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  1. #1
    Join Date
    Dec. 16, 2003
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    Staunton, VA, USA
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    Default A question for those of you (veterinarians) who manage IR horses

    What do you think are the chances of reversing or correcting the metabolic imbalance that is IR?

    Recognizing that we by no means have all the answers yet.

    Here's the scenario;

    I do a certain amount of research on IR?Cushings horses. Limited due to not having an actual lab!

    But with use of a glucometer, and using the Rutgers protocol we can run glucose curves on horses, doing a simple glucose challenge test.
    Basically the test consists of a Pre-test, then we feed a meal of standard sweet feed, (25% NSC) and then take blood and test for glucose levels at 30 min intervals over 4 hrs.

    I have done a number of these (testing various ingredients for the supplements) and I am well versed with the shape of the curve in an IR horse vs a normal horse.
    (IR horses have a flattened curve that goes down very slowly over 3-4 hrs, vs the sharp peak and steep fall of a normal horse).

    So I was wanting to run some more tests, and of course I need IR horses. I recently lost two of my 'best' IR horses, one whose owner moved away and one who died.

    So I was looking to replace them and I wanted to try out the new test protocol from Perdue.

    The new test is a simplified curve as in, they take a glucose reading and then give normal insulin ().1IU/KG BW), 30 mins later they re read the glucose. If the blood glucose has dropped by 50% or more the horse is normal, ie is responding to insulin, if the blood glucose does not drop by 50% then the horse is IR, ie; resistant to the insulin.

    I had 2 horses that I had used extensively last year for testing and all last year they had classic curves wherein the glucose was still high 3-4 hrs after the meal, eg no clearance of glucose from the bloodstream.

    I had my normal control and I have the 4 horses I was testing to see if they were IR.
    The two mares from last year have all the classic morphological symptoms, overweight, cresty neck, fat pockets, and both have a history of laminitis.

    So we do our test and to my amazement the two mares from last year had good response to the insulin, well one was close, she cleared but only just, right at 45% (50% being the cut off remember).
    the other one had a clearance of well over 60%.

    So what has happened. We have managed these two well over the winter, we manage all of our IR horses, I don't want them to get laminitis, but they usually give me the abnormal flattened curve even if 'normal' in appearance.

    Are they no longer IR? I guess I need to do a full glucose clearance test on them to see what shape the curve is.

    Any thoughts on this?

    And I realize that COTH is probably not the best forum to ask this question on, but there are some veterinarians and other nutritionists who read this and I'd love some feed back.

    Ideas on a better forum would be welcome as well.

    Thanks
    Yours
    MW
    Last edited by Melyni; May. 14, 2012 at 09:15 PM. Reason: clarity
    Melyni (PhD) PAS, Dipl. ACAN.
    Sign up for the Equine nutrition enewsletter on www.foxdenequine.com
    New edition of book is out:
    Horse Nutrition Handbook.

    www.knabstruppers4usa.com



  2. #2
    Join Date
    Dec. 16, 2003
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    Staunton, VA, USA
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    Default

    bump
    Melyni (PhD) PAS, Dipl. ACAN.
    Sign up for the Equine nutrition enewsletter on www.foxdenequine.com
    New edition of book is out:
    Horse Nutrition Handbook.

    www.knabstruppers4usa.com



  3. #3
    Join Date
    Dec. 16, 2003
    Location
    Staunton, VA, USA
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    Default

    bump (again) I keep hoping someone will see it and reply!
    Melyni (PhD) PAS, Dipl. ACAN.
    Sign up for the Equine nutrition enewsletter on www.foxdenequine.com
    New edition of book is out:
    Horse Nutrition Handbook.

    www.knabstruppers4usa.com



  4. #4
    Join Date
    Sep. 16, 2001
    Location
    VA
    Posts
    314

    Default

    We're there any differences in terms of BCS or exercise levels from one testing period to the other? Really interested in your answer...I haven't proven it, but I get the sense from our IR patients that getting them at a BCS of 5 to 6 really improves insulin sensitivity. I also wonder if IR is a continuum with some severely affected and some just being IR due to obesity causing decreased insulin sensitivity.
    Cathy



  5. #5
    Join Date
    Aug. 28, 2006
    Posts
    10,713

    Default

    Quote Originally Posted by DVM2003 View Post
    We're there any differences in terms of BCS or exercise levels from one testing period to the other? Really interested in your answer...I haven't proven it, but I get the sense from our IR patients that getting them at a BCS of 5 to 6 really improves insulin sensitivity. I also wonder if IR is a continuum with some severely affected and some just being IR due to obesity causing decreased insulin sensitivity.
    Cathy
    I am not a vet but own an IR horse and would likewise be interested in your answer...

    Humans can show a dramatic improvement in insulin resistance with exercise and weight loss.



  6. #6
    Join Date
    Jan. 31, 2003
    Posts
    18,472

    Default

    Let us know if you become interested in info from non-vets.
    "Kindness is free" ~ Eurofoal
    ---
    The CoTH CYA - please consult w/your veterinarian under any and all circumstances.



  7. #7
    Join Date
    Mar. 19, 2010
    Posts
    221

    Default

    Don't see anyone answering your question here, have you made progress finding out elsewhere?



  8. #8
    Join Date
    Dec. 16, 2003
    Location
    Staunton, VA, USA
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    Default Of course I'd like to hear from non-vet as well!

    Quote Originally Posted by EqTrainer View Post
    Let us know if you become interested in info from non-vets.
    Be glad to hear from you.
    Melyni (PhD) PAS, Dipl. ACAN.
    Sign up for the Equine nutrition enewsletter on www.foxdenequine.com
    New edition of book is out:
    Horse Nutrition Handbook.

    www.knabstruppers4usa.com



  9. #9
    Join Date
    Dec. 16, 2003
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    Staunton, VA, USA
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    Default Not so much exercise level, but a big change in BCS.

    Quote Originally Posted by DVM2003 View Post
    We're there any differences in terms of BCS or exercise levels from one testing period to the other? Really interested in your answer...I haven't proven it, but I get the sense from our IR patients that getting them at a BCS of 5 to 6 really improves insulin sensitivity. I also wonder if IR is a continuum with some severely affected and some just being IR due to obesity causing decreased insulin sensitivity.
    Cathy
    There was a big change in BCS. During the winter the mare lost a LOT of weight. Not entirely sure why, except that I was experimenting with a couple of ingredient mixes and she was on one of them (as well as her limited grazing/hay, LinPro and chaff hay), so much so that while I was in Florida, my barn manager called and asked permission to start giving her some grain, as she had dropped to a BCS of 4-5, rather than the 6-7 she normally is.

    I have read about the cases in humans where a precipitous weight loss causes an apparent reversal if IR, so I wondered if it was that weight loss that did it.

    This horse has been IR for about 4-5 years up to this point. When we started with her she had a BCS of 8-9, at that time she did have laminitis, we got her down to a 6-7, and managed her such that she never got the laminitis again, but her glucose clearance curves were always flattened and extended out.

    I guess I need to re do a full curve on her and see what shape it is before I declare her 'cured'!
    MW
    Melyni (PhD) PAS, Dipl. ACAN.
    Sign up for the Equine nutrition enewsletter on www.foxdenequine.com
    New edition of book is out:
    Horse Nutrition Handbook.

    www.knabstruppers4usa.com



  10. #10
    Join Date
    Aug. 21, 2004
    Location
    Guanajuato, GTO, Mexico
    Posts
    2,564

    Default

    My non-vet musings on the matter:

    I believe there are different forms of IR. That it is a symptom brought on in various ways. Some forms are reversible and others are not. When you view a chart depicting glucose metabolism you can see there are many different places for it to get broken. Many different enzymes are involved that are easy targets for genetic mutation. There might be problems with glucose receptors, overproduction of insulin in the pancreas, inflammatory cytokins can drive some pathways, changes in pathways in the liver converting fructose to glucose, etc. Many more. It seems reasonable that this is why effective treatment may need to be individualized for each form of IR.

    There is one form that is brought on by being obese, and weight reduction reverses it. These are the easy ones to manage. I know of horses that foundered on pasture when obese with characteristic abnormal fat deposits, but when recovering from starvation, could eat spring grass with impunity, even during rapid (needed) weight gain. Some IR is reversed when PPID is treated with proper dosage of pergolide, also fairly easy. Some horses may normalize under a certain diet- exercise regimen, but would reverse if the regimen is not followed. I owned, and have been told about other horses with genetic forms of IR that have high insulin and severe cases of laminitis even when exercised regularly, on strictly controlled diets and kept fit and at good weight. Those are the ones that will break your heart and seem impossible to reverse in spite of everything you do.

    There does seem to be controversy among researchers as to which testing protocol is best, as well as a large amount of intra and inter variability in test subjects. Some may be defined as IR under one protocol, but not another. Then it seems there's always one in the control group that tests IR, which they tend to throw out of the data set. That does not bode well for current definitions. That's why some are advocating multiple testing protocols for horses that 'look' IR but may not test IR under one protocol. I would think you need to look at insulin curves as well.



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