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  Discussion on Testing for Cushing's
Author Message
Member:
Lindac

Posted on Saturday, Apr 2, 2005 - 1:05 pm:

Dr. O,

When a horse is given the dexamethasone suppression test is it necessary for it to have 5 blood cortisol levels taken - ie: one prior to administration of dex and then again at the 2, 4, 6, and 24 hour intervals as mentioned. Although the article states it's not foolproof, can the same type of results be achieved with just 2 tests - one before administration of dex and then again approx. 19 hours later? Would the results of two tests be enough to establish decreased coritsol and baseline levels for a Cushing's diagnosis?

Thanks.
Moderator:
DrO

Posted on Monday, Apr 4, 2005 - 10:03 am:

Hello Linda,
I went and looked at the diagnostic section and have updated it with the complete 2 check method and reviewed other common diagnostic methods available. If you have questions after reviewing them post them here.
DrO
Member:
Lindac

Posted on Monday, Apr 4, 2005 - 3:58 pm:

DrO,
For the past couple of years my mare (20 yrs. now) has been showing some of the signs of Cushing's. My vet however is unwilling to treat her based on signs only and wants to confirm her condition with testing. So I was somewhat surprized when she said she would only be taking 2 samples (one at 3:00pm and one the following morning at 10:00am). I was concerned the results might not be accurate, but after reading the updated version you posted I'm feeling much better about the whole testing procedure.

Thanks so much!

Linda
Moderator:
DrO

Posted on Monday, Apr 4, 2005 - 6:09 pm:

What if the tests are negative, will she continue to choose to not treat? What are her list of rule outs for your horse's clinical signs?
DrO
Member:
Lindac

Posted on Thursday, Apr 7, 2005 - 1:33 am:

DrO,
This is what I'm concerned about. Starting about 3 yrs. ago my mare started to have coat/skin problems. She suddenly became very allergic to the fly spray I had used on her for years and developed a flaky skin condition (like seborrhea). She became very itchy and her hair fell out in spots. Skin biopsies were done but nothing conclusive was found. I was not thinking Cushing's at this time. I stopped using the spray, her hair came back, but the seborrhea stayed and she lost all her shine. That fall she went off her feed and started to colic on a regular basis. It ended up she had developed an ulcer condition. Fortunately she responded well to ulcer medication. Over the last couple of years her back has DrOpped significantly and she now has a swayback and small pot belly appearance. As well during the last year her neck has become slightly cresty. Although she's always been somewhat moody, there has been a definite change, she's become more irritable and somewhat depressed at times, there are times when she seems to have no energy. Then last summer she shed out early (in August) and came in with a longer summer coat, which then caused her a great deal of discomfort (excessive sweating). As winter neared her coat became very dense and thicker than normal with a slight wave developing on her neck. This mare has always had "peach fuzz" for a winter coat. Although my vet is well aware of all these things she feels this could be due more to "old age" rather than Cushing's. Just the other day I showed the vet where there's been some muscle wasting on one side of the mare's neck and the vet's response was "you don't ride her as much as you used to, so that's probably what's caused it." (If that's the case why wouldn't it happen to both sides of her neck?)

Unfortunately, I live in an area where there are no other equine vets to ask a second opinion. There is however a large equine clinic/research centre approx. 4 hours away. This is actually where her blood tests will be sent. I have been in touch with one of the vets there and he's given me some general advice about Cushing's, vaccines, testing, etc. but suggested I work with my own vet. I could take her there but they will require a referral from my vet. Kind of caught between a rock and a hard place.

I would really appreciate to hear your thoughts on the above. I realize this mare may not be showing all the "classic signs" of Cushing's but do you think this is more than just "old age"?

Thank you.
Moderator:
DrO

Posted on Thursday, Apr 7, 2005 - 10:13 am:

Huhh...caused by old age? Does she think as hair follicles age they produce more hair? Most of the symptoms that we associate with old age are caused by Equine Cushingnoid disease. Is your veterinarian not aware of how prevalent pituitary ademona's are in the old horse (70% of the horses by age 26). The hirsuitism (long coat) is almost certainly caused by Equine Cushingnoid Disease.
DrO
Member:
Lindac

Posted on Thursday, Apr 7, 2005 - 12:15 pm:

Thank you DrO!! This is how I've felt for some time now, but it feels like every time I mention Cushing's to my vet she's just not on board with me. To have an "expert" second opinion, even if it's over the internet, is enough for me. I will definitely insist that my horse be referred to the equine clinic for a second evaluaton if the results do happen to come back negative. I, just like you, wonder if my vet will choose not treat her based on negative results even when these other symptoms exist.

Her "dex test" is scheduled for later in April (20th & 21st). I will keep in touch and let you know what happens ..... should be interesting!

Linda
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