How accurate is the Cushings test?

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Ruftysdad

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I ask this because several horses I know, including mine have shown positive for Cushings recently. Most of them are oldies but one is a youngster. Some of them had no symptoms but were tested as a precaution.

Following on from that it is likely that most older horses will have raised levels? and that in the past horses have died younger and not shown any signs, but did have it in the early stages? When I was younger it was something that was rarely mentioned. However I knew many horses who got laminitis and the cause put down to being overweight and on rich grass.

I have also heard of several horses and ponies recently that have been diagnosed as having EMS as well. Again I had never heard this mentioned until recent years.

Summing up, is it better awareness of these diseases and better testing that is showing up the high levels of insulin etc or are the tests not 100% accurate?
 
I think the testing needs to be looked at as part of a wider picture and I believe false negatives were common - all the signs and symptoms there but blood results suggested not. I really don't know about accuracy as the tests depend on fasting and since the system is disrupted anyhow (by the Cushing's) so I can imagine it is easy to get inconclusive or incorrect results?

The awareness of EMS, it's origins, heritability, direct causes and disasterous implications when linked with Cushing's in later years is now huge, and very much at the forefront of animal welfare. Historic ignorance and mild tut-tutting over podgy ponies is past and obesity should now be getting the strict reprimands (and penalties to the perpetrators) that it deserves.

It's a MASSIVE welfare issue. No pun intended.
 
its more awareness I think . how many older horses and ponies grow excessively long coat? I always thought it was because they felt the cold more when they were old, it now appears that it is a sign of cushings...years ago(im old so a very long time ago) ponies and horses who were not able to do a job were put down so the later symptoms of cushings wouldn't have been seen.. . I got my mare tested because she didn't shed her coat properly and her character had changed to being grumpy and not wanting to be handled.....since being on the medication she is back to the happy mare she always was so her test was right...
 
I think it tests different at different times in the year/diet. My mare tested negative but has a lot of the symptoms bar a bad coat. I plan to test her again in winter.
 
splashgirl45 said:
its more awareness I think . how many older horses and ponies grow excessively long coat? I always thought it was because they felt the cold more when they were old, it now appears that it is a sign of cushings...years ago(im old so a very long time ago) ponies and horses who were not able to do a job were put down so the later symptoms of cushings wouldn't have been seen.. . I got my mare tested because she didn't shed her coat properly and her character had changed to being grumpy and not wanting to be handled.....since being on the medication she is back to the happy mare she always was so her test was right...
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This.

equi said:
I think it tests different at different times in the year/diet. My mare tested negative but has a lot of the symptoms bar a bad coat. I plan to test her again in winter.
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So you are not treating for it yet?
 
Interesting question. I also wonder how accurate the test is as well.

Mine has just tested positive despite having no symptoms whatsoever. I only had it done as the vet was testing my other horse (laminitis) as the first test he had done could have been affected by pain.

We had the discussion that possibly half of horses in their mid twenties could have it without anyone ever knowing.
 
I sometimes think we're too desperate to have a biological reason for things when sometimes it's just the way it is. We have an enormous horse on our yard. He looks a prime candidate for both cushings and EMS. Tests say otherwise. His poor owner has tried everything to keep the weight off him.

He's a 22yr old 16.2 IDxTB, retired due to arthritis so can't be ridden to get weight off him. Even when he was in full work, novice eventing fit, he was still a bit porky and had to do loads of fitness work. He can't be stabled as stiffens. He winters out, unrugged and barely loses anything. He escapes a muzzle in 10 seconds flat. When she's tried to restrict his intake in the past, he's had ulcers. She's tried walking him in hand - he can cope with about 25 mins a day - and she lost a stone in 3 weeks while he lost nothing.

She made the decision at the start of the summer to just turn him out and if he ends up ill because of it, she's resigned to having him PTS and at least he'll die happy. He's been fine all summer. Well not fine, the weight he is must put a strain on his legs but he seems perfectly happy, hasn't had lami or any other lameness issues. He's just (like me unfortunately) genetically pre-disposed to weight gain and without the exercise he had before it's piling on.
 
annagain said:
I sometimes think we're too desperate to have a biological reason for things when sometimes it's just the way it is. We have an enormous horse on our yard. He looks a prime candidate for both cushings and EMS. Tests say otherwise. His poor owner has tried everything to keep the weight off him.

He's a 22yr old 16.2 IDxTB, retired due to arthritis so can't be ridden to get weight off him. Even when he was in full work, novice eventing fit, he was still a bit porky and had to do loads of fitness work. He can't be stabled as stiffens. He winters out, unrugged and barely loses anything. He escapes a muzzle in 10 seconds flat. When she's tried to restrict his intake in the past, he's had ulcers. She's tried walking him in hand - he can cope with about 25 mins a day - and she lost a stone in 3 weeks while he lost nothing.

She made the decision at the start of the summer to just turn him out and if he ends up ill because of it, she's resigned to having him PTS and at least he'll die happy. He's been fine all summer. Well not fine, the weight he is must put a strain on his legs but he seems perfectly happy, hasn't had lami or any other lameness issues. He's just (like me unfortunately) genetically pre-disposed to weight gain and without the exercise he had before it's piling on.
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what a lovely owner , at least he is having a good time and better a shorter life enjoying himself, this is why I keep my cushings horse as natural as poss and I it shortens her life, so be it!!
 
My own experience is that the tests themselves vary in accuracy.

Our pony (in her 20s) was displaying symptoms but the ACTH test came back borderline.

Vet and I were so convinced that she did have Cushings that we did the TRH test, which came back with a high reading.

I gather the ACTH test has a rep for false negatives.

Friend's pony has no outward symptoms, and is 12. But she recently came down with lami and and tested (ACTH test) positive. Now on Prascend and very strict management.
 
The test isn't the most reliable for a few reasons and must be used alongside clinical signs for a diagnosis.

http://www.thelaminitissite.org/ppid.html

*'Diagnosis of PPID

See the Equine Endocrinology Group's Recommendations for the Diagnosis and Treatment of Pituitary Pars Intermedia Dysfunction (PPID) October 2013

The diagnosis of PPID is not straightforward. The slow progressive neurodegeneration means that the horse is likely to be ill before blood tests confirm PPID, and our lack of understanding of the disease makes it difficult to validate existing or potential diagnostic tests. Comparing current blood test results to histological changes in the pituitary gland has shown that mild and moderate (grade 3 and 4) changes are often present in the pituitary gland before blood tests become positive. Early symptoms often go unnoticed, and vary greatly between horses. A positive blood test appears to be diagnostic of PPID (if seasonally adjusted reference ranges are used), but a negative blood test does not necessarily mean that the horse does not have PPID. Although laboratories set cut-off values for diagnosing PPID, there may be a grey area either side of the cut-off value, and the clinical symptoms must always be considered along with the diagnostic test results.
For advanced cases of PPID the clinical signs and presence of hirsutism (long curly coat which sheds abnormally) can be sufficient for a diagnosis. However hirsutism is often one of the last signs to appear. Dianne McFarlane has suggested that PPID is a clinical syndrome of different causes, therefore it is unlikely that one testing method will be best in all cases (source: Vet Clin North Am Equine Pract. 2011 Apr;27(1):93-113 Equine pituitary pars intermedia dysfunction McFarlane D).

Two blood tests are commonly used to diagnose PPID (please see the individual tests for instructions):
ACTH test (resting plasma ACTH concentration) - no risk of laminitis, advisable for monitoring pergolide dosage, single vet visit and blood draw, can be used at any time of the day and year and is the only reliable test during the autumn seasonal rise (if a seasonally adjusted reference range is used).
Dexamethasone Suppression Test (DST) - possible risk of laminitis, doesn't specifically measure ACTH reduction due to pergolide, more expensive as requires two vet visits (unless the owner administers the dexamethasone), cannot be used during the autumn seasonal rise.

The TRH stimulation test, testing ACTH (not cortisol), may be useful when ACTH or DST results are borderline or unexpected (i.e. if a horse with physical symptoms tests negative for PPID). ACTH is tested before and soon (10 mins or 30 mins) after injecting 1mg TRH. Retesting resting ACTH during the seasonal rise (August - October northern hemisphere) may be just as useful.'
 
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