Equine laminitis is a painful condition affecting the horse’s hooves. Cases of laminitis range in severity from mild foot tenderness to chronic founder, potentially impeding the horse’s ability to walk and decreasing quality of life.

Laminitis is the bane of any horse owner’s existence. Horses affected by laminitis suffer excruciating pain as the soft hoof structures, known as laminae, become unstable.

While laminitis does not usually kill horses, per se, owners may make the decision to euthanize if the prognosis is poor or treatments do not work. 7% of equine deaths are associated with laminitis in some way. [1]

Fortunately, most horses will recover from laminitis to some degree, but it can take time. Once recovered, the horse could be more short-strided than before laminitis struck.

Laminitis is always an equine emergency. Call your vet immediately if your horse develops symptoms of this potentially life-altering condition. Prompt treatment can often prevent further damage when caught at an early stage.

The most important thing in any case of laminitis is to identify and remove the cause.

What is Equine Laminitis?

The term laminitis literally means inflammation of the hoof’s laminaebut not all types of laminitis actually have inflammation as a key feature. The laminae within the hoof keeps the coffin bone adhered to the hoof wall.

The coffin bone, also known as the distal phalanx or third phalanx, is totally encased within the hoof and provides attachment for the deep digital flexor tendon.

In laminitis, the laminae elongate and weaken then may start separating. Should separation occur, the coffin bone loses support and rotates side-to-side and/or downward. A rotated coffin bone puts focal pressure on the sole and its blood supply and nerves.

In the worst-case scenario, the coffin bone loses all laminar support. The coffin bone can sink and even rupture out the sole of the hoof. Recovery from penetration is possible but takes a prolonged course of intensive nursing.

 
Healthy vs. Laminitic Horse Hoof

Although laminitis is a disease of the hoof, the events leading to laminar breakdown have their origins in the animal’s immune system, gastrointestinal tract, or endocrine system.

Once a horse develops laminitis, recurrence is possible. Careful management is key to preventing recurrence and keeping the horse as sound as possible.

Some horses will recover fully from a bout of laminitis, and others may prove serviceably sound for less demanding work. There are horses who never regain soundness after laminitis. In some equines, it becomes a chronic issue.

Signs and Symptoms of Acute Laminitis

Laminitis is a painful condition. If your horse exhibits reluctance to walk, is laying down frequently, “walks on eggshells”, or acts like they’re trying to shift weight off their forehand standing or turning tightly, you should suspect laminitis.

Although all four hooves can be affected, laminitis is more obvious in the front feet because they bear more of the horse’s weight.

Signs of laminitis include:

  • Heat in the hooves
  • Increased digital pulse
  • Sensitivity to hoof testers, particularly over the toe
  • Reluctance to move
  • Laying down more frequently
  • “Rocking back” or shifting weight off the forehand
  • Tentative walking on concrete or hard surfaces, particularly when turning tightly
  • Coronary softening
  • Rigid head carriage (either high or low) and loss of the normal swing to the back at the walk
  • Muscular tension in the shoulders, back and hindquarters

In the most severe cases, a bloody exudate may seep from the coronary band. The prognosis for equines who reach this point is poor.

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Chronic Laminitis

Horses with chronic laminitis sport telltale rings on the affected hooves. These rings correspond to abnormal hoof growth that occurs during laminitic episodes. They are usually wider at the heel than the toe.

There are horses who experience mild cases of laminitis that go undetected by caretakers, but the rings in the hoof will eventually appear if there is rotation.

With chronic laminitis, hoof walls may become dish-shaped and may display separation at the white line, referred to as seedy toe. If the coffin bone rotates, the sole will appear convex or bulges.

Horses with chronic laminitis are prone to frequent subsolar abscesses. Foot abscesses often occur in a single hoof, but you should always have your vet confirm your horses is indeed suffering from an abscess and not a recurrent episode of laminitis or other emergency.

Horses with undiagnosed and untreated metabolic syndrome will have internal changes in their feet but may not be suspected to be laminitic because they are not having an acutely painful episode. [5] In these cases, their first bout of “acute” laminitis is actually the culminating event of months or years of damage.

Founder vs. Laminitis

Laypeople often use the terms “laminitis” and “founder” interchangeably, but they are not synonymous. Founder occurs when the horse’s coffin bone has sunk or rotated, indicating a more severe or chronic case of laminitis.

Causes of Laminitis

There are three major types of laminitis:

Endocrinopathic laminitis

Endocrinopathic laminitis includes pasture-associated laminitis (“grass laminitis”), and represents 90% or more of cases. The cause of the abnormal lengthening and weakening of the laminae is high insulin. It has been established there is no inciting inflammatory response in this type of laminitis. [6]

Sepsis-associated laminitis

Sepsis-associated laminitis, which occurs in cases of severe systemic inflammation, is associated with serious illness and bacterial endotoxin production. Examples include salmonellosis, colic, bastard Strangles, Potomac Horse Fever, and retained placenta.

Laminitis caused by experimental fructan overload or the “horse got into the grain bin” scenario are also triggered by a systemic inflammatory response when bacterial byproducts gain access to the blood via a damaged gut wall.

Supporting limb laminitis

Support limb laminitis (SLL), the least common type of laminitis, occurs in horses suffering a non-weight-bearing lameness. Laminitis develops in the opposite supporting limb due to prolonged excessive weight-bearing. An example of SLL most people are familiar with is Kentucky Derby winner Barbaro, who was euthanized after developing laminitis in his supporting limb following surgery to repair his hindlimb fracture. [2]

Other scenarios that can trigger laminitis include: [3]

  • “Road founder” or excessive concussion on hard surfaces, more common in driving horses
  • Pregnancy-induced insulin resistance
  • Toxins entering the body, such as from a snake bite
  • Bedding on black walnut shavings. As little as 10% of black walnut residues in the bedding can result in laminitis. [4]
  • Ingestion of Hoary allysum plants on pasture or baled into hay
  • Tall fescue endophyte ingestion
  • Severe white line disease
  • High grade clubbed foot
  • Cephalosporin antibiotic use
  • Use of highly potent corticosteroids such as betamethasone may also predispose horses to laminitis by inducing insulin resistance

Risk Factors for Laminitis

While any equine may develop laminitis, some are more vulnerable than others. Risk factors for laminitis include:

Horses who have received high or long-term doses of corticosteroids are at increased risk of developing laminitis because these drugs induce insulin resistance. In particular, horses with pre-existing metabolic syndrome may develop laminitis with the use of any corticosteroid, including those administered by joint injection.

Animals with poor hoof or limb conformation also have a greater risk of this condition due to abnormal biomechanics.

Certain breeds and types of horses are known to have a higher risk of laminitis. These include:

As a general rule, the types of horses known as “easy keepers” run a greater risk of laminitis. That is because these are the equines most likely to have metabolic syndrome.

Keep in mind that any horse with free access to a grain bin who consumes a large amount of feed is a laminitis candidate. If you discover a horse who has gorged himself on feed, call your veterinarian immediately!

What To Do if You Suspect Your Horse is Laminitic

If your horse shows symptoms of laminitis, take the animal off pasture and stop feeding any grain at once. Call your vet immediately. Do not feed anything other than soaked grass hay until cleared by your veterinarian.

Liz Leahy, DVM, of Foundation Equine Wellness and Performance, Crosswicks, New Jersey, recommends that while waiting for the vet, to put the horse in a deeply bedded stall or small area with soft footing where movement can be restricted. The horse should not be forced to exercise.

Additionally, Leahy advises against owners giving any medications before consulting with their veterinarian.

Lastly, many owners are curious about icing the feet during laminitis episodes. Unless you’re able to keep the feet submerged in ice continuously (which is difficult to achieve even in hospital settings), it is best not to ice.

Icing after laminitis pain is evident may help dull the pain but could be contraindicated in endocrinopathic laminitis because they are already vasoconstricted and cold further impairs blood flow.

Diagnosis & Treatment Factors

Gather the following information for the vet:

  • Current diet, including any recent changes in diet
  • Whether this is the first incidence of laminitis or a chronic issue
  • Any current medical conditions, such as Pituitary Pars Intermedia Dysfunction (PPID) or Equine Metabolic Syndrome (EMS)
  • Current health status including if the horse is being treated for things like diarrhea, infection, or musculoskeletal injury
  • All current medications

Note that some signs of laminitis may be confused with other conditions. For example, standing with their hind legs underneath them sometimes leads to a misdiagnosis of hock pain. Being very familiar with your horse’s history can help achieve a more timely and more accurate diagnosis.

Treatment will depend on the cause of the laminitis. For example, a mare with a retained placenta must have the remaining placenta removed and her uterus flushed.

Use of NSAIDs

Non-steroidal anti-inflammatory drugs (NSAIDs) are universally prescribed for laminitis but are only therapeutic in laminitis related to a systemic inflammatory response.

NSAIDs are not very effective for controlling pain in endocrinopathic laminitis because the cause is not related to inflammation. In horses with endocrinopathic laminitis, there will be a clean-up inflammatory response if damage to the hoof tissue is present. NSAID use for the first few days is reasonable but should then be stopped.

Side effects of NSAIDs

Horses on NSAIDs are at risk of developing digestive complications, including gastric ulcers. Your veterinarian may recommend probiotics or other gastro-protectant medications to mitigate these side effects.

However, combining NSAIDs with omeprazole, the active ingredient in Gastrogard® is known to increase the risk of colon damage. [7]

If your horse is prescribed pain medication, veterinarians will recommend strict stall rest for horses for a specified period so that the horse does not move too much and do further damage.

Working With a Farrier

Good farrier care is essential for any horse. With a laminitic animal, it can mean the difference between life and the owner’s decision regarding putting the horse down.

Good farrier work, performed in conjunction with veterinary recommendations, can bring many horses back to a useful life.

After the veterinarian treats the immediate laminitic episode, the next step is a consultation between the vet and the farrier.

X-rays are necessary to assess the extent of the damage and show the degree of hoof rotation, providing a baseline for therapeutic farriery. No coffin bone rotation means that founder did not occur.

A trim with short toe and angle of the coffin bone with the ground no higher than 5 degrees is the goal. With rotation, a toe bevel can be used to move the hoof breakover back to where it should be and avoid strain on the laminae.

Barefoot with boots and pads works best because trim intervals of 2 to 3 weeks are advisable during recovery.

It is best to take a regular series of X-rays as the horse recovers to view bone remodeling or rotation. Changes may continue for months. These radiographs provide a way for the farrier to determine the best treatment for the particular horse.

Many types of corrective shoes and other devices are available but their success depends on achieving and maintaining a correct realigning trim.

Every animal is different, and the farrier may have to try a few methods before finding out what works best for that particular equine.

Medications

It is common for phenylbutazone and other NSAIDs to be prescribed for reducing inflammation in laminitis. However, they are not very effective in 90% or more of laminitis cases (endocrinopathic laminitis) where inflammation is not the root cause.

With those animals, controlling insulin is the most important “treatment”, along with getting an experienced hoof care professional to do a realigning trim.

The horse can be allowed turnout in a dry lot alone or with a quiet companion to move around at will. This improves circulation to the feet which is impaired by high levels of the vasoconstrictor, endothelin-1. [8]

Plenty of vigorous exercise is actually the best “medicine” for controlling insulin but many laminitic horses cannot be worked.

If a horse with high insulin also has PPID, diet control will not be enough. Those horses needed to be treated with pergolide. The correct dose is the one which keeps the ACTH levels well under control.

Some horses with severe metabolic syndrome do not have insulin levels return to a safe level with diet control alone and remain at risk for ongoing laminitis. These animals can be treated with metformin or drugs in the SGLT2 inhibitor class.

Metformin is a human antidiabetic drug which is being used in horses and works by improving insulin sensitivity. A dosage of 30 mg per kg body weight given twice a day can cause large drops in insulin within the first week of use. [12] Unfortunately for some animals it does not work at all while for others it loses effectiveness over time.

An alternative is the SGLT2 inhibitors: Invokana® (canagliflozin) or Steglatro® (ertugliflozin). These drugs work by blocking the reuptake of glucose in the kidneys, allowing more glucose to be lost in urine and effectively reducing the work that insulin has to do. They are highly effective in horses. [13][14]

However, SGLT2 inhibitors have a risk of high blood triglycerides and fatty liver because of fat mobilization. [22] This has to be managed by allowing free choice hay with beet pulp and in some instances the addition of certain amino acids to support fat burning and glucose levels.

Dietary Management for Laminitic Horses

Laminitic horses with metabolic syndrome will need careful, lifelong dietary management. A horse with known or suspected metabolic syndrome should be placed on the emergency diet described by the Equine Cushing’s and Insulin Resistance group. [#]

Endocrinopathic laminitis is caused by high intakes of starch or simple sugars (Ethanol soluble carbohydrates – ESC) triggering elevated insulin levels in equids that have metabolic syndrome. ESC plus starch is referred to as hydrolyzable carbohydrates (HC) – carbohydrates digestible in the small intestine. Equines with metabolic syndrome need HC limited to 10% or less of the diet.

The details of a low sugar (ESC) and starch diet with mineral balancing were described in 2004 and it remains effective today. [9] Although the feed industry is starting to recognize there is a need for extremely low sugar and starch feeds (under 10%), most bagged feeds and ration balancers are still too high.

NSC (non-structural carbohydrates) is an outdated and inaccurate way to look at the safety of hays for animals with metabolic syndrome. NSC contains fructans, which are a storage carbohydrate and do not cause an insulin response. It is the hydrolyzable carbohydrates (HC), which are ESC and starch, digested in the small intestine which determine insulin response.

If a horse owner knows their hay is high in simple sugars (ESC), they can soak it in warm water for one hour prior to feeding. Doing so should cause between 15 and 25 percent of the sugars to leach out.

The only way to know the HC content of your hay is to submit a sample for analysis. This will provide the starch and ESC content as well as the protein and energy content and mineral profile.

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Laminitis Prevention

Good management practices can prevent many cases of laminitis. All horses should have regular farrier care.

Many laminitis cases occur in the spring when horses with metabolic syndrome are allowed to graze on high sugar young grasses and/or high starch clover. Research has shown the risk of pasture-associated laminitis is related only to insulin levels. [10]

The lowest HC levels in pasture are in grasses which have grown to full height and dropped their seed. Some metabolic syndrome cases may tolerate limited grazing on those pastures but others cannot graze at all.

If you breed horses, keep careful track of the placenta after foaling. Contact the vet immediately if you suspect the mare has retained part of the placenta or if the placenta has not passed within 6 hours of foaling.

Finally, keep grain bins in a location where horses cannot get access. Should a horse escape the stall in the middle of the night, odds are he will head for the feed storage area.

The same holds true if the horses live out. If they get loose, the grain bin is a big attraction. This simple act of prevention can save you enormous heartache.

Meeting the Mineral and Vitamin Needs of the Laminitic Horse

Meeting your horse’s mineral and vitamin needs is critical when it comes to supporting laminitis recovery. Deficiencies in the diet can hinder hoof growth and exacerbate metabolic dysfunction.

Consider the mineral and vitamin supplement AminoTrace+, formulated to meet the needs of laminitic horses. It was designed specifically to support horses with insulin resistance, PPID, and EMS, conditions putting your horse at greater risk for laminitis.

AminoTrace+ contains higher levels of antioxidants, organic trace minerals, and other nutrients required to support hoof health and insulin sensitivity.

In particular, high levels of chelated copper and zinc in AminoTrace+ help to form the structural tissue that makes up the hoof. These essential microminerals work within the enzymes that crosslink collagen and elastin together.

Higher levels of copper and zinc are also needed to counteract the effects of excessive iron in hay. Iron overload is common in horses with metabolic syndrome. [11]

Amino acids are the building blocks of protein required to build strong hooves. AminoTrace+ contains the three most limiting amino acids in the horse’s diet, lysine, methionine and threonine, helping to ensure protein synthesis keeps up with your horse’s demands.

AminoTrace+ also provides 20 mg of the B-vitamin biotin, an amount which is clinically proven to improve hoof quality in horses.

Formulated in a low-NSC pellet with no added sugars, AminoTrace+ supplies nutrients necessary for your horse to fight inflammation and boost digestive health. AminoTrace+ is a complete ration balancer meaning there is no need to feed additional supplements with this product.

Wondering if this supplement is appropriate for your horse? Submit your horse’s diet for analysis online and Mad Barn’s nutritionists can provide personalized recommendations.

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  • Complete mineral balance
  • Supports metabolic health
  • Formulated for IR/Cushing's
  • Hoof growth

Other Supplements

Jiaogulan is a Chinese herb with a potent ability to stimulate the production of nitric oxide inside blood vessels. [15] This counteracts the high endothelin-1 production to support normal circulation in the hooves. Jiaogulan also supports the normal homeostatic regulation of inflammation. [16]

Acetyl-l-carnitine is a naturally occurring metabolite of L-carnitine. It has neuroprotective effects, including in various models of neuropathic pain. [17] Neuropathic changes have been found in chronic laminitis. [18]

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References

  1. What is Laminitis? Royal Veterinary College. University of London.
  2. Drape, Joe. Barbaro Is Euthanized After Struggle With Injury. The New York Times. January 20, 2007.
  3. Laminitis: Prevention & Treatment. AAEP. Accessed February 6, 2024.
  4. Horses and Black Walnut Shavings. OMAFRA. Accessed February 6, 2024.
  5. Johnson, P.J. et al. Laminitis and the equine metabolic syndrome. Vet Clin North Am Equine Pract. 2010
  6. Patterson-Kane, J.C. et al. Paradigm shifts in understanding equine laminitis. Vet J. 2018.
  7. Ricord, M. et al. Impact of concurrent treatment with omeprazole on phenylbutazone-induced equine gastric ulcer syndrome (EGUS). Equine Vet J. 2021.
  8. Gauff, F. et al. Hyperinsulinaemia increases vascular resistance and endothelin-1 expression in the equine digit. Equine Vet J. 2013.
  9. Kellon, E. Treatment of Equine Metabolic Syndrome. Compendium of Continuing Education for the Practicing Veterinarian. 2004.
  10. Menzies-Gow, N.J. et al. Prospective cohort study evaluating risk factors for the development of pasture-associated laminitis in the United Kingdom. Equine Vet J. 2017.
  11. Kellon, E.M. and Gustafson, K.M. Possible dysmetabolic hyperferritinemia in hyperinsulinemic horses. Open Vet J. 2020 .
  12. Durham, A.E. et al. The effect of metformin on measurements of insulin sensitivity and beta cell response in 18 horses and ponies with insulin resistance. Equine Vet J. 2008.
  13. Sundra, T. et al. Preliminary observations on the use of ertugliflozin in the management of hyperinsulinaemia and laminitis in 51 horses: A case series. Equine Vet Educ. 2022.
  14. Kellon, E.M. and Gustafson, K.M. Hypertriglyceridemia in equines with refractory hyperinsulinemia treated with SGLT2 inhibitors. Open Vet J. 2023.
  15. Tanner, M.A. et al. The direct release of nitric oxide by gypenosides derived from the herb Gynostemma pentaphyllum. Nitric Oxide. 1999.
  16. Aktan, F. et al. Gypenosides derived from Gynostemma pentaphyllum suppress NO synthesis in murine macrophages by inhibiting iNOS enzymatic activity and attenuating NF-kappaB-mediated iNOS protein expression. Nitric Oxide. 2003.
  17. Sarzi-Puttini, P. et al. Acetyl-L-carnitine in chronic pain: A narrative review. Pharmacol Res. 2021.
  18. Jones, E. et al. Neuropathic changes in equine laminitis pain. Pain. 2007.