There is a bunch (like MANY MANY) different thyroid meds. My Billy sounds much like your dog -- MAJOR mega allergies last year -- I use both a holistic vet (who uses Chinese herbals and acupuncture) AND my regular vet -- Billy got antihistamine, a bunch of different herbals to help control the wild skin problems that result from the allergies, I was bathing him EVERY day, and genrally just breaking my life into bits to try to keep this dog's skin whole. To NO avail.
He was on antibiotics so many time I can't track them all (and I'm anal about such stuff) and even pred several times to get the inflammation down to a liveable level. NOTHING was working ... not at all.
I had him on half what Luna eats -- and both weighed around 30 pounds. Billy is taller than she is, she is longer than he is. But the old MOstlie Sheltie ate more than Billy got and he could NOT get off any weight. I was virtually starving him.
Finally late last summer I suggested we get his thryoid tested AGAIN (it had been done like 3 times in a year -- 'low end of normal' but not "low") but this time send it to either Dr. Dodds or Michigan STate (who uses her protocols and she built their lab).
YEP, he came back a definite LOW. Not super low -- but 'low' -- so Dr. D (the holistic vet) asked me to use Armour Thyroid (which is porcine thyroid - not a 'synthetic' at all). She says she's gotten super results and better skin results with it. My regular vet didn't care.
I didn't notice ahuge difference -- other than just a bit less lethargic. But more 'normal' acting -=- like when he first came here.
It took me a month to even begin to see any results on the skin -- and in fact, because it was a time of year when the allergies are just violent in Florida the skin got a bit worse and he had to go on antibiotics.
BUT once the skin cleared up -- it STAYED pretty clear. Way better than it had been BUT ... it was also "winter" and I suspected most of the 'change' was weather -- NOT thyroid **yet**. I didn't bump up the thyroid meds yet
It's January and NOW allergy season begins in Florida and a year ago it was the start of a MAJOR nightmare - skin-wise. We also had some major stress here because we lost Foxy the end of February .
Somewhere at the end of January since it had been over 4 months and I asked to have him retested -- he actually still showed 'low' - but borderline. We came to a difference of opinion between the holistic and regular vets. The regular vet said "since he's being supplemented I'd expect it to be mid-range normal!" The holstic vet felt it was within 'range' so leave it alone. I did for a while ...
Right about then things got difficult here -- Billy had some skin issues about the time Foxy died and honestly it was mostly because his skin reacted to allergies and I didn't start responding to it herbally AT ALL til after we lost Fox. (We'd had a few weeks of it being really difficult here)
I had to have Billy on an herbal 'antibiotic' (nothing as stiff as pharmaceutical antibiotic) and one shot of dex (a minor steriod injection -- only intended to bring his skin back to level short term -- NOTHING like what he'd had in the past).
BUT during this time I decided it was time to bump up the thyroid (I'd only been on the fence for a few weeks trying to get the whole vet agreement thing settled AND dealing with Foxy being sick.).
So I compromised with the two vets and I bumped him to a 1 1/4 pills (the Armour Thyroid are 2 gr pills) so this meant he was getting 2 1/2 grains - 1/4 of a pill isn't a huge increase.So I compromised with the two vets and I bumped him to a 1 1/4 pills (the Armour Thyroid are 2 gr pills) so this meant he was getting 2 1/2 grains - 1/4 of a pill isn't a huge increase.
AHA -- I see a little more energy -- But even better, the skin holds!!
It worked and his skin has 'held' SINCE and we're having the worst allergy year Florida has ever seen.
Now ... right now is a super challenge because the pollen is SO wicked here at present -- but gosh ... I'm thrilled. Rather than use the herbals so heavily, I'm using homeopathics on Billy (because frankly they have almost zero side effects and I want to phase out the Benedryl if at all possible to be kinder to the kidneys). Controlling allergies with such minimal stuff compared with last year??
HEAVEN!!
7 months have brought such HUGE changes. And it's the thyroid meds doing it.
I'm totally pleased with the Armour thyroid. Billy's coat is soft and shiney. HE feels better. When his skin is so bad, it affects him a great deal emotionally.
My point in all this is DON'T expect fast change. Your dog is an "allergy dog" -- that is NOT going to change. However ... the low thyroid sets the body up not to deal with the allergies well.
Don't think because it's a pill that it will act fast. It takes TIME for the body to break down skin-wise because of allergies. Allergies are an immune problem -- and bringing the thyroid into a level state only then helps the body react more normally TO allergens and to what other things are going on.
It's sort of like having a personal financial emergency when you are out of work and way in debt, and THEN you get a job. Not a zillion dollar inheritance ... just a JOB.
Are you immediately going to recover financially? No. But slowly since you are now working and CAN pay all the 'normal debts' you manage your finances so you have a little extra to pay off the past debt. It goes away slowly and you recover ... slowly.
It takes a whle having the thyroid 'level' for the body to regain it's health simply because the thryoid isn't a ":cause" -- it's jsut something that will exacerbate an already existing problem.
So honestly don't even LOOK for a difference for 2-3 months. And then keep in mind whatever season it is. After 6-8 months you will be able to evaluate things better.
Don't forget to have the blood tested

eriodically. That's REALLY important.
And don't forget to watch for signs of high blood pressure. If the dog flip flops because the dose is too high -- watch for agitation or the dog just not being 'settled'. (there is a difference between more energy and a dog that is 'agitated' and unable to settle). If your dog looks at all 'bug eyed' -- CALL THE VET. You do not want high blood pressure (which results from thyroid being too high). And any med can cause that over-reaction. I hope you don't see it, but it's one of those symptoms that can be really super hard to pin down if you aren't WATCHING for it.
Hope that helps.
I didn't go the shots route -- I have a basic problem with the concept -- the shots basically "desensitize" the dog to the allergen -- in essence it dampens the immune system in that area and I feel that's too risky. So we wanted to do it without. I don't hold it against anyone who does it -- but that's my thinking on why I didn't do it for Billy.