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This post is about our experiences thus far with Soloxine, an inexpensive synthetic hormone currently manufactured and distributed by Virbac. Soloxine is one of the most popular name brands for Levothyroxine Sodium, designated specifically for veterinary (animal) use. Another brand for animals is Thyro-Tabs, which we have no experience with. Brand name L-thyroxine is apparently more effective than generics, and these two were the brands specifically recommended by Dr. Jean Dodds.

When Bowdu had his first thyroid panel done in August 2010, the results came back with his T4 levels below minimum, and his FT4 levels at 1 pmol/L within normal, at the bottom end of the reference range. My vet called it “borderline low,” but based on his concurrent clinical symptoms, I was ready to start him on thyroid supplementation immediately.

Once thyroid supplementation begins, it is usually expected that the dog is to remain on thyroid supplements for the rest of his life. Clinical signs of hypothyroidism, which clearly matched Bowdu’s physical condition, usually indicate that the thyroid has already been mostly destroyed by its own immune system. Long-term hormone replacement would result in the shutdown of any natural hormone production as well, which is why it is important to get an accurate diagnosis with both T4 and Free T4 panels, at the very least.

Meanwhile, we got a second opinion from Hemopet, which confirmed hypothyroidism.

We began with one pill twice a day, at a dose of 0.2 mg based on his weight (at the time) of 33 pounds. Soloxine’s site recommends an initial dose of 0.1 mg per 10 pounds. Hemopet suggests 0.1 mg per 12 – 15 pounds, then adjusting the dosage as necessary according to follow-up bloodwork.

Results were rapidly observable and satisfactory.

I had no hesitation about starting Bowdu on thyroid supplements, as I’d heard anecdotal accounts that they made a huge and immediate difference. I was also less concerned about this medication, given that thyroxine is supposed to be in his system anyway. However, as with all drugs, this one is not completely without side effects, though I think they were of minimal concern and far outweighed by benefits.

One of the more undesirable side effects that I would ascribe to the thyroid medication (though I don’t know for sure if this is the cause) is exhibited in this video:

Video taken 23 September 2010

About a week after Bowdu started thyroid supplementation and continuing for a couple months, he would exhibit bouts of confusion or just plain weird behavior. In this video, he’s still battling his raging allergies, as he had been all summer, which is why he’s in the cone. These episodes only happened at night, either right before or a few hours after his evening pill. He would get strangely clingy or antsy, and his tail would droop. He’d pant. He’d crawl into corners as if he was looking for something, or try to squeeze himself underneath endtables, or in this case, he’d poke at objects in corners of rooms, like this paper shredder that has always been there. Another time, he jumped up into bed, stepping all over my head in the process (he’s usually more conscious of personal space than that), moved from there to the nightstand, and pawed at the bedside lamp. When I pulled him towards me and held him, I could feel his body trembling.

The trembling was very similar to this video:

Video taken 29 August 2010

The above was taken when Bowdu appeared to be asleep. However, he was awake and very conscious in other episodes of shaking.

My only guess is that these were episodes of short-term thyrotoxicosis, or thyroid drug overdose. According to Soloxine’s drug information insert, the symptoms of thyrotoxicosis include: “polydipsia [increased thirst], polyuria [increased urination], polyphagia [increased appetite], reduced heat tolerance and hyperactivity or personality change.” The last bit seems overly generalized to me, and doesn’t adequately compare to even Wikipedia‘s description: “In excess, [thyroid hormone] both overstimulates metabolism and exacerbates the effect of the sympathetic nervous system, causing ‘speeding up’ of various body systems and symptoms resembling an overdose of epinephrine (adrenaline). These include fast heart beat and symptoms of palpitations, nervous system tremor such as of the hands and anxiety symptoms…”

As I understand it, thyroid hormones are normally secreted as necessary to keep overall levels stable. With synthetic supplementation, artificial “peaks and valleys” are created. While dosing twice a day (BID) as opposed to once every 24 hours (SID) creates more “stable” levels, no doubt the body still responds to the changing level of hormones. If Bowdu’s levels had been low for some time, it would stand to reason that these elevated thyroid levels would feel disorienting, even if they were being maintained at “normal” levels.

So for the sake of minimizing these shocks to his system, I thought it was important to keep Bowdu’s doses as close to 12 hours apart as possible. We’ve developed a pretty good system where he gets his medication first thing in the morning, about an hour before breakfast. Knowing that I have a hard time functioning before coffee, I’ve made things as easy as possible by preparing his marshmallow-wrapped morning dose in advance. A weekly round of morning pills rests conveniently on the nightstand; I don’t even have to be fully awake to pop one out of the case, lean over the edge of the bed to slip it to Bowdu, then hit the snooze bar.

The other half of the daily dose awaits in the kitchen, where it is offered in the evening, about 2-3 hours after dinner.

9 January 2011

Getting Bowdu used to his pills wasn’t hard, though it took a few tricks to turn it into routine. He has a bit of a sweet tooth, so we wrap his pill in a fat-free, but oh-so-sugary mini marshmallow. He also gets more interested if he sees me consuming something first, so at first I made a big show out of eating some marshmallows before offering him one. It also helped to lick the surface of the marshmallow I was offering him, so that it would become a little gooier, thus sticking more to his palate.

Marshmallows are also a great treat for catching in mid-air. Sometimes to liven up the routine of pilling, I’ll grab maybe three or four, one of them stuffed with Soloxine, and gently toss the treats for Bowdu to snap out of the air. When pilling becomes a game, the task is just easier.

About six weeks after he started taking Soloxine, we had a follow-up thyroid panel. Results were within normal range, as expected, so he remained on the same dosage. This will probably change over the years, but for now, we’ll maintain this regimen.

Also, the episodes of oddness depicted in these videos seem to have stopped for now. Something new may arise in the future. As for what came before, I can definitely say we’ve made progress when I compare the archives to his current state.

Pretty all right
Photo taken 31 December 2010

He’s not perfect, but at least he’s all right.