Assessment of criteria used by veterinary practitioners to diagnose hypothyroidism in sighthounds and investigation of serum thyroid hormone concentrations in healthy Salukis.
OBJECTIVE
To assess use of serum thyroid hormone concentrations by veterinarians to diagnose hypothyroidism in sighthounds and to evaluate serum thyroid hormone concentrations in healthy Salukis.


METHODS
Retrospective case series and cross-sectional study.


METHODS
398 sighthounds of various breeds with a diagnosis of hypothyroidism and 283 healthy Salukis.


METHODS
Pretreatment thyroid hormone assay results from sighthounds subsequently classified as hypothyroid by practitioners were retrieved from a laboratory database. In healthy Salukis, serum concentrations of total thyroxine (T(4)), free T(4), total triiodothyronine (T(3)), free T(3), and thyroid-stimulating hormone (TSH) and antibodies against thyroglobulin and thyroid hormones were assayed.


RESULTS
Records indicated hypothyroidism had been diagnosed in 303 (76.1%) sight-hounds on the basis of low serum thyroid hormone concentrations alone and in 30 (7.5%) others despite all thyroid hormone indices being within reference limits. Only 65 (16.3%) dogs had a high TSH concentration or positive thyroglobulin autoantibody result to support the diagnosis. In healthy Salukis, median (reference limits) serum concentrations of total T(4), free T(4), total T(3), free T(3), and TSH were 13.0 nmol/L (2.8 to 40.0 nmol/L), 12.0 pmol/L (2.0 to 30.3 pmol/L), 1.0 nmol/L (0.4 to 2.1 nmol/L), 4.0 pmol/L (1.6 to 7.7 pmol/L), and 0.18 ng/mL (0 to 0.86 ng/mL), respectively.


CONCLUSIONS
Diagnosis of hypothyroidism by practitioners was most often made without adequate supportive laboratory evidence. Thyroid hormone values in healthy Salukis differed markedly from standard reference limits for some, but not all, thyroid hormone indices. Breed-specific reference limits should be used when interpreting thyroid hormone profiles of sighthounds.
Shiel
Robert E
RE
Unit of Small Animal Clinical Studies, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland. robert.shiel@ucd.ie
Sist
MaryDee
M
Nachreiner
Raymond F
RF
Ehrlich
Claire P
CP
Mooney
Carmel T
CT
D000818:Animals; D003430:Cross-Sectional Studies; D004283:Dog Diseases / Q000097:blood / Q000175:diagnosis*; D004285:Dogs; D005260:Female; D007037:Hypothyroidism / Q000097:blood / Q000175:diagnosis / Q000662:veterinary*; D008297:Male; D012189:Retrospective Studies; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine