Originally Posted by
labblab
Well, um, then I'd have to venture a guess that your vet has not had a lot of experience with treating Cushing's dogs. Please bear in mind that I'm not a vet myself, but I did learn a lot about macrotumors back when my own dog was ill, and as you've read, we've had a number of dogs here with confirmed enlarged pituitary tumors that have suffered from symptoms that are consistent with Ambro's.
Since you only have one more day to wait until Thursday, it's likely not a big deal to hold off on the prednisone. It's probably best to get the neurologist's opinion about that, anyway. But it seems striking to me that your vet hasn't even entertained the possibility of a macrotumor. Back when my own dog was ill, our internal medicine specialist said that any time he sees a Cushing's dog with a cortisol level that hasn't dropped too low but who is inappetant, the first thing he suspects is a macrotumor due to the possibility that the tumor is placing pressure on the part of the brain that controls hunger and thirst.
As far as the helpfulness of a head CT, the neurologist will be your best guide in that regard. My general understanding is that both a CT and an MRI can reveal the presence of a pituitary tumor, but I've never been clear as to their relative advantage or disadvantage in terms of the best imaging for this purpose.
Just to let you know, when dogs are initially diagnosed with Cushing's, it's typically an abdominal ultrasound that is performed in order to determine whether the disease is likely due to a pituitary or adrenal tumor. This is because abnormalities with the adrenal glands will give you important clues. When Cushing's is pituitary-based, both adrenal glands will typically be enlarged. However, a mass or growth seen in one adrenal gland alongside a shrinking of the other gland suggests that an adrenal tumor is the culprit.
At this point, however, my guess is that if you are able to spend money on imaging and the neurologist recommends it, a view of Ambro's head would be the top priority. As Betsy's mom says, even if he doesn't have a pituitary tumor, he could be suffering from some other brain tumor. As you saw in my post on the Macroadenoma thread, my husband and I didn't proceed with any head imaging, partly due to the expense and partly due to the fact that in our boy's case, we wouldn't have felt able to launch into the extensive radiation treatment that would have been necessary to try to treat him in the event that he did have a macrotumor. So I definitely understand that it's not an easy decision to proceed with any imaging.
But the first step will be to let the neurologist examine him and find out his impressions and recommendations. At that point, you can make your decision about moving forward. I confess that I'm a bit bothered that the ER vet apparently didn't check his cortisol level in addition to his electrolytes, because dogs treated with trilostane can suffer effects of adrenal oversuppression even in the face of apparently normal sodium and postassium levels. However, since you report that Ambro had worsened again even during the time that his trilostane was halted, in my own mind that does point more towards neurological issues separate from medication effects. However, once again, the neurologist should be much better able to draw some conclusions after examining Ambro and going over his history of problems.
No matter what, please do keep us in the loop and let us know how things go. Again, I'm so very sorry that you guys are going through this, including sweet Ambro. I'll never forget the difficult days and nights I spent worrying about my own Cushpup. If only they could talk, and tell us what is wrong. It's such an awesome responsibility to try to figure out the best path forward, but I believe you're doing exactly the right thing at the moment. So hang in there, and keep us updated.