Hoof Health - The Difference Between Laminitis and Founder
Although used interchangeably, laminitis and founder mean two slightly different things. But horse owners and lovers know they are horrible conditions with uncertain and often lengthy outcomes. There are a few critical differences between laminitis and founder, which happen as this disease progresses.
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The Basic Difference Between Laminitis and Founder
- Laminitis is swelling of the laminae. The laminae is the sensitive soft tissue surrounding the coffin bone (also called the P3, distal phalanx, or the pedal bone) and attaching it to the hoof wall.
- Founder in horses happens when the laminitis damage allows the coffin bone to shift, rotate, or drop. Some coffin bones may rupture the sole of the hoof.
- Laminitis does not always end in founder, but founder always begins as laminitis.
Laminitis in Horses: The Basics
Horses develop inflammation of the laminae due to a few reasons:
- They have an injury in one leg that adds stress to the other. Over weeks and months, this can become standing limb laminitis.
- Fevers, retained placentas, and diseases like Potomac Horse Fever create whole-body inflammation that triggers laminitis.
- “Road founder” happens as a result of concussion, usually on hard surfaces. It can happen after one event or over time.
- Exposure to black walnut shavings is another cause.
What a horse eats AND how they eat (slow vs. fast) impacts the risk of laminitis and founder.
Metabolic disorders, sugars, and starches
- The most common reason for laminitis developing is an underlying metabolic issue that interferes with insulin regulation, such as pituitary pars intermedia dysfunction (PPID or Cushing’s disease), equine metabolic syndrome (EMS), or insulin resistance (IR).
- When sugars and starches digest in the hindgut of a horse with metabolism disorders, the resulting changes to pH in the gut trigger laminitis more easily than that of a non-metabolic horse.
Sugars and starches
- Overeating lush pasture, horse feeds, grain overload, or any other overdose of sugars and starches can trigger the onset of laminitis. The horse’s body can’t handle the digestive upset, regardless of a horse’s metabolic changes. Grass founder is the colloquial term for horses that get mild inflammation of the laminae to severe laminitis cases due to lush grass or breaking into the feed room.
What happens during laminitis
- The laminae are a series of folded tissues between the hoof wall and the coffin bone. They essentially keep the hoof bones in the correct position and help support the horse’s weight.
- When the laminae swell, the blood flow to the hoof is compromised. Tissues need blood flow and oxygen to stay healthy, and that’s not always possible with decreased blood flow. Additionally, the solid hoof wall prevents the swelling from “escaping.” This inflammation causes severe pain and lameness.
Defining Founder in Horses
- As laminitis lingers or progresses, the damaged laminae cannot fully support the horse’s weight and keep the coffin bone in alignment.
- There are other forces at play, too. A horse’s lower leg walks, trots, and canters due to the action of several tendons and ligaments. Of particular note is the deep digital flexor tendon (DDFT). This tendon attaches to the underside of the coffin bone and brings the hoof and leg backward. It flexes the hoof, lifting it off the ground.
- As laminitis continues, the tension in the DDFT continues. With unstable laminae, the DDFT can pull the coffin bone down and back, even when the hoof isn’t walking. This rotation, sinking, twisting, or shifting of the coffin bone is equine founder, and the DDFT assists it.
- You will see an increase in pain, and in some cases, you begin to see the outline of the coffin bone on the sole of the hoof. It might break through the sole.
You can see how the DDFT attaches here. The tension creates movement of the coffin bone with damaged laminae.
Early Signs and Symptoms to Watch For
The annoying thing about hoof problems in horses is that they all appear the same. If you see any of the following, call the vet for a proper diagnosis and treatment plan:
-
- Lameness
- Hot hooves
- Increased digital pulse
- Resistance moving forward
- Unease when picking hooves
- Hesitation when turning or moving from soft to hard ground
- Colic-like symptoms
- An unusual stance
- Increase vital signs, especially pulse and respiration rate, signal extreme pain
- The hair around the coronary band pointing out or up
These signs are your horse’s way of telling you there is:
- An abscess
- Hoof bruising
- Laminitis
- Soft tissue injury
- Severe white line disease, also called seedy toe
- Thrush
- Colic
- Your horse’s best chance for a complete and fast recovery is to have your vet out for a diagnosis and plan as soon as possible when you see clinical signs of hoof trouble. By the time your horse is screaming, “I HAVE LAMINITIS,” the damage is severe, and the risk of the founder is much greater.
You can see a line across this hoof that indicates a health interruption. There’s also seedy toe and some smaller cracks to contend with.
FAQ – The Difference Between Laminitis and Founder
Does laminitis lead to founder?
It can. Founder is the terrible sequel to laminitis. As the swelling and blood flow compromise continues, the laminae will continue to deteriorate, and the DDFT will continue to exert force to move the coffin bone creating the rotation.
How do you prevent laminitis?
The first step to preventing hoof problems is understanding your horse’s metabolic status by testing them periodically. Feed a low-sugar, low-starch diet, ice their hooves after exercise, be mindful of the footing they live and exercise on, and use grazing muzzles to slow down pasture eating. Add in preventative and regular farrier care, and know how to check your horse’s digital pulses.
What does equine founder do in the long term?
A horse with founder may suffer from long-term pain, recurring bouts of acute laminitis, repeated abscesses, and generally a lower quality of life. Long-term stall rest and supportive care can only go so far. Many severe cases of founder result in euthanasia to spare the horse further pain, more rotation of the coffin bone, and more damage to the hoof structure.
What happens to the hoof over time after founder?
Many horses will have permanent lameness and changes to the hoof capsule anatomy. You can see growth rings on the hoof wall, indicating times of distress. There may be episodes of laminitis, like a flare. A foundered horse must maintain a healthy weight, a low-sugar diet, and pain management over time. Founder isn’t limited to older horses, and is not exclusively specific to the front or hind hooves.
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