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Discussion on New Cushings Diagnosis
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Member:
erika
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Posted on Wednesday, Oct 31, 2007 - 6:34 pm:
Dr. O, my 18 year old Saddlebred mare was recently diagnosed with Cushings via thyroid tests and Domperidone test. I did not see the Domperidone test in your article on Cushings.
This mare does have typical signs of Cushings: long hair, little muscling, weird little hard fat patches while slim body build, exercise intolerance with easy sweating, etc. She also tends toward laminitis in the fall if I don't watch her like a hawk (slight episode this September, seems sound now), and a little arthritis. Boy! what a wreck for only eighteen! Seems to have aged rapidly in the past couple of years.
I realize that many horses that are prescribed Thyro-L really aren't low thyroid, but I am giving it to her on my vet's recommendation because of the Cushings diagnosis.
Sugar is also getting .5 mg Pergolide/day (850lb horse).
Now for the issue at hand: as stated in your article, many horses will test false positive for Cushings in the fall. Does that mean that I should retest later, or based on the physical presentation as typical, can I go ahead and trust this diagnosis?
Do you think in light of the Pergolide treatment that the Thyro-L is also necessary, or does the Pergolide help normalize the thyroid?
Would love to keep my vet bills down if retesting isn't necessary. Any recommendations?
Thanks,
Erika
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Moderator:
DrO
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Posted on Thursday, Nov 1, 2007 - 9:16 am:
Hello Erika,
Which thyroid tests were run? Simple serum thyroxin (T3/T4) levels alone can neither diagnose cushings or even thyroid dysfunction. For more on this see the article on tyroid disease. In recent years a thyroid releasing hormone test has been suggested as a diagnostic test for Equine Cushings based on measuring the concurrent rise in cortisol and comparing it to normal horses. However, McFarlane et al. recently found a greater than 30% and greater than 50% increase in cortisol concentration in 10 of 16 and 7 of 16 normal horses, respectively, which indicates that the TRH stimulation test may not be a useful test.
Presented at the 2006 AAEP Convention was a paper detailing a interesting experimental finding in horses:
Domperidone Causes an Increase in Endogenous ACTH Concentration in Horses With Pituitary Pars Intermedia Dysfunction (Equine Cushing’s Disease)
Janice E. Sojka, VMD, MS; L. Paige Jackson, DVM; George Moore, DVM, PhD; and Margaret Miller, DVM, PhD
Horses with pituitary pars intermedia dysfunction (PPID) react to domperidone administration with an exaggerated increase in endogenous adrenocorticotropins (ACTH) concentrations. Specifically, a dose of 2.5 mg/kg domperidone orally resulted in an endogenous ACTH concentration in PPID horses that was 2.9 times baseline values at 4 h post-administration.
Endogenous ACTH concentrations in horses without PPID do not exhibit a similar increase. Further research is needed to derive a dose-response curve in PPID animals; the optimal dosage and time interval need be established, and the domperidone-response test should be compared to other conventional methods of diagnosing PPID in horses.
I agree that this test looks promising but there is one significant weakness with this paper as proof of such promise: all of the cushingnoid horses either had obvious symptoms of Cushings or were positive to the Dex suppresion test. Further work needs to be done to determine procedure, accuracy, and usefulness of this test at differnet stages of the disease, but I agree it looks promising. Then again so did many of the current tests now cast aside.
DrO
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Member:
erika
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Posted on Thursday, Nov 1, 2007 - 10:39 am:
Thanks, Doc. Unfortunately. I am traveling for the next few days. Vet sent me the lab reports and they are home, so I will check which thyroid test she ran.
Do I understand you correctly that the domperidone test is probably accurate? I have those labs also.
Will post more info when I return home.
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Moderator:
DrO
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Posted on Thursday, Nov 1, 2007 - 5:59 pm:
While the domperidone test looks promising, its accuracy is yet to determined in my opinion. The most accurate way of diagnosing this disease is in our article (see diagnosis summary in the article) and of interest is that it is the same as the parameters used to identify the individuals as having PPID in order to conduct the above experiment.
DrO
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Member:
erika
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Posted on Thursday, Nov 8, 2007 - 8:29 pm:
Okay, home again for a couple of days.
Here are the lab numbers:
On 9/07/07(during first symptons of mild laminitis)
Glucose specimen-plasma, nos
Glucose 137 H mg/dL
Lipemia 9
Hemolysis 10
Icterus 2
9/11/07
ACTH & insulin
ACTH baseline 29.5 pg/ml
insulin 156.24
T4Baseline 0.85
10/12/07
1.ACTH baseline 31.4 pgmL
2. 4 hours Post domperidon 57.7 pg/mL
3. 8 hours post " 68.1 pg/mL
T4 (thyroxine)baseline 4.59 (after treatment with Thyro-L for three weeks)
So there's what I can glean from the reports! Again, I guess my major question is should I retest in the spring due to common false positives in the fall?
Or do you think that these test results in combo with her typical Cushings symptoms and appearance are adequate for diagnosis?
As I said she is currently on .5 mg. of Pergolide and one scoop of Thyro-L per day(cut in half since last thyroid test--she was getting two scoops a day.)
I leave tomorrow night for flood ravaged Chiapas, Mexico, so I hope I can communicate while there. If not, I will check in upon return.
Thanks so much for your time.
Erika
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Moderator:
DrO
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Posted on Friday, Nov 9, 2007 - 11:48 am:
I think the clinical signs you describe are enough to try a course of treatment to see if the laminitis responds and the problems you associate with aging improve. The labs support the diagnosis.
DrO
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Member:
erika
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Posted on Friday, Nov 9, 2007 - 2:24 pm:
Thank you very much for the opinion, Dr. O. I hope to see her grow young again before my very eyes!
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Member:
erika
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Posted on Wednesday, Jan 23, 2008 - 2:35 pm:
Update on Sugar:
No noticeable bodily changes--she still looks rather lumpy, and her bad knee still threatens to buckle if I hold up the opposite foot long.
BUT, my trimmer was here the other day and remarked on how much her feet have improved! YAY!! This has been a big problem in recent years. Sugar always had great feet until a few years ago when she began to get tender, and her white line became very stretched. I pulled her shoes and have been barefoot trimming for three years to try to get them back in shape.
They continued to be problematic despite supplements, topicals,etc. Until now! Even I could see a remarkable improvement.
So I assume that this means the pergolide is helping. I hope to see more improvement in hair, etc. by spring. Will let you know...
Erika
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Member:
scooter
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Posted on Thursday, Jan 24, 2008 - 7:22 am:
Erika do you think the hoof improvements are because of the pergolide or better trimming? My arab gelding has cushings too. He is prone to founder, has that lovely hair that doesn't shed and is "lumpy". The vet told me a couple years ago I could control it with diet and a new farrier, so far he is doing VERY good, but fall is his worse and I must be very vigilant with his diet..and care. Other than that and shaving him in the spring, you would never know there was a thing wrong with him. I had been tempted to try the pergolide for the hair thing, but the vet said no he didn't need it at this point. Let us know if she sheds this spring I would be interested. Are you going to re-test her this spring? We never tested my gelding...just went by symptoms. Sometimes I wonder if he isn't just IR, if it wasn't for the hair.
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Member:
erika
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Posted on Thursday, Jan 24, 2008 - 10:54 am:
Hi Diane, I am going to take a leap and give credit to the Pergolide for the hoof improvement.
We have been trying for three years with good trimming and hoof supplements, improving the ground in the paddock, even hand walking with special pads.
Trimmer has commented that nothing was improving despite our best efforts and pronounced her feet looked like @#$%!
A few months after the Pergolide, (second trim later) she noticed that Sugar shed a large portion of her frog, and said that she sees "remarkable improvement" in the quality of her frogs, and the tightening of the white line.
I just reread Dr. O's article on Cushings. Even though we did test, Dr. O seems pretty clear that if it looks like Cushings, it probably is. So I doubt if I will spend the money and time to retest later.
My vet recommend a pharmacy that sells Pergolide quite inexpensively. If my memory serves me correctly, I got a six month supply for under a hundred dollars (don't quote me, could be old age). I know I was pleasantly surprised at the price because I always heard it is expensive.
If you are interested in talking to them, I can dig out the receipt from my files and get the number.
Oh boy, fun and games with the aging equine population, right? I have two older ones now that require special care. Why is it that the less riding you can do, the more it costs you? 
Hope the info is what you were looking for.
Erika
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Member:
scooter
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Posted on Thursday, Jan 24, 2008 - 8:59 pm:
Thanks Erika, I am more interested in if she sheds, my gelding seems to be "under control" otherwise.
I guess clipper blades are cheaper than pergolide tho...well maybe
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Member:
paul303
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Posted on Thursday, Jan 24, 2008 - 10:50 pm:
I must say that it was my old mare's front feet that opened my eyes. She had symptoms, the irregular long hair coat with odd textures, inadequate patchy shedding, sagging back ( muscle loss ), heavy drinking and urination, but I ( and everyone else - including two vets ) chalked it up to age. Then one day the farrier grabbed her front foot and said "This foot is HOT". Bang! Everything came together then and I immediately called my vet. She's been on pergolide 3.5 years now, and the first change I noticed, was in her attitude. In about 3 weeks she perked up and got interested in living again. Her shedding improved greatly the next spring and her erratic eating habits disappeared. She grew more active again, and her topline evened out....and...no more problems with laminitis. We had her on 1mg for quite awhile, but then i started to see a slight return of symptoms ( not in her feet )and had the vet out. Her dose was increased to 1.5, and eventually to 2mg, where she's been for the last year, bright-eyed and bushy tailed.
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Member:
erika
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Posted on Friday, Jan 25, 2008 - 9:14 am:
Oh Lee, that is such good news! I hope all of our laminitis battles are over.
I watch Sugar like a hawk, but was traveling last fall when she stayed out just a bit too long, and wham! It is so brutal.
My mare is only on .5/day right now. I will see if we notice further changes come spring. She is still rather saggy/lumpy, but it's only been a few months and she hasn't been exercising much.
I would love to see overall improvement because Sugar is the sweetest mare, and my favorite of all the horses I've known. It was heartbreaking to see her age so fast at such a young age.
Thanks for sharing your experience.
Erika
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