Physiological variables of horses after road transport

Abstract

In order to investigate the effects of short road transport stress on total and free iodothyronines, body weight (BW), rectal temperature and heart rate (HR) changes, 126 healthy stallions were studied in basal conditions, before and after transport. A total of 60 Thoroughbred and 66 crossbred stallions aged 4 to 15 years with previous travelling experience were transported by road in a commercial trailer for a period of about 3 to 4 h (distance under 300 km). Blood samples and functional variables were collected in each horse box, one week before loading and transport in basal conditions (control samples), one week later immediately before loading (pre-samples) and again after transport and unloading (about 3 to 4 h) in each new horse box, within 30 min of their arrival at the breeding stations (post-samples). Compared to the before-transport values, increases in circulating T 3 , T 4 and fT 4 levels ( P , 0.01) were observed after transport, irrespective of breed, but not for fT 3 levels. Lower T 4 and fT 4 levels were observed in basal II (at 1100 h) ( P , 0.01) than in basal I (at 0800 h) conditions and before transport. Thoroughbreds showed higher fT 3 ( P , 0.05) and fT 4 ( P , 0.01) levels after transport than crossbred stallions. No significant differences were observed for T 3 and T 4 . Compared to the before-transport values, significant increases in rectal temperature ( P , 0.01) and HR ( P , 0.05) were observed after transport. No differences were observed between basal I, II and before values for functional variables. Significant correlations between T 3 and rectal temperature, BW and HR were found. The results indicate that short road transport induces a preferential release of T 3 , T 4 and fT 4 hormones from the thyroid gland in relation to different breed, and an increase in rectal temperature and HR. No significant changes in BW were observed. No differences were observed in relation to different ages. The data obtained suggest that the stallion's thyroid hormones and functional variables may play an important role in assessing the effects of transport stress and a horse's coping strategy.Keywords: horse, iodothyronines, rectal temperature, heart rate, transport ImplicationsThe results of the current study suggest that the stallion's thyroid hormones and functional responses may play an important role in providing complementary information for the assessment of transport stress and animal coping strategies. In addition, the existence of a significant correlation between T 3 and rectal temperature, body weight and heart rate confirms that T 3 is the most metabolically active iodothyronine. Moreover, the importance of the thyroid hormone, namely triiodothyronine (T 3 ) generated locally by 5 0 -monodeiodinase (5 0 -MD) in the muscle tissue for metabolic needs during transport is still under investigation. In addition, when using circulating iodothyronine changes for the evaluation of transport stress the presence of peripheral 5 0 -MD should be further investigated. This may indicate that T 3 gen...

Plasma total antioxidant status in horses after 8-hours of road transportation

“…In our study, the heart rate and respiratory rate were significantly increased ( P  = 0.0169 and 0.0155 respectively), while the body temperature and CRT were not changed during transport or during the post-transport period. These observations are consistent with results of other authors, who studied the impact of road transport on basic clinical signs [17,18]. The respiration rate was increased in horses in response to a 12 hour transport period and the heart rate was increased in horses after a 24 h transport [7].…”

Dynamics of Total and Free Iodothyronines of Jumping Horses on the Responses to Competition and Transport

“…The results obtained showed that transport and show jumping competition differently influenced the thyroid responses of trained sport horses to physiological and psychological stress, according to the individual experimental sessions. The increase of total and free iodothyronines after transport (session T0) confirmed previous data observed in sport horses after road transport, underlining the metabolic active effects of thyroid hormones in response to stressful stimuli previously described in sport horses [3] and in Thoroughbred and Crossbred stallions [4] after road transport of 100 and 300 km, respectively. The greatest release of T 3 and T 4 after transport could represent the final result of preferential release of T 3 from the thyroid gland and/or a probably increase of peripheral monodeiodination of T 4 , although a synchronous release of T 4 was observed.…”

“…Testing procedure was based on enzyme-linked immunosorbent assay/competition to polyclonal biotinylated ovine iodothyronine antibodies using streptavidin technology. Limits of detection were 0.24 nmol/L for T 3 , 5.79 nmol/L for T 4 , 0.15 pmol/L for fT 3 , and 1.3 pmol/L for fT 4 . Intra-and inter-assay coefficients of variation were 7.3% and 11.4% for T 3 , 2.3% and 5.7% for T 4 , 4.2% and 11.9% for fT 3 , 6.6% and 9.6% for fT 4 , respectively.…”

“…The biologic activity of T 3 is much higher than that of T 4 . Free T 3 (fT 3 ) is the most potent and active thyroid hormone in circulation, and its measurement can give a clearest picture of true contribution of extrathyroidal tissues, such as the musculoskeletal system, as a consequence of the thyroid stimulation and/or changes in capacity to bind iodothyronines [4][5][6]. Thyroid hormones are considered as markers of stress in horses, showing changes according to training [7], pretraining status and circadian changes [8], exercise [5,6,9], and transport and previous experience [3].…”

Using eye temperature and heart rate for stress assessment in young horses competing in jumping competitions and its possible influence on sport performance

“…Schmidt et al (2010) reported high HR values (higher than basal HR values) up to 6 h after a journey duration of 8 and 3.5 h. In our study, horses arrived at the competition centre 1 day before the jumping exercise. Fazio et al (2009) suggested a cumulative effect on an individual horses's HR due to novel environments experienced during transport. Taking into consideration that the animals used in this study were young (4 to 6 years old) and thus more inexperienced, the stress related to 'journey duration' together with the stress related to the competition event, could increase this cumulative effect, leading to a decrease in the horse's physical resistance and workload and, hence, its performance ability.…”