cushing's misdiagnosed as hypothyroidism?

[monbon7]

Hellloooo!

I have a 9 yr old female spayed boxer, diagnosed with hypothyroidism in Jan 2019, 60 pounds.

Initially her T4 was hovering between 0.3 and 0.5 for a few months. Her symptoms were excessive shedding, dull fur, chronic UTIs and skin infections, aggressive when being body handled, bladder leakage, poor digestion of high fat foods, weight loss, exercise intolerance, anxiety, grouchy-ness. She’s been on 0.8 mg of soloxine daily (0.4 mg twice a day) since then and in the beginning she was also given a "Thyro Complex" supplement which has thyroid and adrenal glandulars, iodine, and kelp. She immediately lost a bunch of weight, starting drinking water excessively, super hungry, and leaking urine. But her coat also got way softer and she was much less anxious, seemed healthier overall. I tried giving her half the thyroid complex capsule and that seemed to be the trick that stopped the thirst/hunger/urine issues for the most part.

After 3 months on soloxine her T4 didn’t change. I then put her on trazodone for anxiety and one month later her T4 shot up to 1.5 (April 2019). It continued to go up consistently with each blood workup. Eventually in July 2019 she got another UTI and staph infection on her skin. She also started getting some lethargy and wouldn't want to walk more than 10 min. At this point I was exasperated! As a shot in the dark I started giving her “Adrenal Harmony” drops from amazon which are typically for dogs with Cushings. Within a week she was like a different dog. Spunky, full of energy, no urine issues. She also started to gain a little weight (she was previously at 50-55 but never more and could see ribs slightly). I stopped giving her the thyroid complex supplement and have been sticking with the adrenal drops. I recently dropped the bottle and it shattered everywhere so we had to wait 3 days for a replacement and in those 3 days she truly became so lethargic and clingy.


Additionally, switching her to Orijen (very high protein diet) did wonders for her anxiety as well.

Now her most recent T4 as of 14 days ago is 3.5.

I’m just wondering if it was possible that she had some kind of precursor to or milder form of Cushing’s? I just don’t understand why her T4 shot up only after the trazodone and why the soloxine did not improve any of her symptoms but some herbal drops did? I was just worried that she may not need the soloxine anymore since her T4 is at the very top of the range. Has anyone else dealt with this? Seeing the vet again in 10 days but was curious about dropping the soloxine.
Thanks!

[labblab]

Hello, and welcome to you and your girl! Upfront, I’m going to make a testing recommendation for you to discuss with your vet, and then I’ll tell you the reason why. If your dog’s hypothyroidism was diagnosed solely via low T4 readings on general blood chemistry panels, if she were my own dog, I’d stop all thyroid supplementation for 4-6 weeks and then submit blood to a specialized lab for a comprehensive thyroid panel. As an example, the vet school at Michigan State University is well-known for their expertise in thyroid disease, and their lab accepts samples from anywhere in the country for analysis. Here’s a link to one of their pages that offers interpretation tips to vets. Without even needing to understand the technical jargon, you’ll see that there can be several complexities involved in making appropriate thyroid diagnoses:

https://cvm.msu.edu/vdl/laboratory-sections/endocrinology/thyroid-function-in-dogs

Your girl’s situation seems complicated enough to warrant a through analysis of her thyroid function, and as you’ll see in that link, a dog needs to be free of any thyroid supplementation for at least a month in order to allow the diagnostic results to be accurate.

One of the possible issues is that low T4 readings can be secondary to other illnesses or even certain medications. Cushing’s is indeed a primary illness that can prompt low T4 readings in dogs, and due to the ease of finding a low T4, it’s not uncommon for a Cushpup to be diagnosed as bring hypothyroid before Cushing’s is even suspected. That’s what happened with my own dog. But after several months of thyroid supplementation that didn’t ease his symptoms, we ended up looking further. Some dogs genuinely suffer from both diseases in their own right. But for dogs in which the low T4 is secondary to Cushing’s, the thyroid readings can normalize all on their own once the elevated cortisol of Cushing’s comes under proper control. A complete thyroid panel can help tease out some of these variables and offer better treatment guidance.

Turning to your girl, her situation seems complicated enough to warrant this more involved testing. I can’t hazard a guess as to whether or not the Adrenal Harmony plays a role in this. Anecdotally, we’ve been told by some folks that it has helped ease Cushing’s symptoms, but as far as we know, the supplement has never been subjected to any genuine research or clinical trials. One of our staffers has contacted them periodically for any research support, and the manufacturer has had none to offer. Also, I don’t know whether there’s any interaction between trazodone and soloxine that might affect the manner in which the soloxine is metabolized. So that might be another variable here.

In addition to low T4, dogs with Cushing’s typically exhibit other lab abnormalities. Most common are elevated liver enzymes and high cholesterol. White blood cell and platelet counts may also show irregularities. Urine samples are highly dilute. To your knowledge, has your girl exhibited any lab abnormalities other than with her thyroid? That would be very helpful to know.

Anyway, to return full circle, under these circumstances, I’d probably first want to explore her thyroid function in greater detail. But once again, welcome, and we’ll be anxious to hear more about your girl.

Marianne

[monbon7]

Hi!! Thanks so much for the reply. Sorry it took me so long to get back to you. Just moved into a new apartment so things have been crazy.

In terms of her bloodwork she recently had a very high PSL of 283, urine is always high in pH, as well as a consistently high platelet count. Also her free T4 before beginning soloxine was 11.4 if that matters at all.

Thanks so much for the info. Will definitely bring all of this up to our vet next week!