Quote Originally Posted by Squirt's Mom View Post
In some reading yesterday on imaging used in PDH, I found nothing that mentioned finding a micro - they all referred to seeing a macro. Now whether that is because no scan was done prior to the tumor starting to grow or whether a micro simply cannot be seen on an MRI, I haven't determined. As previously stated, it IS possible for a pup to have both PHD and ADH - even PDH with "duel" ADH (tumors on both adrenal glands) BUT these are very rare cases. Maybe someone here knows if a micro can be seen with MRI imaging? I would think a cat scan would be more apt to pick something that small up.
Hi Patti, I surely understand why these are such difficult decisions for you. If only we had that crystal ball...

As you continue to gather information, though, here's a quote that seems to imply that pituitary microtumors may indeed be present but too small to show up on imaging. The quote is taken from a 2007 article, so it is not the most recent. But it still may remain accurate. At that time, the author (Dr. Ellen Behrend) was throwing out the possibility that all dogs diagnosed with PDH might benefit from imaging of the head in order to determine tumor status from the outset. Due to the expense (and maybe also for other reasons) that idea has not gained much traction. But per this quote, it appears that tiny pituitary tumors are often not visible.

Based on this information, recognizing that the number of dogs studied is small, the recommendations are: All dogs with PDH should have a CT or MRI at the time of diagnosis. If no mass is visible, medical treatment should be implemented and no follow-up is needed. If a mass 3-7 mm in greatest vertical height is seen, medical therapy should be implemented with a repeat scan in 12-18 months. If a mass > 8 mm in greatest vertical height is seen, radiation therapy should be done and medical therapy used only if clinical HAC fails to resolve within 3-6 months of finishing radiation. These recommendations are based on clinical experience and theoretical considerations53 and no studies have been performed to date to assess their validity.
For what it's worth, I've gotten the impression that an MRI is actually the more precise imaging tool for pituitary tumors. When we suspected that our own Cushpup had an enlarging tumor, our specialist told us he could perform a CT at is office which could reveal the tumor, but that if we were considering radiation therapy, the vet school we were considering would likely want to perform an MRI of their own in advance of actual treatment. So even though he didn't explicitly state that an MRI is more precise, that's the impression I was left with.

Also, hopefully Kim will stop back by to talk about the urine testing for pheos because I think it was her (or perhaps Trish) who mentioned it in the past.

Marianne