Laminitis, a life-threatening condition characterized by severe pain and lameness, isn’t a disease itself but a symptom of other diseases. In fact, many diseases can lead to laminitis, and the veterinarian must first determine its underlying cause. Only then can carefully designed diets help the horse heal. While not all affected horses survive or return to athletic function, rapid and targeted medical and dietary intervention maximize the chances of a good outcome.
Laminitis triggers are vast and varied but generally fall into one of four categories:
- Feed-related (eg, grain overload)
- Sepsis (eg, retained placenta, colitis)
- Endocrinopathic (related to hormones)
- Mechanical (eg, supporting-limb laminitis after an injury)
In each of these cases, laminitis ultimately develops due to a breakdown of the “binding” between the coffin bone and the hoof wall.
“A tissue called laminae is the sole tissue responsible for suspending the coffin bone inside the hoof. The laminae are highly vascular and have an extensive nerve supply,” explained Stephen Duren, PhD, PAS, of Performance Horse Nutrition, based in Weiser, Idaho, during his 2022 EquiSUMMIT presentation.
That binding, the laminae, is the only thing holding the horse’s entire musculoskeletal system off the ground.
“If the laminae become inflamed, as they can in each of the four above-described conditions, then there is altered blood flow to the laminae and an enzyme cascade is initiated that further damages the laminae,” said Duren. “Breakdown of the binding means the coffin bone is no longer secure in the hoof wall and can actually penetrate the sole of the foot.”
Not surprisingly, laminitis is exquisitely painful. Affected horses appear as if they’re walking on eggshells; adopt a sawhorse stance, rocking backward in an attempt to take weight off their feet; and have bounding digital pulses and warm feet due to the increased blood flow to the laminae.
Endocrine Issues: The Leading Cause of Laminitis
Feed-related laminitis might be the most familiar type of laminitis to horse owners, but Duren assured the audience that endocrine-related laminitis is by far the leading cause of laminitis in domesticated horses. He explained that equine metabolic syndrome, pituitary pars intermedia dysfunction (formerly called equine Cushing’s disease), insulin resistance, inactivity, obesity, and even corticosteroid administration all fall into the category of endocrine-related laminitis.
“In these situations, changes in blood glucose and insulin concentrations result in (dysfunction of the cells) that control blood flow and nutrient supply to the laminae,” explained Duren. “The primary culprits are high insulin, glucose, and cortisol levels in the horse’s circulation that have a negative effect on the laminae.”
What To Feed a Horse With Laminitis
Laminitis, said Duren, is an absolute medical emergency. Once the horse is stable, the veterinarian must establish the underlying cause of the laminitis before recommending an appropriate diet that will best facilitate the horse’s recovery.
In the case of endocrine laminitis, dietary strategies include reducing sugar/starch intake to control large spikes in insulin.
“This hormone is released into the circulation in response to a high sugar/starch meal. If we reduce sugar/starch intake and eliminate pasture, then we can minimize those insulin spikes and decrease the negative effect that insulin has on the laminae,” Duren said.
Duren recommended first looking at the horse’s forage when managing endocrine-related laminitis.
“Forage will always be the single largest ingredient of a horse’s diet, and we need to select the proper forage to feed these horses,” he said. “Forages differ and bring different things nutritionally to the table that can either help the horse survive or make the laminitis worse.”
His key suggestions for nutritionally supporting horses that have endocrine-related laminitis include the following:
- Offer a low-sugar/-starch forage (laboratory analyzed at <10% total sugar/starch) such as teff grass, Bermuda grass, or alfalfa. This controls surges in insulin, which is released in response to a sugary meal.
- Eliminate pasture, again to reduce a sugar surge.
- Decrease body weight by 10% of their ideal weight to get weight off their feet while recovering.
- Supplement with a low-intake ration balancer to ensure the horse is receiving adequate vitamins and minerals.
- Consider including supplements that target gut health and reestablish the intestinal microbiome.
“Due to the pain, suffering, and loss of function associated with laminitis, it is far better to prevent laminitis rather than treat it,” Duren said. “Prevention of endocrine-associated laminitis involves routine evaluation of bloodwork screening for endocrine disease markers, along with routine body condition assessment and dietary adjustment to prevent obesity.”
Detailed information regarding the other three categories of laminitis and how those can be managed through diet, particularly forage, is provided in Duren’s recorded session available online.