Please correct me on this statement as I may not be writing it correctly.

Cushings is caused by a tumor on the pituitary gland. It is not genetic,
and cannot be caused by man. It just happens.

Now this question is for Dr. Kellon: IF a horse does have a pituitary
tumor, will it over time affect how they move, react, their mannerisms, etc?
What part of a horses brain does a pituitary tumor effect? Can a pituitary
tumor grow if Cushings is uncontrolled, despite pergolide, as in not being
able to keep up with the increase yearly?

The reason for this question is Guy has been Cushings for 10 yrs now, he is
23. He is Cushings/IR/Lyme/congestive heart failure. This is the first
year I have been able to get his IR AND Cushings under control. All other
years it has been one or the other, but never both. Now that he is falling
apart (literally), his brain doesn't seem to connect with his body. He wants to
move, but takes a lot of "thinking" in order to get somewhere. He has
also gotten to where he is asking for weird things. We open his door for him
to make his way out to his field, and he will wait, and ask for a lead rope,
by grabbing one or staying in his stall until we get one. We do not have
to lead him, it just has to be there for us to touch. You have to touch him
to make his brain connect with his body. His rear end is not working
correctly and this will be his downfall, I am afraid. But you can see him
thinking about how to make it work to walk. He isn't not walking because of pain,
he acts more like a paralyzed person that is in physical therapy trying to
make their body work to walk again. It is very hard to explain. But would a
tumor in the pituitary area cause this type of movement?

To add this: Guy is not on the best controlled diet at this time, I am
feeding him what I can get him to eat, while he is still happy. He is not
getting oats/grass/etc, but his diet could be tighter. I am trying to keep him
comfortable and happy for the next couple of months, that I hope to spend
with him. I do not expect him to make it through the winter. For those that
believe in animal communication, we have done that too, and I know that he
is leaving me, and while I am sad, it is for his own good at this point. He
is not ready to be put to sleep, but he is fading away slowly.

Megan Vogel
Spring Hollow Sir Guy
August 2003

--- In EquineCushings@..., jetandguy@... wrote:

Cushings is caused by a tumor on the pituitary gland. It is not genetic,
and cannot be caused by man. It just happens.

The only information we have so far is that it is linked to oxidative stress in the brain. In people, this type of damage is often caused by high mineral levels, iron or manganese.

Now this question is for Dr. Kellon: IF a horse does have a pituitary
tumor, will it over time affect how they move, react, their mannerisms, etc?

Horses with uncontrolled PPID are often very lethargic and "out of it". It will not change how they move though.

What part of a horses brain does a pituitary tumor effect?

The loss of dopaminergic neurons that allows the pituitary to be overactive occurs in the hypothalamus. Both the hypothalamus and the pituitary are primitive areas of the brain, not involved with movement or personality.

Can a pituitary

tumor grow if Cushings is uncontrolled, despite pergolide, as in not being
able to keep up with the increase yearly?

Yes, it can grow. The most common consequence of a large tumor is blindness because it presses on the optic nerve origin in the brain. The need for touch and hesitation to move could be consistent with losing sight. However, the hind end disconnection sounds more like a degenerative spinal problem, unrelated to the PPID. This is fairly common in older horses but not well described as to cause because complete necropsies are rarely done. It may be spinal arthritis. EPM is another possibiliity.

Eleanor in PA
www.drkellon.com
EC Co-owner
Feb 2001

He wants to move, but takes a lot of "thinking" in order to get >somewhere. He has also gotten to where he is asking for weird >things. We open his door for him to make his way out to his field, >and he will wait, and ask for a lead rope, by grabbing one or >staying in his stall until we get one. We do not have to lead him, >it just has to be there for us to touch. You have to touch him
to make his brain connect with his body.

Hi Megan,

This sounds very much like my blind horses,especially as they were getting used to their new circumstances. Not saying that necessarily is the case here,but have you checked his sight out??


Lorna in Ontario,Canada
ECIR Moderator 2002
*See What Works in Equine Nutrition*
http://www.ecirhorse.com/images/stories/Success_Story_3_-Ollies_Story__updated.pdf

I Understand about finding it staggering regarding the number of horses with these benign tumors.  But I question as to whether or not it is genetic.  Given breeding practices and so many with same lineage it would explain the number of these cushing horses.  I have two!

Interesting re: if genetic.  I still can't get my head around the entire HYPP population tracing back to Impressive.  That discovery happened when I was a little kid and the idea that this beautiful, gleaming halter stallion was the reason for so much disease was, and is, staggering to me. 

But for PPID:  are there certain breeds over-represented?  And certain lines in these breeds?  My PPID is a grade PMU mare from Canada.

Is the cause hubandry?  Pharmaceuticals used throughout a horse's life?  Fly sprays?  Vaccines?
Certain feedstuffs?  Or lack of anti-oxidants? 
Or is it just the "old age cancer" that each species tends to have over-represented in their geriatric populations (dogs = hepatic/splenic hemangiosarcoma; cats = GI lymphoma; horses = benign pituitary cancer)?

Interesting stuff.  Wouldn't it be cool if our generation witnessed the arrival of the answer?

Kerry