Vetoryl dosing and testing

[Alison]

It's been a long time since I've been on as we sadly lost Cairo in 2018.

We run a dog rescue and currently, one of our dogs has not long been diagnosed with Cushings.

He was diagnosed 0n 7th March, with ACTH stim test results of

Baseline 193 nmol/l
Post ACTH 830nmol/l

ALKP 433 U/L (23 - 212)

TT4 8 nmol/l (13-51)

He weighs 32kg and was started on 60mg vetoryl once a day.

It would appeat that the testing has now changed from when we had Cairo and instead of doing the stim test 4-6 post meds, they are now doing Pre-Cortisol monitoring - taking baseline bloods one hour prior to him receiving his vetoryl.

His first test on 22nd March after treatment of 60mg started was

176 nmol/l

His dose was then increased to 70mg per day

His next test on 13th April came back at

191 nmol/l

His dose has been increaed now to 80mg

I'm no vet, but I cannot understand how testing his blood one hour before he's due his meds can give an accurate reading of what's going on

Surely there will be no vetoryl in his system at that point, so his cortisol would have climbed back up to what it was prior to treatment?

The vet can't understand why his last bloods are nigh on back to what they were when he was diagnosed and not on any treatment.

So, I turn to you guys for some help and advice please

[labblab]

Hello again, Alison! It’s so good to see you again, but I’m so sorry to hear about your loss of Cairo — what a sweet boy he was. It would be our privilege to add Cairo to our 2018 memorial thread of honor if you wish to tell us the date he passed. We can also add a photo link if that would please you. Just let me know, and we can talk about that some more.

Turning to your current rescue boy, how kind you are for getting him the treatment he needs for his Cushing’s. I understand why the new pre-pill testing protocol is raising questions for you, and I’m honestly not that well-versed in the research that supports it. So I’m afraid I can’t knowledgeably answer your question, other than to speculate that the assumption is that if a dog’s cortisol is in a range that is considered well-controlled immediately prior to receiving his next pill, it’s assumed that it will never be elevating far above that point at any time during a 24-hour cycle. In other words, the overall adrenal function is being suppressed sufficiently to avoid big swings in cortisol production at any point in time.

You’ve probably already seen this, but here’s a link to a monitoring flowchart that corresponds to the pre-pill protocol. Actually, the recommendation is to *not* increase a Vetoryl dose during the first month of treatment since cortisol levels frequently continue to drift downward during the first 30 days even when a dose is unchanged. However, in your new dog’s case, it appears as though his cortisol level is instead increasing, even on a higher dose. That is indeed puzzling. Anyway, here’s the link:

https://drive.google.com/file/d/1gqUchP2gvFIyG8udZgNS1bWfppWW6fin/view?fbclid=IwAR2DelBbsQeFErzcG9ZODzfWJnFdlbMmZz49 p8wpQPcumL9Y6RtbrcaKAE8

A couple of questions for you. First, just to make sure, your dog is receiving his Vetoryl along with a full meal, correct? In order to be metabolized properly, Vetoryl must be given along with food. Secondly, has he had any diagnostics that point to a pituitary vs. an adrenal tumor as being the cause of his Cushing’s? The results of an ACTH test don’t differentiate between between the two — it typically takes a LDDS test or imaging from an abdominal ultrasound to make that distinction. The reason why I ask is because adrenal tumors seem to be capable of producing more erratic cortisol levels than pituitary tumors.

Last but not least, it simply may be the case that your boy would respond more favorably to being dosed twice a day rather than just once daily. You’ll see that option noted in the monitoring protocol link that I’ve given you. There is a fair amount of variability in the speed with which different dogs metabolize Vetoryl, and for some dogs it does indeed clear the body *very* quickly. For those dogs, splitting the daily total in half and administering it every 12 hours can help to keep adrenal function more consistently under control at all times.

So those are my initial thoughts, but please feel free to ask additional questions. And also, once again, we’ll always remember sweet Cairo as one of our K9C family angels. Always.

Best wishes,
Marianne