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Topic:Heat Stress
Heat stress in horses refers to the physiological and metabolic challenges that occur when horses are exposed to elevated environmental temperatures and humidity levels. Horses regulate their body temperature through sweating and respiration, but excessive heat can overwhelm these mechanisms, leading to heat stress. This condition can affect various bodily functions, including cardiovascular, respiratory, and muscular systems. Signs of heat stress in horses include increased respiratory rate, elevated heart rate, dehydration, and lethargy. Prolonged exposure can lead to more severe issues such as heat exhaustion or heat stroke. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms of heat stress, its effects on equine physiology, and strategies for prevention and management in different environmental conditions.
Effect of the Depth of Insertion of the Thermometer on the Rectal Temperature of Donkeys During the Hot-Dry Season in a Tropical Savannah. The objective of the present study was to evaluate the effect of the depth of insertion and environmental parameters on the rectal temperature (RT) in donkeys during the hot-dry season in a tropical savannah zone of Nigeria. The experimental subjects were comprised of thirty donkeys divided into three groups based on age: group I, 10 foals (40.67 ± 2.20 kg; 1.50 ± 0.02 months); group II, 10 yearlings (91.53 ± 0.54 kg; 1.51 ± 0.01 years); and group III, 10 adults (140 ± 0.71 kg; 8.03 ± 0.06 years). Each group was divided into 5 male and 5 female donkeys. Measurements of the RT were ...
A Comparison of Five Cooling Methods in Hot and Humid Environments in Thoroughbred Horses. Horses need aggressive cooling to prevent exertional heat illness after strenuous exercise in hot and humid conditions. This study compared various methods for cooling horses in such conditions, testing the hypothesis that continual application of running water would be the most effective method to decrease core temperature. Five Thoroughbreds were exercised on a treadmill at wet-bulb globe temperature of 31.8 ± 0.1°C until their pulmonary artery temperature reached 42°C. The time until the pulmonary artery temperature returned to <39°C (t) and the rectal temperature at 30 minutes afte...
Validation of exercise-response genes in skeletal muscle cells of Thoroughbred racing horses. To understand the athletic characteristics of Thoroughbreds, high-throughput analysis has been conducted using horse muscle tissue. However, an in vitro system has been lacking for studying and validating genes from in silico data. The aim of this study is to validate genes from differentially expressed genes (DEGs) of our previous RNA-sequencing data in vitro. Also, we investigated the effects of exercise-induced stress including heat, oxidative, hypoxic and cortisol stress on horse skeletal muscle derived cells with the top six upregulated genes of DEGs. Enriched pathway analysis was conduct...
Insertional characteristics of three types of transfixation pin taps in third metacarpal bones from equine cadavers. To compare heat generation and mechanical bone damage achieved with 2 tapered and 1 cylindrical transfixation pin taps in third metacarpal bones from equine cadavers. Methods: 18 pairs (36 specimens) of third metacarpal bones from euthanized horses with no known metacarpal disease. Methods: In each bone, an investigator drilled 3 holes for placement of a 6.3-mm cylindrical transfixation pin, a 6.3-mm tapered pin using a prototype tapered tap, and a 6.3-mm tapered pin using a revised tapered tap. One bone of each pair was tapped by hand and the other with an electric drill. Temperatures of the ...
Effects of hair coat characteristics on radiant surface temperature in horses. Horse owners may lack knowledge about natural thermoregulation mechanisms in horses. Horses are managed intensively; usually stabled at night and turned out during the day. Some are clipped and many wear a blanket, practices which reduce the horse's ability to regulate heat dissipation. The aim of this study was to investigate the relationship between hair coat characteristics, body condition and infrared surface temperatures from different body parts of horses. Under standard conditions, the body surface temperature of 21 adult horses were investigated using infrared thermography. From severa...
Season’s Effects on Some Clinical, Hematological Parameters and Blood Cortisol Level in Sedated Arabian Horses With Xylazine. Influence of heat or cold stress in sedated animals is unclear and requires further investigations. The present study aimed to evaluate the season's effects on some clinical, hematological parameters and blood cortisol level in sedated Arabian horses with xylazine. Therefore, seven Arabian horses were used to investigate heart and respiratory rates, and capillary refill time and serum cortisol level were recorded before (0) and at 5, 15, 60, and 180 minutes postsedation. Heparinized venous samples were collected before (0) and 3 hours postsedation for analysis of hematological analysis. Arte...
Risk factors for exertional heat illness in Thoroughbred racehorses in flat races in Japan (2005-2016). Exertional heat illness (EHI) is recognised in horses, but few reports have investigated its risk factors. Objective: To identify risk factors for EHI in racehorses participating in flat races in Japan. Methods: Descriptive epidemiology and retrospective unmatched case-control study. Methods: Between 2005 and 2016, veterinary records of horses diagnosed with EHI after flat races were reviewed retrospectively and data of the months from April to September were used for a case-control study. For each case, three control horses were randomly selected from starts between April and September. Race ...
Prevalence of post-race exertional heat illness in Thoroughbred racehorses and climate conditions at racecourses in Japan. Despite growing recognition of post-race exertional heat illness (EHI) in the horse racing industry, reports on its prevalence are limited. The purpose of this study was to investigate the prevalence of post-race EHI and climate conditions at racecourses in Japan. The overall prevalence of EHI from 1999 to 2018 was 0.04% (387 cases for 975,247 starters) in races operated by the Japan Racing Association (JRA). The yearly prevalence has been increasing, exceeding 0.07% in the last four years of the studied period. The overall prevalence in summer (May-September) was 0.086% (352 cases for 409,908...
Probiotic potential of Weissella strains isolated from horse feces. In this study, we isolated four Weissella confusa strains from the healthy horse feces to test their potential as equine probiotics. The identification and characteristics of these isolates were determined as per standard methods. Resistance and susceptibility of the isolated strains were tested to low pHs, different heat treatments, commonly used antibiotics and against the pathogenic strains of Salmonella, Pasteurella, Staphylococcus aureus, and Escherichia coli. After 3 h cultural in different pH medium, the 4 strains still had a certain amount of survival above pH 3.0. WH2 and WH4 were s...
Evaluation of semen characteristics, oxidative stress, and biochemical indices in Arabian horses of different ages during the hot summer season. Egypt is anticipated to be potentially influenced by the global climate warming. Therefore, the current study aimed to evaluate the influence of age on the fertility potential of Arabian stallions during summer breeding months. Arabian horses grouped according to their age into three groups, each involved six stallions: young (5-6 years), middle (11-12 years) and old (15-20 years) age groups, were weekly sampled during the months of July-August. Ejaculates were collected using artificial vagina, Missouri model, and examined for pH, volume, concentration, motility, livability and morphological ...
Heat shock stress: Profile of differential expression in Corynebacterium pseudotuberculosis biovar Equi. Transcriptome studies on Corynebacterium pseudotuberculosis have recently contributed to the understanding about this microorganism's survival mechanisms in various hostile conditions. The gene expression profile of the C. pseudotuberculosis strain 1002 (Ovis biovar), has revealed genes that are possible candidates responsible for its maintenance in adverse environments, such as those found in the host. In another strain of this bacterium, 258 (Equi biovar), a high temperature condition was simulated, in order to verify which genes are responsible for promoting the persistence of the bacterium...
Is shade for horses a comfort resource or a minimum requirement? Shade or shelter as protection from extremes of weather is required for horses at agricultural research and teaching facilities and is recommended or required by many states, professional organizations, and industry groups. The focus of this paper is the recent research on the responses of horses to hot, sunny weather, which has begun to provide scientific evidence that characterizes how and when shade is used and any benefits shade confers on horses. These behavioral and physiological findings support provision of shade as a resource for thermal comfort and the expression of normal behavior t...
Heat-shock protein 70 expression in the equine cornea. Expression of the 70-kDa heat-shock protein (HSP70) has been demonstrated in normal canine corneal epithelium, and inducible expression has been suggested to facilitate wound resolution through organized migration, proliferation, and adhesion of the corneal epithelial cells. Diminished expression of HSP70 may therefore contribute to prolonged healing in the pathologic cornea of other companion animal species, including the horse. Methods: Normal and pathologic equine cornea was evaluated to determine whether the expression of HSP70 is correlated with appropriate corneal epithelial wound healin...
A Survey on Transport Management Practices Associated with Injuries and Health Problems in Horses. An online survey was conducted to determine associations between transport management and transport-related injuries and diseases in horses in Australia. The survey was composed of three sections: respondents' demographic information, transport management strategies or procedures (before, during and after transportation) and transport diseases experienced in the previous two year period. Univariate and multivariate modelling was performed exploring associations between variables (respondents' details and transport management strategies) and the following transport-related diseases as outcomes:...
Exertional heat illness: a review of the syndrome affecting racing Thoroughbreds in hot and humid climates. Metabolic heat produced by Thoroughbred racehorses during racing can rapidly elevate core body temperature (1°C/min). When environmental conditions are hot and humid, the normal physiological cooling mechanisms become ineffective. The heat accumulated may exceed a critical thermal maximum (estimated to be 42°C), which may trigger a complex pathophysiological cascade with potentially lethal consequences. This syndrome has been labelled exertional heat illness (EHI). EHI is described in humans, but has not been well documented in Thoroughbred racehorses. The clinical signs described in racehor...
New insights in professional horse racing; “in-race” heart rate data, elevated fracture risk, hydration, nutritional and lifestyle analysis of elite professional jockeys. Weight-making practices have been shown to impair musculoskeletal and physiological function of jockeys. This study investigated the "in-race" heart rate (HR) responses and hydration status during competitive racing, as well as selected physiological and lifestyle parameters of professional jockeys based in Hong Kong. "In-race" HR responses and early morning hydration status of 20 male jockeys were examined in hot and moderate climactic occasions. Additionally, bone mineral density (BMD), dietary intake and lifestyle choices were assessed. Osteopenia was observed in the calcanei of jockeys (le...
Environmental heat and airborne pollen concentration are associated with increased asthma severity in horses. Clinical exacerbations of severe equine asthma (formerly recurrent airway obstruction [RAO]) are more frequently reported during winter when horses are exposed to airborne dusts during stabling. However, we have also observed a worsening of clinical signs on days during a heatwave. Objective: To investigate the association between environmental temperature and humidity and clinical signs of asthma in horses during clinical exacerbation of the disease. Methods: Retrospective longitudinal study. Methods: Historical data on 14 severe asthmatic horses exposed to a dusty environment and evaluated u...
Preference for shelter and additional heat in horses exposed to Nordic winter conditions. Horses may adapt to a wide range of temperatures and weather conditions. Owners often interfere with this natural thermoregulation ability by clipping and use of blankets. Objective: To investigate the effects of different winter weather conditions on shelter seeking behaviour of horses and their preference for additional heat. Methods: Observational study in various environments. Methods: Mature horses (n = 22) were given a free choice test between staying outdoors, going into a heated shelter compartment or into a nonheated shelter compartment. Horse location and behaviour was scored using i...
Shade use by small groups of domestic horses in a hot, sunny environment. Horses in the United States are commonly managed in outside pens or pastures in small groups. Limited research on shade use by domestic horses housed singly in individual pens has shown benefits and a preference for using available shade. The objective of this study was to examine the amount of shade use and the behavioral and physiological responses of small groups of horses when housed with access to shade (SH) and without access to shade (SUN). Thirty-six horses were randomized into 3 consecutive trials using 3 horses per group and 4 groups per trial. Groups experienced 5 d in each treatmen...
On-site veterinary medical evaluation and care of working dogs and horses at the 2012 Republican National Convention. To describe on-site veterinary medical care for working dogs and horses deployed for the 2012 Republican National Convention (RNC) in Tampa, Fla, August 24 to 30, 2012. Methods: Retrospective case series. Methods: 130 dogs and 45 horses. Methods: Data collected included breed, age, history, task assignment, reason for evaluation, and physical examination findings. A patient encounter report was recorded each time an animal was seen by veterinary staff for a physical evaluation. Results: 46 of the 130 (35%) dogs and all 45 (100%) horses underwent at least 1 on-site veterinary evaluation, for a ...
24-h sheltering behaviour of individually kept horses during Swedish summer weather. Provision of shelter for horses kept on summer pasture is rarely considered in welfare guidelines, perhaps because the benefits of shelter in warm conditions are poorly documented scientifically. For cattle, shade is a valued resource during summer and can mitigate the adverse effects of warm weather on well-being and performance. We found in a previous study that horses utilized shelters frequently in summer. A shelter with a roof and closed on three sides (shelter A) was preferred and can reduce insect pressure whereas a shelter with roof and open on three sides was not utilized. However, sh...
Daytime shelter use of individually kept horses during Swedish summer. In Sweden, no provision for summer shelter to protect horses from heat and insects is required, although access to shelter for horses kept outdoors 24 h during winter is a requirement. This study investigated horses' daytime shelter-seeking behavior in relation to weather conditions and insect activity during a 2-wk period in summer. Eight Warmblood riding horses had access to 2 shelters of different design to test which shelter design is preferred by horses. Furthermore, rectal and skin temperatures and insect-defensive behavior were measured to test whether horses would benefit from the prov...
Embryo transfer in competition horses: Managing mares and expectations. Embryo transfer (ET) is an accepted and successful technique for obtaining foals from mares without interrupting their competition careers. Recent research, however, suggests that the potential of factors including heat, exercise, repeated embryo flushing and repeated manipulation of the reproductive cycle using exogenous hormones to have a negative impact on fertility may have been underestimated. This paper reviews the evidence base for involvement of these factors in repeated failures to recover embryos from nongeriatric competition mares without obvious clinical or pathological indications...
Identification of heat shock protein 10 within the equine embryo, endometrium, and maternal peripheral blood mononuclear cells. Early pregnancy factor has been identified as a 10-kDa extracellular homolog of heat shock protein 10 (Hsp10). Hsp10 has been detected during early pregnancy in serum of mice, sheep, pigs, horses, cows, and humans by the rosette inhibition test. Hsp10 has also been associated with several neoplastic and autoimmune diseases. The goal of the present study was to determine if Hsp10 could be detected in the early equine embryo through the use of immunohistochemistry and quantitative real-time PCR. Additionally, analysis of systemically harvested peripheral blood mononuclear cells (PBMCs) from both...
Diurnal and seasonal fluctuations in rectal temperature, respiration and heart rate of pack donkeys in a tropical savannah zone. The study was designed to determine diurnal and seasonal changes in basic physiologic responses of donkeys adapted to the tropical Savannah. The rectal temperature (RT), respiratory rate (RR) and heart rate (HR) of six male Nubian pack donkeys, and the dry-bulb temperature (DBT), relative humidity and heat index of the experimental site were concurrently recorded hourly, from 06:00 h to 18:00 h (GMT +1), for three days, spread 1 week apart, during the cold-dry (harmattan), hot-dry and humid (rainy) seasons, in an open grazing field. Values of the physiologic parameters recorded during the morn...
Preference of domestic horses for shade in a hot, sunny environment. Provision of shade is recommended by best practice guidelines for horses living in hot, sunny environments despite a lack of research focused on potential benefits. We found in a previous study that horses without access to shade showed greater rectal temperature (RT), respiration rate (RR), and skin temperature (SK) and exhibited more sweat than horses that were completely shaded. Yet not known is whether horses will choose to stand in the shade when given a choice of areas with and without this resource. Our objective was to assess horse preference for shaded and unshaded areas in the hot an...
Physiological, behavioral, and serological responses of horses to shaded or unshaded pens in a hot, sunny environment. Housing recommendations for horses invariably include providing access to shade on hot, sunny days, but the potential benefits have not been scientifically studied. This experiment measured physiological, behavioral, and serological responses of horses confined individually to completely shaded (SH) or completely unshaded (SUN) drylot pens during the summer in Davis, CA. Twelve healthy adult horses in a crossover design experienced both treatments for 5 d each. Rectal temperature, respiration rate, skin temperature, and sweat scores were recorded hourly from 1230 to 1730 h daily. Observations ...
Diversity of flora used for the cure of equine diseases in selected peri-urban areas of Punjab, Pakistan. Plants have widely been used and documented for their therapeutic potential in many parts of the world. There are, however, few reports on the use of plants for the treatment of diseases of equines. To this end, participatory epidemiology and rapid rural appraisal techniques were used to document the plants having pharmacotherapeutic significance against different ailments of equines in selected population of Punjab, Pakistan. Methods: A survey was conducted to interview a total of 450 respondents (150 from each of the districts of Faisalabad, Lahore and Sargodha of Pakistan) to collect inform...
Scoring of sweat losses in exercised horses–a pilot study. Based on a series of exercise tests which included the estimation of sweat losses, this article proposes a novel sweat scoring system for exercising horses. This provides a practical estimate of individual animal exercise-induced sweat losses, based on visible appearance of sweat on the coat after work, which takes into account the effect of various influencing factors. In terms of accuracy and flexibility, the score seems to provide advantages over estimates based on current general recommendations from reference books. Additional studies are needed to validate this scoring system and its use...
Case series of equine pituitary pars intermedia dysfunction in a tropical climate. The clinical manifestations of equine pituitary pars intermedia dysfunction (PPID) in temperate climates are well described. The classic presentation is that of an older animal with hirsutism, laminitis, poor muscle tone, pendulous abdomen and weight loss. This case series highlights the additional clinical signs of anhidrosis and heat stress with secondary exercise intolerance that were seen as primary presenting problems in equids with PPID in the hot, humid conditions of a tropical climate. The clinical signs resolved with medical treatment for PPID.
