The Latest on Feeding Laminitic Horses

The Latest on Feeding Laminitic Horses

Don't allow laminitis-prone horses to have unrestricted grazing; rather, turn them out in a drylot or a grass-free paddock.

Photo: iStock

If your horse falls into the at-risk category, consider these diet changes

The basic principles of feeding laminitic horses are well-established: Avoid high-sugar and -starch feeds and lush green grass. However, recent research has given us even more insight into how to manage horses affected by or vulnerable to laminitis. 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.

Laminitis Risk Factors

Laminitis is an inflammatory disease of the leaflike laminae that suspend the coffin bone within the foot. In serious cases, the laminae can fail and separate from the coffin bone and the hoof wall, causing the bone to rotate or sink.

Michelle Coleman, DVM, PhD, Dipl. ACVIM, of Texas A&M University’s (TAMU) College of Veterinary Medicine & Biomedical Sciences, in College Station, was the study coordinator for the American Association of Equine Practitioners (AAEP) Foundation’s Laminitis Research Working Group. In the group’s four-year case-control study (, veterinarians looked at 199 cases of laminitis within four weeks of the onset of clinical signs. They compared these cases to 198 healthy horses and 153 horses that were Grade 3 to 5 lame in one forelimb with no history of laminitis. One hundred and nine veterinarians in 32 states and three Canadian provinces supplied the data for these 550 cases.

“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 TAMU. “Reducing the risk of obesity may be important in reducing the risk of laminitis.”

The study results showed that horses with a body condition score (BCS) of 7 or higher on the 1-9 Henneke scale or with generalized or regional adiposity (fat distribution all over or in certain areas) are at a greater risk of developing pasture- and endocrinopathy-associated laminitis (PEAL). The team found the following factors also increased a horse’s laminitis risk: 

  • 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 (PPID, 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 laminitis. (Coleman cautioned that researchers need more supportive evidence of this potential—only 6% of horses met the criteria.)

“That study gives us further evidence that the hormonal situation of the horse is important to consider in terms of laminitis risk,” says Nicholas Frank, DVM, PhD, Dipl. ACVIM, professor of large animal internal medicine at Tufts ­University’s Cummings School of Veterinary Medicine, in Grafton, Massachusetts.

Veterinarians already know there’s a connection between obesity and insulin resistance and EMS in many laminitic cases. Normally, the pancreas produces the hormone insulin when glucose enters the bloodstream after a meal so cells can store and use glucose as an energy source and for metabolic processes in the body. Insulin resistance occurs when the body’s cells become resistant to glucose uptake, and the pancreas produces more and more insulin to try to keep blood glucose concentrations within normal limits. Excess insulin in the bloodstream is called hyperinsulinemia. Insulin resistance and hyperinsulinemia both fall under the umbrella of insulin dysregulation. It’s important to remember that not all insulin-resistant horses are obese and not all obese animals are insulin-resistant, but these two often go hand in hand.

Insulin dysregulation is one component of EMS, which is similar to metabolic syndrome in humans. Other EMS clinical signs can include previous or current laminitis; obesity; abnormal reproductive cycles; and abnormal fat deposits on the neck, back, sheath, tailhead, 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. “These are dynamic states, and we need to recheck to make sure we know what the status of the horse is,” says Frank.

The evaluations should include an oral sugar test and testing for PPID in middle-aged and older horses using a blood plasma adrenocorticotropic hormone (ACTH) test or a thyrotropin-releasing hormone (TRH) stimulation test. These tests usually run $100-300, says Frank. 

“Many horses that experience high insulin concentrations can be very well-managed, and we really can control these problems,” says Frank. “It’s heartening to know that we can improve the situation for the horse through good management.”

This article continues in the November 2017 issue of The Horse: Your Guide To Equine Health Care. Subscribe now and get an immediate download of this issue including this in-depth article on diet changes for your at-risk horse.

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About the Author

Sarah Evers Conrad

Sarah Evers Conrad has a bachelor’s of arts in journalism and equine science from Western Kentucky University. As a lifelong horse lover and equestrian, Conrad started her career at The Horse: Your Guide to Equine Health Care magazine. She has also worked for the United States Equestrian Federation as the managing editor of Equestrian magazine and director of e-communications and served as content manager/travel writer for a Caribbean travel agency. When she isn’t freelancing, Conrad spends her free time enjoying her family, reading, practicing photography, traveling, crocheting, and being around animals in her Lexington, Kentucky, home.

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