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Discussion on Cushings Screen
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Member:
Skeller
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Posted on Tuesday, May 31, 2005 - 7:42 pm:
My vet performed a Cushings Screen on my 11 year old gelding and determined that yes he is Cushingnoid based on the "poor rhythm" assessment from the lab. (see reaction to vaccination, tucked up and trembling for the initial laminitis case).
This was sent to BET Laboratories in Lexington KY. Blood was taken in the AM (before first feeding) and PM approximately 8 hours apart.
Here are the results:
T4 a.m. (low) - 5.8
T4 p.m. (low) - 6.8
Insulin a.m. - 9.8
Insulin p.m. - 13.2
Cortisol a.m. - 37.3
Cortisol p.m. - 30.4
(triangle symbol) 18% - poor rhythm
Can you tell me what how the 18% is calculated? Also is this test considered a reasonable indicator for Cushings? (I know the article says that the cortisol rhthym test is not. However I wasn't sure if this was the exact test described)
Since he reacted to his 5/1 vaccination, my vet was in discussion with the vaccination manufacturer (who was very helpful and called both me and my vet) and this is the test they suggested.
At the time he was an active laminitis case so she didn't do the dex sup test. He does have a slightly cresty neck and fat deposit on his rear. (he's now on an Insulin Resistance diet) Is a bit lazy. This was his first active laminitis case, but he has been a bit ouchy at times. No other outward physical signs of Cushings.
We started pergolide during the initial laminitis instance. Currently he's on .6 mg pergolide a day. This was started about 2 weeks before this test.
He's doing great but I was wondering when I should do additional blood work and if pergolide will be necessary for the rest of his life? (he's on a completely revitalized low carb diet with added Vit E, Selenium - as per article; Magnesium - Quiessence; and Biotin - 50 mg.)
Thanks! Sandi
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Moderator:
DrO
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Posted on Wednesday, Jun 1, 2005 - 7:51 am:
Hello Skeller,
Though it has occurred it seems unlikely to be Cushingnoid in a 11 year old horse. It would seem they took the difference in the 2 cortisol values and divided by the AM reading but I know of no work to suggest this is a useful test. Since your horse is obese I think you are more likely dealing with metabolic synDrOme. If the horse is healthy and stable at this time you should discuss with your vet to wean off the pergolide. But until you get the horses obesity under control and watch the exposure to rich grass you will continue with the mild recurrent bouts of founder.
DrO
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Member:
Skeller
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Posted on Wednesday, Jun 1, 2005 - 8:39 am:
Now don't hurt Cody's feelings (obese is a strong word!) he's actually nice and trim these days!  . Truthfully he was about a 6-7 on the scale when the laminitis occurred and is now a 5. You can barely see his ribs. He's 15.1 and 807 lbs on a fine boned frame. From what I've read the fat bump and crest can continue even on a thin horse until the sugar in the diet is controlled. He's on a pretty strict Timothy Hay diet and 2 lbs Nutrena Safe Choice per day. No grass, no treats. Energy level is definitely increasing so I feel that you are right about the metabolic synDrOme.
I'm hoping we can get him off the pergolide, basically so it will be a choice if we need it in the future. I know not much is known about developing resistance but reading some of the posts on the Cushings groups it does seem that this happens.
I believe that the reason the vet feels there may be Cushings (prior to the screening) is his low thyroid. They also feel that there's no such thing as hypothyroidism in horses, but that correcting the abnormalities in the adrenal gland with the pergolide, will also correct the T4. Any thoughts on this?
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Moderator:
DrO
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Posted on Thursday, Jun 2, 2005 - 7:14 am:
My apologies to the newly trim and slim Cody and it sounds like you have the major issue under control.
Actually if the horse had been cresty for a while it is hard to reduce it no matter what you do. We had some recommend a high magnesium diet but I have seen this recommendation less and less perhaps indicating lack of efficacy, a search should turn up the particulars. The relation between thyroid function and Cushingnoid Disease has been investigated and it has been found to not accurately reflect it, but this information is in the article on Cushingnoid Disease. I don't think horses develop resistance to pergolide, but I do think in time the disease worsens requiring larger and larger doses.
DrO
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