ACTH stim versus seasonal rise...suspected cushings?

[Critter]

So my old guy (17yo) has been struggling with his fitness this year. Last November he tore a suspensory branch (just goofing around outside)…but was never lame. He had the winter off and a slow return to work in the spring. I could just never seem to get him feeling fit. He also put on a ton of weight (despite eating very minimal grain)…which I blamed on good grazing. One day in the spring he came in a bit slow/tender and I panicked about him foundering…so I started putting him on the “diet” field where there is limited grass. He then seemed fine from a soundness point, but he wasn’t loosing any weight (even with being back in work).

So I called my vet thinking maybe it was time to do his hocks since he just didn’t feel himself working (he’s PSG/I1 level…I’ve had him since he was 3 and he is a very easy and consistent horse to ride). Vet watches him and says, nope he’s sound, but agrees that he’s not himself and was worried about his weight and lack of energy.

We ran baseline ACTH (41), insulin (30). She also suggested we do the stim test as she’s had a few cases where the baseline number is fine but they jump way up on the stim. She just sent me the stim results, 249.

I know there are some articles that talk about the seasonal rise and that the testing this time of year is not reliable. I’ve also read some studies that say that stim results over 100 during the fall is considered a positive test. I am waiting for a call back from the vet to see what she says.

Really the only issues/symptoms are the weight (lots of fat deposits despite similar feeding routine/work)…exercise intolerence…the worry of laminitis (seems to be fine now, but I was really worried in spring). Coat is great.

I went through a sudden founder with my heart horse when he was 27…he probably was cushings (never tested positive, but had the classic look)…I don’t ever want to go through that again as it was pretty horrible. So I want to be more proactive with my current old guy…just not sure how reliable those results are given the season.

Again, I will talk to the vet, but also wanted general input about the test numbers/time of year.

[luvmyhackney]

When I had my pony tested in the fall, his numbers were lower than your horse and was started on meds as he had some of the signs. Vet felt it was better safe than sorry. He had slight fat pads around eyes and sheath edema.

I’m not sure if it’s different with horses vs ponies, but I am so glad we started meds even though numbers were elevated only slightly above normal.

After 2 weeks on meds he was acting like he felt so much better.

[JB]

ACTH during the seasonal rise is MUCH better than other times.

The TRH testing should be done early December (some say mid-November is ok) through early July, as there aren’t any reference numbers to evaluate anything against in the July-Dec months.

According to The Laminitis Site, in Week 37 (this week, 41 isn’t indicative of PPID

249 for the Stim test would indicate PPID in those correct testing months, but there isn’t any data to say it is (or isn’t) a positive result this time of year

You could re-do the Stim test the first of December and go from there. Or, treat his symptoms as being PPID, start meds, and see what happens.

[Jackie_amp_Starlette]

A great place to ask these questions is the ECIR group. I have learned a lot from them. Dr. Keller seems to always be available as this seems to be her passion. Yes the sight is old-school but loaded with information.

main groups.io Group

[Natalie]

Agreed with treating the symptoms. Start the meds and see what you get. My guy starting showing some relatively subtle symptoms (mostly just losing some topline muscle, had a suspensory injury in light work) and his test came back borderline. We put him on half a Prascend pill, and within two weeks he looked noticeably better. My vet said that the general guidance now is to treat the symptoms, not chase numbers on the tests.

[Critter]

Thanks for the input. I talked to my vet…she said years ago she wouldn’t have done the stim based on his baseline for this time of year. Then she had a client with similar issues go do an endoocrine consult. After that, they told my vet that they are catching more horses earlier using the stim testing, even during this time of year.

So, we are going to start him on a low dose - 1/2 tab and see how he looks. Vet said it might be that he could even come off during Jan-June and then be on the 1/2 tab during the summer/fall so we don’t risk laminitis. So the plan is 1/2 tab until the end of the year…then we may take him off and retest the stim response and see what his numbers are in Jan/Feb. That way we know if he needs to be on the meds year round or maybe seasonally.

[JB]

@Critter

Vet said it might be that he could even come off during Jan-June and then be on the 1/2 tab during the summer/fall so we don’t risk laminitis.

Personally, I can’t imagine any reason to take a horse of Prascend unless it’s negatively impacting his quality of life. Just because Jan-June are the naturally lowest levels of ACTH, doesn’t mean his disease isn’t progressing. It’s much better to continue to slow the progression even while the season is 'best"

Prascend isn’t simply about seasonally controlling symptoms, or controlling the ACTH during the higher level months. It’s about slowing the actual cause, which is a dysfunction of the pituitary.

[S1969]

@JB

Prascend isn’t simply about seasonally controlling symptoms, or controlling the ACTH during the higher level months. It’s about slowing the actual cause, which is a dysfunction of the pituitary.

Agreed. And I have a human friend who had an adrenal gland tumor, so suffered from “pseudo-Cushings” and we’ve talked a lot about what that means. It is a whole body disorder - so many symptoms that seem like nothing until they get bad. E.g. subtle things like lack of stamina, which is hard to pinpoint/measure because it could be many things. (Body aches, insomnia, fatigue, muscle atrophy, weight gain, etc. etc. etc.)

We can’t ask our horses about these things, and we can’t objectively measure them. If we believe they have a pituitary disorder, we should just treat it. If they don’t, they don’t need Prascend.

[Critter]

I agree with you - but just reporting what my vet suggested. A lot of the plan will probably center around how he does respond to the Prascend. He got his first dose yesterday. We will still likely retest stim response in Jan/Feb to make sure we have an idea of what his numbers are when we aren’t in the seasonal rise period.

[rubygirl1968]

@JB

Personally, I can’t imagine any reason to take a horse of Prascend unless it’s negatively impacting his quality of life.

Would you consider diarrhea to affect quality of life? I do, but I know most around me do not agree.

He’s always had fecal water but this was spattering diarrhea, no form at all.

He’s my first horse and I don’t have a knowledgeable barn owner to ask so I come here.

The vet will be out Tuesday and I have a list to ask her.

[JB]

@Critter

He got his first dose yesterday. We will still likely retest stim response in Jan/Feb to make sure we have an idea of what his numbers are when we aren’t in the seasonal rise period.

You have to take them off Prascend to get any valid Stim testing. I’m not sue the withdrawal period.

[JB]

@rubygirl1968

Would you consider diarrhea to affect quality of life? I do, but I know most around me do not agree.

He’s always had fecal water but this was spattering diarrhea, no form at all.

He’s my first horse and I don’t have a knowledgeable barn owner to ask so I come here.

The vet will be out Tuesday and I have a list to ask her.

Yeah, I’d consider spattering diarrhea to be a QoL issue. Have you tried APF Pro? It’s helped a ton of horses deal with pergolide, either to get them past whatever hump, or long-term.

[rubygirl1968]

I ordered some but it hasn’t arrived yet.

[Calhoun]

What is APF Pro? What does it do for cushings horses?