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Topic:Temperature
Temperature regulation in horses involves physiological processes that maintain the animal's core body temperature within a narrow, optimal range despite external environmental changes. Horses, being homeothermic animals, rely on mechanisms such as sweating, respiration, and blood flow adjustments to dissipate excess heat or conserve warmth. These thermoregulatory processes are influenced by factors such as exercise, humidity, and ambient temperature. Variations in temperature can affect a horse's performance, health, and overall well-being. This page aggregates peer-reviewed research studies and scholarly articles that explore the mechanisms, effects, and implications of temperature regulation in equine physiology.
Epidural analgesia with morphine or buprenorphine in ponies with lipopolysaccharide (LPS)-induced carpal synovitis. This study evaluated the analgesia effects of the epidural administration of 0.1 mg/kg bodyweight (BW) of morphine or 5 μg/kg BW of buprenorphine in ponies with radiocarpal joint synovitis. Six ponies were submitted to 3 epidural treatments: the control group (C) received 0.15 mL/kg BW of a 0.9% sodium chloride (NaCl) solution; group M was administered 0.1 mg/kg BW of morphine; and group B was administered 5 μg/kg BW of buprenorphine, both diluted in 0.9% NaCl to a total volume of 0.15 mL/kg BW administered epidurally at 10 s/mL. The synovitis model was induced by injecting 0.5 ng of lipopol...
Impact of successive freezing-thawing cycles on 3-T magnetic resonance images of the digits of isolated equine limbs. To assess the impact of cycles of freezing and thawing on magnetic resonance (MR) images (obtained by use of a 3-T magnet) of equine feet examined ex vivo. Methods: 9 forelimbs from 9 horse cadavers. Methods: 9 forefeet underwent MR imaging first at ambient temperature within 12 hours after the horses' death and then after each freezing-thawing cycle. Three digits underwent freezing and thawing (at 4°C for 36 hours) 2 times, 3 digits underwent freezing and thawing (at 4°C for 36 hours) once and rescanning after 24 hours at ambient temperature, and 3 digits underwent freezing and thawing at a...
Effects of short-term training on thermoregulatory and sweat responses during exercise in hot conditions. There is evidence that extensive training in cool conditions results in improvements to heat dissipation that contribute to successful acclimatisation. In horses, the effects of a less extensive training regimen have not been determined. Objective: This study investigated whether 10 consecutive days of moderate intensity treadmill training in cool conditions would improve thermoregulatory and sweating responses of horses to exercise in the heat. Methods: Six unfit Thoroughbred horses completed a standardised treadmill exercise test (SET) in hot, dry conditions (32-34 °C, 45-55% RH) before (SE...
Effects of collecting blood into plastic heparinised vacutainer tubes and storage conditions on blood gas analysis values in horses. Plastic heparinised vacutainer tubes are used for blood gas analysis in horses. This collection method may not be ideal because influx of atmospheric O(2) through the permeable plastic wall of the vacutainer tube and loss of CO(2) into the gas phase above the blood sample should increase blood PO(2) and decrease PCO(2), respectively. Objective: To determine the effects of collecting blood into plastic vacutainer tubes and storage conditions on blood gas analysis values. Methods: Blood was obtained from 6 healthy horses and tonometered at 37 °C with 12% O(2) and 5% CO(2). Three ml aliquots of ...
Risk factors for exercise-induced pulmonary haemorrhage in Thoroughbred racehorses. Risk factors for occult exercise-induced pulmonary haemorrhage (EIPH) are poorly defined or quantified. Objective: To investigate the importance of putative risk factors for EIPH amongst Thoroughbred racehorses in Australia. Methods: Tracheobronchoscopy was used to determine EIPH status of 744 Thoroughbred racehorses after flat racing in Melbourne, Australia. Horses were identified for study before racing, and over 50% of horses racing during the study period were examined. Statistical analysis included use of bivariate and multivariate logistic regression analysis to account for simultaneous ...
Absence of a serum melatonin rhythm under acutely extended darkness in the horse. In contrast to studies showing gradual adaptation of melatonin (MT) rhythms to an advanced photoperiod in humans and rodents, we previously demonstrated that equine MT rhythms complete a 6-h light/dark (LD) phase advance on the first post-shift day. This suggested the possibility that melatonin secretion in the horse may be more strongly light-driven as opposed to endogenously rhythmic and light entrained. The present study investigates whether equine melatonin is endogenously rhythmic in extended darkness (DD). Methods: Six healthy, young mares were maintained in a lightproof barn under an LD...
The effect of environmental storage conditions on bone marrow fat determination in three species. Diagnostic laboratories are frequently required to assess the antemortem nutritional condition of deceased animals. The percentage of fat in the bone marrow is used to diagnose starvation because this fat depot is typically the last in the body to be depleted. Diagnosticians rely on measurement of bone marrow adipose content using fat solvent-extraction methods; however, the effects of tissue storage conditions before processing have not been fully assessed. The current study focuses on evaluating the effects of 3 storage conditions (refrigeration [4 °C], freezing [-20 °C], and ambient tempe...
Assessment of the impact of collection temperature and sampler design on the measurement of exhaled breath condensate pH in healthy horses. The pH measurement of exhaled breath condensate (EBC) may provide a non-invasive method of assessing the lower airways of horses but the methodology used may influence findings. The aim of this study was to investigate the effect of two sampling devices and three methods of condensation surface cooling (ethanol slush, -100°C; dry ice, -75°C; water ice, 0°C) on EBC pH. Each method was tested 30 times using six healthy ponies. Sample pH was determined before and after de-aeration with argon for 10 min. Sampler design was found to significantly affect pH. Samples collected as a liquid had a si...
West Nile virus range expansion into British Columbia. In 2009, an expansion of West Nile virus (WNV) into the Canadian province of British Columbia was detected. Two locally acquired cases of infection in humans and 3 cases of infection in horses were detected by ELISA and plaque-reduction neutralization tests. Ten positive mosquito pools were detected by reverse transcription PCR. Most WNV activity in British Columbia in 2009 occurred in the hot and dry southern Okanagan Valley. Virus establishment and amplification in this region was likely facilitated by above average nightly temperatures and a rapid accumulation of degree-days in late summer....
The effect of cooling on the contractility of equine digital small lamellar arteries: modulating role of the endothelium. The equine hoof displays thermoregulatory functions, and the blood vessels lying under the hoof wall are temperature sensitive. The aim of this study was to investigate the effect of cooling on the contractile responses to α-adrenoceptor and 5-HT receptor stimulation in equine small lamellar arteries using wire myography. The role of the endothelium in the response mediated by 5-HT was also evaluated. Moderate cooling caused a reduction of the contraction induced by depolarizing Krebs solution (DKS, containing 118 mm KCl) and the maximal contraction caused by UK-14304 (α(2)-adrenoceptor agon...
Analysis of Ca2+/Mg2+ selectivity in alpha-lactalbumin and Ca(2+)-binding lysozyme reveals a distinct Mg(2+)-specific site in lysozyme. The triggering of Ca(2+) signaling pathways relies on Ca(2+)/Mg(2+) specificity of proteins mediating these pathways. Two homologous milk Ca(2+)-binding proteins, bovine alpha-lactalbumin (bLA) and equine lysozyme (EQL), were analyzed using the simplest "four-state" scheme of metal- and temperature-induced structural changes in a protein. The association of Ca(2+)/Mg(2+) by native proteins is entropy-driven. Both proteins exhibit strong temperature dependences of apparent affinities to Ca(2+) and Mg(2+), due to low thermal stabilities of their apo-forms and relatively high unfavorable enthalpi...
[The extent of temperature sense and pain appreciation recovery in the dermatomes of cauda equine roots after lumbar intervertebral dischernia elimination]. Temperature sense and pain appreciation has been studied in the dermatomes of cauda equine roots in patients with lumbar intervertebral disc hernia before treatment, in the immediate and long-term periods of observation after disc hernia elimination. Temperature sense and pain appreciation has been determined to be disordered not only in the dermatome of compressed root, but in the dermatomes located proximally and distally as well. The manifestation of negative changes was observed to a greater extent during temperature sense examination. After disc hernia elimination the recovery of temperat...
Effect of temperature on race times on a synthetic surface. Differences in racing times have been noted on synthetic track surfaces that appear to depend on the temperature of the track. No published study to date has considered this effect in a systematic manner. Objective: To investigate the relationship between temperature of track and speed of horses racing on a synthetic surface. Potential changes in the wax component of the synthetic track were investigated as one possible cause of changes in the track speed at the temperatures observed. Methods: At Del Mar racetrack (California, USA), the air, surface and subsurface temperatures at 4 depths in t...
Membrane permeability parameters for freezing of stallion sperm as determined by Fourier transform infrared spectroscopy. Cellular membranes are one of the primary sites of injury during freezing and thawing for cryopreservation of cells. Fourier transform infrared spectroscopy (FTIR) was used to monitor membrane phase behavior and ice formation during freezing of stallion sperm. At high subzero ice nucleation temperatures which result in cellular dehydration, membranes undergo a profound transition to a highly ordered gel phase. By contrast, low subzero nucleation temperatures, that are likely to result in intracellular ice formation, leave membrane lipids in a relatively hydrated fluid state. The extent of free...
Heat shock protein 70 gene expression in equine blastocysts after exposure of oocytes to high temperatures in vitro or in vivo after exercise of donor mares. Heat above homeothermy can be detrimental to embryonic development, and cells may produce heat shock proteins to try to mitigate these effects. The authors examined the developmental competence of equine oocytes after a single heat exposure (42 degrees C, 2 or 4 h) during early or late stages of in vitro maturation. Rates of nuclear maturation, cleavage after intracytoplasmic sperm injection, and advanced embryonic development (morula or blastocyst) were compared to those for unexposed controls. Concentrations of heat shock protein 70 (HSPA1A) mRNA were determined by real-time RT-PCR in result...
Stabling causes a significant increase in the pH of the equine airway. Regulation of pH homeostasis in the equine lung is poorly understood. Measurement of exhaled breath condensate (EBC) pH provided a simple, highly repeatable and noninvasive method for the longitudinal investigation of changes in airway pH in response to environmental changes. Stabling of horses was found to lead to a small (approximately 100-200 parts/billion) but significant (P < 0.001) increase in ambient ammonia concentration when compared to pasture. This increase in exposure to ambient ammonia concentration was associated with significant (P = 0.002) increases in EBC pH and exhaled amm...
Rho kinase activation and ROS production contributes to the cooling enhanced contraction in cutaneous equine digital veins. A decrease in environmental temperature can directly affect the contractility of cutaneous vasculature, mediated in part by alpha(2)-adrenoceptors. Most of the cellular mechanisms underlying the cooling-enhanced contractility to alpha(2)-adrenoceptor agonists have been reported in cutaneous arteries but little information is available on cutaneous veins. To investigate the cellular mechanisms associated with the cooling-enhanced contraction to UK-14304 (alpha(2)-adrenoceptor agonist), isolated equine digital veins (EDVs) were studied at 30 degrees C and 22 degrees C. The effects of inhibitors ...
Mass gathering medical care: to calculate the Medical Usage Rate of Galway Races. Medical Usage Rate (MUR) of Galway Races: The Galway Races is the most popular horse-racing festival in Ireland. It takes place for a week starting from the last Monday in July. The races are held at Ballybrit race course in Galway. During the 7 days of racing, about 180,000 people attend. The average temperature in Galway around that time of the year is around 15-200C. The aim of this study is to calculate the MUR of Galway Races and to develop a model to predict the MUR for Galway Races in future. The MUR of Galway Races is calculated by looking retrospectively at the medical records of the ...
Magnetic resonance signal changes during time in equine limbs refrigerated at 4 degrees C. When ex vivo magnetic resonance (MR) imaging studies are undertaken, specimen conservation should be taken into account when interpreting MR imaging results. The purpose of this study was to assess MR changes during time in the anatomic structures of the equine digit on eight cadaver limbs stored at 4 degrees C. The digits were imaged within 12 h after death and then after 1, 2, 7, and 14 days of refrigeration. After the last examination, four feet were warmed at room temperature for 24 h and reimaged. Sequences used were turbo spin echo (TSE) T1, TSE T2, short tau inversion recovery (STIR), a...
Proliferation of Streptococcus zooepidemicus and Pseudomonas aeruginosa within a simulated subpalpebral lavage flushed with equine serum. To evaluate whether equine serum administered via a simulated subpalpebral lavage system (SPL) supports proliferation of Streptococcus zooepidemicus or Pseudomonas aeruginosa within the tubing. Methods: A sterile i.v. catheter with injection cap was inserted into sterilized silicone tubing (Mila). To mimic an SPL within the dorsal conjunctival fornix, the tubing was secured to an elevated platform. The tip of the tubing extended from the platform into a vial containing culture medium just inoculated with approximately 1.5 x 10(8) CFU/mL P. aeruginosa or S. zooepidemicus. To mimic administratio...
In vitro comparison of cortical bone temperature generation between traditional sequential drilling and a newly designed step drill in the equine third metacarpal bone. To compare heat generation and time to finish between a new step drill and sequential drilling in order to create a 6.2 mm pilot hole for insertion of a positive profile transfixation pin into the equine third metacarpal bone. Methods: Nine pairs of equine third metacarpal bones from cadavers of adult horses were used. Maximum temperature rise of the bone was measured continuously at the cis- and trans-cortices 1, 2 and 3 mm from the final pilot hole during creation of a 6.2 mm hole using a step drill and sequential drilling with 4.5, 5.5 and 6.2 mm drill bits. Five holes were drilled into the...
Functional role of alpha2-adrenoceptor subtypes in the cooling-enhanced vasoconstriction of isolated cutaneous digital veins of the horse. Cooling-enhanced contractile responses in cutaneous arteries have been reported to involve the activation of alpha(2C)-adrenoceptors, but their role in cutaneous veins is not clearly understood. The aim was to pharmacologically characterize the subtype of postsynaptic alpha(2)-adrenoceptors in the equine digital vein mediating contraction at two temperatures. The increase in isometric tension of endothelium-denuded equine digital vein in response to UK-14304 was studied in the absence and presence of relatively selective alpha(2)-adrenoceptor antagonists at temperatures of either 30 degrees C ...
Effects of fecal collection and storage factors on strongylid egg counts in horses. Fecal analyses are becoming increasingly important for equine establishments as a means of parasite surveillance and detection of anthelmintic resistance. Although several studies have evaluated various egg counting techniques, little is known about the quantitative effects of pre-analytic factors such as collection and storage of fecal samples. This study evaluated the effects of storage temperature, storage time and airtight versus open-air storage on fecal egg counts. The experimental protocols were replicated in two study locations: Copenhagen, Denmark and Athens, Georgia, USA. In both loc...
Viability of Rhodococcus equi and Parascaris equorum eggs exposed to high temperatures. There is great concern about the potential pathogen contamination of horse manure compost spread in the same fields horses graze in. To ensure that pathogen destruction occurs, temperatures need to be sufficiently high during composting. Here, we investigated the survival rate of two marker organisms, Rhodococcus equi and Parascaris equorum eggs, exposed to temperatures potentially encountered during horse manure composting. Our results show that the time required to achieve a 1 log10 reduction in R. equi population (D-value) are 17.1 h (+/-1.47) at 45 degrees C, 8.6 h (+/-0.28) at 50 degrees ...
Managing the effects of the weather on the Equestrian Events of the 2008 Beijing Olympic Games. This paper describes a 3 year project to investigate and manage the effects of the local weather conditions on horses competing in the 2008 Olympic Games. The first part of the investigation involved estimating the expected heat load on horses during competition and suggesting measures to ensure their safety based on data collected from dedicated weather monitoring at both Olympic venues during August 2006, 2007 and 2008. The aim of the second part was to establish a reliable system of point forecasting to monitor and predict inclement weather that might affect the competitions. This involved ...
