Cushings - false negative test result?

OldNag

OldNag

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Veteran (early 20s) pony has come down with lami. We've had her on loan 3 years and have always managed her very carefully, and we have avoided lami so far (though it looks like she has had it previously).

Had Cushings test this week and it's come back borderline. I (and vet) think she is showing plenty of Cushings symptoms so we were expecting a positive result. Vet mentioned another test which requires 2 blood tests, which might be more accurate. But suggested that I just keep her in for another 2 weeks and gradually reintroduce turnout (muzzled).

She only has it in fronts and is looking much perkier. Currently on a huge bed, Danilon and soaked hay.

I'm wondering how common it is for a Cushings test to result in a false negative and whether it is worth having another test done. I was so surprised at the result, especially given that she's come down with lami now.

I asked vet about testing for EMS too, but her opinion was that she didn't look like a pony with EMS.
 
If she is showing symptoms as well I am surprised that the vet hasn't suggested trying prascend anyway.
 
Depends on what you mean by symptoms as many of those associated with Cushings are also associated with general old age and other problems. A retest once the pony has recovered from lami is more in line than just sticking on Prascend anyway if pony is improving.
If she's a native pony then EMS is a strong possibility regardless of how she looks.
 
glenruby said:
Depends on what you mean by symptoms as many of those associated with Cushings are also associated with general old age and other problems. A retest once the pony has recovered from lami is more in line than just sticking on Prascend anyway if pony is improving.
If she's a native pony then EMS is a strong possibility regardless of how she looks.
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Thanks - it's a tricky one isn't it. She certainly doesn't look like a youngster!

I did ask for EMS test but vet said she didn't have the physical signs she'd be looking for? Don't know her breeding but I am guessing she's mostly Welsh B.

When we got her she had a "foal belly", does have a Cushings-esque coat, used to be a bit cresty. Since we've had her though, she has been muzzled Mar/April through to Oct/Nov, and I have been giving supplements on the basis that she has Cushings/EMS or both. We got her weight down, the foal belly got a lot more reasonable, and we've avoided crestiness. She does have fat pads on her bum though, even when she lost a fair amount of weight last winter and was looking too lean.

Her owner was reluctnant to have her tested initially but has given the go-ahead, hence us getting her tested this week.

I am reluctant to just leave things and just wait and see if lami strikes again... will ring vets in the week. Who knows, she may not get it again (she's avoided it for some years) but I don't want to risk things. She's in early 20s now so is probably more prone.
 
I would probably ask the vet if I could trial her on a low dose of Prascend for a couple of months to see if it helped.
 
A Prascend trial is probably cheaper than a second test, and more reliable TBH but vets are wary of prescribing it because it is dopamine, you might have to persuade him. A friend of mine has battled with a QH with metabolic problems for years and tests always came up negative. She persuaded her vet and Prascend has transformed him.
 
I suppose I just think I wouldn't want to have a pony struggling with lami when it might have an underlying metabolic issue that won't be helping. It seems quite widely reported on here that the levels often don't match the associated symptoms which are essentially the things that will benefit from treatment.
 
Mmm food for thought.

I am convinced she does have Cushings, I had thought that Prascend would not be prescribed unless test result indicated it. I would be happy to try her on low dose of Prascend.

I will book a vet visit for towards the end of her box rest (2 weeks) and get a retest done, and ask that we try a low dose anyway.

I don't want her to come down with lami again. She means a lot to us and I want to keep her happy and well as long as I can.

Thanks everyone.
 
I *think* that Autumn is the most reliable time for testing ACTH levels, so it might be worth getting her retested then if possible.

Do you know which test they have done? The basal ACTH is the standard one done, but if there is an inconclusive result there are a few other options (TRH stimulation test and Low-dose dexamethasone stimulation test) but tbh I'd be wary about doing those if she has/is particularly prone to lami. The downside of just starting them on Prascend/pergolide without a proper test result is that it makes monitoring levels pretty difficult, but if you and your vet are happy to try and just monitor by how she looks/seems it could be worth a try; see what your vet thinks.
 
sarahandwilby said:
I *think* that Autumn is the most reliable time for testing ACTH levels, so it might be worth getting her retested then if possible.

Do you know which test they have done? The basal ACTH is the standard one done, but if there is an inconclusive result there are a few other options (TRH stimulation test and Low-dose dexamethasone stimulation test) but tbh I'd be wary about doing those if she has/is particularly prone to lami. The downside of just starting them on Prascend/pergolide without a proper test result is that it makes monitoring levels pretty difficult, but if you and your vet are happy to try and just monitor by how she looks/seems it could be worth a try; see what your vet thinks.
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Thank you. It was the basic ACTH. When we discussed the result, Vet mentioned doing the TRH but didn't think it was worth doing at this stage...

I agree about trying with Prascend without a proper test result - which is why I'd like another test done in a fortnight. If that comes back raised then we know, if it's the same then we take a view on whether to do the TRH....

My gut instinct says it is Cushings, I'm half inclined though to ask again for the EMS test. There must be a trigger for her to come down with lami at this time of year.

Arrh it is so difficult to know what to do for the best. I just want to make sure pony is OK!
 
JFTD said:
Yes, the test does throw false negatives sometimes - it's a little notorious for it!
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Yes, I've heard this, too. Isn't it because the hormone is secreted in pulses, rather than at a steady rate? Maybe the blood was taken in a lull between the pulses.

Certainly some vets are happy to give a prascend trial, if enough symptoms fit, even if the ACTH levels are below the threshold.
 
JFTD said:
Yes, the test does throw false negatives sometimes - it's a little notorious for it!
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certainly was for mine. He tested at 18. His symptoms suggested cushings. Retested him at a different lab (Liphook) and he came back at 11!!!

Put him on a prascend trial and to me the question was would be respond to prascend. He did. Considerably. I haven't bothered to retest, there seems no point. It has been easy enough to monitor him from his symptoms response to prascend.

My vet was great and didn't quibble at all over a prascend trial.
 
Ems and Cushings can go hand in hand so your vet saying she doesn't look like an ems case is quite stunning frankly.. i am surprised at her response to you asking for a test! Quite often, a laminitic can actually have ems but not cushings!
Have a look at 'thelaminitissite' where there is lots of info on all three, lami, cushings and ems symptoms, feed, grazing, etc etc plus facts about all three...
My horse was also borderline but i put him on prascend anyway and he improved no end although i altered his management in general ie feed, ridden work...my farrier actually thought he had ems initially...hence the call out for the vet ( he did have low grade lami too and was v lethargic)
Just start on half a tablet (if you do go down the route of prascend) and build up to 1 tablet if thats what your horse is prescribed, stops the veil occurring ( see the website for info)
Good luck
 
Micky said:
Ems and Cushings can go hand in hand so your vet saying she doesn't look like an ems case is quite stunning frankly.. i am surprised at her response to you asking for a test! Quite often, a laminitic can actually have ems but not cushings!
Have a look at 'thelaminitissite' where there is lots of info on all three, lami, cushings and ems symptoms, feed, grazing, etc etc plus facts about all three...
My horse was also borderline but i put him on prascend anyway and he improved no end although i altered his management in general ie feed, ridden work...my farrier actually thought he had ems initially...hence the call out for the vet ( he did have low grade lami too and was v lethargic)
Just start on half a tablet (if you do go down the route of prascend) and build up to 1 tablet if thats what your horse is prescribed, stops the veil occurring ( see the website for info)
Good luck
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That's reassuring in a way, I do wonder if she has EMS too. I would be so surprised if she doesn't have one or the other. I have looked on the laminitis site, it's really good. Arrgh it woudl have made things much easier if we had both tests done.

I wonder how hard it wil be to get vet to prescribe Prascend without the test being positive? Will report back!

Thank you.
 
My horse was borderline and vet was happy to start him on prascend to alleviate the symptoms he had...surely vet would be ok with it? Never went down the ems test route as it seems generally to be a feed/exercise regime that keeps them ok :)
 
A little update. Pony is on second week box rest, off Danilon and looking good. She us desperate to go out, poor love.
I have spoken to vet and talked options - I wasn't happy to leave things without knowing what triggered the lami.

Vet not happy to go for Prascend without firm diagnosis so we are going to do the TRH test and hope for a more conclusive result. If that is negative (and I will eat my hat if it is) I think we will presume EMS.

Just want to do everything possible to prevent further bouts. She is early 20s and just the sweetest pony going. .

Can gradually start to turn out at the weekend and start gentle work.
 
Bless her, good luck with it all....have a look at the TRH test blurb on the laminitis site, something about it is ringing bells (but can't remember for life of me what it is)
 
Vet came out today to do the TRH.

Originally I had asked for Cushings and EMS test but the first vet (same practice) said pony didn't look like she had EMS, so we arranged just for the ACTH, which came back borderline.....

Today's vet thinks pony looks like she has EMS.....!

Upshot is that we will probably manage as if she has EMS, with or without the Cushings. But I am still a little bemused at first vet's opinion that she doesn't look EMS-y. She has all the signs. Think I trust second vet more. I am inclined to ask for a short course of Metformin whether we end up on Prascend or not.

Will report back on the TRH outcome.

Meanwhile pony is looking very trim indeed and seems far happier than a few weeks back (she absolutely hated box rest) though still has very stubborn fat pads on her bum.
 
My mare had 5 attacks of laminitis and just as many negative ACTH tests. She had the other test done and her levels were sky high. She is now on Prascend - I wish the other test had been available sooner.

JFTD said:
Yes, the test does throw false negatives sometimes - it's a little notorious for it!
Click to expand...
 
If your pony had laminitis then she most likely had EMS...the best treatment for that is weight loss which you seem to have done anyway. Metaformin is useful if the pony is obese and can't exercise ie, while it has laminitis but if you have managed to get the weight of then it unlikely to be needed. (check with vet)
The Cushings test should alaways be used alongside symptoms as it is pretty unreliable otherwise (as you have found). If she has the symptoms then I don't see why your vet is reluctant to try a Prascend trial if you are prepared to pay?
Is she laminitis free now?
I would recommend trying the Facebook group EMS, Cushings and Lmainitis UK which is run by the laminitis site. Andrea on there is a wealth of knowledge and will help you make sense of it all.
 
_HP_ said:
If your pony had laminitis then she most likely had EMS...the best treatment for that is weight loss which you seem to have done anyway. Metaformin is useful if the pony is obese and can't exercise ie, while it has laminitis but if you have managed to get the weight of then it unlikely to be needed. (check with vet)
The Cushings test should alaways be used alongside symptoms as it is pretty unreliable otherwise (as you have found). If she has the symptoms then I don't see why your vet is reluctant to try a Prascend trial if you are prepared to pay?
Is she laminitis free now?
I would recommend trying the Facebook group EMS, Cushings and Lmainitis UK which is run by the laminitis site. Andrea on there is a wealth of knowledge and will help you make sense of it all.
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Thank you.
Yes the lami has gone.
Vet wouldn't prescribe Prascend without doing the TRH test.
I am pretty sure she has EMS whether there is Cushings there or not. Was rather taken aback by first vet saying she didn't look like it!
Thanks for the fb group , I will have a look there.
 
Hi, I have a 14.2 successful 12 year old new forest pony in the yard who has Cushings and is on Prascend. Within the past couple of months he has four minor fits which started with him falling forwards on to his knees, his eyes rolling back, shaking and being unable to stand and has now progressed to a full blown fit where he fell to the floor, his eyes again rolled back, he staggered to get to his feet and then in a rigid stance went up in the air (not rearing, more like an electric shock) and then fell over backwards, he then staggered to get his feet underneath him but was not instant or easy for him. When he finally did get to his feet he braced himself in a doorway with splayed legs (as a nervous traveller would do in a lorry). The whole thing took approx 2 minutes, then he was quiet but happy and a few minutes later eating his hay as if nothing had happened, although had bitten his lip and tongue.
The thing is, he was diagnosed with acute Cushings and is given a Prascend pill once a day, it did not seem to be working (still really lethargic and unable to trot) so vet suggested upping the dose to two pills, which I did although fits had just started beforehand. Now the options are very limited but before I make that heartbreaking decision I just wondered, has anyone had a similar experience or know of anyone whose horse has suffered in this way?
Ps I have two other 12.2 ponies in the yard on the same meds and they are fine.
 
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