So rather than simply worrying about your horse's prospects for developing the condition, you can assess his risk and take steps to mitigate it. The more “yes” answers you end up with, the greater your horse's risk of pasture-related laminates --brought on by the ingestion of starches and sugars found in grasses--which accounts for 70 percent of all cases.
Answer the following questions to determine your horse's risk, then use what you've learned to develop a targeted prevention program. After recovery from laminates, the internal structures of a horse's foot may be more vulnerable to the condition in the future.
Many cases of “recurrent” laminates are simply flare-ups of an ongoing condition: Although the horse improves or learns to compensate enough to appear sound, the underlying mechanisms of inflammation never truly subside and any new insult causes it to worsen. The reasons for these tendencies are not fully understood, but research suggests that in some horses a “thrifty” gene may be responsible.
So far, research to identify these inherited tendencies has focused on Welsh and Dartmoor ponies, but experts believe that the phenomenon probably exists in other breeds as well. When a horse consumes more NSC's than his stomach can handle, they spill over into the hindgut--the cecum and large intestine--where the sugars begin to ferment, creating an acidic environment that causes a die-off of microflora.
The typical “grain binge” laminates seen in feed-room raiders is caused by this hind gut imbalance, but it also can happen without massive overindulgence. In fact, two or three extra pounds of grain can trigger the disastrous chain of events in some horses.
Lush pastures contain higher levels of sugars, which can overwhelm the digestive system of vulnerable horses. Lush or improved pasture grasses not only provide lots of calories, they also may contain high levels of fractal, the one NSC not digested in the fore gut.
Fractal is broken down primarily in the hind gut, where it contributes to acidic conditions that can lead to laminates. Fractal levels vary with growing conditions and time of day, and even plants that do not look green or lush can contain high concentrations.
The easiest way to manage this risk, and by far the best prevention you can take against laminates, according to some experts, is to simply muzzle horses out on pasture to significantly limit their grass intake. In a 2004 study, 28 of 40 (70 percent) of horses referred to the University of Pennsylvania's New Bolton Center because of laminates had Cushing's syndrome, technically known as pituitary pars intermedia dysfunction (Paid).
In a horse with Paid, a pituitary gland malfunction leads to the release of excessive amounts of the hormone adrenocorticotropin (ACTH). High blood cortisol levels then precipitate elevated insulin, which has been directly linked to laminates risk.
Signs of Paid include a shaggy hair coat, loss of muscle mass, lethargy and increased risk of infection. But even if a horse's hormonal imbalances are controlled with medication, he remains at high risk for laminates, which means it's wise to limit his access to grazing and carbohydrate-rich foods.
A hormone secreted by the pancreas, insulin “unlocks” glucose receptors in individual cells, allowing them to utilize the sugar for energy. In fact, a 2007 Australian study suggests a direct link between elevated insulin levels and the development of laminates.
Blood tests, along with diagnostic investigation, can confirm insulin resistance, which can be managed with dietary changes to reduce sugar and starches in grains, hays and pasture. For some very easy keepers who seem to “live on air,” the emphasis falls on exercise, which means real workouts, not just walking from water trough to hay pile.
In a 2008 study, Virginia Tech researchers found that ponies with “crest” necks were 19 times more likely to have elevated insulin levels, as well as an associated increase in laminates risk. Any horse may develop a crest neck as he gains weight, but those of some breeds and bloodlines are more likely to have these particular fat deposits.
If your horse has a crest neck, consider him at genetic risk of laminates and work with your veterinarian to devise an all-over weight-loss regimen. Once the chain of events that produce this condition gains momentum, there is no way to reverse or even reliably slow the devastation.
The only way to truly beat laminates is to assess your horse's risk and tailor your management program to prevent it from happening in the first place. First and foremost, we must identify at-risk horses and ponies, monitor them, and adjust how we manage them daily to help prevent this devastating hoof disease from developing.
Laminates is an inflammatory disease of the leaf like laminae that suspend the coffin bone within the foot. Achim, of Texas A&M University’s (Tame) College of Veterinary Medicine & Biomedical Sciences, in College Station, was the study coordinator for the American Association of Equine Practitioners (4AEP) Foundation’s Laminates Research Working Group.
In the group’s four-year case-control study, veterinarians looked at 199 cases of laminates within four weeks of the onset of clinical signs. “What we found is obesity was one of the biggest risk factors,” says Coleman, who is an assistant professor of large animal internal medicine at Tame.
High body morphometrics, such as the body condition score and generalized and regional adiposity, already mentioned, along with larger neck circumference and decreased height (as in a pony); Recent diet or stabling changes; Exposure to lush pasture; Endocrine disease, such as pituitary pars intermedia dysfunction (Paid, or equine Cushing’s disease) and equine metabolic syndrome (EMS) ; and Glucocorticoid administration, such as dexamethasone or prednisolone, within 30 days of the onset of clinical signs of laminates. “That study gives us further evidence that the hormonal situation of the horse is important to consider in terms of laminates risk,” says Nicholas Frank, DVD, PhD, Dial.
Other EMS clinical signs can include previous or current laminates ; obesity; abnormal reproductive cycles; and abnormal fat deposits on the neck, back, sheath, tail head, and above the eyes or as lumps along the body. Frank recommends owners have their veterinarians perform wellness evaluations on horses in any of these at-risk categories at least yearly and/or when management changes occur.
She advises owners to feed their at-risk or laminated horses according to the animals’ energy requirements and use without overfeeding. Most importantly, avoid diets high in nonstructural carbohydrates (NSC's) such as glucose, fructose, sucrose, lactose, and starch.
Frank also suggests owners offer a balanced vitamin/mineral supplement to those forage diets lacking nutrients. Luck Equine Research Center at the University of Kentucky, presented at the 2017 Equine Endocrinology Group’s Summit, showed that supplementing 16 grams of an algal source of the omega-3 docosahexaenoic acid to horses with EMS for 46 days reduced inflammation and improved insulinemic responses.
Because of all these complexities, Frank recommends consulting a veterinarian or nutritionist about at-risk horses diets. An abrupt change in a horse’s grass intake is another risk factor for developing laminates.
When it comes to preventing laminates, Harris says owners should be particularly careful when changing forage (fresh or preserved) types. Under such circumstances she recommends owners replace pasture with hay containing less than 10% WSC on a dry matter basis or use a suitable forage replaced to control calories and WSC intake while allowing horses to maintain their natural browsing (forage ingestion) behavior.
Frank says he rarely recommends keeping a horse in a stall because the isolation causes stress, which can raise insulin concentrations. Harris, Annette Longhand, PhD, DIC, and other British researchers have studied the benefits of a well-fitted grazing muzzle as part of a weight management program.
They found that WSC intake decreased significantly in muzzled vs. muzzled ponies during a three-hour turnout. It improved insulin sensitivity in those ponies using the dynamic feeder consistently and traveling more than 1.8 miles per day.
Lastly, Harris suggests monitoring affected and at-risk horses body condition scores regularly. Both Frank and Coleman are interested in investigating the intestinal tract’s role in laminates risk.
“Are there changes in the microbial population within the intestinal tract that play a role in the development of laminates and even in the exacerbation of hyperinsulinemia?” Frank says, adding that initial results from research in progress have shown some microbial differences between horses with EMS and those without. Extension is expanding its online education and resources to adapt to COVID-19 restrictions.
High amounts of sugars in grasses can bring about laminates in horses susceptible to the disease. Founder or laminates, is swelling of the tissues that connect the hoof wall to the coffin bone.
Rapid intake of nonstructural carbohydrates (or sugar) stored in pasture plants can cause laminates. Cool season grasses like orchard grass, bluegrass, and timothy tend to store more carbohydrates.
High sugars found naturally in Minnesota forage species can trigger pasture-caused founder in susceptible horses. For extremely sensitive horses, there is no completely safe time to graze.
Grazing during these times or scenarios doesn’t guarantee the sugar content will be lowed. During periods of cool nights and warm sunny days (fall or early spring).
Many factors affect the amount of sugar present in forages including: During daylight hours, grasses make and store sugars as they take in water, sunlight and carbon dioxide (photosynthesis).
So plant sugars are higher in the late afternoon and lower in the early morning. Minnesota’s cool spring and fall weather may also cause plants to collect sugar.
Warmer weather or dark periods (night hours or cloudy days) offer better times to graze as plants are using sugars for quick growth. Allowing pasture grasses to become more mature should also reduce the sugar content and result in less (and a slower) eating.
Grazing muzzles limit the amount of forage a horse can eat. Regular exercise and good body condition will help lower the risk of pasture-caused laminates.
Most forage species store sugars in the bottom 3-4 inches of growth. Correctly fertilize pastures and avoid grazing susceptible horses during times of plant stress.