About this Blog

Meet my very 1st horse, Lazarus.
I couldn't wait for Santa anymore or ask one more time for a pony for my bday (after age 30 it got embarrassing). I took matters in my own hands and I finally decided to pick a pony that needed a new home. Laz found me as I contemplated with this idea. He was sweet yet very sassy, fresh off the track, Thoroughbred (OTTB).
Join us for our re-training, rehabbing from laminitis and testing all parts of mixed up horsemanship and partnership, and luck...

Wednesday, July 20, 2011

Explanation of IR

What is "IR"
"IR" stands for Insulin Resistance
Not to be confused with PPID (pituitary pars intermedia dysfunction) or Cushing's (PCS)

Why am I concerned about IR?
It's strongly associated with horses that have had laminitis 
(maybe as a reason for A. causing it or B. how they react to diet after laminitis)

The science of it-for the nerds like me:

Physiology Review-  taken from online www.ivis.org
Insulin is a hormone secreted by the pancreas that stimulates the uptake of glucose by tissues when
sugar is abundant (i.e., after feeding). Skeletal muscle and adipose tissues are the major sites of
insulin-mediated glucose uptake, but the liver also
responds to insulin by increasing the uptake of glucose from the blood. 
Insulin binds to receptors on the surface of plasma membranes. 
It triggers aseries of internal events that results in the movement of glucose-transporter proteins (GLUT4) to the
cell surface, which facilitates rapid glucose uptake.
Insulin plays an important role in the storage of energy by moving glucose into cells where it can be
stored as glycogen or converted into fat.
This condition is defined as the failure of tissues to respond appropriately to insulin. 
There are numerous mechanisms responsible for IR including reduction in the density of i
nsulin receptors on the cell surface, malfunction of insulin receptors, defects in
internal signaling pathways, and interference with the translocation or function of GLUT4 proteins.
 IR and Laminitis
All of the pieces of the puzzle must be assembled
before we can fully understand the association between IR and pasture-associated laminitis in horses
and ponies. There are two broad mechanisms by
which IR could pre-dispose horses to laminitis:
(1) insulin resistance might impair glucose delivery
to hoof keratinocytes, or (2) insulin resistance could
alter blood flow to the foot. The first theory is supported by results of a study performed by Pass et al
in which it was shown that hoof tissue explants kept
in culture separate at the dermal-epidermal junction when deprived of glucose.
 Furthermore, GLUT4 proteins
are found in equine keratinocytes, which suggests
that insulin-stimulated glucose uptake occurs in the
hoof. Studies examining the relationship between
IR and blood flow have not been performed to date in
horses; however, insulin is known to act as a slow
vasodilator in humans, and IR has been associated
with a decrease in peripheral vasodilation.
If IR is a determinant of susceptibility to pastureassociated laminitis, then what triggers the laminitis episode itself? It seems that non-structural
carbohydrates (NSC) within pasture grasses play an
important role in this process. Most NSC measurements include simple sugars, starch, and fructans
(polymers of fructose), and levels of these components vary considerably within grass according to
geographical location, soil type, weather conditions, and time of day.
NSC are likely to affect the susceptible horse in two ways. First, excessive sugar
consumption could exacerbate IR like it does in diabetic humans. Second, consumption of large
quantities of NSC might alter the bacterial flora
found within the large intestine. These alterations
in bacterial flora are thought to increase the production of as yet unidentified triggering factors for laminitis that may include exotoxins, endotoxins, or vasoactive amines.
Alterations in large intestinal bacterial flora have been induced by orally administering oligofructose (a fructan) to horses.
Here is another great site to read for IR and why it's becoming more prevalent in our horses
Whoa, right????
Yea, welcome to my world.
To simplify-there are reasons things happen.
I'm trying to figure out WHAT caused Laz's laminitis.
Was it Putomac? If so, that means he didn't have an IR reaction to grass that caused his laminitis. 
If so, is he now considered a true IR horse, or non IR? 
Did that bout make him more susceptible to becoming an IR horse?
Laminitis to me, is like Pneumonia. Once you have it, you can get it again much easier so I want to have all the answers I can to allow for his diet to be catered to his needs and his health.

Here are some easy symptoms to look for if you suspect your horse may be IR and shows signs of foot sore:
cresty neck
voracious appetite
'easy keeper'
patchy fat (sholders, rump, elbows, neck)
orbital eye fat
weepy/draining eyes
stretched white line

According that list, Laz has the last two symptoms, so we MAY be lucky and he may not be IR, which will help me adjust his lifestyle/diet.

If you think your horse's feet are sore-start dissecting their diet (and trim).
They are RELATED completely. Not always (but so so so often!!!)

Luckily, I have Michigan State University so close to us, and they are one of the TOP schools for Animal Science
The IR test that I am doing is THIS

There is so much more to IR and diet and horse's hoof health, this post could go on for hours.  Many of you could add to this, and please feel free!!! 


  1. Kristen, did you read this bit of recent research? http://hoofcare.blogspot.com/2011/07/laminitis-research-australian.html So interesting!!

  2. I nominate you for Best Horse Mom of The Year! ;-)

    At one of my old barns, there was a Quarter Horse mare who was literally the poster child for IR -- she was a very easy keeper, drank a TON and peed about 50 gallons a day (interestingly, this is also a symptom of diabetes), and had already foundered even though she was only FIVE years old. She was cresty, obese, etc. The owner was a teenage girl who would come out maybe once every few weeks and ride the snot out of her, then not show up for another few weeks.

    I printed out a list of IR symptoms/eplanations, plus printed out the feed suggestions and made a list of which feeds would be good for the horse. Left it all in her trunk, to be discreet. When she found it, she was apparently very flippant and saying, "My horse is fine!! She doesn't have this!" and totally ignored it. Well, guess what? Apparently several VETS had already suggested that the horse could be IR, and yet the girl refused to listen to any of them. SO frustrating!!

    And guess what she was feeding the mare? Sweet feed!!! Isn't that just a kick in the head?! Absolutely the worst possible thing they could have given the mare. You would think she would take good care of her, considering her parents spent something like $25,000 on the horse.

    Anyways, sorry to be long-winded as usual. But you're right, IR is very serious. Laz is lucky to have such a conscientious (sp?) owner. Fingers crossed for you guys tomorrow!

  3. A cortisol test (it's done at intervals over a multi-hour period) is actually very helpful in diagnosing IR, often even more helpful than glucose testing - there are only a couple of labs in the country that do this test so your vet has to be informed.

    IR is absolutely related to hoof trouble, including abscesses, and there are IR horses that don't meet the profile - our Dawn is one - she has almost none of the physical markers but she's an TB ex-racehorse so probably was dosed with steroids when she was young, which can predispose a horse to develop IR.

    We use a chromium/magnesium/selenium/vitamin E supplement (horses who are not in low-selenium areas shouldn't supplement with selenium) - ours is a custom supplement but D Barb Balance is a good approximation - the chromium is the key thing (mag is important too) and makes a big difference for IR horses in metabolizing glucose.

    Glad you're getting educated on this - most horse owners (and trainers and even vets) seem less than well informed on the topic.

  4. That should have been D Carb Balance!

  5. @Andrea-very interesting and yes I'm sure we are on the brink of understanding how insulin is directly related within the feet. It's also interesting that studies have shown that wild horses don't suffer from laminitis!!

    @Frizzle-just crazy. Poor horse under lack of caring owner. Don't we see this a lot though.

    @Kate-yes the supplements you talk about are VERY important and key for IR management and aids the horse. The interval testing is done more for Cushing's than IR or so I was told via Cornell, MSU, and other sources BUT I never dismiss anything completely. It seems hard to test for something once and think you have a 100% sound answer. Weather changes, diet changes,etc I'm sure all attribute to how a more sensitive horses system works.

    Here is also another link for more explanation, etc for IR: http://www.ecirhorse.com/index.php/insulin-resistance/treatment-of-ir

  6. Very cool, thanks for the super IR update!! You again write soooooooooooooo well:)

  7. Kate, are you confusing insulin resistance with cushings?

    Kristen, good luck with all of this. Insulin resistance, laminitis, etc, are all tough topics because I think we still know so little about what is actually chemically and physically going on in these horses.

    Something else that I think is important to consider in all of this is weight and exercise. If Laz does end up being IR it will be really important to keep him on the lean side and try to make sure he gets exercised often (as it sounds like you already do). Diet is totally the key, but sometimes I think people forget about those other management aspects as well.

    I think it's also important to consider that even if the test comes back in the normal range is that he may still have a problem. Hormones fluctuate a lot, and you will only be looking at one small snapshot in time. One of my vet's horses has tested normal every single time she has tested him but she has to feed him like an IR horse or he has problems.

    Did Laz actually have Potomac? If so, I would put lots of money on that is what gave him the laminitis. However, I personally agree that once they have laminitis they are more likely to get it again (I think some horse's feet never really quiet down all the way and they are much closer than your average horse to having another episode). Perhaps Laz does now have some IR and is sensitive to the NSC.

    I'm not sure if any of that made sense, I'm pretty sleep deprived and totally rambling. I had Prince tested for IR and Cushings after his laminitis and it came back all normal, but I still am careful about what he eats. You can never be too safe with it you know?

  8. I don't know if you have been following my brumby's feet saga this summer, but I had quite a scare thinking that she had actually foundered. It was no fun realizing that might be what was going on and I called a vet. Luckily, the xray confirmed there was no rotation. But before that, i went over her diet and her pasture rotration for a long (and fretful) time. As it turns out, with the vet's help, we discovered 2 things: 1. This is a horse that must wear shoes all the time. And 2. She had Lyme disease.
    I just wish all of our horses could be 100% comfortable 100% of the time. I will be reading to learn along with you about insulin, Laminiits and Laz.

  9. This is a very interesting post. Thank you for sharing it. How long will it be before you get the results?

  10. @Jessica-almost 100% sure it was Potomac. He was vaccinated for it and the one test we did said it wasn't Potomac BUT all signs show and even vet thinks it possible, as did Dr. Bowker and others. I think so too. I agree about the IR results and still being careful, it is just a snap in time and the elevations rise and lower with seasonal change as I hear, so I probably would keep to his diet as well. I would like to get him on pasture IF it's possible too but would always like a dry lot option.
    @Kate-check out http://www.californiatrace.com/ too for vitamin options too, it may price out less?

    @BSB-I emailed you some info to your email for Lilly! Hope you got it :)

  11. For some reason I can't comment on your latest post, called Updates. Just wanted to say Laz looks AWESOME! Gorgeous and happy and healthy. :D You're doing such a great job with him. Good luck finding a new barn and have fun on your vacation.

  12. I still can't comment on the new post, but when I saw the pictures it reminded me of Chrome right now. His rain rot started out as small bumps all over, however they don't disappear, reappear or move around at all so it's still probably an allergic reaction of some sort. Just thought I would mention it.