Cross-Latitudinal, Seasonal and Diurnal Comparisons in Thyroid Hormone Concentrations in Sled Dogs

Kriya L. Dunlap; Arleigh J. Reynolds; Kent R. Refsal; Wendell w. Kerr; Lawrence K. Duffy

doi:10.3844/ajavsp.2008.96.103

Article Details

Cross-Latitudinal, Seasonal and Diurnal Comparisons in Thyroid Hormone Concentrations in Sled Dogs

Authors:

Kriya L. Dunlap | Arleigh J. Reynolds | Kent R. Refsal | Wendell w. Kerr | Lawrence K. Duffy

Publisher:

Science Publications

Journal:

American Journal of Animal and Veterinary Sciences Vol.3 Issue 4, pp.96-103

Document Type:

Article

Publication Date:

12/2008

Document Language:

English

Document ID (Org No.):

2001396225

pISSN:

1557-4563

DOI:

10.3844/ajavsp.2008.96.103

Keywords:

Abstract:

 Problem Statement: Hypothyroidism has been a common disorder in humans and dogs. Amongst a sundry of functions, the thyroid gland plays a key role in metabolism and consequently, hypothyroidism has been a common diagnosis for a decrease in performance in sled dogs. Research has indicated that a variety of environmental factors influence thyroid hormone production, of which, light exposure, climate, latitude, exercise and season demonstrate pronounced effects. Sled dogs are exposed to many of these variables and often display thyroid hormone levels that are clinically below normal ranges. Approach: This study took a cross-latitudinal naturalistic approach in determining the effects of day length, time of day, season, climate and exercise on thyroid hormone function in sled dogs. In the process, appropriate reference ranges for racing sled dogs were established that correlate with other studies involving working dogs. Results: There was a clear indication that thyroid hormones play an integral role in thermoregulation and are greatly affected by environmental cues. Unexpectedly, sled dogs in the sub Arctic were not more prone to hypothyroidism but in fact, had higher levels of most thyroid hormones than dogs residing at lower latitudes. Conclusion: An evolutionary adaptation may account for up-regulation of thyroid function in times of environmental extremes. Consequently, the normal range for most thyroid hormones in sled dogs is lower than clinical standards.

Article Details

Cross-Latitudinal, Seasonal and Diurnal Comparisons in Thyroid Hormone Concentrations in Sled Dogs

Authors:

Kriya L. Dunlap | Arleigh J. Reynolds | Kent R. Refsal | Wendell w. Kerr | Lawrence K. Duffy

Publisher:

Science Publications

Journal:

American Journal of Animal and Veterinary Sciences Vol.3 Issue 4, pp.96-103

Document Type:

Article

Publication Date:

12/2008

Document Language:

English

Document ID (Org No.):

2001396225

pISSN:

1557-4563

DOI:

10.3844/ajavsp.2008.96.103

Sled dogs

diurnal

thyroid hormones

seasonality

Alaska

exercise

Issues

Article Details

Cross-Latitudinal, Seasonal and Diurnal Comparisons in Thyroid Hormone Concentrations in Sled Dogs

Authors: Kriya L. Dunlap | Arleigh J. Reynolds | Kent R. Refsal | Wendell w. Kerr | Lawrence K. Duffy

Publisher: Science Publications

Journal: American Journal of Animal and Veterinary Sciences Vol.3 Issue 4, pp.96-103

Document Type: Article

Publication Date: 12/2008

Document Language: English

Document ID (Org No.): 2001396225

pISSN: 1557-4563

DOI: 10.3844/ajavsp.2008.96.103

Sled dogs

diurnal

thyroid hormones

seasonality

Alaska

exercise

Issues

Authors:

Kriya L. Dunlap | Arleigh J. Reynolds | Kent R. Refsal | Wendell w. Kerr | Lawrence K. Duffy

Publisher:

Science Publications

Journal:

American Journal of Animal and Veterinary Sciences Vol.3 Issue 4, pp.96-103

Document Type:

Article

Publication Date:

12/2008

Document Language:

English

Document ID (Org No.):

2001396225

pISSN:

1557-4563

DOI:

10.3844/ajavsp.2008.96.103