Re: How long does it take to show results with pergolide?


Hi Michelle,

So good to hear that Shadow is making good progress.

When you were increasing the pergolide, were you increasing slowly, by 0.25 mg every 3 days?   This method decreases the chance of side effects like loss of appetite and dopiness.  APF helps with this too, so good you have added that, but will still need to change the pergolide dose slowly.


(Should you decide to try to withdraw the APF at some point, do that very slowly too.  Do not just stop it abruptly.)


If you were increasing pergolide in small amounts every 3 days, and he was still going off feed, Shadow may need to be increased even more slowly, and may need to remain on each small increase a few more days or a week before going up to the next level.   If you notice going off feed again, then go back to the last dose for a bit longer until he has stabilized, then try the increase again.


Thanks for the link to your case history. I noticed a few things that could be adding to Shadow’s problems…..


If you did not know, ACTH results from MSU have been found to be unreliable by a member on this list.   For years, her horse was testing normal at MSU, but began having symptoms of uncontrolled Cushings.  Then she sent identical samples to MSU and Cornell –  ACTH normal from MSU, but high outside the upper range at Cornell!!!  This scenario was also confirmed by Dr Kellon from other sources. 

    The CliniLab used for ACTH by your vet could send out the sample to another lab.  There is no harm in contacting that lab directly yourself and asking if they perform their ACTH tests in house or if they send out the samples to another lab, and which lab would that be.   Cornell is the lab recommended on this list since it has been the most reliable for test results and reliable results are vital to keep the Cushings under control.  There is free shipping to Cornell.  We hope you can convince your vet to use this lab next time. 


An IR horse on pasture, especially “grazed nubs” where the highest sugar is, needs a taped muzzle.


If this hay is not tested for sugar/starch, are you soaking it?


If “black oiler seeds” are black oil sunflower seeds, these are not recommended because they are much higher in the omega 6 fatty acids than the omega 3, and can promote inflammation, so it would be best to eliminate these.  High fat diets are not recommended either.  Now that Shadow is eating better, he may be interested in more hay for those calories, or you could increase the flax by a small amount if needed, but try using your other feeds first.


The recommended NRC daily iodine intake for a 1000 lb horse is 3.2 mg.  Using the full scoop found in the Source will provide 14 g of minimum 660 ppm product containing a MINIMUM of 9.2 mg iodine. This is 2.8 times the NRC recommendation, and likely contains even more.   Using 5 g of Source would contain at least 3.3 mg of iodine, and likely more, since this product is not standardized to provide a defined amount.


We add 1 to 2 ounces (28-56 grams) table salt to the daily ration to meet the minimum sodium needs  for optimum health.  We do not assume that a horse will consume enough on his own to prevent dehydration.  When on a hay diet, it is especially important to make sure they drink enough, and adding salt to the ration will promote this.  As well, if a horse does not drink well, he will also not eat.  So adding the salt to your  mineral mix might help his appetite and low weight as well.

If providing enough kelp (Source) to meet the iodine requirement, do not feed iodized salt.   


When you get in your new hay, make getting a good core-sampled analysis and a “Dr Kellon/ECIR style” mineral balanced diet with appropriate calories a priority.  Shadow really needs it.



SW Ontario

March 2005,   NRC Plus

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