Hypothyroidism

[greyhead]

It's too hard to keep trying to make this argument every time someone else asks whether and on what basis they should believe their dog might be hypothyroid. So I'm starting this thread to put my arguments in one place and I'll just cite to it in the future. Please feel free to join in.

 

When questions arise about hypothyroidism in our greyhounds, I keep alluding to the fact that individual differences (called "interindividual differences" below) may mean that what is normal for the reference group on which the norms are based is not normal for the invididual dog. Here's the link to the article from which this excerpt is drawn: http://edrv.endojour...nt/full/29/1/76. It is "The Clinical Significance of Subclinical Thyroid Dysfunction" and appears in a 2008 volume of Endocrine Reviews. It's an analysis, but not a statistical meta-analysis, of research findings. Although the article reviews studies on humans, the principles of analysis are what are important. Btw, SCTD below refers to subclinical thyroid dysfunction, which is what they call it when the TSH is in normal range but the thyroid hormones themselves are below normal. CI means "confidence interval"; Google it if you dare.

 

The finding that individuals have a set-point of the hypothalamic-pituitary-thyroidaxis was a breakthrough in our understanding of SCTD (12). Therelationship between serum FT4 and TSH in an individual canbe considered to establish the individual's hypothalamic-pituitary-thyroidaxis "set-point." Andersen et al. (12) measured serum TSH concentrationseach month in 16 healthy male volunteers and found that thewidth of individual 95% CI of TSH values was approximately halfthat of the whole group. Consequently, it is theoretically possiblethat a test result may be abnormal for an individual but stillbe within the laboratory reference limit.

Interindividual differences in the hypothalamic-pituitary-thyroidaxis set-point are genetically determined (42, 43). Moreover,genetic variants have been found to affect both blood pressureand serum TSH levels (44). Consequently, interindividual differencesin the hypothalamic pituitary-thyroid axis set-point might explainthe different symptoms, signs, and peripheral thyroid hormoneeffects in subjects with exactly the same hormonal pattern.Furthermore, the biological activity of thyroid hormone, interms of T₃ availability, is regulated by type 1, 2, and 3 iodothyroninedeiodinases (D1, D2, and D3) (45). The efficiency of conversionof T₄ to T₃ by D2 increases as the serum T₄ decreases (45).Consequently, in the presence of a low level of T₄ or in caseof a hypothyroid state, D2 is increased and can generate a significantquantity of plasma T₃. Moreover, polymorphisms in genes involvedin thyroid hormone metabolism may affect thyroid hormone bioactivity(46). Deiodinases are tissue specifically regulated, and thismay have consequences for the peripheral effects of thyroidhormone and for set points of endocrine feedback regulation(47).In conclusion, a serum TSH level within the normal range, evenif it is below 2.5 mIU/liter, may not be as sensitive a parameterof thyroid dysfunction for individual subjects as had previouslybeen thought. Therefore, it is important to evaluate and integratethe laboratory results in relation to the clinical assessment,e.g., the patient's symptoms, physiological status (e.g.,age, pregnancy, etc.), and underlying health status (other comorbiditiesand drug intake).

There's more to discuss in this vast topic, but I'm going to sleep now!

Edited December 9, 2010 by greyhead

[Guest Stripeyfan]

Greyt info, thanks! Hopefully we won't ever need it (I have enough grey hairs with Kelly already as you know!) but it's useful to know.

[tbhounds]

While I understand that this is hugely debatable topic I don't understand how you can compare human medicine to veterinary medicine. Something else to consider is while our beloved hounds are considered canines they most certainily are atypical of any other breeds. How do you feel about their lower platelet values, lower WBC, higher PCV%

higher hemoglobin., the bleeding disorder, the higher incidence of OS.....??? That is all accepted--ok I'll say it--as normal findings for our hounds. Why in earth can't we accept the fact that they have different thyroid values?

Edited December 9, 2010 by tbhounds

[Guest Swifthounds]

You want more fun? Take a raw fed dog to the vet and let them try to compare the lab results of a raw fed and remarkably healthy greyhound to the values for a kibble fed something or other (maybe a greyhound, maybe)... Oh, and according to the blood workup, the abdominal ultrasound, the full thyroid panel and the exam my 13 year old was in better shape than the dogs in there (two were greyhounds) who were half his age.

 

If you base treatment on numbers rather than the dog's physical condition, you're bound to have issues. IF they had just done my boy's T4 they would have thought he was hypo...

[Guest Bamn]

I have used the OSU greyhound blood work panel for greyhounds as my "normal" to work with. Auggie's T4 was 0.5, now on medication is still only 0.9. He was clinical at his low but now is "normal". I have also had to educate some veterinarians on "normal greyhound blood work" - we no longer use that vet. OSU seems to have the most complete data that I have tried to find.

 

https://greyhound.osu.edu/resources/freeresources/makingsenselabwork/index.cfm

 

Hope this info helps - it helped me to have a lot of it in one place.

[kudzu]

I am very glad to have awakened to find someone else started this topic. As I went to bed last night I was pondering this very issue & considering starting the topic myself. I would not have had that reference though & am happy someone saved me from the searching.

 

... I don't understand how you can compare human medicine to veterinary medicine.

The point, I believe, is that you must treat the dog not just the numbers. Just as Greys as a whole may have thyroid related values that are not WNL for other breeds, individual Greys may have their own norms fall out of the normal limits for their breed. Some dogs test values fall outside normal limits just as some humans do. You most definitely can compare human medicine to veterinary medicine. There is no big line dividing medicine between human & vet med except in our imaginations. There have been advancements made in human medicine that spring directly from vet med & vice versa. It's all medicine.

 

Yes, there is great variety within species. Of course you cannot assume that what happens in a human will automatically happen in another species. No one is suggesting that. It would be foolish though to believe that because an individual patient lands in the vet med category its individual hormone levels will land WNL for their species or breed. That is not the case for humans & there is no reason to believe it would be the case for a Greyhound.

 

... Why in earth can't we accept the fact that they have different thyroid values?

 

Unless I missed some posts, it does not seem like anyone on GT is arguing the generally accepted believe that the average, apparently healthy Grey can have thyroid values that vary significantly from those of other breeds. Nor have I seen suggestions that we start treating them all as hypo-T based on their low T4 values as compared to the general canine norm. It would be wrong to take an asymptomatic Grey & start dosing with levothyroxine because of an incidental finding on an annual wellness panel. Though depending on what that finding was, further investigation may be in order.

 

If you accept that Greys' thyroid values are skewed from canine norms & you've been presented with a symptomatic dog, what's a vet to do? First & best option would seem to be to compare the current lab work to the dog's prior lab work. From there you decide what you want to do. That could be starting treatment, doing different &/or more detailed lab work or continued monitoring. If the values have changed in the direction of hypo-T, follow up lab work confirms that trend & that individual remains symptomatic without indication of another disease process then trying supplementation is a valid treatment option. Absent several sets of prior values for that individual you could have no way to know what that individuals norms are. In that case it may not be appropriate to start treatment especially if the statistics show hypo-T is rare in the breed. Monitoring & follow up may be the best idea but it would be decided on a case by case basis.

 

Here is my main point. The lab work does not diagnose hypo-T. It is only part of the research process on the road to reaching a diagnosis. And why do I care so much? Well...

 

My dog started having a variety of vague symptoms. Was it age causing her to slow down? Was less activity causing her to gain weight? Was her food no longer providing her the proper nutrients to sustain a good coat? What's with the expanding baldness on not only her thighs but her entire lower legs? Why is her skin getting flakey? Why have her thyroid values trended subtly but noticeably in the direction of hypo-T? At that point, without any evidence pointing to a condition other than hypo-T, I don't give a rat's patoot about anyone's belief on the rarity of the condition within her breed. We put her on L-thyroxine. Her symptoms improved. We lowered the dose & the symptoms worsened. We upped it again & the symptoms diminished. Her T-4 values were up to 1.4 at last check & that is right where the vet wants it. Are we repeating the entire thyroid panel each time? No. Do I worry about that? No. Assuming all continues well we'll do it all again in the Spring. Until then I am content to just monitor my dog & keep an eye towards the trend in her T4. My dog is doing well & I am happy.

[seeh2o]

 

Here is my main point. The lab work does not diagnose hypo-T. It is only part of the research process on the road to reaching a diagnosis. And why do I care so much? Well...

 

My dog started having a variety of vague symptoms. Was it age causing her to slow down? Was less activity causing her to gain weight? Was her food no longer providing her the proper nutrients to sustain a good coat? What's with the expanding baldness on not only her thighs but her entire lower legs? Why is her skin getting flakey? Why have her thyroid values trended subtly but noticeably in the direction of hypo-T? At that point, without any evidence pointing to a condition other than hypo-T, I don't give a rat's patoot about anyone's belief on the rarity of the condition within her breed. We put her on L-thyroxine. Her symptoms improved. We lowered the dose & the symptoms worsened. We upped it again & the symptoms diminished. Her T-4 values were up to 1.4 at last check & that is right where the vet wants it. Are we repeating the entire thyroid panel each time? No. Do I worry about that? No. Assuming all continues well we'll do it all again in the Spring. Until then I am content to just monitor my dog & keep an eye towards the trend in her T4. My dog is doing well & I am happy.

Take it one step further, Carl didn't just have a few vague symptoms, he had a rare symptom. I'm glad I question "conventional" wisdom.

[Batmom]

Carl's symptom was uncommon but was thyroid-specific and well-documented as such. It's very odd that a board-certified ophthalmologist wouldn't pick that up.

 

The problem with supplementing thyroid when the test results don't warrant it and when the symptoms are not thyroid-specific is that thyroid meds have a very broad impact. A dog could have untreated babesiosis and appear enormously better on thyroid meds. That's what thyroxine does.

 

A dog that "just isn't doing right" and/or drinking a lot, for example, could also have high blood pressure, a stomach tumor, a heart condition, diabetes insipidus, Cushing's disease ... and in at least two of those cases, thyroid supplementation wouldn't just be useless. It could kill.

 

In cases where the dog doesn't have a contraindication such as high blood pressure, thyroid supplementation can still cause problems -- seizures, bone loss, you name it. It is not a benign medication.

 

What surprises me is that you still see owners and vets starting thyroid meds on the basis of a T4. T4 is a poor test in any breed, not only in greyhounds. The T4 level fluctuates from hour to hour and day to day. It can be zero in the morning and over 2.0 in the afternoon, in a perfectly normal dog. A low level for the breed + specific symptoms are a good reason for further testing. A low level + no symptoms or symptoms strongly suggestive of something else? Not so much.

[Guest Swifthounds]

What Batmom said.

 

Honestly, the T4 test and the resulting placement of way too many dogs needlessly or harmfully placed on thyroid supplementationis a near perfect example of the ways in which the veterinary profession and owners have failed pets by treating a symptom rather than looking at the whole picture. You can treat a symptom or a test value, then treat the adverse effects of that treatment, add a few things for the side effects and pretty soon the entire picture is skewed. We, as vets and owners, should be treating the whole dog based on all of the factors present, not a single value.

[tbhounds]

What Batmom said.

 

Honestly, the T4 test and the resulting placement of way too many dogs needlessly or harmfully placed on thyroid supplementationis a near perfect example of the ways in which the veterinary profession and owners have failed pets by treating a symptom rather than looking at the whole picture. You can treat a symptom or a test value, then treat the adverse effects of that treatment, add a few things for the side effects and pretty soon the entire picture is skewed. We, as vets and owners, should be treating the whole dog based on all of the factors present, not a single value.

[greyhead]

While I understand that this is hugely debatable topic I don't understand how you can compare human medicine to veterinary medicine. Something else to consider is while our beloved hounds are considered canines they most certainily are atypical of any other breeds. How do you feel about their lower platelet values, lower WBC, higher PCV%

higher hemoglobin., the bleeding disorder, the higher incidence of OS.....??? That is all accepted--ok I'll say it--as normal findings for our hounds. Why in earth can't we accept the fact that they have different thyroid values?

If you don't see how you can compare vet and human medicine, you haven't thought about it enough. Kudzu explained it very well.

 

You're a very smart person, tbhounds, have been a great help to me with Spencer's intestinal problems, and I like you enormously. So I hope you'll think more about what can be learned from human medicine to the benefit of our animals. It would be a shame to refuse to even consider such findings as I quoted when they may in fact help us understand why our greyhounds don't all present the same way when they do have thyroid difficulty.

 

As to atypical greyhound values, most of them make logical sense when considering what these dogs have been bred to be and what their experience has been as racers. It's perfectly logical that they would have higher hemoglobin, for instance. OS may be pure genetics or a combination of that and certain stressors; in any case, we don't call it "normal" for greyhounds just because so many get it.

 

I try very hard to understand the reasons for things; if I don't understand something in conventional terms, I pursue it from a different angle. The thyroid findings don't entirely make logical sense to me. The reason I don't just accept group norms is because I've studied statistics just enough to know that they have their limits and to know that correct interpretation of results is an analytical problem, not a mathematical one.

 

I came by this interest five years ago when, after a complete thyroid panel using equililbrium dialysis -- with an initial T4 at the very bottom of the range but technically within normal limits -- followed by treatment, my first greyhound's "aggression" disappeared. (I've since come to think of it as "defensiveness," but that's another story.) The only "classic" symptom he has was lack of energy. I requested the full panel because I know that any value at the poles of any range is suspect, due to the standard error of measure. So Spencer recovered immediately and is still with us. But right after that testing, the vet told me that his vet partner had previously put down two greyhounds for aggression, one of them her own. They were killed without a full thyroid panel because the T4 was WNL. One case was thought to be due to "brain inflammation," but no reason was found in the other case. So knowing the stakes can be life-or-death, I get very queasy about just uncritically accepting the idea that greyhound thyroid values are lower just "because they are," and that greyhound group norms should be uniformly applied to each and every case, with no willingness to consider that that dog may just be different from the group.

 

What I'm suggesting is that one shouldn't just look at lab values and say the dog must not have a thyroid problem if its lab values are within group norms. The individual set-point for that dog may vary. To suggest that that finding in humans is worth considering when deciding whether to pursue further testing and/or treatment for a dog is not far-fetched when you consider that we are all mammals and as such have a huge number of physical processes in common. And it's not like I'm suggesting that we evaluate quadruped gait on the basis of biped standards, for crying out loud!

 

What Kudzu said!

[Batmom]

What I'm suggesting is that one shouldn't just look at lab values and say the dog must not have a thyroid problem if its lab values are within group norms. The individual set-point for that dog may vary.

 

That is certainly true.

 

I think some of us tend to focus on the other side of the coin for this particular malady because so many greyhounds are put on thyroid meds without proper testing or evaluation of symptoms, and that is not good. In my experience at least, it happens far less often that a dog should have thyroid meds and isn't put on them. (There are plenty of other conditions where dogs should be tested and probably put on meds but aren't.)

Edited December 9, 2010 by Batmom

[greyhead]

Whew, thanks Batmom! I type better without the boxing gloves.

 

To move the discussion along a bit, let's consider this sentence from the quotation in the OP:

Furthermore, the biological activity of thyroid hormone, interms of T₃ availability, is regulated by type 1, 2, and 3 iodothyroninedeiodinases (D1, D2, and D3) (45). The efficiency of conversionof T₄ to T₃ by D2 increases as the serum T₄ decreases (45).Consequently, in the presence of a low level of T₄ or in caseof a hypothyroid state, D2 is increased and can generate a significantquantity of plasma T₃.

This offers to my mind a suggestion -- only a suggestion -- about how it is that greyhounds or anybody else can get along so well with very low levels of T4. When it's really low, conversion to T3 increases. T3, as folks may or may not know, is the form of thyroid hormone that is bio-available, or biologically available to do the body's actual work. And it's created when T4 drops an atom and through that conversion becomes T3 instead. If we want to know why it's set up that way, we might have to ask God, but that's how it is. (My endo says he has patients who tell him just to give them T3 and skip the T4 med altogether. That's how powerful T3 is.)

 

Okay, good, we critters can get by as long as we have a bunch of T3. But I'm not sure we know how long anybody can keep up that increased conversion efficiency. And it also raises the question of trade-offs, of whether there is a cost to increased efficiency of T3 conversion in the presence of low T4. I'm reminded of the study some years ago on women in underdeveloped countries, showing that they became more fertile when they were starving. It appears this is nature's way of guaranteeing that the human race survives despite things like famine. But this shift in fertility arguably does no big favor to the individual starving women and their health. While that may not be the best available example, it hopefully serves to indicate the lines our thoughts could travel in pondering this.

 

I also recall hearing, way back when dealing with Spencer's thyroid initially, that testing T3 in dogs is not all that useful or illuminating. But given the finding cited above, it seems very useful indeed. Just in case anyone's tempted not to do the full thyroid panel.

 

After we get this out of the way, I'll start another slugfest -- in this thread, yes -- about classic thyroid symptoms and other symptoms, as a couple people touched on earlier. Or anyone else can feel free to start it instead. Thanks and hugs to all those brave enough to join the conversation, including those who disagree with me.

Edited December 9, 2010 by greyhead

[GeorgeofNE]

Here is my main point. The lab work does not diagnose hypo-T. It is only part of the research process on the road to reaching a diagnosis. And why do I care so much? Well...

 

My dog started having a variety of vague symptoms. Was it age causing her to slow down? Was less activity causing her to gain weight? Was her food no longer providing her the proper nutrients to sustain a good coat? What's with the expanding baldness on not only her thighs but her entire lower legs? Why is her skin getting flakey? Why have her thyroid values trended subtly but noticeably in the direction of hypo-T? At that point, without any evidence pointing to a condition other than hypo-T, I don't give a rat's patoot about anyone's belief on the rarity of the condition within her breed. We put her on L-thyroxine. Her symptoms improved. We lowered the dose & the symptoms worsened. We upped it again & the symptoms diminished. Her T-4 values were up to 1.4 at last check & that is right where the vet wants it. Are we repeating the entire thyroid panel each time? No. Do I worry about that? No. Assuming all continues well we'll do it all again in the Spring. Until then I am content to just monitor my dog & keep an eye towards the trend in her T4. My dog is doing well & I am happy.

Take it one step further, Carl didn't just have a few vague symptoms, he had a rare symptom. I'm glad I question "conventional" wisdom.

 

Those symptoms are not vague--they're fairly classic signs of a thyroid problem!

[seeh2o]

Carl's symptom was uncommon but was thyroid-specific and well-documented as such. It's very odd that a board-certified ophthalmologist wouldn't pick that up.

 

It was the board certified ophthalmologist who did finally diagnose it (after 3 misdiagnosis). My first vet that I took Carl to referred me to a guy who turned out to be a quack...runs a veterinary ophthalmology clinic, but is only a vet who took classes in ophthalmology, was never board certified! Ugh, I'll never recoup that money thrown down the rat hole. I changed vets, was referred to real ophthalmologist and now his eyes are much better, though not 100%

Edited December 10, 2010 by seeh2o

[tbhounds]

Yikes--this is tiring Finally ditched my iphone (have you ever tried to post from there-gezz) and got to my laptop-yea. Re-read the prior posts (ok-I admit--didn't really read them throughly) and actually I think we are really all on the same page--ok--for the most part. I think my biggest issue is the fact that there appears to be an awful lot of hounds placed on supplementation w/o having complete panels run. Some pups may have a hypo symptom whether it be hair-loss, lack luster attitude, weight gain, skin lesions, seizures, cold intolerance......and so on and the vet runs a T4 which in all likelyhood will return low or borderline low (or returned low because the pet is euthyroid sick) will start the pet on supplementation. It's an easyout diagnosis for the vet and is it truly warranted?? Will the dog act better?? Most likely yes, but, did the clinician truly do his/her job and treat the pet properly--no, the pet will still have that underlying disease. I guess one can argue the if the original symptom resolves then, continuing supplementation is warranted or can you assume the symptom may resolve on it's own regardless of the proper medical treatment such as antibotics etc.. Gotta stand firm on this--supplementing w/o warrant can cause harm (as a side note I do know a person that tried to loss weight and put herself on light supplementation--ended up hosptialized in the cardiac unit). Now, that being said there are most likely hypodogs not being diagnosed too.

I just recently saw a 12yr English Bulldog that was brought into a clinic that had end-stage ear-disease and horrible bi-lateral hairloss combined with a nasty staph infection. He was so lethargic he couldn't hold his head up. Was he hypo?? The owners never tested---did he fall through the loop hole? Did the owners decline blood work? The dog was PTS. A sad ending for that pup.

As far as human-veterinary medicine link wow-don't talk to PETA about that one--pretty hot topic. I do think they complement each other--of course (as all of the research labs will tell us)human medicine has benefited via animal research and actually Dr Couto is sharing his research of OS with a childs hospital in Ohio. So, while the undeniable link is there I still feel that we can be on opposite sides of the spectrum too--don't think anyone would argue that fact that we metabolize drugs differently and so on (if I took my dog's Benedryl dosage I would sleep for a week)---think that was really the heart of my original point.

Still wonder why we can't understand or maybe I should say I can't understand why it can't be accepted that our hounds have lower thyroid values. Our GH's didn't read the how to be a canine book before they were presented here on earth. Sure some of the atypical values (compared to other breeds-not including other sighthounds) can be explained because of their long standing race history such as higher hemoglobin but, how does one know if the lower hypo values haven't evolved the same way--I dunno. I suppose if we had that answer this thread would come to a grinding holt.

So, I guess bottom line is we must agree to disagree and there is not really a right or wrong way. Admittedly, I will follow Dr Couto's protocol and my own common sense to diagnose and treat hypothyroidism in Greyhounds. PHEW

Did you really think I didn't need to edit this??

 

https://ckm.osu.edu/sitetool/sites/greyhoundpublic/documents/About/Newsletters/9-ghwpNewsletterWinter2010-Thyroid.pdf

Edited December 10, 2010 by tbhounds

[seeh2o]

Ugh, the editor crapped out on me as I was editing my post above.

 

 

My point, problems don't necessarily present themselves to you as standard fare on a silver platter, you need to look at the dog's health and behavior in totality, not just the numbers.

[greyhead]

My point, problems don't necessarily present themselves to you as standard fare on a silver platter, you need to look at the dog's health and behavior in totality, not just the numbers.

Exactly. Thank you.

 

My worry is that sometimes here on GT I see well-meaning statements made that seem to suggest that a low T4 finding is so common in GH's that their person's money would be better spent looking at something other than thyroid to figure out why their dog isn't right. Even when a nod is made to the idea that behavior must be considered along with numbers, symptoms that haven't been statistically associated with hypothyroidism (such as "aggression", for instance) are dismissed as probably due to something else. So a full panel may not be pursued when it really should be.

 

I think those of us who have some degree of pride in our rationality, which is most of us, don't want to see ourselves or have others see us as tilting at windmills. If people who seem to know more than we do tell us that something is unlikely, we may feel foolish to continue investigating it. Naturally, we want to pursue the avenues that are most likely to lead to the right answer. And then there's the $$ issue.

 

So I've offered the article cited to underscore that all individuals -- GH's or otherwise -- are not alike and that all manifestations of thyroid disease are not classic. I'd prefer to see people encouraged to pursue complete thyroid testing if there's any chance that that could be the dog's problem. For one thing, it's a very easy fix. For another, the cost to a dog of not having it fixed can be really harsh even if they don't let us know. Because they're so darned stoical, and they can't talk to tell us they have sore joints and frequent heartburn! Can we agree on that much? (Well, except for the drama queens, and they only seem to get histrionic over the small stuff.)

[greyhead]

Yikes--this is tiring

It is tiring -- and now late! I made my last post while trying to watch "Bones" and I think I'm done for the night.

 

I think my biggest issue is the fact that there appears to be an awful lot of hounds placed on supplementation w/o having complete panels run. ...(trimmed) ... Now, that being said there are most likely hypodogs not being diagnosed too. ...(trimmed here too)...

Still wonder why we can't understand or maybe I should say I can't understand why it can't be accepted that our hounds have lower thyroid values.

I'll get back to this tomorrow. But I should say that I think I just have a different bias than those like yourself who hold sway on this subject. I'm acutely aware of the problem of under-diagnosis, while others are trying mightily to prevent over-diagnosis. So we've had a thread recently where a greyhound has twice tested low on a complete panel, I believe, using greyhound norms and still is discouraged from pursuing thyroid as the likely culprit! Nobody is saying "don't do it," but they're pointing the owner in different directions.

 

Hopefully tomorrow I'll be able to explain my questions about greyhound norms. Meanwhile, can anyone help me find the studies that established those norms? I need to know how many GH's were studied in total, at what stage(s) of their lives, by how many studies, who performed them, and in what years. I haven't looked at the OSU material in quite a while; is it in there?

[kudzu]

A dog that "just isn't doing right" and/or drinking a lot, for example, could also have high blood pressure, a stomach tumor, a heart condition, diabetes insipidus, Cushing's disease ...   It is not a benign medication.

 

What surprises me is that you still see owners and vets starting thyroid meds on the basis of a T4.  

Don't think any of us would argue your points. The concern I have recently are the various versions of statements that often come across as essentially saying, "Dr Couto says hypo-t is so rare in Greys as to be almost nonexistent so there is almost no chance your dog has hypothyroidism. 

 

Suggest the full panel. Offer the info on what is currently considered Greyhound norms. Suggest other possible avenues of investigation. That is all good. But it is also wise to accept that it is a possibility for Greys. Individuals have their own normal. I understand the concerns but it is disturbing to see the pendulum swing so far in the other direction that some folks are

[kudzu]

Those symptoms are not vague--they're fairly classic signs of a thyroid problem!

Of my own girl's symptoms i could have more accurately worded it as "nonspecific" rather then "vague". Whatever way you say it she had symptoms classic for but not specific to hypothyroidism. No evidence of other sideward process was found. Her thyroid panel as compared to her own prior test results had trended toward hypo-t.

[kudzu]

No evidence of other sideward process was found.

"Sideward process"?? OMG! What was someonse saying about iPhones? LOL that should be "disease process" instead.

[Guest Swifthounds]

Interesting reading. This thread definitely highlights the difficulty that vets and owners seem to have in putting together an overall assessment of a dog's health and arriving at a diagnosis without relying solely on number on paper. Honestly, I've seen lots of low T4 dogs who were asymptomatic, but I've never seen a symptomatic dog with thyroid problems present with T4 well in the normal range. What people usually term "unusual" or atypical symptom tends to be anything out of the top 5 types of symptoms

[kudzu]

Interesting reading. This thread definitely highlights the difficulty that vets and owners seem to have in putting together an overall assessment of a dog's health and arriving at a diagnosis without relying solely on number on paper. Honestly, I've seen lots of low T4 dogs who were asymptomatic, but I've never seen a symptomatic dog with thyroid problems present with T4 well in the normal range. What people usually term "unusual" or atypical symptom tends to be anything out of the top 5 types of symptoms

OK, so can you elaborate a bit on this. What is causing you to think some folks in this thread may be "relying solely on number on paper." Perhaps I am misunderstanding what you are getting it. What is your definition of "well in the normal range"? It would help me to better understand your point.

[greyhead]

Couldn't find the actual studies, with methods included, so I can't evaluate them. But before I run off, at least for a while, I want to post a couple links. The first is one cited in a previous thread by Batmom and is the most complete explanation of the possibilities in canine thyroid dysfunction that I've seen. It doesn't cover 100% of possible symptoms, but after reading it one can understand why no one can cover 100%. . http://www.veterinar...A&S=0&C=0&A=461 It surveys the body systems affected in hypothyroidism. Anybody who thinks they may have a thyroid dog should read it. (Did you know that sludgy blood is a symptom? It was news to me.)

 

Norming is not as simple as it might sound. How the sample of subjects is chosen is crucial. It may not be a representative sample, so the results may not be legitimately generalizable to all of Greyhounddom. This is also a problem in human research, and researchers are still disagreeing about what the proper range of TSH values is for humans, even after decades of human thyroid supplementation! Here's a link to the abstract of a really interesting article that details some of the problems in settling on human norms, about which there continues to be disagreement: http://jcem.endojour...tract/90/9/5483 Once there, you can clink on a link in the right-hand column to get free access to the entire article, by the way, and it's worth reading if you have any curiosity in this area. The point is that all research, including that on greyhoundsand on humans, is subject to the same problems of measurement, methdology, and analysis. Even publication in peer-reviewed scientific and academic journals is no guarantee of complete correctness. (Yeah, that came as a shock to me too. But I've had 20 years to get used to the idea.) <BR style="mso-special-character: line-break"> <BR style="mso-special-character: line-break"> To be clear, I am not saying that the thyroid norms for greyhounds are wrong. I'm saying I don't know for absolute sure and, in the absence of better information about the studies performed and their methodologies, I choose to keep an open mind. Which is what I spent a lot of tuition being trained to do. "Cuz so-and-do says so" is not a good basis for reaching a conclusion, and I doubt Dr. Couto would disagree with that. But this is incidental to the main point that needed to be made, which is that group norms do not infallibly describe the thyroid health of every single dog. So it behooves us, I think, to have some humility and restraint about the subject when we try to advise others. And please, please let's not handle ourselves in such a way that greyhounds become under-treated. Heartbeat irregularities can occur with untreated hypothyroid too.

In my humble opinion. Love to all. (I've been recalled to my regularly-scheduled life for at least the next week, so don't take it personally if I'm not responding for the next week or two.)

 

Edited: trying to fix that <BR style="mso-special-character stuff above. No luck.

Edited March 5, 2011 by greyhead