Thyroid

[Guest chigal950]

Molly's T4 came back a little low so her vet and I agreed to do a full panel. I asked for it to be sent to MSU and he agreed to do so even though its an extra hassle setting up an account. He did say the MSU has the best Thyroid in the country.

 

When I mentioned that greys have different thyroid values than other dogs and that I felt most comfortable that MSU would make the proper distinctions from other breeds, he had never heard this . While he didn't say so I could tell he didn't believe it. I am the first to admit that you should not believe everything you read on the internet. So...

 

Can you please post direct links to legitimate, recognized, scientifically-based studies and/or well-respected veterinary opinions which indicate that greys indeed have different thyroid readings and/or other bloodwork readings as contrasted with other breeds. My vet is very open minded and if it is something I can share with him he will definitely take it as a positive learning for the future. But it needs to be from a scientific source not just some message board discussion.

 

Thanks!

[Burpdog]

If you email me at Burpdog@msn.com I'll email you Dr. Feeman's papers.

 

Have your vet join Veterinarians for Retired Racing Greyhounds by contacting:

 

 

 

 

Dr. Bill Feeman

FeemanDVM@aol.com

 

 

or

 

Couto Guillermo Professor Veterinary Clinical Sciences (614) 292-3551 couto.1@osu.edu

 

[Batmom]

Here are a couple refs to tide you over until Burpdog can email you more thorough stuff:

 

http://home.comcast.net/~greyhndz/hypothyroid.htm

http://www.vet.osu.edu/2098.htm

http://home.comcast.net/~greyhndz/blood.htm

http://www.vet.osu.edu/2376.htm

[Guest chigal950]

Thanks guys!

[Guest CindiLuvsGreys]

Here is a link to the medical page of my Greyhound adoption group. It gives you levels for "normal" dogs and also what is normal for Greyhounds.

 

 

http://mysite.verizon.net/vze1q4t0/phillyg...ection/id5.html

 

 

Here is some of the info:

 

Greyhound bloodwork has enough differences from “other dog” bloodwork to sometimes make it deceivingly “normal” or “abnormal” if one isn’t familiar with these differences. The salient differences are discussed below.

 

Greyhounds:

 

RBC: 7.4-9.0

Hgb: 19.0-21.5

PCV: 55-65

Other Breeds:

 

RBC: 5.5-8.5

Hgb: 12.0-18.0

PCV: 37-55

Greyhounds have significantly more red blood cells than other breeds. This elevates parameters for RBC, hemoglobin, and PCV/HCT, and is the reason greyhounds are so desirable as blood donors. Most veterinarians are aware of this difference.

Never accept a diagnosis of polycythemia — a once-in-a-lifetime-rare diagnosis of pathologic red cell overproduction — in a greyhound.

Conversely, never interpret a greyhound PCV in the 30’s-40’s as being normal just because it is for other dogs. A greyhound with a PCV in the 30’s-40’s is an anemic greyhound. Here in Arizona, a greyhound PCV less than 50 is a red flag to check for Ehrlichia.

 

WBC

 

Greyhound: 3.5-6.5

Other dog: 6.0-17.0

Other greyhound CBC changes are less well known. The greyhound’s normally low WBC has caused more than one healthy greyhound to undergo a bone marrow biopsy in search of “cancer” or some other cause of the “low WBC.”

 

Platelets

 

Greyhound: 80,000-200,000

Other dog: 150,000-400,000

Likewise, greyhound platelet numbers are lower on average than other breeds, which might be mistakenly interpreted as a problem. It is thought that greyhound WBCs, platelets, and total protein may be lower to physiologically “make room” in the bloodstream for the increased red cell load.

Compounding these normally low WBC and platelet numbers is the fact that Ehrlichia, a common blood parasite of greyhounds, can lower WBC and platelet counts. So if there is any doubt as to whether the WBC / platelet counts are normal, an Ehrlichia titer is always in order. The other classic changes with Ehrlichia are lowered PCV and elevated total protein. But bear in mind that every greyhound will not have every change, and Ehrlichia greyhounds can have normal CBCs.

 

T.P. & Globulin

 

Greyhound TP: 4.5-6.

Other dog TP: 5.4-7.8

Greyhound Globulin: 2.1-3.2

Other dog Globulin: 2.8-4.2

Greyhound total proteins tend to run on the low end of normal — T.P.s in the 5.0’s and 6.0’s are the norm. While the albumin fraction of T.P. is the same as other dogs, the globulin component is lower.

 

Creatinine

 

Greyhound: .8-1.6

Other dogs: .0-1.0

Greyhound creatinines run higher than other breeds as a function of their large lean muscle mass. A study at the Auburn University College of Veterinary Medicine found that 80% of retired greyhounds they sampled had creatinine values above the standard reference range for “other dogs.” As a lone finding, an “elevated creatinine” is not indicative of impending kidney failure. If the BUN and urinalysis are normal, so is the “elevated” creatinine.

 

T4

 

Greyhound: .5-3.6 (mean 1.47+/- .63)

Other dogs: 1.52-3.60

These figures are from a University of Florida study of thyroid function in 221 greyhounds — 97 racers, 99 broods, and 25 studs — so it included both racers and “retired.” While greyhound thyroid levels are a whole chapter unto themselves, a good rule of thumb is that greyhound T4s run about half that of other breeds.

 

Urinalysis

 

And lastly, the good news — greyhound urinalysis is the same as other breeds. It is normal for males to have small to moderate amounts of bilirubin in the urine.

 

Sources: M.R. Herron, DVM, ACVS, Clinical Pathology of the Racing Greyhound , 1991. C. Guillermo Couto, DVM, ACVIM, “Managing Thrombocytopenia in Dogs & Cats,” Veterinary Medicine, May 1999. J.Steiss, DVM, W. Brewer, DVM, E.Welles, DVM, J. Wright, DVM, “Hematologic & Serum Biochemical Reference Values in Retired Greyhounds,” Compendium on Continuing Education, March 2000. M. Bloomberg, DVM, MS, “Thyroid Function of the Racing Greyhound,” University of Florida, 1987. D. Bruyette, DVM, ACVIM, Veterinary Information Network, 2001.

 

Edited May 29, 2007 by CindiLuvsGreys

[feemandvm]

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 budsmom]

Have your vet also request the written evaluation of the test results from MSU. They take into consideration the breed of dog in their analysis, and it can be very helpful if your vet is unfamiliar with greyhounds.

[Guest SquanHound]

Also, please make your vet aware that the folks at MSU are great and are more than willing to get on the phone to discuss panel results. I spoke with one of the endocronlogists at MSU for a good 30 minutes the one day and he was more than willing to answer any questions I had. Here's the link with all of the MSU contact info

[Guest paulamariez]

I have been know to go to my vet, bearing copies of the above mentioned information to leave with them. And usually they have no problems with it. I think they're glad they don't have to go searching the internet for the information themselves! I think if the vet has a bad attitude about the greyhound differences and isn't willing to learn, then it's on to a new vet for me!

[ahicks51]

The last time we went to re-test Coco's thyroid (several months ago), MSU informed us they were not doing T4 by dialysis, which I understand to be the most accurate technique. Hopefully things have changed and they're back to testing in that manner, but you might call their lab services number (they're infallible) if there is any doubt.

 

I went with Jean Dodds over at Hemopet instead. I'm not sure if they do it on site (unlikely) or send it out, and I don't know which lab they use if they do send it out. It may just be IDEXX, same as about half the vets use anyway.