Effects of racing and training on serum thyroid hormone concentrations in racing Greyhounds

Hill, Richard; Fox, Leslie E.; Lewis, Daniel D.; Beale, Karin M.; Rf, Nachreiner; Scott, Karen C.; Sundstrom, Deborah A.; Jones, Galin L.; Butterwick, Richard

doi:10.2460/ajvr.2001.62.1969

Cited by 27 publications

(36 citation statements)

References 35 publications

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“…Studies of Greyhounds have shown that they have their basal TT4 concentrations below the non-breed-specific reference range, and that their fT4 concentrations are also relatively low, although not to the same degree as TT4. No significant differences were detected between the concentrations of cTSH in Greyhounds and other breeds (Hill et al 2001;Gaughan and Bruyette 2001). Similar results were also found in Whippets, where the mean TT4 values were significantly lower in comparison to the control group, but no significant differences were seen between Whippets and control dogs for fT4 and cTSH (Geffen et al 2006).…”

Section: Discussionsupporting

confidence: 75%

Seasonal influence on the thyroid gland in healthy dogs of various breeds in different weights

et al. 2012

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The aim of our study was to evaluate the influence of seasonal ambient temperature on the thyroid gland function in terms of serum total thyroxine (TT4), free thyroxine (fT4), total triiodothyronine (TT3), and canine thyroid stimulating hormone (cTSH) concentrations in healthy dogs of various breeds living outdoors and to compare them with those living indoors in flats and houses. The monitoring was conducted for 5 years and our study included 162 indoor dogs and 148 outdoor dogs of both sexes from 2 to 12 years of age, categorised into 3 groups according to their body weight: large (n = 17), medium (n = 16) and small (n = 17) breeds.Comparison of the seasonal serum TT4 and fT4 concentrations in both the indoor and outdoor dogs confirmed their fluctuation in relation to the ambient temperature in all weight groups with the lowest average of TT4 and fT4 concentrations recorded in summer and the highest ones in winter. In dogs kept outdoors, the fluctuation of hormone values was significant (P < 0.05). Seasonal serum cTSH fluctuation was found to be significant (P < 0.05) only in the medium breeds living outdoors, but their concentrations did not exceed the reference ranges. The 5-year monitoring of serum TT3 in indoor and outdoor dogs of large, medium, and small breeds clearly showed that its concentrations were not influenced by varying ambient temperature. The study provides for the first time evidence that serum TT4 and fT4 concentrations in dogs kept outdoors directly depend on ambient temperature. This correlation was also expressed by mathematical equations. Dog, ambient temperature, thyroxine, thyreotropineThyroid hormones influence numerous physiological and biochemical events in cells, and are essential for healthy growth and development of neurological and skeletal systems. They have catabolic effects on muscle and adipose tissue and regulate cholesterol synthesis and degradation. Thyroid hormones have positive ionotropic and chronotropic effects on the heart (Scott-Moncrieff 2007). Thyroid hormones markedly stimulate Na + K + ATPase activity, which is connected to Na + and K + transport through the plasma membrane (Schaafsma et al. 2002;Slob et al. 2004). This process increases ATP utilisation. As a great part of oxygen consumption in the whole organism maintaining this transport system, the principal effect of the thyroid gland on the basal metabolism is expected to be correlated exactly with this effect. Thyroid hormones increase the metabolic rate and oxygen consumption of most tissues, with the exception of the adult brain, testes, uterus, lymph nodes, spleen and anterior pituitary (Ferguson 1988; Freake and Oppenheimer 1995). They increase the 2,3-diphosphoglycerate production in erythrocytes, which facilitates oxygen release from haemoglobin and they stimulate the generation of heat. This supports the hypothesis that total thyroxine concentrations should vary in relation to ambient temperature and should reflect seasonal variation, too (Freake and Oppenheimer 1995).

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Section: Discussionsupporting

confidence: 75%

Seasonal influence on the thyroid gland in healthy dogs of various breeds in different weights

et al. 2012

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“…23 Most Greyhounds with low resting T4 and fT4 concentrations are not hypothyroid. 24 Therefore, hypothyroidism may have been overdiagnosed in this study population.…”

Section: Discussionmentioning

confidence: 87%

Results of a Web-Based Health Survey of Retired Racing Greyhounds

Lord¹,

Yaissle²,

Marín³

et al. 2007

J Vet Int Med

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Background: Adoption of retired racing Greyhounds has become increasingly popular during the past decade. To date, research has focused on the physiologic and clinicopathologic peculiarities of Greyhounds but there is little published information on disease prevalence in the breed.Objective: The objective of this study is to determine the prevalence of disease in retired racing Greyhounds. Animals: In this study, 747 Greyhounds were used. Methods: A standardized survey method was used, and survey responses were collected by an Internet survey. Owners could answer a survey for every Greyhound that they had owned since January 1, 2005.Results: Of the 692 eligible participants, 441 (63.7% response rate) completed surveys for 747 Greyhounds. The mortality rate for Greyhounds within the 2-year period was 15% (113 of 747 died). The most common cause of death reported was cancer (66 dogs, 58%), and the most common type of cancer listed as the cause of death was osteosarcoma (28 dogs, 25%). The most commonly reported groups of diseases or disorders were skeletal (232 dogs, 33%), skin (197 dogs, 28%), digestive (132 dogs, 18%), cancer (94 dogs, 13%), and endocrine (85 dogs, 11.9%). Forty-five percent of Greyhounds diagnosed with cancer and 6% of the overall population had osteosarcoma.Conclusions and Clinical Importance: The results of this study can be used by veterinary researchers to continue to investigate the most common diseases in this population. As more retired racing Greyhounds enter the pet population, the results of this study will help educate veterinarians and owners about the most prevalent diseases in the breed.

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“…After sprint racing, total T 4 but not fT 4 concentration decreased after adjustment for hemoconcentration (Hill et al, 2001). After sprint racing, total T 4 but not fT 4 concentration decreased after adjustment for hemoconcentration (Hill et al, 2001).…”

Section: Athletic Trainingmentioning

confidence: 89%

Hypothyroidism

Scott‐Moncrieff¹

2015

Canine and Feline Endocrinology

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Effects of racing and training on serum thyroid hormone concentrations in racing Greyhounds

Abstract: Except for total T4, thyroid hormone concentrations in Greyhounds are affected little by sprint racing and training. Greyhounds with low resting total and free T4 concentrations may not be hypothyroid.

Cited by 27 publications

References 35 publications

Seasonal influence on the thyroid gland in healthy dogs of various breeds in different weights

Seasonal influence on the thyroid gland in healthy dogs of various breeds in different weights

Results of a Web-Based Health Survey of Retired Racing Greyhounds

Hypothyroidism

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