Founder In Horses

Updated 19/09/2023

If your horse is experiencing lameness, there could be a chance they’re suffering from founder, otherwise known as laminitis - something you should also get clued-up on if you're horse sitting, as a precautionary measure.

Here, we explore what founder in horses is, the symptoms, treatment, prevention, and some of the questions often asked about the condition.

If your horse is experiencing any of the symptoms of laminitis in horses we discuss, make an appointment with your vet as soon as you can or contact our vet advice line if you’re not sure. Laminitis in horses is a serious condition that causes extreme pain and can sometimes be fatal. So, the sooner you involve your vet, the better.

While being the pet parent of a horse is a full-time job, you might never have considered leaving them at home while you jet off. While we wouldn’t recommend leaving a horse with suspected founder, you could consider welcoming an animal sitter if your horse is healthy and you need a break! Here’s how to find a sitter.

What is founder in horses?

A horse with founder has inflamed laminae inside the hoof which can rotate the pedal bone (otherwise known as the coffin bone). This results in extreme pain, a lack of movement and sometimes life-long issues. What’s the laminae, though? And why does the inflammation of it cause problems? Let’s take a look…

A horse with founder has inflammation of the laminae inside the hoof. This can lead to rotation of the pedal bone (the coffin bone – the lowest bone within the foot). Both of these can lead to extreme pain, uncomfortable movement and lifelong issues.

Inside the hoof of a horse is bone and laminae. Laminae are finger-like pieces of tissue that, when working as they should, hold the hoof wall onto the horse’s foot (which contains the pedal bone). When these elements are healthy, they allow the horse to stand, walk, run, and get on with all daily movements.

The normal hoof of a horse contains the lowest bone (the pedal or coffin bone), and the hoof you can see is attached to the bone on the inside by finger-like pieces of tissue called laminae. When these elements are healthy, they allow the horse to stand, walk, run and get on with daily life, and allow the hoof to grow downwards naturally from the coronary band (the top of the hoof).

If the laminae become inflamed, it can cause the horse to become lame in the leg of the affected hoof, meaning restricted or no movement. This inflammation can occur due to reduced blood flow to the laminae which causes it to swell, and results in inflammation. If the inflammation persists, the cells of the laminae become damaged due to the lack of oxygen and nutrients travelling through the blood vessels and reaching them.

This causes serious pain (a bit like a worse version of when we crush a fingernail) and hence lameness and reduced movement in the leg of the affected hoof. Inflammation can occur for a number of reasons but largely results in reduced blood flow and associated swelling of the laminae. If this persists, the cells of the laminae become significantly damaged due to a lack of nutrients and oxygen reaching them via the bloodstream.

A prolonged lack of nutrients to the laminae can eventually cause them to die off. This means that the pedal bone no longer has any support and loses its connection to the hoof, meaning the weight of the horse can no longer be held up and the pedal bone can collapse and rotate downwards away from the hoof. In extremely unfortunate cases, this can cause the pedal bone to poke through the sole of the foot, causing irreversible lameness and awful pain.

Causes of founder in horses

Diet

Horse founder can be caused by a diet containing large amounts of simple sugars and carbohydrates, like starch. Excessive carbohydrates drive abnormal digestion and metabolism and this can reduce blood flow to the hooves. Sudden excesses of carbohydrates (such as when a horse breaks into a feed store) are also a major risk factor for laminitis.

Overeating

Horses are wired to chew, so if too much food is in front of them, it’s likely they’ll eat it. An overweight or obese horse will have far more pressure on their ligaments and joints which can cause restricted blood flow and inflammation which can lead to laminitis.

Insulin resistance

Like other mammals, horses can develop insulin resistance, which is similar to (but not exactly the same as) diabetes in humans. Insulin plays a huge role in the health of the laminae, so a resistance to this and subsequent metabolic problems can result in horses developing founder (although it’s not guaranteed that your horse will develop founder if they’re insulin-resistant). Insulin resistance is known as EMS (equine metabolic syndrome) in horses and can be also associated with PPID (Cushing’s disease). Reduce the chances of your horse getting laminitis by reducing grains and sweet foods from their diet, paired with lots of exercise.

Pregnancy

Weight gain can result in founder, so the added weight that pregnancy brings as well as the hormones released during gestation can cause founder. Pregnancy can also cause horses to become insulin-resistant, which can make them more likely to develop laminitis.

Medications

Overuse of steroids and other medications can cause laminitis over time. If your horse is fed a diet high in carbohydrates and they’ve been on steroids for an extended period, they could be more likely to develop laminitis than horses on a healthier diet.

Exposure to black walnuts

Black walnuts contain a toxin that’s pretty harmful to horses. It’s also present in their tree, bark and leaves, and prolonged exposure to black walnuts and the plant can result in chronic laminitis.

Breed of horse

Some claim that the type of horse you have will affect their likelihood of developing founder. Dakota Hills Veterinary have said that horses more likely to get laminitis are Ponies, Arabians, Quarter horses, Paints, and Morgans. Some ponies and horses are also more likely to put weight on and this can then subsequently increase their risk of laminitis.

Exercise surfaces

Horses ridden too hard and fast can be more likely to develop acute and chronic laminitis if care hasn’t been taken. When considering how to best care for your horse’s feet, think about what sort of surface they’ll mostly be riding on. This will help your farrier decide which shoes are most appropriate for them, helping to protect their hooves and reduce impact when riding. And while exercising on hard surfaces can’t always be avoided, be sure to balance it out with a soft surface to run and play on as well. Hard surfaces are one possible cause of trauma to the hooves, and trauma is an important risk factor for laminitis.

Colic surgery and other medical issues

While it’s unlikely, some surgeries and types of infection are associated with a medical condition called endotoxemia (similar to sepsis in humans), which can then lead to laminitis. There are preventions available though, so be sure to check these out with your vet before your horse is due to go into surgery.

Nail length

Nails that are too long can cause your horse’s feet to stand at an awkward angle, which can lead to founder. A lack of foot care, or poorly done foot care, can both predispose to laminitis.

Symptoms of founder in horses

If your horse has any of these founder symptoms, book an appointment with your vet as soon as you can. While they may not be diagnosed, laminitis can be seriously painful, so the sooner they’re checked, the better. Laminitis usually affects the front legs but can affect any leg.

Changes in gait. If your horse is walking differently to usual, get them checked for founder. Horses with founder will be very stiff and try and rock back on their feet (putting the weight on their heels and taking the weight off the front of their toes).
Swelling. If your horse has swelling around their foot and/or ankle, it could be a sign of inflammation and potentially founder.
Noticeable pulse in the foot area. Increased pulses at the back of the leg heading down to the foot are an important symptom. The hoof wall itself might also be hot.
Standing with their front legs extended forward rather than straight. This is known as ‘sawhorse stance.’
Unwillingness to move. Some horses are so sore they will not move at all.
Visible pedal bone sticking out from the bottom of the foot (in very severe cases). This is an emergency scenario.

Types of founder in horses

Founder can be acute or chronic - let’s take a look at what each of these refer to, and what you can look out for.

Acute founder in horses

It’s a seriously painful condition for your horse and can even be life-threatening in some cases. Horses with acute laminitis might become suddenly lame along with increased heat in the hoof wall, along with sensitivity over the horse’s toes. You might also notice an increase in your horse’s digital pulses. This is the pulse that can be felt (and sometimes seen, if your horse has laminitis) at the back of the leg on both sides at the bases of the splint bones, as the blood moves through the artery and into the hoof. If the laminae or tissues in the leg are inflamed, the blood flow becomes restricted which makes the pulse stronger, easier to feel and sometimes visible.

Chronic founder in horses

Chronic laminitis describes the damage that acute laminitis has caused which hasn’t been corrected, i.e. the movement of the pedal bone caused by inflammation from the acute stage. Symptoms of chronic laminitis include widening of the white line, horizontal rings on the hoof wall, and a sinking or flattened look to the sole of the horse’s foot. Chronic laminitis is still sore but is not usually as severely painful as acute laminitis, and is not as potentially life threatening.

Diagnosis of founder in horses

When diagnosing your horse, if your vet suspects founder, they’ll ask you a series of questions that’ll help them to understand your horse, their history, and therefore their condition better. They’ll ask about your horse’s age, whether they’re considered overweight for their breed and height, how much grass and grain is in their diet, whether their diet has changed recently, whether they’ve suffered from another condition recently (such as colic or lameness), and finally they’ll also want to know about any medications your horse is currently taking, or has recently been on.

Your vet will then examine your horse, looking for lameness to help with the diagnosis. They might get your horse to have a walk around to test the length and speed of their gait, along with their ability to walk in a circle in both a clockwise and anti-clockwise direction.

They’ll also check for the presence of visible pulses traveling to the horse’s hoof - a horse with laminitis has restricted blood flow to this area due to swelling. So, if the digital pulse is visible, it’s a key indicator of inflammation, swelling, and therefore potentially foundering in your horse.

The vet will also test the sensitivity of your horse’s hoof, as soreness in this area can be a symptom of laminitis. This is because a foundered horse will have a rotated pedal bone which comes closer to the sole and can lead to soreness and sometimes extreme pain.

Radiographs (x-rays) will then be taken so that the vet can decide whether your horse has founder or not. A horse with chronic founder will have a rotated pedal bone, but those with acute founder may not. That’s because the cells of the laminae may not have degenerated enough for the bone to twist yet. X-rays help plan treatment and footcare.

What treatments are there for founder in horses?

Here we’ll describe some of the common treatments used by vets for horses with founder.

Common treatments used for acute founder

Non-steroidal anti-inflammatory drugs can help to reduce the inflammation around the horse’s hoof which can reduce swelling, increase blood flow and therefore nutrients to the laminae. These also relieve the intense pain of laminitis.
Drugs to increase blood flow are sometimes prescribed.
Ice boots or cold hosing are sometimes used to reduce inflammation, especially in the first few days. Cold hosing twice a day can be a great help to cool down the feet.
Rest to help your horse heal and reduce discomfort during an episode of acute founder. Rest is absolutely essential to give the laminae time to heal. Affected horses should be strictly rested for at least 6 weeks after an attack, not just until they seem better. Stabling with a deep, comfortable bed is important.
In some cases, bandaging the affected feet with soft supports can help take the pressure off painful toes and improve comfort.
Diet changes such as decreasing carbohydrate intake. Reducing simple sugars by feeding a healthier diet makes a big difference. Hay nets can be soaked overnight to dissolve simple sugars and just leave the complex, healthier sugars in there for your horse.
Change in medication.
Weight loss if necessary.

Common treatments used for chronic founder

Weight loss if necessary, alongside improvements in diet
Stabilisation and pain management. This may need to be long-term.
Corrective shoes. Having a good farrier is vital!
Heel cuffs or foam supports.
Surgery is sometimes considered as a last resort in some serious cases.

After care for foundered horses

As we’ve seen, founder in horses is often caused by another issue or condition, like insulin resistance. If the condition that’s caused founder in your horse is treatable and the acute founder hasn’t progressed to chronic, then your horse may be able to make a recovery. The most important thing to do is to look out for the signs discussed, and make an emergency appointment with your vet if you suspect founder.

Manage your horse’s diet, reducing carbohydrates and sugary foods to help prevent any further issues with founder. Horses with chronic founder can be in extreme pain, causing life-long lameness. Often, medication is diagnosed in these cases to help with pain management, and it’s recommended that the horse rests as much as possible. Together with your vet, you can decide whether euthanasia is needed, depending on how much severe pain your horse is experiencing.

What can be done to prevent founder in horses?

Don’t overfeed your horse - if you’re not sure how much you should be feeding them, ask your vet.
Avoid a high-carbohydrate and sugar-intensive diet.
Avoid grain overload.
Invest in proper horse shoes appropriate for the sorts of riding they’ll be doing.
Make sure they’re seen for regular check ups with the farrier to make sure the shoes are protecting your horse’s feet properly.
Avoid running and exercising on only hard surfaces.
Get your horse’s nails trimmed regularly, especially if they ride without shoes.

Meet our veterinary expert, Greg

This article has been checked by veterinarian Dr Greg Steele MA VETMB MRCVS. A mixed vet working in the UK since qualifying from Cambridge University in 2015. Greg enjoys working with all species of animals in all settings, but equally takes pride in communication and education of clients too. He lives with his wife and their cat, and enjoys a variety of sports, gardening, and the great outdoors.