Thyroid Levels In An Ig

[Guest gurehaundo]

I went the cheap route and had my vet run a T4 test on my going bald IG, Tovi. After talking to another IG person regarding the results, I'm wondering what some other people think. Tovi's level is at a 1.4. The normal range is 1 - 4. Tovi has no other hypothyroid symptoms, just the hair loss. If she were your hound, would you suck it up and get the full panel done? The vet thinks it's a dead end. If you'd like to see some pictures, please click on my Facebook link. There's an album dedicated to Baldy Tovi. Thanks for any advice you'd be willing to share!

[Batmom]

If the T4 is in the normal range, there generally isn't a need to follow up with a panel. The same is not true of a T4 below the normal range -- in that case, you would want to follow up with a full panel.

 

The reasoning is this: If the T4 is normal, you've shown that the thyroid is capable of adequate operation. You don't need a full panel to sort that out -- you've already shown what you wanted.

 

On the other hand, if the T4 is below normal, you haven't shown that the thyroid is NOT capable, and you need the full panel. Why? Because T4 fluctuates from hour to hour and day to day. It's perfectly normal for it to fluctuate. At the moment you drew the blood for the test, the T4 may have been low as part of the dog's normal circadian rhythm. Two hours later, the T4 might be in the normal range for the breed. A full panel helps to get around that problem by showing some other measures that help the vet (and owner) gauge whether the dog's thyroid is capable of operating correctly or not.

 

Hope that helps more than it confuses.

[krissn333]

My Skimmie (IG) was bald too...chicken-based foods seem to make the issue worse. He has been on Taste of the Wild Pacific Stream for several years now and he does have more hair than he used to. Some of it is sorta like peach fuzz, but, he does have hair

[JJNg]

I agree with Batmom's excellent explanation. And since Tovi's T4 is in the normal range, that pretty much rules out hypothyroidism. From your FB album, the pattern of hairloss makes me think it's CDA (color dilute alopecia). I do agree with you that she looks almost too red to be a true blue fawn, but color expression does have some variability. Do you know what color her parents were?

[greyhead]

I agree with Batmom's excellent explanation. And since Tovi's T4 is in the normal range, that pretty much rules out hypothyroidism.

 

This confuses me because even though the thyroid may produce adequate T4, it's not fully useful if too much of it is bound to proteins in the blood, which only a free-T4 test would indicate. Is that not of interest too in understanding whether there is sufficient usable thyroid hormone available to the animal? Or are we only concerned with the health of the thyroid gland itself?

[Batmom]

The test normals account for that most of the time. That is why the T4 range is higher than the FT4 (free T4) range.

 

Where test normals don't adequately account for the difference, you generally have a different condition, such as pregnancy, and not hypothyroidism. That is why you want a panel with FT4 when the T4 measure is below normal.

Edited July 14, 2012 by Batmom

[krissn333]

I didn't see any pics of Tovi but I wanted to mention that Skimmie is also blue fawn...

[greyhead]

Liza, Tovi's pattern of hair loss doesn't look like the pattern I've seen in thyroid dogs, which involves more the sides, chest and throat, as well as the bum, but not the back.

[Guest gurehaundo]

Thank you all so much! Your words of wisdom have helped me immensely.

 

Both of Tovi's parents were blue, her mom being blue and white and dad solid blue. Her brother was blue and white. I guess she definitely could be a blue fawn.

 

Tovi and the other dogs were on Taste of The Wild until the recall. They were doing very well on it, too.

 

Again, thank you all very much. :-)

[JJNg]

This confuses me because even though the thyroid may produce adequate T4, it's not fully useful if too much of it is bound to proteins in the blood, which only a free-T4 test would indicate. Is that not of interest too in understanding whether there is sufficient usable thyroid hormone available to the animal? Or are we only concerned with the health of the thyroid gland itself?

 

It would be very rare to have a normal total T4 with a low free T4. The amount of T4 that binds to protein is usually a factor of the total amount present in the bloodstream, so if total T4 is normal, it's usually assumed that there is enough free T4 as well. Of course, there are exceptions to every rule, so if clinical signs are consistent with hypothyroidism, it wouldn't be a bad idea to also check free T4 and TSH levels.

 

The protein that binds T4 is called thyroxine binding globulin (TBG), and in human medicine, they sometimes test for TBG as well. If total T4 is normal but free T4 is low, that usually indicates an increased level of TBG in the bloodstream, which is caused by certain medical conditions, and normally occurs with pregnancy. TBG testing is not used in veterinary medicine, and I'm not sure this is an area that has been studied much in dogs.

 

Liza, Tovi's pattern of hair loss doesn't look like the pattern I've seen in thyroid dogs, which involves more the sides, chest and throat, as well as the bum, but not the back.

 

The pattern of hair loss along the top of the back is why I thought this looks more like color dilution alopecia (CDA), where that pattern is typical. Here's a good article with more information about CDA.

 

Both of Tovi's parents were blue, her mom being blue and white and dad solid blue. Her brother was blue and white. I guess she definitely could be a blue fawn.

 

If both of Tovi's parents are blue, then she definitely is a blue fawn. Since the dilute gene is recessive, 2 dilutes bred together can only produce dilute offspring.