Cushings tests and fasting

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weebarney

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Can anyone tell me why some people have to fast their horse before a cushings test and some don't? There was never any mention to myself when I got my old pony tested yet my friends up the road who use the same practice had to fast their pony.
 
There's no need to fast for a Cushings test (I assume you mean ACTH rather than dex suppression?). However it is commonly done in conjunction with other tests eg. insulin assay which does require overnight fasting for accuracy.
 
You don't need to fast for the cushings blood test, but you do for EMS.

My vet won't do the two tests together as it's very likely that a horse with cushings will present with insulin resistance at first, but once the cushings is treated the insulin resistance goes away, as it's a side effect of what's going on due to the cushings. If they treat for cushings and don't see improvements, then they follow up with the EMS test at a later date. Or, if they think EMS rather than cushings, they do the EMS test first and follow up with cushings if no progress after treatment.

You can get Cushings horses that are also insulin resistant in their own right, and IR horses who don't have cushings, so it's a bit of a minefield.
 
Tell me about it my friends pony presented classic cushings symptoms yet they were told to fast. We have been asked to meet the vet about their other pony who they think has lami again as they can't be there. I suspect cushings is behind it yet when my mam rang the receptionist at the vets she said the pony would have to be fasted for 24 hours before the cushings test. I'm just gonna wait for the vet and ask him as I don't think the receptionist knows what she's talking about.
 
weebarney said:
when my mam rang the receptionist at the vets she said the pony would have to be fasted for 24 hours before the cushings test
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I had my pony tested for Cushing's and insulin a few months ago and so I had to fast her overnight for the insulin test. It was a 12 hour fast though, 24 hours seems terribly excessive to me.
 
Ring the vets and ask to speak to a vet, not the receptionist!
IR or insulin resistant and EMS have to be fasted from 10pm the previous night, bloods are taken the following morning, then a glucose (sugar) feed is given and the vet will come back after 2 hours and take another lot of bloods. Then your horse is free to eat whatever (recommend soaked hay).
Cushings ( or PPID) is a simple blood test with no fasting.
It should take about 2/3 days for the results to come back.
24 hours is not necessary anymore due to the advances in testing.
 
It's all right I spoke to the vet when he was out . He doesn't want to test for cushings at the moment as he said the results could be unreliable this time of year.
The receptionist obviously gave my mam dodgy advice re fasting.
 
Mine was fasted overnight at vets for insulin resistance / EMS, he was in for lameness work up anyway so was as easy for it all to be done at vets and have an overnight stay. Cushings test just involved taking blood at home on a separate occasion.
 
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