Ultrasonographic measurement of the adrenal gland in neonatal foals: reliability of the technique and assessment of variation in healthy foals during the first five days of life.

Background: Adrenal gland ultrasonographic measurements are useful in clinical evaluation of patients with adrenal dysfunction in several species. In human healthy neonates, the ultrasonographic size of the adrenal glands decreases during the first days of life. Ultrasonography of adrenal glands was demonstrated to be feasible in neonatal foals.

The effect of long-term oral L-carnitine administration on insulin sensitivity, glucose disposal, plasma concentrations of leptin and acylcarnitines, and urinary acylcarnitine excretion in warmblood horses.

Background: Insulin resistance in horses is an emerging field of interest as it is thought to be a contributing factor in the pathogenesis of many equine conditions.

Objectives: The objectives of the present study were to determine the effects of long-term oral administration of L-carnitine on insulin sensitivity, glucose disposal, plasma leptin concentrations and acylcarnitine spectrum both in plasma and urine.

Animals And Methods: Six 3-year-old healthy warmblood geldings were used.

Risk factors associated with health disorders in sport and leisure horses in the Netherlands.

Horses are used for a wide variety of purposes from being used for recreational purposes to competing at an international level. With these different uses, horses have to adapt to numerous challenges and changes in their environment, which can be a challenge itself in continuously safeguarding their welfare. The objective of this study was to assess the prevalence of health disorders with clinical examination and identify possible risk factors of health disorders affecting horse welfare in professional husbandry systems in the Netherlands.

Glucose homeostasis and the enteroinsular axis in the horse: a possible role in equine metabolic syndrome.

One of the principal components of equine metabolic syndrome (EMS) is hyperinsulinaemia combined with insulin resistance. It has long been known that hyperinsulinaemia occurs after the development of insulin resistance. But it is also known that hyperinsulinaemia itself can induce insulin resistance and obesity and might play a key role in the development of metabolic syndrome.

Skeletal muscle transcriptome profiles related to different training intensities and detraining in Standardbred horses: a search for overtraining biomarkers.

Training horses improves athletic capabilities by inducing skeletal muscle-specific and systemic adaptations. However, rest is required to recover from exercise or else overtraining may occur and affect performance and welfare. Biomarkers would be useful to identify early chronic overtraining in animals.

Effects of intensified training and subsequent reduced training on glucose metabolism rate and peripheral insulin sensitivity in Standardbreds.

Objective: To determine the influence of intensified training and subsequent reduced training on glucose metabolism rate and peripheral insulin sensitivity in horses and identify potential markers indicative of early overtraining.

Animals: 12 Standardbred geldings.

Procedures: Horses underwent 4 phases of treadmill-based training.

Assessment of endogenous growth hormone pulsatility in gelded yearling horses using deconvolution analysis.

Hypothesis/objectives: Defining normal Growth Hormone (GH) secretory dynamics in the horse is necessary to understand altered GH dynamics related to issues like welfare and disease.

Animals And Methods: Twelve healthy yearlings and two mature Standardbreds were used to quantify GH secretion. Endogenous GH half-life was determined after administration of 1.

The incidence and severity of gastric ulceration does not increase in overtrained Standardbred horses.

Reasons For Performing Study: Gastric ulceration can be caused by different pathophysiological mechanisms including dietary factors, psychological stress and exercise. Overtraining is a medical syndrome in performance horses associated with altered hormone levels, altered feed intake, altered behaviour and decreased performance. These components might lead to a higher incidence of gastric ulceration in overtrained horses.

Amino acid profile during exercise and training in Standardbreds.

The objective of this study is to assess the influence of acute exercise, training and intensified training on the plasma amino acid profile. In a 32-week longitudinal study using 10 Standardbred horses, training was divided into four phases, including a phase of intensified training for five horses. At the end of each phase, a standardized exercise test, SET, was performed.

Differential expression of equine muscle biopsy proteins during normal training and intensified training in young standardbred horses using proteomics technology.

The major aim of the present study was to investigate the proteome of standardbred horses at different stages of training and intensified training. We searched for biomarkers using small skeletal muscle biopsies of live animals. 2D gel electrophoresis and mass spectrometry were successfully applied to investigate training-induced differential expression of equine muscle biopsy proteins.

Normal function of the hypothalamic-pituitary growth axis in three dwarf Friesian foals.

Serial blood samples were collected from three dwarf Friesian foals to examine their endogenous growth hormone (GH) profiles, and the integrity of the GH-insulin-like growth factor-1 (IGF-1) axis was tested in one of them by examining its responses to the administration of GH-releasing hormone (GHRH) and to 10 days of treatment with recombinant equine GH. The basal serum concentrations of IGF-1 in the three dwarf foals were compared with those in nine age-matched normal foals. All the dwarf foals secreted endogenous GH.

Effects of acute exercise and long-term exercise on total Na+,K+ -ATPase content and Na+,K+ -ATPase isoform expression profile in equine muscle.

Objective: To investigate the effects of acute exercise and long-term training on Na(+),K(+)-ATPase content, mRNA isoforms, and protein concentration in equine muscle.

Animals: 6 Standardbreds.

Procedures: Horses performed a bout of exercise on a treadmill before and after 18 weeks of combined interval and endurance training.

Overtrained horses alter their resting pulsatile growth hormone secretion.

The influence of intensified and reduced training on nocturnal growth hormone (GH) secretion and elimination dynamics was studied in young (1.5 yr) Standardbred geldings to detect potential markers indicative for early overtraining. Ten horses trained on a treadmill for 32 wk in age-, breed-, and gender-matched fixed pairs.

Plasma acylcarnitine and fatty acid profiles during exercise and training in Standardbreds.

Objective: To evaluate alterations in skeletal muscle carnitine metabolism during exercise and training by measuring changes in plasma acylcarnitine concentrations in Standardbreds.

Animals: 10 Standardbred geldings with a mean +/- SD age of 20 +/- 2 months and weight of 384 +/- 42 kg.

Procedures: In a 32-week longitudinal study, training on a treadmill was divided into 4 phases as follows: phase 1, acclimatization for 4 weeks; phase 2, 18 weeks with alternating endurance and high-intensity exercise training; phase 3, increased training volume and intensity for another 6 weeks; and phase 4, deconditioning for 4 weeks.

(Over)training effects on quantitative electromyography and muscle enzyme activities in standardbred horses.

Too intensive training may lead to overreaching or overtraining. To study whether quantitative needle electromyography (QEMG) is more sensitive to detect training (mal)adaptation than muscle enzyme activities, 12 standardbred geldings trained for 32 wk in age-, breed-, and sex-matched fixed pairs. After a habituation and normal training (NT) phase (phases 1 and 2, 4 and 18 wk, respectively), with increasing intensity and duration and frequency of training sessions, an intensified training (IT) group (phase 3, 6 wk) and a control group (which continued training as in the last week of phase 2) were formed.

Effects of exogenous insulin on luteolysis and reproductive cyclicity in the mare.

Insulin is a pancreatic hormone that classically regulates carbohydrate and fat metabolism, but also appears to play a role in various reproductive processes. A preliminary study suggested insulin production by day 10 to 18 equine conceptuses. The aim of the present study was to examine the hypothesis that insulin is the conceptus signal responsible for maternal recognition of pregnancy (MRP) in the mare, or otherwise influences reproductive cyclicity during the MRP period.

Hormonal responses to acute exercise, training and overtraining. A review with emphasis on the horse.

Overtraining is an imbalance between training and recovery leading to symptoms associated with a neuroendocrine dysbalance called the overtraining syndrome, a disease characterized by behavioral, emotional and physical symptoms similar with depression. Although the prevalence of overtraining is high in human and equine athletes, at present no sensitive and specific test is available to prevent or diagnose overtraining. Nowadays, it is believed that combination of different (hormonal) parameters appear to be the best indicators of overtraining.

The effect of long-term exercise on glucose metabolism and peripheral insulin sensitivity in standardbred horses.

Reasons For Performing Study: To study the possible long-term effect of improved glucose tolerance in horses after long-term training, as the impact of exercise training on glucose metabolism is still unclear in the equine species. It is not known whether there is a direct long-term effect of training or if the measurable effect on glucose metabolism is the residual effect of the last exercise session.

Objectives: To determine the chronic effect on glucose metabolism and peripheral insulin sensitivity of long-term training in horses by use of the euglycaemic hyperinsulinaemic clamp technique.

Effect of exercise on activation of the p38 mitogen-activated protein kinase pathway, c-Jun NH2 terminal kinase, and heat shock protein 27 in equine skeletal muscle.

Objective: To investigate the effects of exercise on activation of mitogen-activated protein kinase (MAPK) signaling proteins in horses.

Animals: 6 young trained Standardbred geldings.

Procedure: Horses performed a 20-minute bout of exercise on a treadmill at 80% of maximal heart rate.

Effects of short- and long-term recombinant equine growth hormone and short-term hydrocortisone administration on tissue sensitivity to insulin in horses.

Objective: To determine the effects of short-term IV administration of hydrocortisone or equine growth hormone (eGH) or long-term IM administration of eGH to horses on tissue sensitivity to exogenous insulin.

Animals: 5 Standardbreds and 4 Dutch Warmblood horses.

Procedure: The euglycemic-hyperinsulinemic clamp technique was used to examine sensitivity of peripheral tissues to exogenous insulin 24 hours after administration of a single dose of hydrocortisone (0.