The Ins and Outs of Equine Laminitis with Dr. Kirstin Park
Have you ever heard the saying “no hoof, no horse?” Laminitis, often referred to as founder, is one of the most important diseases to be aware of as a horse owner as it is one of the most catastrophic. This disease can result in a vast spectrum of consequences from temporary loss of use to career-ending or life-threatening circumstances. It can happen to any horse at any time, although certain genes do predispose breeds such as Quarter Horse, Morgan, Saddlebreds, Arabians and any pony breed.
Before we get into the details of the disease, it is important to first understand the anatomy of the hoof to have a better idea of why laminitis is so threatening for many horses.
The hoof wall surrounds and protects the lower part of the short pastern, the pedal and navicular bones, as well as the lower part of the deep digital flexor tendon. The hoof wall grows downwards from a band of tissue called the coronary band or coronet.
Horses bear weight on their coffin bone (otherwise known as the third phalanx/P3/pedal bone/distal phalanx). The coffin bone is covered in a soft tissue structure called the corium, which is responsible for providing nutrition to the hoof. The outermost layer of the corium forms microscopic finger-like projections often referred to as “sensitive” laminae due to their vascularity and nerve supply. On the inner edge of the hoof capsule lie “insensitive” laminae and the two layers of tissue anchor the coffin bone to the hoof wall by interlocking like velcro, essentially suspending the horses weight inside the hoof capsule. An extension of this region of attachment can be seen on the ground surface of the hoof, and is commonly referred to as the white line.
To further understand this disease and it’s process, we asked Westhills own Dr. Kirstin Park to answer some of the most common laminitis questions!
What is laminitis?
Laminitis means inflammation of the laminae. It can be acute (short term) or chronic. When laminitis occurs, the tissue becomes inflamed and lacks strength. In mild cases, prompt diagnosis and treatment can resolve the episode. However in severe or chronic cases, due to the inflammation causing lack of strength in the laminae that suspend the pedal bone, it can sink or rotate within the hoof capsule and cause fatal/irreversible damage. If laminitis is suspected, prompt veterinary assessment and treatment is essential to preventing long term effects and achieving a good outcome.
What are the common signs of laminitis?
Shifting weight on front or back limbs
Heat in feet and elevated digital pulses.
Lameness (often front feet, can be all 4, rarely just hinds)
Stiffness, reluctance to move
Depressed attitude, quieter than normal, not interested in feed etc. May show a facial “grimace” / painful facial expression.
Laying down/increased time spent in recumbency
“Rocked back” stance - pending severity (often noticed first when asking horse to turn, however can be just at rest too). This is the result of the horse trying to get weight off it’s front limbs.
Careful foot placement/walking on eggshells.
Not picking up front feet, quick short steps (not wanting to have feet off ground for long)
Hypermetric movement (more common with hindlimb laminitis cases)
Hoof specific signs that may indicate chronic laminitis, or previous laminitic episodes:
Rings in the hoof wall that become wider as they are followed from toe to heel
Dropped soles or flat feet
Dished hooves – the result of unequal rates of hoof growth
Seedy toe – a widened white line, with the occurrence of bruising, recurrent abscesses, etc.
Stone bruises or bruised soles, especially at the toe
What causes laminitis?
There are three main groups of laminitis causes:
Endocrine associated laminitis:
Equine metabolic disease (EMS) and equine PPID/Cushings both predispose to laminitis.
Dietary causes of laminitis can sometimes fit into this category too - too much rich pasture/high sugar grasses (eg fresh spring grass), high carb/sugar diet, high body condition score (BCS)/overweight horses.
2. Septic/systemic inflammatory (endotoxemia) - Diseases which cause bacteria, or bacterial toxins, to spread through the blood.
Severe systemic illness/infections (severe infection, colic, diarrhea. eg Potomac horse fever)
Retained placenta
Grain overload/severe carbohydrate overload, ingestion of toxic materials.
3. Limb overload/Support limb laminitis
Severe lameness on one side/limb can lead to excessive weight bearing on the “sound” leg - this can cause the “sound” leg to develop laminitis. This occurs due to increased stress on the limb, along with decreased perfusion/blood flow to the foot/laminae.
Mechanical laminitis can also occur - neglected hoof care/lack of trimming, severely long toes/poor foot shape, etc.
How do you diagnose laminitis or it’s cause?
Clinical signs
X-rays of the feet are strongly recommended in any case of laminitis. In very new/acute cases, there may not yet be any visible changes as it can take anywhere from 3 days to 2-3 weeks to be visible. Radiographs allow assessment of foot angles and coffin bone location (is there any sinking or rotation?). Chronic changes to the coffin bone may also be visible from previous laminitic episodes.
Blood testing, like insulin/glucose or ACTH, is often recommended to check for metabolic conditions that may be predisoposing the horse to laminitis.
Hay/feed analysis may be indicated to assess levels within the feed.
In severe cases with suspected coffin bone compromise, or significant changes within the foot, a venogram can be performed to assess blood flow/perfusion within the foot.
How can we treat laminitis?
The mainstay of laminitis is supportive care - providing pain relief, supporting the hoof and helping to reduce pressure on the hoof wall/laminae, etc. If you are concerned your horse may have laminitis, it is important to see a vet right away - they can assess the severity, provide pain medication, and formulate a treatment plan. Prompt treatment can be the difference between permanent rotation or sinking of the coffin bone.
Pain medication - different medications are prescribed based on the severity of pain. There are several anti-inflammatory/pain medications we commonly use for laminitis. Typically bute, and/or a combination of other medications. We want to get the inflammation under control as quickly as possible!
The next most important thing is supporting the foot - deep bedding, padded stalls, soft footing like sand etc - allows some of the horses weight to transfer through the sole and take some pressure off the wall. The horse can also adjust the position/angle of their foot to whatever is comfiest for them.
Padding the feet with a cushioned boot (eg soft rides), special shoes, styrofoam pads etc, can also help to provide some comfort and support.
Strict rest is essential - any movement can result in increased stress and damage to the laminae when they are in such a fragile state.
Diet/weight loss - a low calorie diet is important. Remove any grass from diet and only feed soaked hay or cubes (must be low in sugars).
Typical recommendation is 1.5% of horses body weight in dry forage/hay. Soak hay for at least 4 hours to remove sugars, and discard the water before feeding. Spread out over several feeds, and use slow feed hay nets or double nets to increase the time taken to eat. A low calorie balancer like Buckeye Safe N Easy can be used to ensure the horse is still receiving key vitamins and minerals.
Icing/cooling the feet may be beneficial, depending on the cause of the laminitic episode.
Farriery:
In early treatment, the goal is to stabilize the coffin bone by providing support to the foot and adjusting biomechanics if warranted.
For more chronic cases, or any case where rotation/sinking of the coffin bone has occurred, regular remedial farriery is key for minimizing further coffin bone rotation/sinking. These cases can end up in special shoes/clogs for months to years.
Although the above treatments help to support the horse and manage clinical signs, they will not always treat the cause of the laminitic episode. It is important that the cause of laminitis is determined, and any predisposing factors should be addressed (eg diet), otherwise treatment is often unsuccessful and recurrence is likely.
Is my horse at an increased risk for laminitis?
Any horse can be at risk of laminitis. However, as stated eariler, there are certain factors that can predispose to the disease, including:
Breed (morgans, ponies, minis, anything “easy keeper”, QHs, etc.)
Overweight/high BCS
Injury to opposite limb
Illness (colic, retained placenta, severe infection)
Endocrine conditions (PPID/EMS)
Previous history of laminitis
High carb/sugar diet
Foot shape/conformation, lack of farrier care/neglected hooves
Sometimes - no great reason at all!
How can I prevent laminitis in my horse?
Maintain a healthy body condition. Keep an eye out for “fat pads” over the shoulders, ribs, and hindquarters - this can be a sign of metabolic disease, or obesity. A weigh tape can also be used for monitoring weight.
Addressing any PPID/EMS - Talk to your vet about endocrine testing and treatment if the horse shows any signs of endocrine disease.
Maintain a balanced diet and exercise.
Contact your vet for an exam and nutrition plan if your horse is either under or overweight.
Be cautious with turnout on rich grass, especially in spring.
Short grass can be worse than long grass as the sugars are very concentrated in the grass, and it is often lower in fiber.
Regular farriery with appropriate trimming of the feet. Long toes = larger breakover = more pressure/pull on laminae
Prompt vet involvement and early treatment of severe lameness, and suspected systemic illness/infection (eg for retained placenta, systemic illness, severe grain overload etc)
Thank you to Dr. Kirstin Park of Westhills Equine Veterinary Services for her detailed description of equine laminitis, a serious but very preventable disease.
Dr. Kirstin Park
Westhills Equine Veterinary Services