Hormonal Laminitis is Different

There are many causes of laminitis, including dietary overloads, hormonal disruptions, toxic plants, severe intestinal disorders and bacterial infections.  It has been estimated that 80% or more of laminitis cases fall under the category of hormonal/endocrine pathologies but until recently detailed research has focused on other causes.

INSULIN STRUCTURE

Protein Structure of the Hormone Insulin

Research has shown that both toxic laminitis (black walnut) and hind gut carbohydrate overload (starch/fructan) are characterized by activation of tissue degrading matrix metalloproteinase enzymes, the MMPs, breakdown of the basement membrane and inflammation revealed by large numbers of invading neutrophil white blood cells.

However, studies over the past few years have shown that this does not happen with laminitis caused by high insulin, which may have a lot to do with why this type of laminitis does not respond particularly well to antiinflammatory drugs like phenylbutazone.  The cascade of tissue destruction caused by inflammation does not occur in laminitis related to this hormonal disruption.

We do not yet understand the complete mechanism behind endocrinopathic laminitis but there are important clues.  High levels of insulin lead to high levels of endothelin-1, an extremely potent vasoconstrictor which interferes with blood supply to the laminae.  A large body of literature also links insulin resistance and oxidative stress, high levels of reactive oxygen species.

With acute endocrinopathic laminitis,  the core of treatment is to reduce the simple sugar and starch content of the diet by feeding only low sugar/starch hay and supplements as needed to balance the minerals in the hay fed in a low sugar/starch carrier such as rinsed and soaked beet pulp, soybean hulls or Brewer’s/Distiller’s dried grains.  Potent antioxidant supplements containing both plant based (e.g. Turmeric, Ginger, Grape Seed extract, Boswellia) and nutrient sources (N-acetyl-cysteine, vitamin C, lipoic acid, vitamin E) work just as well, if not better, in controlling pain in acute episodes compared to NSAID (nonsteroidal antiinflammatory) drugs and without the potent side effects.

Supporting blood flow to the hoof in the face of high endothelin-1 concentrations is also important.  The herb Jiaogulan, Gynostemma pentaphylluma, is an extremely potent vasodilator.  It is well accepted by horses, safe and effective in relieving pain in a high percentage of laminitic horses.  It works by stimulating production of the vasodilator nitric oxide inside vessels.  This is supported by supplementation with the amino acid L-arginine, the precursor for nitric oxide.

Endothelin-1 levels are even higher in horses with chronic laminitis pain, so nitric oxide support is indicated for these as well, in addition to meticulous attention to diet and an appropriate trim.  There are also chronic cases where pain is contributed to by actual changes in the nerves and the spinal cord – neuropathic pain.  Acetyl-L-carnitine, “ALCar”, is a naturally occurring metabolite of L-carnitine in the body and has shown clear benefit in different types of  neuropathic pain in many species.  It has also been effective in horses.

We have much more to learn about hormonal laminitis but have made decent inroads and the most important realization for moving forward is that this is different from other causes of laminitis. The solutions need to be different too.

Eleanor Kellon, VMD

 

 

About Dr. Kellon

Graduate of University of Pennsylvania Veterinary School. Owner of Equine Nutritional Solutions, www.drkellon.com, industry and private nutritional consultations, online nutritional courses. Staff Veterinary Expert at Uckele Health and Nutrition.
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9 Responses to Hormonal Laminitis is Different

  1. Charles Owen says:

    This article is incorrect-there is only one single pathway and all stressors of laminitis should be treated the same

    • uckeleequine says:

      I have to disagree. Research has clearly shown that endocrinopathic laminitis caused by elevated blood insulin levels is associated with elongated and attenuated secondary epidermal laminae without activation of MMP enzymes or neutrophil infiltration seen in laminitis of other causes. It is not an inflammatory event. Secondary inflammation may occur later if the weakened tissue fails and laminae separate but inflammation is not part of the root cause. Failure to address the cause of the elevated insulin dooms the horse to ongoing issues while correcting it can result in dramatic improvement in a very short period of time.

  2. Cam says:

    Dr. Kellon,
    Why do you recommend by-products such as beet pulp, soybean hulls or Brewer’s/Distiller’s dried grains, and more? And in your recommendations of soy products are you educating the consumer of GMO ramifications?

  3. Judith Morris says:

    My 18 year old MFT has been on one Prascend since diagnosis January 10. She is in day 4 of being so sore footed she hardly moves and in fact, seems not only sore footed but really stiff all over. I have her on bute. She only nibbles at her hay. She had been on 6 weeks of Quiessence and her cresty neck seems even worse. I had been feeding her soaked alfalfa pellets and Nutrena Safe Choice senior.
    PLEASE what do I need to for her? Her vet is quite tired of my phone calls but so much is not adding up. I feed her like I do because she gets too thin otherwise. This being hormonal laminitis makes perfect sense.
    Thank you!

  4. Billy says:

    Dr Kellon,
    Does this me that insulin related laminitis might not show whiteline stretching (lamina wedge) that you often see in toxic laminitis?

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