Category: Supplements

Turmeric pellets reduce coat, sweating of horse with Cushing’s disease

Posted on: February 15, 2021

Kurt's hair is dry in 6-degree weather on Feb. 7, 2021

Kurt’s hair is dry in 6-degree weather on Feb. 7, 2021.

Post reviewed on Nov. 26, 2022

Turmeric pellets may be a relatively cheap and easy-to-use treatment if your horse is dealing with Cushing’s disease and related symptoms, such as sweating.

I cannot say turmeric pellets improve laminitis issues in the hoof.

But turmeric pellets have reduced my gelding’s sweating during the winter, including when the temperature drops to zero, and made him much more comfortable, improving his quality of life dramatically.

Turmeric, an herb belonging to the ginger family, is the major source of curcumin, a polyphenol (micronutrient) that has been shown to have anti-inflammatory and antioxidant effects, according to many studies.

However, a major problem with curcumin is its poor bioavailability.

I initially started trying to give my horses turmeric in powdered form in December 2014, because of its chelation activity. It removes iron from the cells of the body and lowers ferritin levels, according to many sources, including the Hemochromatosis Help website. If my horses indeed suffer from iron overload, as I’ve suspected for years, the turmeric should help.

Adding turmeric powder lasted only a few weeks each time I tried it because the horses wound up colicking. I assumed that the turmeric, along with the horses’ on and off again use of bute, was making ulcers flare up.

During the three winters prior to the 2019-2020 winter, Kurt, my last horse and a longtime sufferer of laminitis, developed a huge, curly coat and sweated all winter, even when the temperature dropped below zero. He didn’t mind his wet coat icing over like everything else in sub-freezing temperatures, but I panicked through every deep cold snap.

In the fall of 2019, I noticed that SmartPak was selling turmeric in pellet form. I have no affiliation with SmartPak and receive no compensation or discount for saying the brand name.

Kurt started on the supplement Oct. 31, 2019. Two months later, it was obvious the turmeric was having a positive effect on his coat. Sweating was greatly reduced on warm days and nonexistent on cold days.

That is still true.

Here are photos of Kurt’s excessive coat in December 2016 and January 2019 and then his much lighter coat in December 2019, two months after he began the turmeric pellets, and in February 2020.

And here are pre- and post-turmeric-pellet photos of Kurt’s wet coat icing over on Dec. 10, 2018, a day with a morning low of 14 degrees, about the time when the photo was taken, and his coat completely dry in 6-degree weather on Feb. 7, 2021.

I give the turmeric pellets to Kurt separately after he eats his forage balancer. He likes the pellets more than his forage balancer and treats them like dessert. The dose is one scoop a day of 10,000 mg of turmeric. At least one study has used a higher amount.

I’ve tasted it and it tastes like someone dumped a spice rack in my mouth, but it’s not bad.

I don’t know why Kurt can ingest the pellet with no issues, while the powdered turmeric always led to a bouts of colic. Some studies suggest turmeric actually improves ulcers.

A study presented at the 2020 AAEP meeting by Michael St. Blanc, DVM, from Louisiana State University’s School of Veterinary Medicine, indicated that turmeric and devil’s claw fed together as a supplement to horses with pre-existing equine gastric ulcers did not worsen the ulcers, according to a report on thehorse.com. In fact all study horses — those fed the supplement and the control horses — saw their ulcers improve, likely due to the change in management of the horses once they were enrolled in the study, St. Blanc said. The turmeric dose in that study was 12,000 mg.

Cushing’s syndrome in horses is unique, according to VetFolio, in that it involves hyperplasia (an increase in the number of cells) in part of the pituitary gland rather than tumors in a different part of the gland — which occurs in humans.

Either condition can result in excessive production of adrenocorticotropic hormone (ACTH).

The excess ACTH causes the adrenal glands to make too much cortisol, which can lead to immune suppression and insulin resistance.

The website vetspecialists.com, a joint venture of the American College of Veterinary Internal Medicine (ACVIM) and the American College of Veterinary Surgeons (ACVS), says equine Cushing’s disease, or pituitary pars intermedia dysfunction (PPID), is the most common endocrine disorder in horses, ponies, donkeys and mules. PPID most often affects older horses (teenage or older) but has been observed in some younger than 10 years of age.

Affected horses are prone to chronic infections such as sinusitis, dental disease, and sole abscesses.

The website lists these signs and symptom, and my gelding Kurt had them all (expect the abnormal heat cycles in mares):

1. Failure to shed hair fully each spring.
2. Long, wavy/curly hair.
3. Chronic infections.
4. Repeated laminitis episodes sometimes with associated hoof abscesses.
5. Excess or inappropriate sweating.
6. Increased water intake and urination.
7. Lethargy.
8. Loss of muscle mass, typically noticed over the back and hind quarters, as well as the “pot-bellied” appearance.
9. Infertility or abnormal heat cycles in mares.

There seems to be ample evidence in human studies that turmeric can help alleviate the cell activity behind Cushing’s disease. I am not finding a study in horses that examined curcumin’s effect on the pituitary gland or Cushing’s symptoms.

Authors of a German study in humans and rodents said their research “demonstrated for the first time that curcumin has anti-tumorigenic actions on rodent and human pituitary tumor cells in vitro and in vivo.” The research was published in 2009.

Given all the money I’ve thrown at laminitis supplements so far, the price of the turmeric pellets seemed more than reasonable.

I will keep Kurt on the turmeric pellets for the rest of his life, assuming they are available.

Check hay, feed for high iron levels when treating laminitis in horses

Posted on: March 26, 2017

Post reviewed Nov. 26, 2022

Many owners of laminitic horses test their hay to ensure the sugar levels are low.

I found out in winter 2016 that the mineral levels in the hay and feed are equally important, and I hadn’t been looking at those.

Let me say up front that I am not a person who pushes myself to do math. But horse owners need to do just that, since feed and hay providers generally don’t provide the detailed information we need to feed our horses properly.

Both my horses looked awful in December. They were sweating profusely, and their hair was far too long and thick, even for Connemara horses and ponies in winter. Kurt looked as if he would pass out at any minute. The temperature dipped to zero a couple of times, and both horses were still sweating. I’ve never seen that in 20 years of dealing with laminitis. They fit the classic description of horses with Cushing’s disease. And, of course, this affected their feet. I kept the horses upright, but their feet looked as bad as their hair.

The one interesting factor in that development was they didn’t look like that 30 days earlier.

Robin colicked for three days Nov. 7 to 9, 2016. It was not an impaction colic; he was eating, drinking, and eliminating waste normally. But the colic (discomfort when eating) came with a very high fever of 105.4 degrees. My vet came out Nov. 9 to look at him. We reached no conclusions on the cause of the colic. Robin returned to relative normalness in three days after taking banamine orally for those three days.

At any rate, the vet saw both horses Nov. 9, and they were not sweaty furballs ready to pass out.

If I had asked the vet to come back in December, she would have said, “What changed to cause this?”

What changed was a new load of hay delivered Nov. 9 by my regular hay provider (my sixth hay provider over the last 20 years). The horses had been eating a second cutting of hay prior to that, and they hated it. The hay provider switched back to the first cutting of hay Nov. 9.

Nothing else changed.

In late December, I bought a different source of hay from the local feed store and fed the same amount. The horses immediately stopped sweating and shrank in size by February. I won’t say they lost weight, because no Connemara loses weight in that short period of time. I think inflammation was reduced. But the horses appeared smaller, and Kurt’s hair started falling out in chunks in January and February.

I tested the hay from the hay provider (through Equi-Analytical, the equine division of Dairy One), and the sugar and starch levels were very low. I selected a test (“Equi-Tech” option on the form) that included the mineral levels. The iron level was 52 milligrams per pound of hay (mg/lb), or 114 milligrams per kilogram (mg/kg). That doesn’t sound like a lot until one does a little math.

The National Research Council, part of the U.S. National Institutes of Health, provides a list of “Nutrient Requirements of Horses” along with a calculator.

The NRC recommends 400 mg of iron per day for a 500 kg (1,100 pound) adult horse on maintenance feed (click the “Other Nutrients” link at the top of the calculator). A kilogram is 2.2 pounds.

The Alberta Agriculture and Forestry Service says the NRC recommendations are the minimum levels one should provide.

The toxic threshold for iron in horses is generally listed as 500 mg/kg (Juliet Getty Ph.D., Eleanor Blazer).

Unfortunately, that’s a ratio of iron to feed. It’s not a maximum total.

I generally give the horses as much hay as they want, based on equine nutritionist Juliet Getty’s theory that horses will eat less and be much happier if they have hay in front of them all day. When they start trashing the hay, I give less.

If my horses were given an estimated eight flakes of hay a day (3.75 pounds each), the horses were given 30 pounds of hay a day and 1,560 mg of iron. It’s hard to tell what they eat when you put out a lot of hay and let them pick through it all day.

Next, I tested the Enrich Plus, a balancing feed marketed as a “low sugar, low starch formula.” One might conclude that the product is good for insulin-resistant laminitic horses. I know I did. Testing Enrich Plus cost me $54 using the “Trainer” option at Equi-Analytical, so please download the Enrich Plus results and pass them around. That’s a fair amount of money for something that should be printed on the bag, in my opinion.

The sugar level in Enrich Plus is low. But the iron level is 1,200 mg/kg, or 544 mg per pound, and each horse was getting about a pound a day.

With hay and feed, the horses’ daily iron intake totaled 2,104 mg of iron.

Since I don’t have a maximum tolerable iron total, I have to use a little logic. The horses are getting more than five times the daily recommended level of iron in their feed and hay alone. If I were eating five times the recommended amount of salt in my diet, my physician would lock me up. I’m going to conclude the horses’ iron level from two parts of their diet was unhealthy.

Getty, the nutritionist, says, “Studies have shown a direct correlation between iron intake and insulin levels in the blood, making it an important factor in managing the diet for these horses.”

What about the grass?

I didn’t have much grass to test during the winter (and testing grass requires shipping it in dry ice) so I tested the soil.

Tests on my two upper fields, where the horses hang out the most, showed the soil is very acidic, at a pH level of 4.4 (despite me adding a little lime last spring to try to get it closer to 6 or 7) and has an iron level of 797 mg/kg (mg/kg is the same as ppm). The level was marked as excessive by the testers. That level would convert to about 398 mg of iron per pound of grass.

Getty says, “Forages grown from acidic soils will be higher in iron.”

Note that I’ve been working hard since January 2016 filtering the excess iron out of the water, assuming that was the issue. All the while, the horses have been drowning in iron.

The iron level in the horses’ current hay is 31 mg per pound, and the horses don’t want as much hay now. At six flakes a day (2.1 pounds per flake), the horses are offered 403 mg of iron from the hay. They’re probably not eating that much.

I switched them to Triple Crown 30 as a forage balancer. Thank you to Triple Crown for listing the iron level on the bag and saving me another $54 in testing fees. This product has 750 mg/kg, or 341 mg per pound, of iron, and the horses are getting half a cup three times a day for a total of about 10 ounces a day and 213 mg of iron per day. It’s not zero, but better.

Iron overload likely caused my horses’ laminitis

Posted on: July 12, 2015

Toxicology test on horses' iron level

Toxicology test on horses’ iron level.

Hematology test on horses' iron level

Hematology test on horses’ iron level.

Post reviewed Nov. 27, 2022

In “Clue” like fashion, I’m declaring the cause of my six horses’ laminitis over the last 18 years as an excess intake of iron from weeds, trace mineral blocks and well water, leading to insulin resistance and the insulin form of laminitis.

The insulin resistance and laminitis were exacerbated by me following veterinary guidance to restrict the horses’ hay, keep the horses on dry lots and prevent the horses from eating so-called “lush grass.” I now believe these moves were the exact opposite of what was needed to get the horses’ metabolism functioning properly.

In the game of “Clue,” I’d get immediate confirmation of whether my assertion is correct. Unfortunately, with the laminitis, I will receive no such feedback.

But a cascade of events led me to this conclusion.

In October 2014, I needed to have my leaking well fixed (the water pressure was down considerably, and a pond had formed to the west).

But I also wanted to have my horses’ iron levels tested at Kansas State University’s lab. I suspected iron as the cause of the horses’ laminitis for a decade but had no proof.

A previous iron test done through the local zoo did not provide useful results.

Several experts recommended KSU for these tests (I’m not making such a recommendation at the moment). I was hoping to do a three-test panel of serum iron, TIBC and ferritin (a hematology test) and a serum trace mineral panel (a toxicology test). I admit I didn’t know what I was doing. I wanted some data.

There wasn’t enough money to do the tests and fix the well.

The iron tests for my two living horses totaled $400, including my vet’s fees. I chose to do the tests and hope for the best with the well.

My vet didn’t provide this iron test as a regular service but agreed to draw the blood if I did the mailing.

I sent the package in a vet-provided cooled envelope by overnight shipping on a Thursday. KSU said shipping on Thursday was fine as long as the package arrived Friday morning. I don’t know what happened to the package after it got under way. I don’t know when it arrived or was tested, and all may have gone as planned.

I received results from KSU that suggested my horses had toxic levels of iron (see images at top).

A university vet who provided comments on the tests said the toxic level “could be indicative of artifactual hemolysis” within the submitted sample. In other words, the blood got too warm or tainted in transit.

I talked to a lab person by phone, and the blood was indeed considered compromised.

I personally believed the results were correct as far as the horses having too much iron but couldn’t be sure, and I couldn’t do the tests again due to the cost.

I had my own iron level tested through a company I found online, Lab Corp, for considerably less money, and my iron level was normal, making me think the iron theory had come up short.

My sister told me my iron results did not seem normal, given that all the women in my family were anemic. She said I likely was anemic, too, and was being affected by the iron in the water.

Meanwhile, also in 2014, veterinarian Frank Reilly, a leading advocate for laminitic horses, posted on his website the iron levels of common pasture weeds (scroll down to the tab titled “Equine Insulin Resistance High Iron“). The iron levels are really high. Excess iron can fuel insulin resistance. His site provides plenty of research on that, too.

I knew my horses had been eating more weeds than anything else in recent years because I had intentionally ignored the grass, thinking that less grass was better. The grass went away, and the horses ate the weeds.

I was suspicious of the well water having too much iron, since the water turns everything rust colored and has eaten through the bottom of all my aluminum tanks. But I still didn’t have proof there. A water test in 2005 showed nothing suspicious.

I did find out that the horses’ trace mineral blocks were 25 percent iron, and I threw those away in 2012.

In November 2014, I emailed Dr. Reilly, asking how one might reduce the iron level in horses through supplements. He spent his Thanksgiving holiday investigating this idea. He emailed back that curcumin and ginkgo could reduce the iron level, and he provided suggested amounts and where to buy it. Purebulk.com sells the curcumin (250 grams, $70 at the time — it’s gone up). Reilly suggested feeding 1/2 tablespoon a day. Starwest Botanicals sells ginkgo leaf cut and sifted (1 pound bag). Reilly suggested feeding 1 tablespoon in the morning and 1 tablespoon in the evening.

After giving the horses the two supplements for a few weeks, I stopped because my gelding Kurt was breaking out in drenching sweats as we entered yet another frigid winter. We eventually figured out the sweats were caused by thyroid powder (no longer given).

Also, a friend had sent me a camping filter for the well head to filter out iron, but I don’t use the well head during the winter due to the hose always being frozen. I carry buckets of hot water outside. So I didn’t put on the filter.

All these things nagged at me, but polar vortex winters tend to keep one busy.

I considered putting the horses back on the curcumin and ginkgo, but I wanted to do the iron tests again to see if the previous tests were correct. Does one want to chelate iron from a horse that doesn’t have excess iron?

There was no money to repeat the tests, and the situation with the well was becoming more of an emergency.

Everything came together in May 2015, when I finally had the well fixed, and a well company employee blurted out, “You must have an iron problem” when telling me how deep the well was. The casing is 350 feet deep (very deep) and collects iron all along the shaft, which gets transferred to the water as the water sloshes through, according to the well guy, an industry veteran.

The irony is not lost on me that fixing the well gave me more information than the iron tests.

University of Edinburgh pulls out all stops with online equine nutrition course

Posted on: March 5, 2013

The equine nutrition course that I took online through the University of Edinburgh was excellent, and I have compiled all the information to share with you.

This course was a massive open online course, or MOOC, offered through the education site Coursera. It was free, but don’t let the price fool you. The University of Edinburgh pulled out all the stops.

Dr. Jo-Anne Murray

This was so well done that some of the students who took the course asked for the school to put up a link where they could donate money in appreciation, and people are being quite generous, according to the latest email we received.

The course was taught by Dr. Jo-Anne Murray, senior lecturer in animal husbandry and nutrition at the Royal (Dick) School of Veterinary Studies at the University of Edinburgh. Before the course started, she sent out an email welcoming us and mentioned that 260,000 students had signed up. I’m not sure if that was a typo. She said in a video mid-course that 23,000 were actually taking the class.

The course ran five weeks, and online students worked through a dashboard.

We watched two or three videos each week on our own. These were accompanied by a PDF that we could use to follow along for spellings and such. Once we went through the material, we took a review test for practice and then a real test.

There were several instructors involved in this, and they all monitored the forum that was provided. The idea was that we should learn on our own, but the instructors were very hands on and helpful. I’m sure they were ready to collapse once it was over, because horse people can be quite enthusiastic when it comes to forums.

After each week, the instructors posted another video on our dashboard to respond to trending topics and questions.

Once we had watched the material for Week 5, there was a final assessment test, which was challenging, even though it was open book.

I specifically asked in the forum how much of this material we could share with others. Dr. Murray said it was all open source. Share it all.

I downloaded all the videos because it was easier for me to play them on my software than through the dashboard. And I wrote down everything Dr. Murray said. I’ve included all the material I have.

Week 5 addresses laminitis a lot, but all weeks are relevant for understanding how a horse can get into trouble eating sugar and starches. For me, it’s just important to finally learn more about what and how horses should be eating.

However, now that I understand all this better, it makes me sadder that we are so ill-equipped to feed horses properly, given how their systems are designed to eat.

I was going to try to edit down my notes and present a summary, but there’s too much material. Just editing my notes to make sure you could read them took forever.

The one thing I do want to post here is this interesting tidbit. In Week 5, Dr. Murray discussed the idea of putting a horse on pasture only some of the time. Here’s the little problem she pointed out, and I had never read this:

“There have been studies done that when we remove horses or ponies from pastures for half a day, they will actually do compensatory eating. They can actually eat as much in 12 hours as they can in 24 hours if brought inside part of the time. There has been some work done that ponies can eat up to 40 percent of dry matter intake in a period of three hours. So, bringing them into a stable and then turning them out for limited periods may not be as effective as we think.”

I hope you get as much out of this as those of us who took the course did. I stand in awe of this team of equine nutrition instructors at the University of Edinburgh. We owe them big time.

Here is the course material.

University of Edinburgh’s online equine nutrition course

Posted on: March 5, 2013

This is the open-source course material that accompanied the University of Edinburgh’s equine nutrition course in January and February 2013. I have tried to arrange it in a way that is clear.

The course was five weeks in length. Each week’s material includes video files, PDFs provided by the school and notes typed by me. I would call the notes transcripts, but I did some rewriting.

INTRO

Video: Introduction to the course
Slides: Introduction to Equine Nutrition
List: Abbreviations used in videos

WEEK 1

Video: Week 1 Digestive Tract Part 1
Video: Week 1: Digestive Tract Part 2
Notes: Week 1
Slides: Week 1

WEEK 2

Video: Week 2: Nutrient Digestion Part 1
Video: Week 2: Nutrient Digestion Part 2
Notes: Week 2
Slides: Week 2

WEEK 3

Video: Week 3: Nutrient Sources Part 1
Video: Week 3: Nutrient Sources Part 2
Video: Week 3: Nutrient Sources Part 3
Notes: Week 3
Slides: Week 3

WEEK 4

Video: Week 4: Diet Part 1
Video: Week 4: Diet Part 2
Video: Week 4: Diet Part 3
Notes: Week 4
Slides: Week 4
Slides Full Page: Week 4

WEEK 5

Video: Week 5: Clinical Nutrition Part 1
Video: Week 5 Clinical Nutrition Part 2
Notes: Week 5
Slides: Week 5
Slides Full Page: Week 5

Should laminitic horses get a thyroid supplement?

Posted on: June 9, 2012

Kurt's sides are lumpy despite years of taking thyroid supplements to boost his metabolism.

Kurt’s sides are lumpy despite years of taking thyroid supplements to boost his metabolism.

Editor’s note on June 15, 2015: I wrote this post before reading Juliet Getty’s post on treating the insulin resistant horse. Thyroid supplement may help the laminitic horse lose a little weight, but I think it’s a poor substitute for helping a horse restore balance in its diet and life. Even before I read Getty’s post, I had taken Kurt off thyroid powder because it was making him break out in a drenching sweat. It took me a while to figure out the cause of the sweat. The day I stopped the thyroid powder, the sweat went away. Giving thyroid powder to a laminitic horse may cause unintended consequences. I’m leaving the article up, because the reporting of the research is accurate.

Laminitic horses often are put on the thyroid supplement levothyroxine sodium (commonly sold under the brand name Thyroid-L).

While it can be an effective component for treating the insulin form of laminitis, the reasons for using it have fluctuated over the years.

The thyroid is located in the neck of all mammals. The gland secretes the hormone thyroxine, or T4, and to a lesser extent triiodothyronine, or T3. These hormones predominantly affect metabolism, but they also influence growth, development and body temperature.

The pituitary gland and hypothalamus in the brain also play a role in regulating thyroid levels. The anterior pituitary gland releases thyrotropin, a thyroid stimulating hormone referred to as TSH. The hypothalamus releases thyrotropin releasing hormone, or TRH, which affects thyrotropin.

Low thyroid levels may be the result of problems in the thyroid, hypothalamus or pituitary gland, or all three.

According to Nat Messer, DVM, at an AAEP meeting in December 1998, hypothyroidism is uncommon in horses, but widespread misdiagnosis of thyroid dysfunction results in more than $750,000 worth of thyroid hormone supplement being sold for use in horses annually.

So, why have we been using thyroid supplements for laminitic and foundered horses? There was a time when laminitic horses that were “easy keepers” were presumed to have hypothyroidism because their body condition, particularly regional fat deposits, mirrored that of dogs with hypothyroidism, plus the horses had low or low-normal resting serum T3 and T4 concentrations.

But, in a 2006 proceedings paper for the AAEP, Nicholas Frank, DVM, admitted that scientists had come to realize that low thyroid levels were a consequence rather than a cause of the horse’s metabolic issues and may even be the result of use of phenylbutazone, or bute.

That surprised me. In more than 15 years of treating laminitic horses with bute, I was never told that bute might be lowering my horses’ thyroid levels.

Still, many owners of laminitic horses, including me, have been told to try thyroid supplement because it may help speed up the horse’s metabolism so the horse can lose weight, which hopefully will lower the horse’s risk for having a relapse of laminitis. Losing weight is often a battle for foundered horses because they are too lame to exercise and their food needs drop off dramatically due to the fact that they don’t move much.

I can tell you from personal experience that Thyroid-L doesn’t always help a horse lose weight — my horses got 2 grams of Thyroid-L a day for years, and they both were obese.

Where levothyroxine sodium does appear to help is with controlling insulin levels, though insulin’s role in laminitis was only solidified by research in 2007, so Thyroid-L may have been silently doing some good on the insulin front for years while being prescribed as a weight-loss treatment.

In a study published in 2008 in the American Journal of Veterinary Research, Frank said administration of levothyroxine sodium led to weight loss and increased insulin sensitivity in adult horses with healthy thyroid gland functioning. He also said levothyroxine sodium significantly increased the rate of insulin disposal.

Note that the amount of T3 and T4 in the bloodstream regulates the release of TSH by the pituitary gland, so low levels of T3 and T4, for whatever reason, make the pituitary release more TSH. There is no shortage of studies that talk about the link between a high TSH level and insulin resistance in humans.

In a German study published in 2000 in Clinical Endocrinology, researchers concluded that study subjects with normal thyroid function (euthyroidism) but elevated TSH were more obese, had higher triglycerides and an increased likelihood for metabolic syndrome, also known as insulin resistance syndrome.

The concern with the insulin form of laminitis is how much insulin and glucose is circulating in the horse’s bloodstream. If Chris Pollitt’s Australian research team is correct, elevated insulin levels in a horse can lead to the excess insulin in the blood errantly binding with the wrong receptors in a horse’s feet (insulin-like growth factor 1 receptors, rather than insulin receptors, which don’t appear to exist in horses’ feet), leading to out-of-control hoof growth, not unlike cancer, destroying the structure of the hoof wall, coffin bone and laminae.

If Thyroid L can lead to faster disposal of insulin, that alone might be a reason to add it to the diet of the laminitic horse.

At the same AAEP meeting in 1998, Messer addressed some additional factors that may affect thyroid levels, including nutrition. He said short periods of food deprivation can lower thyroid levels, as can diet composition.

Messer and associates conducted a study at the University of Missouri (published in 1995) in which food was withheld from six adult horses with normal thyroid function for four days. Hormone levels decreased more than 50 percent over that time. When the horses returned to a normal eating schedule, their thyroid levels returned to normal.

In a laminitic horse, thyroid levels might be lowered by bute and food deprivation, which are normal treatments for laminitis, and the resulting elevated TSH levels may increase insulin resistance. Elevated insulin would cause even more damage to the feet than had happened already. Given this scenario, it’s easy to see why owners might see some improvement giving a thyroid supplement to a laminitic horse.