Thyroid Question

[Guest Skinnymini]

Hi all,

 

My vet just called about Raven's annual blood work results. Everything's fine, except that she tested low on her thyroid level (she turns 8 this month). I was told the normal range is 15-60, but she tested 8.7. She is not showing any of the typical symptoms of hypothyroidism - i.e., obesity, lethargy etc.

 

We've agreed to wait and repeat the test in 3-4 months, rather than run a complete thyroid profile now (more money than I believe is worth spending at this stage).

 

Does anyone have any knowledge about this? Is this a potential concern, or am I dealing with a greyhound-specific issue that my vet may not be familiar with?

 

Many thanks!

[Guest charmsmom]

Greyhound thyroids run low anyway. I would cross-check her numbers with another vet before starting thyroid meds.

[Guest KennelMom]

Dr. Stack's article on Hypothyroidism in Greyhounds: Link

[Guest Greensleeves]

They *can* be asymptomatic, particularly if the problem is new. But thyroid problems can be life-threatening, so you do want to be cautious. Sometimes dogs can have what's called a "sick thyroid," where something (infection, stress, etc) upsets the normal levels, and they level back out again after a while. Our Baloo came back with low levels last summer, and I had the full panel done because I just didn't believe it. The full panel came back fine, and we tested again six months later--fine again.

 

Of course, you could wait and see if symptoms occur over the next few months and then test. But symptoms can be subtle and hard to know that they're actually *symptoms* of anything, particularly when they come on slowly. Or the symptoms can be unexpected (weight loss instead of weight gain, for example).

 

Good luck!

Edited May 8, 2008 by Greensleeves

[RobinM]

They *can* be asymptomatic, particularly if the problem is new. But thyroid problems can be life-threatening, so you do want to be cautious. Sometimes dogs can have what's called a "sick thyroid," where something (infection, stress, etc) upsets the normal levels, and they level back out again after a while. Our Baloo came back with low levels last summer, and I had the full panel done because I just didn't believe it. The full panel came back fine, and we tested again six months later--fine again.

 

Of course, you could wait and see if symptoms occur over the next few months and then test. But symptoms can be subtle and hard to know that they're actually *symptoms* of anything, particularly when they come on slowly. Or the symptoms can be unexpected (weight loss instead of weight gain, for example).

 

Good luck!

 

Well said. you don't want to wait for them to be symtomactic before you start the meds IF you need the meds. I would go for the full panel so you can know and be done with it. My Chloe's on suboxone for low thryroid. Her T4 was .02.

 

 

[Batmom]

But you don't know you need the meds unless the dog *is* symptomatic.

 

I'd probably wait 6 months to retest, unless you happen to need bloodwork in the meantime. T4 can vary from hour to hour and day to day -- in a dog with no symptoms, there's no reason to even take notice of a low T4 on a CBC.

[ahicks51]

Who did the lab test is also important- IDEXX and whatstheirname are different from other labs. Highly recommended: Michigan State University's lab, along with thyroid interpretation. Their interpreter will give you a sighthound-specific diagnostic consult for a couple of extra bucks.

 

Don't know if they're back to doing it by dialysis or not. Sighthound levels can be low, and most labs don't calibrate their instrumentation in that range.

 

Worst case: try a low dose of soloxine, see if there are any behavioral changes.

[Guest MomofSweetPotatoes]

I too would wait and retest in 3 - 6 months. Watch for symptoms of low thyroid - increased crankiness, tiredness (lethargy), dry skin, increased shedding, weight gain.

 

Yardman is hypothyroid. His only sign - He was cranky. Once his meds were on board and regulated, he was a new dog.

 

Good luck to you.

[Batmom]

Who did the lab test is also important- IDEXX and whatstheirname are different from other labs. Highly recommended: Michigan State University's lab, along with thyroid interpretation. Their interpreter will give you a sighthound-specific diagnostic consult for a couple of extra bucks.

 

Don't know if they're back to doing it by dialysis or not.

 

They are .

[Guest ProudGreyMom]

My vet just put Jake on a low dose (he is almost 10) and we will re-test him again in a few months. We actually saw his results from the lab, it wasn't like she just called and said he needed meds.

 

Thanks for that link and info - very helpful!

[Guest Skinnymini]

Thanks everyone, for the links and comments. It's so wonderful to have this resource when worries arise!

 

And Happy Mother's Day to all the moms and broodies!

[feemandvm]

If there are no symptoms I would NOT start meds UNLESS you had both a low free T4 by dialysis, a low total T4 AND a high TSH. Low free T4 and low total T4 and a normal TSH I would NOT treat unless signs were present.

 

There are a LOT of greyhounds that are on thyroid supplementation for years that have never needed it a day in their life.

 

Share this with your vet:

 

Thyroid Function Testing in Greyhounds

Sm Anim Clin Endocrinol 12[1]:4 Jan-Apr'02 Review Article 0 Refs

C.B. Chastain, DVM, MS, Dipl. ACVIM (Editor) & Dave Panciera, DVM, MS, Dipl. ACVIM (Assoc. Editor) Sm An Clin Endo

Gaughan KR, Bruyette DS.; Am J Vet Res 2001; 62:1130-1133

BACKGROUND: Thyroid function tests are frequently evaluated in greyhounds because of alopecia, infertility, and poor race performance. In most cases, hypothyroidism is not present, despite the finding of decreased serum total thyroxine (T4) concentrations. Sight hounds, including greyhounds and Scottish deerhounds are known to have serum T4 concentrations lower than other breeds of dogs. This can result in an erroneous diagnosis of hypothyroidism.

SUMMARY: Basal serum T4, free T4 (fT4), and the serum T4 and fT4 response to thyroid-stimulating hormone (TSH) administration were evaluated in a group of healthy pet dogs and in two groups of healthy greyhounds. All pet dogs and 56 greyhounds had serum T4 and fT4 response to thyrotropin-releasing hormone (TRH) administration evaluated. Serum concentration of endogenous canine TSH (cTSH) was measured in 18 pet dogs and 87 greyhounds. The pet dog group consisted of 19 dogs of various breeds (no greyhounds), with a mean age of 5.2 years. One group of greyhounds consisted of 37 female dogs with a mean age of 1.4 years that were actively racing and currently receiving testosterone for suppression of estrus. The second group of greyhounds consisted of 61 dogs with a mean age of 4.9 years that were not receiving testosterone. Greyhounds receiving testosterone were significantly younger than those not receiving testosterone and pet dogs. Of the greyhounds not receiving testosterone, none of the females (n = 35) were racing, while 10 of the 26 males were actively racing. No dog had received thyroid supplementation, glucocorticoids, or anabolic steroids with the exception of testosterone within 3 months of study. The mean basal serum T4 concentration was significantly lower in the greyhound groups than in the pet dog group. The mean basal serum fT4 concentration was significantly lower in the greyhound groups than in the pet dog group. The mean serum T4 response to TSH was significantly greater in pet dogs than in greyhounds either receiving testosterone or not. Greyhounds receiving testosterone had significantly higher serum T4 concentrations post-TSH than greyhounds not receiving testosterone. While there was no difference between the mean serum fT4 concentration after TSH administration in pet dogs and greyhounds receiving testosterone, the fT4 concentration in greyhounds not treated with testosterone was significantly less than the other groups. The mean serum T4 concentration in response to TRH administration was significantly lower in both groups of greyhounds than in pet dogs. The mean serum fT4 concentration after TRH administration was significantly lower in greyhounds not receiving testosterone than in greyhounds treated with testosterone or pet dogs. Mean serum cTSH concentrations were not significantly different between any of the three groups. The reference ranges for all greyhounds were established as basal concentrations of T4, fT4, and cTSH were 2.1 to 37 nmol/L, 1.3 to 32.2 pmol/L, and 0.03 to 1.3 ng/ml, respectively. The authors concluded that greyhounds have a lower reference range for serum T4 and fT4 concentrations than that of other breeds.

CLINICAL IMPACT: This study shows that serum T4 and fT4 concentrations in greyhounds are considerably lower than in non-greyhound dogs and clearly demonstrates the difficulty in diagnosing hypothyroidism in this breed. The lower limit of the reference range for T4 and fT4 concentrations in greyhounds is near the lower sensitivity of the assays. Therefore, it may be impossible to establish a diagnosis of hypothyroidism based solely on these hormones. Because the serum TSH concentration was similar to that of other breeds, an elevated cTSH combined with T4 and fT4 concentrations at the low end of the reference range combined with appropriate clinical signs is necessary to diagnose hypothyroidism in greyhounds. Dynamic testing using TSH or TRH stimulation testing may also be useful, but less practical. Testing when appropriate clinical signs are present is of particular importance in greyhounds. Caudal thigh alopecia, common in greyhounds, is not caused by hypothyroidism, and infertility is likely to be only infrequently caused by hypothyroidism in female dogs. Exogenous testosterone used to suppress the estrous cycle does not appear to alter basal serum concentrations of T4, fT4, or c-TSH, but responses to TSH or TRH stimulation may be increased by testosterone administration.

 

Thyroid function testing in Greyhounds.

Am J Vet Res 62[7]:1130-3 2001 Jul

Gaughan KR, Bruyette DS

OBJECTIVE: To evaluate thyroid function in healthy Greyhounds, compared with healthy non-Greyhound pet dogs, and to establish appropriate reference range values for Greyhounds.

ANIMALS: 98 clinically normal Greyhounds and 19 clinically normal non-Greyhounds.

PROCEDURES: Greyhounds were in 2 groups as follows: those receiving testosterone for estrus suppression (T-group Greyhounds) and those not receiving estrus suppressive medication (NT-group Greyhounds). Serum thyroxine (T4) and free thyroxine (fT4) concentrations were determined before and after administration of thyroid-stimulating hormone (TSH) and thyroid-releasing hormone (TRH). Basal serum canine thyroid stimulating hormone (cTSH) concentrations were determined on available stored sera.

RESULTS: Basal serum T4 and fT4 concentrations were significantly lower in Greyhounds than in non-Greyhounds. Serum T4 concentrations after TSH and TRH administration were significantly lower in Greyhounds than in non-Greyhounds. Serum fT4 concentrations after TSH and TRH administration were significantly lower in NT-group than T-group Greyhounds and non-Greyhounds. Mean cTSH concentrations were not different between Greyhounds and non-Greyhounds.

CONCLUSIONS AND CLINICAL RELEVANCE: Previously established canine reference range values for basal serum T4 and fT4 may not be appropriate for use in Greyhounds. Greyhound-specific reference range values for basal serum T4 and fT4 concentrations should be applied when evaluating thyroid function in Greyhounds. Basal cTSH concentrations in Greyhounds are similar to non-Greyhound pet dogs.

 

[Guest Skinnymini]

Thanks Bill, and everyone for their input.

[Guest lauri]

Spend the money and have a FULL panel done. Greys run low by nature - read the Suzanne Stack link. We went to a homeopathic vet, (Miles' 2nd vet), who took our him off of his thyroid meds even when the origonal vet insisted on him being on the stuff, AND kept wanting to increase his doses as his readngs weren't responding. She would not accept the fact that Grey's have different levels. The homeopath listned and read the info we gave her.

 

Miles was off for about 8 weeks, ran a full thyroid panel. He's been off for 5 years and still has no thyroid issues.

 

I know someone that recommended the first vet to us and their Grey was on thyroid meds. She ended up stroking and dying at around 6-7 years old. Maybe it wasn't because of the thyroid meds, but our omeopath said that animals CAN and do sometimes stroke when they take thyroid meds and don't truly need it.

 

The ONLY true way to know if they need the meds is to have a full panel done. Spending less is just a waste of money and may be dangerous to your pup.

[feemandvm]

A new vet reference from 2007:

 

Thyroid hormone concentrations in young, healthy, pretraining greyhounds

Vet Rec. 2007 Nov; 161 (18): 616-619.

RE Shiel, SF Brennan, AJ Omodo-Eluk, CT Mooney

School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland

 

 

Total thyroxine (T(4)) concentrations were below the non-breed-specific reference range in 42 of 46 healthy young greyhounds (91.3 per cent) and 16 (34.8 per cent) were at or below the limit of detection of the assay. Free T(4) concentrations were below the standard reference interval in 20.5 per cent of the animals and 13 per cent were at or below the limit of detection of the assay. In contrast, all the dogs' total tri-iodothyronine concentrations were within or above the non-breed-specific reference range and 67 per cent were within the upper half. All the dogs' thyroid stimulating hormone concentrations were within the non-breed-specific reference range. The results show that young greyhounds have markedly lower total and free T(4) concentrations than other breeds, and neither analyte can reliably be used to investigate the hypothyroidism in this breed as values were found below the limit of detection of each respective assay.