local equine vet.

Pasture-Associated Stringhalt (PSH)

Pasture-Associated stringhalt (PSH), also known as acquired stringhalt or Australian stringhalt, is a specific type of stringhalt that is linked to the ingestion of toxic plants called Flatweed or Hypochaeris radicata. In some regions, this plant is also known as Catsear or False Dandelion.

Australian stringhalt outbreaks usually occur in a distinct seasonal pattern, during the late summer and early autumn. Although the condition has the common name ‘Australian stringhalt’, it’s important to remember that this can affect horses all over the world, including Europe, New Zealand, and the United States.

Horses that suffer from this condition show signs of excessive and prolonged flexion in their back legs, which results in tell-tale symptoms when they move. The severity of the condition can vary, depending on how many of the toxic plants were ingested, and recovery may take around 6 months or as long as 24 months.

Unlike true stringhalt, this variation of the condition can also affect the nerves in the horse’s larynx, or voice box, which can cause unusual vocalizations like wheezing or high-pitched noises when the horse inhales.

Luckily, this is often a temporary condition, with many horses being able to recover spontaneously after the summer or autumn seasons. In some cases, an affected horse can also make a significant improvement as soon as they are removed from the pasture where these plants grow.

How to Treat Stringhalt in Horses

The treatment for stringhalt varies depending on the type and severity of the condition. For example, horses suffering from Australian stringhalt may only need to be removed from the pasture that has toxic plants and be given a well-balanced and high-quality diet. After this, they may make a full recovery after a few months to two years (if the case was severe).

While some of these horses can also make a spontaneous recovery, the damage can be permanent in horses that are severely affected. Similarly, dysfunction or damage to the larynx in these horses may also be permanent if it’s associated with paralysis. For this reason, swift action and treatment by a veterinarian is extremely important.

For true stringhalt, treatment is much trickier. Although there are options for surgeries, it’s important to remember that most of the horses with this condition aren’t able to make a full recovery. In fact, without surgery, it’s impossible for the horse to recover. Additionally, relapses of true stringhalt are common, even during the recovery phase.

Lateral Digital Extensor Myotenectomy

Surgery can be a treatment for progressive cases of stringhalt, with the aim of treating the abnormal movements of the back leg. This surgery is called a lateral digital extensor myotenectomy and involves removing the lateral digital extensor tendon along with a portion (usually around 7 – 10 centimetres) of the belly muscle.

The success rate of the surgery can vary depending on the severity of the case, and it’s unlikely that the horse will make a full recovery. Still, although the surgery isn’t a cure for the condition, it can help to ease the symptoms, which will allow the horse to live and move more comfortably.

Watch this video to see the clinical signs of Stringhalt

FAQs

Can horses with stringhalt be ridden?

Horses with stringhalt can usually be ridden, but it depends on how severe the condition is and whether the horse is uncomfortable or in pain. Because this condition affects the movement of the back legs, it can make riding difficult and even potentially dangerous for the rider and the horse if these movements are particularly jerky.

Before you ride a horse with suspected or diagnosed stringhalt, it’s important to consult with your local equine vet and assess the severity and cause of the condition.

Can stringhalt in horses be prevented?

For cases of PSH, you can usually prevent the condition by assessing the fields and pastures for any signs of toxic plants that may be harmful to your horse. You can also remove your horse from the pasture if it starts to exhibit any of the symptoms of stringhalt or other abnormal behaviours.

On the other hand, cases of true stringhalt usually don’t have a direct or known cause, which means it’s impossible to prevent. Still, giving your horse a well-balanced diet and getting regular checkups to assess their health may help you to catch the condition early if it arises.

Is stringhalt contagious for horses?

Since stringhalt isn’t caused by a virus, bacteria, or any other infectious agent, it’s not contagious in horses. In fact, the most common type is idiopathic stringhalt, which means that it is neurological in nature. While it can sometimes occur in horses of the same herd, this is often due to the horses being kept in the same field with the same toxic plants.

Is stringhalt painful for horses?

Depending on how severe the condition is, stringhalt can range from uncomfortable to painful. In PSH, most horses only exhibit some signs of discomfort, but these signs will usually fade following treatment or removal from their current pasture.

Horses that are affected by idiopathic stringhalt, on the other hand, can sometimes exhibit signs of extreme pain and discomfort. If the horse is unable to stand on its own or move around, its muscles may start to seize, which is the leading cause of discomfort. Additionally, some horses with intense muscle spasms in the affected leg may end up kicking themselves in the stomach, which can be painful.