Please help - new cushings diagnosis - vetoryl not working

Hello! Apologies in advance for the long post I’m so worried about my pup 💔
Back in around March I noticed Bert was losing lots of fur and had bald patches. He was also having lots of accidents in the night and drinking lots. He’s always been a very good eater so hard to know whether he was more hungry than usual. I took him to the vets and they did urine, bloods and thyroid and said it pointed towards Cushing’s. He then had an ACTH test and they diagnosed him with Cushing’s disease and started him on 10mg a day of Vetoryl. After 3 weeks they repeated his ACTH and said his levels were much better but still not where they needed to be so they’d need to up his dose. He’d been drinking much less and only going out once a night so we’d noticed a big improvement too (but no fur regrowth). He was then on 15mg of Vetoryl and had his ACTH repeated after another 3 weeks. The vets called with the results today and said the medicine isn’t working, he’s way off where they’d expect him to be and there must be something stopping it from working. They’ve asked to do an abdominal scan. I’m extremely worried and don’t know what to expect - has anyone else had similar? Why wouldn’t he be responding to the meds? What else do they suspect? I’ve asked them to call me back but it’ll be tomorrow. Thanks so much in advance for any advice x

Hello and welcome! And you need not apologize at all for the length of any post — we’re eager to get as much info as possible, so what you’ve written is a help to us. We surely understand your worry about your sweet boy, and we’ll do our best to help.

I do have a couple of questions for you. Can you tell us how old Bert is, and also how much he weighs? As far as his weight, that’ll give us a better idea as to whether or not the 15 mg. is a relatively higher or lower early dose during these early weeks of treatment. There is a pretty standard formula that the maker of Vetoryl recommends when dogs start taking the medication, and it’s based strictly on weight. However, there can be a great amount of variability in the way any individual dog actually metabolizes the drug. That’s why the initial dose may require movement either upward or downward as time goes on, depending upon the dog. And those dosing changes are based on two things: observable improvement as well as monitoring lab tests.

Apparently your vet is telling you that they’re not seeing as much improvement in lowering the cortisol level as they would like or expect. But on the other hand, you say you’re actually seeing outward symptom improvement. So it doesn’t sound to me as though the Vetoryl is not working at all — perhaps just not yet as effectively as the vet would like in terms of lowering the numbers. But depending upon the age of a dog, symptom relief may be the more important goal of treatment, anyway. For younger dogs, you do want to try to halt silent systemic damage that the chronic progression of elevated cortisol can cause, such as high blood pressure, vulnerability to diabetes or infection, kidney changes, etc. But for older dogs, immediate quality of life may be your chief goal. So observable symptom relief may take top priority over lab numbers.

I’m guessing you may be in the U.K, and if so, we know that sometimes folks can have trouble getting actual lab numbers out of the vet’s office. But if you can find out the actual numerical results for those ACTH tests, we’d love to see them. As I say, our experience here has been that dogs vary quite a bit in their dosage needs. Very large dogs may need doses that are even smaller than those needed by tiny dogs. So it just may be that Bert needs an even higher dose to lower his cortisol more efficiently.

As far as the ultrasound, the vet may just want to check the status of all of Bert’s internal organs to make sure there’s nothing amiss that might be elevating his cortisol aside from Cushing’s. Also, they may want to check to see whether his Cushing’s is being caused by an adrenal tumor as opposed to the more common pituitary tumor. It’s sometimes the case that dogs with adrenal tumors require higher doses of medication to gain optimal control of cortisol.

So these are my first thoughts. And as you can see, I’ve managed to write a much longer post than you did — so I apologize for giving you so much to plow through! And do keep in mind that I’m not a vet myself, and I’ll be hoping your own vet can clarify things when you do get to talk tomorrow. We’ll be anxious to hear what you find out.

Marianne

And as if I haven’t already written enough, I just wanted to make sure of a couple more things. First, that Bert is consistently getting his Vetoryl along with a meal. In order to be metabolized properly, the medication needs to be accompanied by food. And secondly, that the ACTH testing is being done within the same time frame each time — typically 4-6 hours after breakfast and the medication.