Thyroid function in mature horses ingesting endophyte-infected fescue seed.
OBJECTIVE
To determine whether ingestion of fescue seed infected with the endophyte Neotyphodium coenophialum would alter thyroid function in adult horses.


METHODS
Original study.


METHODS
4 adult mares that were not pregnant and 6 adult geldings.


METHODS
Thyrotropin releasing hormone stimulation tests were performed while horses received a standard diet and after infected seed (2.3 kg/d [5 lb/d]) had been fed for 1 and 2 months. Serum prolactin concentrations were measured to verify endophyte absorption.


RESULTS
Serum prolactin concentrations indicated that at least 8 of 10 horses absorbed the endophyte. Baseline concentrations of thyroid stimulating hormone, total and free triiodothyronine, and total and free thyroxine and the change in hormone concentrations in response to administration of thyrotropin releasing hormone (1 mg, i.v.) were not altered by ingestion of endophyte-infected fescue seed.


CONCLUSIONS
Results suggest that ingestion of fescue seed infected with the endophytic fungus N. coenophialum for 2 months has little effect on thyroid function in adult horses that are not pregnant.
Breuhaus
Babetta A
BA
Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA.
D000821:Animal Feed / Q000382:microbiology*; D000818:Animals; D005260:Female; D005516:Food Microbiology; D006734:Horse Diseases / Q000097:blood / Q000382:microbiology* / Q000503:physiopathology; D006736:Horses; D006999:Hypocreales / Q000472:pathogenicity*; D007700:Kinetics; D008297:Male; D006109:Poaceae / Q000382:microbiology*; D011388:Prolactin / Q000097:blood; D012639:Seeds / Q000382:microbiology; D013961:Thyroid Gland / Q000502:physiology*; D013972:Thyrotropin / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D014284:Triiodothyronine; D011388:Prolactin; D013972:Thyrotropin