The effect of rider weight and additional weight in Icelandic horses in tolt: part II. Stride parameters responses.
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ABSTRACT:
SUBMITTER: Gunnarsson V
PROVIDER: S-EPMC5561436 | biostudies-other | 2017 Sep
REPOSITORIES: biostudies-other
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Project description:This study examined the effect of increasing BW ratio (BWR) between rider and horse, in the BWR range common for Icelandic horses (20% to 35%), on heart rate (HR), plasma lactate concentration (Lac), BWR at Lac 4 mmol/l (W4), breathing frequency (BF), rectal temperature (RT) and hematocrit (Hct) in Icelandic horses. In total, eight experienced school-horses were used in an incremental exercise test performed outdoors on an oval riding track and one rider rode all horses. The exercise test consisted of five phases (each 642 m) in tölt, a four-beat symmetrical gait, at a speed of 5.4±0.1 m/s (mean±SD), where BWR between rider (including saddle) and horse started at 20% (BWR20), was increased to 25% (BWR25), 30% (BWR30), and 35% (BWR35) and finally decreased to 20% (BWR20b). Between phases, the horses were stopped (~5.5 min) to add lead weights to specially adjusted saddle bags and a vest on the rider. Heart rate was measured during warm-up, the exercise test and after 5, 15 and 30 min of recovery and blood samples were taken and BF recorded at rest, and at end of each of these aforementioned occasions. Rectal temperature was measured at rest, at end of the exercise test and after a 30-min recovery period. Body size and body condition score (BCS) were registered and a clinical examination performed on the day before the test and for 2 days after. Heart rate and BF increased linearly (P0.05), but negative correlations (P<0.05) existed between body size measurements and Hct. While HR, Hct and BF recovered to values at rest within 30 min, Lac and RT did not. All horses had no clinical remarks on palpation and at walk 1 and 2 days after the test. In conclusion, increasing BWR from 20% to 35% resulted in increased HR, Lac, RT and BF responses in the test group of experienced adult Icelandic riding horses. The horses mainly worked aerobically until BWR reached 22.7%, but considerable individual differences (17.0% to 27.5%) existed that were not linked to horse size, but to back BCS.
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Project description:BackgroundInsulin dysregulation (ID) is an equine endocrine disorder, which is often accompanied by obesity and various metabolic perturbations. The relationship between weight variations and fluctuations of the insulin response to oral glucose tests (OGT) as well as the metabolic impact of ID have been described previously. The present study seeks to characterize the concomitant metabolic impact of variations in the insulin response and bodyweight during repeated OGTs using a metabolomics approach.MethodsNineteen Icelandic horses were subjected to five OGTs over one year and their bodyweight, insulin and metabolic response were monitored. Analysis of metabolite concentrations depending on time (during the OGT), relative bodyweight (rWeight; defined as the bodyweight at one OGT divided by the mean bodyweight across all OGTs) and relative insulin response (rAUCins; defined accordingly from the area under the insulin curve during OGT) was performed using linear models. Additionally, the pathways significantly associated with time, rWeight and rAUCins were identified by rotation set testing.ResultsThe results suggested that weight gain and worsening of ID activate distinct metabolic pathways. The metabolic profile associated with weight gain indicated an increased activation of arginase, while the pathways associated with time and rAUCins were consistent with the expected effect of glucose and insulin, respectively. Overall, more metabolites were significantly associated with rWeight than with rAUCins.
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Project description:Recent studies have reported significant alterations in horse physiological and gait parameters when exposed to increased rider weight during moderate to high intensity exercise. This study aimed to evaluate the effect of increased rider weight (+15% and +25% of the regular rider's bodyweight) on horse behavioral, physiological and gait symmetry parameters during a standard dressage test. Twenty rider-horse equipages performed the same test three times in a randomized, crossover design. Salivary cortisol (SC), heart rate (HR), heart rate variability (HRV), behavior and gait symmetry (GS) were measured. SC concentrations increased from baseline (p < 0.001), but there was no significant treatment effect (difference from baseline (ng/mL): Control: 0.21 ± 0.1; +15%: 0.37 ± 0.1; +25%: 0.45 ± 0.2, p = 0.52). Similarly, there were no overall treatment effects on HR or HRV variables (avg HR across treatments (bpm): 105.3 ± 1.3), nor on GS parameters. There was large individual variation in conflict behavior but no effect of weight treatment. We conclude that increasing the weight of the regular rider by 15% and 25% did not result in significant short-term alterations in the measured parameters. Maximum rider:horse weight ratios were 15-23% and the exercise intensity was relatively low; thus the results should not be extrapolated to other weight ratios and exercise intensities.
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Project description:Iceland is free of the major infectious diseases of horses. However, in 2010 an epidemic of respiratory disease of unknown cause spread through the country's native horse population of 77,000. Microbiological investigations ruled out known viral agents but identified the opportunistic pathogen Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) in diseased animals. We sequenced the genomes of 257 isolates of S. zooepidemicus to differentiate epidemic from endemic strains. We found that although multiple endemic clones of S. zooepidemicus were present, one particular clone, sequence type 209 (ST209), was likely to have been responsible for the epidemic. Concurrent with the epidemic, ST209 was also recovered from a human case of septicemia, highlighting the pathogenic potential of this strain. Epidemiological investigation revealed that the incursion of this strain into one training yard during February 2010 provided a nidus for the infection of multiple horses that then transmitted the strain to farms throughout Iceland. This study represents the first time that whole-genome sequencing has been used to investigate an epidemic on a national scale to identify the likely causative agent and the link to an associated zoonotic infection. Our data highlight the importance of national biosecurity to protect vulnerable populations of animals and also demonstrate the potential impact of S. zooepidemicus transmission to other animals, including humans.IMPORTANCE An epidemic of respiratory disease affected almost the entire native Icelandic horse population of 77,000 animals in 2010, resulting in a self-imposed ban on the export of horses and significant economic costs to associated industries. Although the speed of transmission suggested that a viral pathogen was responsible, only the presence of the opportunistic pathogen Streptococcus zooepidemicus was consistent with the observed clinical signs. We applied genomic sequencing to differentiate epidemic from endemic strains and to shed light on the rapid transmission of the epidemic strain throughout Iceland. We further highlight the ability of epidemic and endemic strains of S. zooepidemicus to infect other animals, including humans. This study represents the first time that whole-genome sequencing has been used to elucidate an outbreak on a national scale and identify the likely causative agent.
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