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.
van der Graaf L, Leigh W, Szmatoła T, Roberts K, Ryan S, Brown B, Van Buren S, Finno CJ, Petersen JL.Anhidrosis is defined as a decreased or absent ability to sweat in response to heat and exercise. In horses, this condition can increase the risk of life-threatening hyperthermia. A prior study has suggested that equine anhidrosis is associated with a missense variant (rs68643109) in the Potassium Voltage-Gated Channel Subfamily E Regulatory Subunit 4 (KCNE4) gene. This project aimed to validate this association in a population of well-phenotyped horses and to determine the allele frequency of this variant in publicly available whole-genome sequence data. Fifty horses within the University of ...
Ciamillo S, Stefanovski D, Kulp J, van Eps A.To determine the relationship between hoof surface (HS), hoof wall (HW), and lamellar tissue (LAM) temperature during distal limb cooling and evaluate 4 cooling methods in ambulatory horses over extended periods using HW to estimate LAM temperature. Methods: 8 healthy, university-owned horses were enrolled. Temperature was measured over 4 hours at LAM, HS, and HW for 4 cooling methods: ice sleeve (SLEEVE), ice pack system (ICEPACK), low-volume ice water immersion (LV-IMMERSION), and high-volume ice water immersion (HV-IMMERSION). The relationship between HW, HS, and LAM was mathematically mode...
Marichal G, Suárez G, Meikle A, Muriel M.The recovery of acid-base and hydro electrolytic balance at medical discharge after Raid races and its association with comfort index (CI) is unknown. Unassigned: To determine hydroelectrolytic and acid-base variations before and at the time of clinical discharge in horses that completed 90 km Raid competitions. Unassigned: Hematocrit, total protein, sodium, potassium, chloride, calcium, and serum pH were determined in samples before and after the race and after hydration in 276 horses and were analyzed using a mixed procedure, including the time of the race, the CI and its interaction. Unassi...
Soroko-Dubrovina M, Åšniegucka K, Dobrowolski M, Dudek KD.The aim of this study was to evaluate the efficacy of thermography in assessing the impact of regular physical effort on changes in the body surface temperature of the upper body parts of young racehorses. The study involved monitoring 33 racehorses aged 3 years in 3 imaging sessions over a period of 3 months. Temperature measurements of the neck and upper part of the forelimbs and hindlimbs from both sides were taken just before and after training. Three regions of interest (ROIs) located at the base of the neck, elbow and quarter on both sides of the body were analysed. Before physical effor...
Parsley AL, Hollingshead NA, Gruber EJ.To minimise storage-related artefacts, EDTA-anticoagulated whole blood should be evaluated promptly or refrigerated, a challenge in ambulatory practice. The effects of suboptimal blood storage on equine leukocyte parameters are not well-documented. Objective: Document changes in leukocyte number, automated and manual differential counts, and morphology in equine blood stored at four temperatures for up to 5 days. Methods: In vitro experimental. Methods: EDTA-anticoagulated whole blood from 13 horses was stored in a refrigerator (4°C), cooler with icepacks (3°C-19°C), room temperature (22Â...
Valderrama-Martinez C, Packham A, Zheng S, Smith W, Plancarte M, Aleman M.Evaluating antibody titers for Sarcocystis neurona for the diagnosis of equine protozoal myeloencephalitis from serum samples is a common practice. However, ensuring timely and proper refrigeration is not always possible. Objective: To evaluate immunofluorescent antibody (IFA) titers for S. neurona from serum samples stored at room temperature and 4°C. Methods: Twenty-two serum samples. Methods: Prospective longitudinal study. Two serum aliquots of 1 mL each were stored at room temperature (20-23.3°C) and 4°C. The unrefrigerated aliquot was immediately tested for IFA titers. Both aliquots...
Silva GC, Nogueira CEW, Scalco R, Pizzi GLBL, Leite TA, Bastos R, Curcio BR.Gestation length (GL) in horses varies widely, influenced by multiple variables, including maternal, fetal, and environmental factors. This study aimed to investigate and quantify the relative contributions of climatic (photoperiod and temperature-humidity index - [THI]), maternal (age and parity), fetal (sex) and environmental (year and month of foaling) variables influencing gestation length in Thoroughbred mares. Retrospective data encompassing 704 pregnancies across nine breeding seasons in tropical and subtropical Brazilian climates were analyzed. Stepwise regression analysis identified f...
Deniz Ö, Aragona F, Murphy BA, Tümer KÇ, Bozacı S, Fazio F.The global climatic changes pose a substantial threat to the well-being and productivity of both humans and animals. Unassigned: This study examined the impact of climate changes during different seasons over a 3-year monitoring period (2021-2023) on various blood parameters including, white blood cells (WBC), neutrophils, basophils, eosinophils, lymphocytes, and monocytes, hematocrit (HCT), hemoglobin (HGB), red blood cells (RBC), platelets (PLT), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH). The study focused on 25 Tho...
Takahashi K, Mukai K, Takahashi Y, Ebisuda Y, Hatta H, Kitaoka Y.The purpose of this study was to elucidate the skeletal muscle transcriptomic response unique to rest duration during high-intensity interval exercise. Thoroughbred horses performed three 1-min bouts of exercise at their maximal oxygen uptake (10.7-12.5 m/s), separated by 15 min (long) or 2 min (short) walking at 1.7 m/s. Gluteus medius muscle was collected before and at 4 h after the exercise and used for RNA sequencing. We identified 1,756 and 1,421 differentially expressed genes in response to the long and short protocols, respectively using DEseq2 analysis [false discovery rate (FDR) cutof...
Folk KM, White RR, Gleason CB.Cryotherapy is often used to reduce inflammation in acute equine laminitis cases. Certain hoof temperatures have been suggested as effective in minimizing the inflammatory process; however, there is limited evidence on which methods are best at achieving these temperatures. Our objective was to determine how different methods of cryotherapy influence the rate and extent of cooling for the equine hoof wall. Four horses received three hoof cooling treatments and a control (CON; no treatment application) in a 4 × 4 Latin square design. Treatments included (1) ice surrounding the hoof in a 5 L fl...
Guertin JE, Losano JA, Salazar S, Callaham J, Daigneault BW.Bottlenecks to the success of equine assisted reproductive technologies (ART) include suboptimal conditions for prolonged storage of stallion sperm. Shipped stallion sperm are transported in cooling devices designed to maintain temperature for up to 48 h. Increasing the storage time of cooled semen while maintaining acceptable motility would relieve logistical ART challenges. Experiments were conducted to test the hypothesis that external regulation of shipment container temperature would prolong storage time of cooled stallion semen. Initial experiments determined the effect of pre-freezing c...
Canisso IF, Amorim GBAG, Magalhaes HB.The objectives of this study were (i) to determine pH and electrolyte concentrations in MGS collected prepartum and at parturition, (ii) to characterize mare milk pH during the first week postpartum, and (iii) to evaluate pre-foaling MGS pH at three storage temperatures. This study outlined two hypotheses: (i) all mares exhibit acidic pH, increased calcium, magnesium, and potassium, and reduced sodium concentrations regardless of prepartum pH and electrolytes; (ii) pre-foaling MGS pH varies with storage temperature and time in an initial value-dependent manner. Twenty-three multiparous mares w...
Jacquay ET, Harris PA, Adams AA.It is unknown whether short-term transportation affects endocrine responses similarly in horses with and without insulin dysregulation (ID). Objective: To characterise the effect of short-term transportation on stress parameters and insulin responses to an oral sugar test (OST) in horses with and without ID. Methods: Longitudinal cohort study. Methods: Fourteen adult non-pregnant, non-PPID mares of mixed light breeds were grouped as either ID (n = 7) or non-ID (n = 7) based on endocrine testing. Over 2 weeks, horses were transported once, in groups of 3-4 in a horse trailer on a roun...
Kerley BS, Harris P, Lea K, McClendon M, Adams AA.Forage low in nonstructural carbohydrates (NSC) is recommended for insulin dysregulated (ID) horses, indicating the importance of an accurate forage analysis. However, it remains to be fully understood how handling forage samples pre-analysis impacts nutrient values. The objective of this study was to compare the effect of fresh-forage storage-handling methods: microwave-oven (MO; 9kw; 70s then stored at -20℃), room temperature (20℃), 3℃, -20℃, and -80℃. Subsamples collected from a mixed-grass pasture and a ryegrass plot were analyzed for crude protein (CP), water soluble carbohydrat...
Ferlini Agne G, Adamson K, McGlinchey L, Kravchuk O, Santos L, Schumacher J.Accuracy of a median nerve block is normally assessed by testing skin sensitivity on the medial and dorsal aspects of fetlock and pastern. The present study evaluated subjective and objective analysis of skin surface temperature obtained with two different infrared (IR) thermography cameras (a high-end [FLIR P640] and a smartphone IR thermography device [FLIR One®]) before and after anaesthesia of the median nerve. Thermographic images were obtained at 0, 30, 60 and 90 minutes after performing a median nerve block with 2% mepivacaine hydrochloride. The subjective analysis of thermographic ima...
Majadi M, Barkó A, Varga-Tóth A, Maukenovna ZS, Batirkhanovna DZ, Dilora S, Lukacs M, Kaszab T, Mednyánszky Z, Kovacs Z.Milk powders are becoming a major attraction for many industrial applications due to their nutritional and functional properties. Different types of powdered milk, each with their own distinct chemical compositions, can have different functionalities. Consequently, the development of rapid monitoring methods is becoming an urgent task to explore and expand their applicability. Lately, there is growing emphasis on the potential of near-infrared spectroscopy (NIRS) as a rapid technique for the quality assessment of dairy products. In the present work, we explored the potential of NIRS coupled wi...
McGill S, Coleman R, Hayes M.Indoor arenas do not always include mechanical ventilation or stirring fans and occupancy by horses and humans can be sporadic and inconsistent, which creates a challenging space for understanding and predicting variations in temperature, moisture, and airflow. To understand the interior environment within indoor arenas, monitoring was conducted at 15 facilities within 200 kilometres of Lexington, KY. Environmental monitoring of dry bulb temperature, relative humidity, dew point temperature, air speeds, and solar radiation took place over 7 days in the winter and summer to examine temporal var...
Poochipakorn C, Wonghanchao T, Sanigavatee K, Chanda M.Single-confinement housing can pose welfare risks to domestic horses. This study investigated horses' stress responses when confined to single stalls in different stable designs in a tropical savanna region to address a gap in the literature. In total, 23 horses were assigned to a stable with a central corridor and solid external walls (A) (N = 8), a stable with one side corridor and solid external walls (B) (N = 6), or a stable with a central corridor and no solid external walls (C) (N = 9). Air velocity, relative humidity, air temperature, and noxious gases were measured inside the stables, ...
An Q, Li Y, Sun Z, Gao X, Wang H.Equine Infectious Anemia (EIA) is a vector-borne persistent viral infection in equine animals. The EIA is characterized by recurrent fever, thrombocytopenia, depression, anemia, rapid weight loss, and lower body edema. Control of EIA is achieved through the elimination or isolation of infected animals, resulting in significant economic losses. In recent years, many countries in Europe have experienced outbreaks of EIA, which could potentially develop into a new wave of epidemic and pose a significant threat to the healthy development of the equine industry. This study utilized spatiotemporal a...
Discepolo DR, Gaare E, Handlos G, Perry EB.Cutaneous pH and transepidermal water loss (TEWL) are commonly utilized measures in dermatological research as they provide information concerning barrier function. The importance of dermal health has become more evident in recent years. Accordingly, the aim of this work was to identify natural fluctuations in the biophysical parameters of healthy equine skin. Cutaneous pH and TEWL was collected on nine mares at 6:00 AM, 12:00 PM, and 6:00 PM daily for five days on the nose, withers, girth area, mid-back, and base of tail. Ambient temperature and humidity were measured at each collection. Stat...
Aragona F, Rizzo M, Arfuso F, Acri G, Fazio F, Piccione G, Giannetto C.The aim of the present study was to investigate eye temperature modifications after road transport in athletic horses habituated to travel. Eight adult Italian saddle horses traveled 100 km and, two weeks later, 300 km. Eye temperature (ET), rectal temperature (RT) and serum cortisol concentration were assessed before (T1), after (T2) and 60 min (T3) after the road transport. ET was evaluated with infrared thermography (IRT) in three regions of interest: EL1 (medial canthus), EL2 (central cornea) and EL3 (lateral canthus). Two-way analysis of variance (ANOVA) for repeated measures showed stati...
Animal welfare has become an increasingly important concern regarding equids working as carriage animals. In the present study, the changes in the markers of stress and inflammatory responses as a result of the work performed by tourism carriage horses under real working conditions in Sicily (Italy) were investigated. Twenty-two Standardbreds performed a normal working day in the carriage tourism business during the months of May, June and July 2022, consisting of one day of work for each month. Blood samples were collected in the stables at rest before the tour route (Pre; 07.00 AM) and withi...
de Carvalho JRG, Del Puppo D, Littiere TO, de Sales NAA, Silva ACY, Ribeiro G, de Almeida FN, Alves BG, Gatto IRH, Ramos GV, Ferraz GC.Diagnosing and treating lameness in horses is essential to improving their welfare. In equine orthopedic practice, infrared thermography (IRT) can indirectly detect soreness. Non-steroidal anti-inflammatory drugs can treat painful and inflammatory processes in horses. Using IRT, the efficacy of meloxicam (Maxicam Gel) was evaluated in pre-treating transient synovitis in horses induced by a middle carpal joint injection of lipopolysaccharides (LPS) from 055:B5 at a dose of 10 endotoxin units. Unassigned: In a cross-over design, six healthy horses were randomly assigned to receive either 0.6 ...
Aragona F, Arfuso F, Rizzo M, Fazio F, Acri G, Piccione G, Giannetto C.This study aimed to evaluate changes in body temperature in athletic horses during two different road transport distances. Six Italian Saddle horses were subjected to a 100 and 300 km transport during different times of day (am and pm). Rectal and cutaneous temperatures were recorded before (T0), immediately (following 5 min- T1) and 1 hour (T2) after transport by means of a rectal digital thermometer and a thermal infrared camera (FLIR T440) respectively, for the evaluation of left and right side of four body regions: jugular, shoulder, croup and inner thigh. There were no differences between...
Ebisuda Y, Mukai K, Takahashi Y, Yoshida T, Matsuhashi T, Kawano A, Miyata H, Kuwahara M, Ohmura H.This study aimed to determine whether heat acclimation could induce adaptations in exercise performance, thermoregulation, and the expression of proteins associated with heat stress in the skeletal muscles of Thoroughbreds. Thirteen trained Thoroughbreds performed 3 weeks of training protocols, consisting of cantering at 90% maximal oxygen consumption (VO2max) for 2 min 2 days/week and cantering at 7 m/s for 3 min 1 day/week, followed by a 20-min walk in either a control group (CON; Wet Bulb Globe Temperature [WBGT] 12-13°C; n = 6) or a heat acclimation group (HA; WBGT 29-30°...
Nawrot K, Soroko-Dubrovina M, Zielińska P, Dudek K, Howell K.The study aimed to evaluate the impact of BEMER (Physical Vascular Therapy) on body surface temperature using infrared thermography (IRT) in the distal parts of the forelimbs in Thoroughbreds. The study tested the hypothesis that BEMER therapy leads to an increase in body surface temperature and blood vessel diameter in the distal parts of the forelimbs. The study involved 16 horses, split into 2 groups: active BEMER ( = 8) and sham ( = 8). The active BEMER group had BEMER boots applied to the distal parts of the forelimbs, whereas the sham group had BEMER boots applied without activation of t...
Taesuji M, Rattanamas K, Yim PB, Ruenphet S.The Flinders Technology Associates (FTA) card, a cotton-based cellulose membrane impregnated with a chaotropic agent, effectively inactivates infectious microorganisms, lyses cellular material, and fixes nucleic acid. The aim of this study is to assess the stability and detection limit of various RNA viruses, especially the avian influenza virus (AIV), Newcastle disease virus (NDV), and African horse sickness virus (AHSV), on the FTA card, which could significantly impact virus storage and transport practices. To achieve this, each virus dilution was inoculated onto an FTA card and stored at r...
Freitas ML, Viana JHM, Dode MAN, Braga TRC, de Oliveira RA.Scrotal surface thermography is a non-invasive method for assessing testicular thermoregulation in stallions; however, few studies have explored the application of this technique concerning the thermal physiology of equine reproductive systems. This study aimed to evaluate the consistency of testicular thermoregulation in stallions over a year using thermography to measure the scrotal surface temperature (SST). Moreover, we assessed the best region for measuring the surface body temperature compared with the SST. Ten light-breed stallions were used in the experiment. Thermographic images of th...
Pala S, MartÃnez-Sáez L, Llobat L, MarÃn-GarcÃa PJ.Leishmaniasis and toxoplasmosis are two of the most common parasitic zoonoses. Leishmaniasis is endemic to 98 countries around the world, whereas toxoplasmosis is widely distributed throughout the world, causing significant health expenditure. Horses can play a relevant role in the transmission of the disease, being a silent reservoir, as clinical signs are not common. Serum samples from 166 horses living in eastern Spain (Mediterranean basin) were analysed to determine the presence of antibodies against Leishmania spp. and T. gondii by ELISA (Enzyme-linked Immunosorbent Assay.) The risk facto...
Reed RA, Berghaus LJ, Reynolds RM, Holmes BT, Krikorian AM, Sakai DM, Ishikawa Y, Knych HK.Understanding the pharmacokinetics and pharmacodynamics of fentanyl in horses is crucial for optimizing pain management strategies in veterinary medicine. Unassigned: Six adult horses were enrolled in a randomized crossover design. Treatments included: placebo, two 100 mcg/h patches (LDF), four 100 mcg/h patches (MDF), and six 100 mcg/h patches (HDF). Patches were in place for 72 h. Blood was obtained for fentanyl plasma concentration determination, thermal threshold, mechanical threshold, heart rate, respiratory rate, and rectal temperature were obtained prior patch placement and at m...
Oldenhof H, Gojowsky M, Wang S, Henke S, Yu C, Rohn K, Wolkers WF, Sieme H.The aim of this study was to determine how different membrane-permeable and -impermeable cryoprotective agents modulate tolerance of stallion sperm to osmotic stress and stabilize membranes during cryopreservation. Special emphasis was on hydroxyl ethylene starch (HES), which exposes cells to minimal osmotic stress due to its large molecular weight. Percentages of motile sperm post-thaw were found to be similar when glycerol, sucrose, and HES were used at their optimal concentrations. Percentages of plasma membrane intact sperm after return to isotonic medium were highest for HES. Fourier tran...
Marlin DJ, Scott CM, Roberts CA, Casas I, Holah G, Schroter RC.Whereas the efficacy of cold water cooling of horses has been demonstrated by several studies, the dynamics of temperature changes within and between compartments (primarily muscle, blood [core], skin and deep core [rectal]) have not been investigated. Changes in body temperature associated with cold water cooling were investigated in the hyperthermic horse. Muscle (TMU), pulmonary artery (TPA), rectal (TREC), tail-skin (TTSK) and coat surface (TCOAT) temperatures, were monitored continuously in 5 Thoroughbred horses during and after exercise in hot humid (30 degrees C and 80% RH) conditions o...
Davis MS, Williams CC, Meinkoth JH, Malayer JR, Royer CM, Williamson KK, McKenzie EC.To determine effects of exercise performed while breathing cold air on expression of cytokines and influx of neutrophils in airways of horses. Methods: 9 adult horses. Methods: In a crossover study, bronchoalveolar lavage fluid (BALF) was obtained 24 and 48 hours after each of 2 submaximal exercise sessions performed by horses while breathing warm (25 degrees C) or cold (-5 degrees C) air. Total and differential nucleated cell counts were determined for each BALF sample. Relative mRNA expression of cytokines in BALF cells was quantified by use of a reverse transcription-PCR assay. Results: Hor...
Soroko M, Śpitalniak-Bajerska K, Zaborski D, Poźniak B, Dudek K, Janczarek I.The aim of the study was to assess the effects of training on haematological and biochemical blood parameters as well as on the changes in body surface temperature in horses. In order to identify the predictive value of surface temperature measurements as a marker of animal's performance, their correlations with blood parameters were investigated. The study was carried out on nine horses divided into two groups: routinely ridden and never ridden. Infrared thermography was used to assess surface temperature changes before (BT) and just after training (JAT) on a treadmill. Seven regions of int...
Smith BL, Jones JH, Hornof WJ, Miles JA, Longworth KE, Willits NH.Stress associated with road transport is believed to be a significant contributor to the pathogenesis of post transport respiratory disease in horses. To determine the effects of road transport on pulmonary function, pulmonary aerosol clearance rates were measured in 4 horses 24 h before, and immediately after, 24 h of road transport by delivering aerosolised 99mtechnetium-labelled diethylenetriaminepentacetate (99mTc-DTPA) to the lungs and monitoring its washout. Each horse was transported twice, once while the trailer was equipped with a leaf-spring suspension and bias-ply tyres (trailer's o...
Meisfjord Jørgensen GH, Mejdell CM, Bøe KE.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...
Bullone M, Murcia RY, Lavoie JP.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...
Wiebke M, Hensel B, Nitsche-Melkus E, Jung M, Schulze M.This review is part of the Festschrift in honor of Dr. Duane Garner and provides an overview of current techniques for cooled storage of semen from livestock animals. The first part describes the current state of the art of liquid semen preservation in boars, bulls, and stallions, including the diluents, use of additives, processing, temperature, and cooling of semen. The species-specific physiology and varying extents of cold shock sensitivity are taken into consideration. In addition, factors influencing the quality of cooled-stored semen are discussed. Methods, trends, and the most recent a...
Allen TE, Bligh J.1. The temporal patterns of cutaneous water vapour loss from the skin of the sheep, goat, ox, horse, donkey and llama during exposure to 40°C Ta and during i.v. injections and infusions of adrenaline are examined.
2. It is concluded that there are marked species variations in the extent to which the discharge of sweat is affected by periodic contractions of the myoepithelium, or by simple displacement of fluid from the filled lumen as more fluid is secreted into it.
Cymbaluk NF, Christison GI.Horses are reared in all types of weather. Temperatures as diverse as -40 degrees C to 40 degrees C are tolerated by horses. The nutrient requirement most influenced by cold weather is energy. In cold weather, feeding good quality hays free-choice is usually sufficient for mature horses in good body condition. Grain may have to be fed when poor quality hays are used. Hot weather (greater than 30 degrees C) necessitates heat loss to maintain body core temperature. Horses sweat to reduce body heat. Heat stress can be minimized by feeding diets that reduce the heat increment. Use of grain and fat...
Lapointe JM, Vrins A, McCarvill E.Sixty Standardbred horses, aged 3 to 10 years, were examined endoscopically for exercise-induced pulmonary haemorrhage (EIPH) 1 h after racing, on at least 3 occasions. Racing time, finishing position and post exercise venous lactate concentrations were also recorded. Horses positive for tracheal blood on endoscopy were classified as having either grade 1 EIPH (one or a few spots of blood in the trachea), or grade 2 (stream of blood). Air temperature, relative humidity and air pollutant levels were recorded on each examination day. Of the 60 horses, 52 (87%) were EIPH-positive on at least one ...
Takahashi Y, Ohmura H, Mukai K, Shiose T, Takahashi T.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...
Di Pol G, Crotta M, Taylor RA.Increases in temperature and extreme weather events due to global warming can create an environment that is beneficial to mosquito populations, changing and possibly increasing the suitable geographical range for many vector-borne diseases. West Nile Virus (WNV) is a flavivirus, maintained in a mosquito-avian host cycle that is usually asymptomatic but can cause primarily flu-like symptoms in human and equid accidental hosts. In rare circumstances, serious disease and death are possible outcomes for both humans and horses. The main European vector of WNV is the Culex pipiens mosquito. This stu...
Fessas D, Iametti S, Schiraldi A, Bonomi F.The thermal stabilities of dimeric bovine beta-lactoglobulin and monomeric equine beta-lactoglobulin were investigated at neutral pH by means of differential scanning calorimetry, circular dichroism, tryptophan fluorescence, and by binding of an hydrophobic probe. Differential scanning calorimetry showed the presence of two structural domains with different thermal stabilities in both proteins. Thermodynamic analysis of the calorimetric signal revealed that the two domains unfold independently according to a mechanism where an equilibrium step is followed by an irreversible transition. The spe...
Geor RJ, McCutcheon LJ, Ecker GL, Lindinger MI.The effect of humid heat acclimation on thermoregulatory responses to humid and dry exercise-heat stress was studied in six exercise-trained Thoroughbred horses. Horses were heat acclimated by performing moderate-intensity exercise for 21 days in heat and humidity (HH) [34.2-35.7 degrees C; 84-86% relative humidity (RH); wet bulb globe temperature (WBGT) index approximately 32 degrees C]. Horses completed exercise tests at 50% of peak O(2) uptake until a pulmonary arterial temperature (T(pa)) of 41.5 degrees C was attained in cool dry (CD) (20-21.5 degrees C; 45-50% RH; WBGT approximately 16 d...
Brinkmann L, Gerken M, Hambly C, Speakman JR, Riek A.Recent results suggest that wild Northern herbivores reduce their metabolism during times of low ambient temperature and food shortage in order to reduce their energetic needs. It is, however, not known whether domesticated animals are also able to reduce their energy expenditure. We exposed 10 Shetland pony mares to different environmental conditions (summer and winter) and to two food quantities (60% and 100% of maintenance energy requirement) during low winter temperatures to examine energetic and behavioural responses. In summer, ponies showed a considerably higher field metabolic rate (FM...
Giannetto C, Arfuso F, Giudice E, Gianesella M, Fazio F, Panzera M, Piccione G.To assess the accuracy of infrared methodologies for daily rhythm monitoring of skin temperature, five clinically healthy Italian Saddle gelding horses, and five not pregnant and not lactating Camosciata goats, were monitored every 4Â h over a 48Â h period. The horses were housed in individual boxes, while the goats in two indoor pens, under natural photoperiod and natural environmental temperature. In each animal, skin temperature was recorded with the use of a digital infrared camera and a non-contact infrared thermometer, in five regions: neck, shoulder, ribs, flank and croup. Recorded valu...
Birch HL, Wilson AM, Goodship AE.Tendons that store energy during locomotion, such as the equine superficial digital flexor tendon (SDFT) and human Achilles tendon, suffer a high incidence of central core degeneration which is thought to precede tendon rupture. Although energy storage contributes to the efficiency of locomotion, tendons are not perfectly elastic and some energy is lost in the form of heat. Recent studies have shown that the central core of equine SDFT reaches temperatures as high as 45 degrees C during high-speed locomotion. In this study, we test the hypothesis that hyperthermia causes tendon cell death and ...
Clerbaux T, Gustin P, Detry B, Cao ML, Frans A.1. The entire oxygen dissociation curve (ODC) and the effects of temperature, pH and 2,3-diphosphoglycerate (DPG) on this curve, have been compared in four mammalians: man, dog, horse and cattle. 2. If the oxyphoric capacities are similar between these species (around 1.39 ml O2/gHb), their P50, measured in standard conditions, i.e. at pH 7.4; pCO2 40 mmHg and T 37 degrees C, varies between 23.8 (+/- 0.8) mmHg for the horse, 25.0 (+/- 1.4) mmHg for cattle, 26.6 (+/- 1.2) for man and 28.8 (+/- 2.6) mmHg for the dog. 3. The higher dispersion of the dog's P 50 is due to difference between breeds;...
Kang H, Zsoldos RR, Sole-Guitart A, Narayan E, Cawdell-Smith AJ, Gaughan JB.Healthy adult horses can balance accumulation and dissipation of body heat to maintain their body temperature between 37.5 and 38.5 °C, when they are in their thermoneutral zone (5 to 25 °C). However, under some circumstances, such as following strenuous exercise under hot, or hot and humid conditions, the accumulation of body heat exceeds dissipation and horses can suffer from heat stress. Prolonged or severe heat stress can lead to anhidrosis, heat stroke, or brain damage in the horse. To ameliorate the negative effects of high heat load in the body, early detection of heat stress and im...
Hinchcliff KW, Morley PS, Jackson MA, Brown JA, Dredge AF, O'Callaghan PA, McCaffrey JP, Slocombe RF, Clarke AF.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 ...
van Eps AW, Leise BS, Watts M, Pollitt CC, Belknap JK.The pathophysiological events inhibited by prophylactic digital hypothermia that result in reduction of the severity of acute laminitis are unknown. Objective: To determine if digital hypothermia inhibits lamellar inflammatory signalling during development of oligofructose (OF) induced laminitis. Methods: Fourteen Standardbred horses were given 10 g/kg bwt OF by nasogastric tube with one forelimb (CRYO) continuously cooled by immersion in ice and water and one forelimb (NON-RX) at ambient temperature. Lamellae were harvested prior to the onset of lameness (24 h post OF administration, DEV ...
Younes M, Robert C, Barrey E, Cottin F.Although cardiac recovery is an important criterion for ranking horses in endurance competitions, heart rate variability (HRV) has hardly ever been studied in the context of this equestrian discipline. In the present study, we sought to determine whether HRV is affected by parameters such as age, exercise duration and test site. Accordingly, HRV might be used to select endurance horses with the fastest cardiac recovery. The main objective of the present study was to determine the effects of age, exercise duration, and test site on HRV variables at rest and during exercise and recovery in young...
Post F, Doster W, Karvounis G, Settles M.The geminate recombination kinetics of CO-myoglobin strongly deviates from single exponential behavior in contrast to what is expected for unimolecular reactions (1). At low temperatures, this result was attributed to slowly exchanging conformational states which differ substantially in barrier height for ligand binding. Above 160 K the kinetics apparently slow down with temperature increase. Agmon and Hopfield (2) explain this result in terms of structural relaxation perpendicular to the reaction coordinate, which enhances the activation energy. In their model, structural relaxation homogeniz...
Oldenhof H, Friedel K, Sieme H, Glasmacher B, Wolkers WF.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...
Guthrie AJ, Lund RJ.Metabolic HP is extremely high during exercise in horses. Thermoregulation in horses is primarily dependent on evaporative heat loss from sweating in particular. Under thermoneutral conditions, these mechanisms are sufficient to allow horses to perform high-intensity exercise for long periods. Under thermally stressful conditions, particularly in high ambient humidity, the efficiency of evaporative heat loss mechanisms is compromised and may result in horses developing hyperthermia. Early recognition and vigorous treatment are essential to limit the consequences of heat stress in horses. Metic...
Dallaire A, Rucklebusch Y.For several weeks, three ponies kept in an environment with controlled light and temperature, were studied for behaviour (time spent in recumbency and time required to consume hay or oats) and for electrical activity of the brain (cortical and sub-cortical) during the night phase of the circadian rhythm. Recumbency was adopted by all the ponies for six or seven periods during the night. With a regimen of hay ad libitum, about four hours were cumulated in sternal recumbency and only one hour in complete lateral recumbency. Various degree of sleep, as identified by cortical and hippocampal elect...
Mfitilodze MW, Hutchinson GW.In a series of laboratory studies the optimum conditions for the development and survival of the free-living stages of strongyle parasites occurring in horses in tropical north Queensland were determined. No differences in behaviour were noted between the strongyle species. Development to the infective stage occurred only between 10 and 35 degrees C. The rate was affected by temperature, taking 15-24 days and 3 days, respectively, at the lowest and highest temperatures for the developing stages to reach the infective third stage. Yields of infective larvae were very low outside the range 20-33...
Soroko M, Zaborski D, Dudek K, Yarnell K, Górniak W, Vardasca R.The impact of a rider's and saddle's mass on saddle thermal pattern distribution was evaluated using infrared thermography (IRT). Eighteen racehorses were ridden by four riders with their own saddle. Images of the saddle panels were captured at each of six thermographic examinations. On each image, six regions of interest (ROIs) were marked on the saddle panels. The mean temperature for each ROI was extracted. To evaluate the influence of load on saddle fit, 4 indicators were used: ΔTmax (difference between the mean temperature of the warmest and coolest ROI); standard deviation of the mean t...
