Comparison of the biological activity of recombinant human thyroid-stimulating hormone with bovine thyroid-stimulating hormone and evaluation of recombinant human thyroid-stimulating hormone in healthy dogs of different breeds.
OBJECTIVE
To evaluate whether use of recombinant human (rh) thyroid-stimulating hormone (TSH) induces equivalent stimulation, compared with bovine TSH (bTSH), and to evaluate activity of rhTSH in dogs of various large breeds.


METHODS
18 healthy research Beagles and 20 healthy client-owned dogs of various breeds with body weight > 20 kg.


METHODS
The 18 Beagles were randomly assigned to 3 groups, and each dog received either 75 microg of rhTSH, IM or IV, or 1 unit of bTSH, IM, respectively, in a crossover design. The 20 client-owned dogs received 75 microg of rhTSH, IV. Blood samples were taken before and 6 hours after TSH administration for determination of total serum thyroxine (T(4)) concentration. Additional blood samples were taken after 2 and 4 hours in Beagles that received rhTSH, IM.


RESULTS
There was a significant increase in T(4) concentration in all dogs, but there were no differences between values obtained after administration of bTSH versus rhTSH or IV versus IM administration of rhTSH. Although there was a significant difference in age and body weight between Beagles and non-Beagles, there was no difference in post-TSH simulation T(4) concentration between the 2 groups.


CONCLUSIONS
Results indicated an equivalent biological activity of rhTSH, compared with bTSH. Use of 75 microg of rhTSH, IV, did not induce a different magnitude of stimulation in large-breed dogs, compared with Beagles. Euthyroidism was confirmed if post-TSH simulation T(4) concentration was > or = 2.5 microg/dL and at least 1.5 times basal T(4) concentration.
Boretti
Felicitas S
FS
Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Switzerland.
Sieber-Ruckstuhl
Nadja S
NS
Willi
Barbara
B
Lutz
Hans
H
Hofmann-Lehmann
Regina
R
Reusch
Claudia E
CE
D000818:Animals; D002417:Cattle; D018592:Cross-Over Studies; D004285:Dogs / Q000145:classification* / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D011994:Recombinant Proteins / Q000009:adverse effects / Q000494:pharmacology*; D013972:Thyrotropin / Q000009:adverse effects / Q000494:pharmacology*; D013974:Thyroxine / Q000097:blood
D011994:Recombinant Proteins; D013972:Thyrotropin; D013974:Thyroxine