Hi,
Welcome to topic 4 for 624EHS - Contemporary Issues in Equine Science.
This topic is all about cooling the horse and problems with exercising in the heat. You are required to contribute to this blog as part of your CW3 assessment. You have from now until 11:59 pm on Friday 10th of March 2023 to contribute to this blog, to debate the issues surrounding the welfare of horses in extreme heat. Ensure you can also evidence your opinions and remember that you are also required to submit a reference list (word document emailed to module leader) by 11:59 pm on Friday 10th of March 2023. You will be graded on the quality and quantity of both your blog contributions and your reference list. Remember, the point of this is to debate the issues, so you should be replying to other posts as well as putting your ideas across. I will be keeping an eye on the blog, but if you have any issues, you should email me. Please remember to register your name with your comments so that I know who has contributed with which comment.
Rosa
The use of water to cool provides the greatest potential for removing the heat, McGill et al, 2021 carried out a study to determine whether forced air movement in combination with drenching would increase the rate of cooling thus bringing the vital signs back to base level quicker thus reducing the risk of overheating. Although no significant differences were found in the rate of cooling, the data indicated that both rectal temperature and heart rate returned to baseline more quickly with the fan and drenching combination as opposed to drenching alone.
ReplyDeleteAlthough potentially not a practical option for many, further research may be warranted to assess a larger sample size, extended amount of time spent with the fan and less walking out; this may prove to be an additional way in which horses can be cooled at the larger competitions in the hot and humid countries where cooling can be an issue.
The Tokyo Olympics were hounded by the heat with humidity levels reaching 70%. Athletes and volunteers were working in brutal conditions due to the heat and high humidity, this then lead to pressure on the organisers to rethink the future of sport in a climate-disrupted world and how this could be avoided in the future. There will be pressure for bigger events to be moved geographically, seasonally and the time of day. Potentially leading to repercussions of limiting which sports can partake.
DeleteThe equestrian events of the Tokyo games were challenging to ensure the health and welfare of the equine athletes, Tokyo regularly experiences exceeding 41c.
DeleteThis poses concerns regarding future Olympic host cities, such as Paris 2024 and Los Angeles 2028 both of which experience hazardous heat waves.
The paper commented above by McGill., (2019) (not 2021), had a limitation that they only used the fans for approximately a third of the horses cool down time. Further studies should be completed to use the fans for different time periods to see if there is a specific time the fan should be used for to gain the best results of cooling horses down alongside drenching.
DeleteBecause of the direct cause that heat exhaustion can have on equines help there was significant research undertaken before the Olympic games, due to the high humidity and heat levels. It was found that is it crucial that owners and competitors have a good understanding of appropriate cooling methods and how humans can assist in this process (Jeffcott and Kohn, 1995)
DeleteWhen environmental temperatures exceed 25°C, horses are potentially subjected to thermal stress. Shade is recommended but this is not always possible in some circumstances. Padalino et al, 2019 carried out a study to investigate whether wearing a light coloured cotton rug can reduce heat stress in comparison to no rug. As a consequence of wearing the rug these horses suffered from an increased internal temperature, increases sweat production thus increasing the risk of thermal stress and loss of electrolytes. Demonstrating that wearing a rug cannot be a substitute for shade in hot temperatures. Limitations, no light coloured horses were used, and only one type of rug,results could be different on varying colours and breeds and different materials of rugs. Yet overall to safeguard horse welfare, rugs must not be used as a replacement for shade.
ReplyDeleteIt's worth noting that Padalino et al. (2019) used a reduced sample size and the behavioural responses assesed with a predetermined ethogram might not be comprehensive of a series of behaviours that might indicate the horse's discomfort in addition to possible observer bias.
DeleteFurthermore, as appreciated by the authors, equids tend to be prone to stress and discomfort hence heart rate, respiratory rate and the occurrence of stress-related behaviors were higher than normal values which in association to the methods used to record these parameters might have skewed the data.
Continuing it was found that alternative ways of cooling horses is cooling blankets (Okima etal., 2022). This decreased respiratory rate along with heart rate. However, limitations of this study include only being suitable for equines that are housed. Along with not being a rapid response more of a gentle, therefore causing confusion on weather this is the horse’s natural reaction after exercise and questioning the effect of the blankets.
DeleteResults of the study by Klous et al. (2020) showed that pre-cooling horses by whole-body cold-water rinsing, directly before moderate intensity training, led to a slightly smaller rise in rectal and skin temperatures in moderate environmental conditions. Considering the relatively small, and late (after 6 min), impact on the thermophysiological parameters, pre-cooling may be most beneficial in moderate- to longer-duration exercise with a high thermoregulatory burden, such as the cross-country test in the eventing discipline. Understanding the individual responses to pre-cooling is important for optimising welfare, and possibly improving performance during training and competition in challenging environmental conditions.
ReplyDeleteLimitations to this study included different environmental conditions on both testing days which was taken in consideration by the authors and that the findings only apply to moderate environmental conditions and exercise intensity used and ther was a lack of data on internal temperature as measuring temperature of internal organs or temperature at pulmonary artery are not feasible in field studies.
DeleteFurther research on effectivness of pre-cooling should consider different exercise intesities in relation to the horses' fitness level and different climates, especially in hotter and/or more humid conditions.
Overall thermoregulatory observation of pre-cooling showed potential benefits on performance in hot climates and the method chosen showed the feasibility of implementig this technique in equestrian events.
Schroter and Marlin (1995) carried out a study to objectively determine the environmental heat load imposed on horses competing to an international level in 3 day events in environments where there is likely to be high heat and humidity. Suggesting the wet bulb globe temperature (WBGT) index be used. This index was originally established for man exercising strenuously under harsh climatic conditions with high solar radiation levels.
DeleteIt is suggested that climatic conditions should be monitored continuously at a site representative of the detailed structure and nature of the terrain of the competition course. The upper limit for the index for competitions involving fit, fully acclimatised horses, running on ground of optimal going, is recommended to be 32.5 degrees C. This limit should be reduced, by an as yet undetermined amount, for unacclimatised and unfit horses or when the going is less good.
This process is used by the FEI and Dr David Marlin was the FEI climate advisor in Toyko.
The effects of pre-cooling on the thermophysiological responsed of elite eventing horses was investigated by Klous et al, 2020; using 10 international event horses which were exercised and either pre-cooled or not pre-cooled with cold water rinsing.
DeleteResults indicated that there was a lower rectal temperature and a lower skin temperature on those who were pre-cooled, indicating that those who are pre-cooled by cold-water rinsing could increase the margin for heat storage, allowing a longer exercise time before a critical temperature is reached and therefore, could potentially improve equine welfare during competition. This is something that could be used in competition in the hot and humid climates.
This is a repetition of the study (Klous et al., 2020) I presented and analysed in fair depth
DeleteWhen talking about exertional heat illness (EHI), as reviewed by Brownlow and Mizzi (2021), even though their investigation revolved around Thoroughbred racehorses, it should be known that not all horses will require aggressive cooling after strenuous exercise. The majority of racehorses possess a remarkable thermoregulatory capacity that enables them to cope with the levels of thermal strain associated with racing in most weather conditions. The technique of cooling and how quickly it should be done, often depends on individual preference and resources available, but should meet essential criteria: it must be practical, and the cooling modality must be capable of achieving rapid cooling rates but it is essential to avoid overcooling the horse and the onset of rebound hyperthermia.
ReplyDeleteThe application of cold water helps elevate eat exhaustion in equines. In a study completed by Marlin etal., (2010) it was found that water temperature of -6 helps cool equines rapidly. However, like previously mentioned this does not allow equines body to recover from excessive sweating (electrolytes lost) and other implications that happen with heat stress. Also using waters of this temperatures, also poses other health risks such as hyperthermia.
DeleteThe combination of heat and humidity and strenuous exercise is challenging for the thermoregulatory system, which can lead to Exertional Heat Illness (EHI). Predicting its occurrence can be difficult; however education is essential for prevention. Lack of knowledge and understanding among those responsible for the horses care can be a major risk factor. The elevated core body temperature that then exceeds the critical thermal maximum will cause destruction to the body cells. The high temperature and duration will dictate the severity of the illness. (Brownlow and Mizzi, 2022).
ReplyDeleteOverheating can cause significant dehydration in equines, which can be fatal. Therefore, it is important that owners are aware of the causes of extreme heat and implications of their knowledge of when horses become dehydrates. Pinching of the equines skin is commonly recommended, however, the validity of this test has been questioned previously, with limited relationship being discovered between this and PCV blood tests (Pritchard etal., 2010), therefore questioning the reliability of this method.
DeleteThere are limitations to this study though as it was only completed in Pakistan, and not worldwide.
The key treatment is early detection, rapid assessment and aggressive cooling. Early detection and treatment for prevention can stop the progression of the condition (Brownlow and Smith, 2020).
ReplyDeleteIdentification of those at higher risk can enable those horses to be treated with rapid cooling as a priority, using a infrared thermometer to detect early signs of EHI can identify those in need of immediate treatment who have a skin temperature of >39c (Brownlow and Smith, 2020)
Apply aggressive cooling, once initiated and the core temperature returns to a normal range within 30 minutes, the damage to the cells is minimal.
Early detection would include looking for the clinical signs; burning hot skin, temperatures >39.0c are a indicator of a greater risk of EHI. Change in behaviour, aggressive, unable to stand still, disorientation, staggering, falling, etc... (Brownlow and Mizzi, 2022).
It is worth recognising that the study by Brownlow and Smith, (2020), has limitations such as the lack of correlation of high SSTs with rectal temperatures and the fact that weather conditions during the course of this study were unstable. Thus, resulting in the abandonment of several of the study meetings before completion. Another limitation is the use of only thoroughbreds that raced in Australia (Brownlow and Smith, 2020). Further research should be done to support this study by finding out if results will be the same for leisure horses, event horses and even those racehorses that may not make it to the track but train just as hard at home.
DeleteThe most rapid rates of cooling are with cold water, but as the water becomes warmer, the cooling rate decreases. The need for how much aggressive cooling will be determined by the severity of the signs of EHI.
ReplyDeleteDependent upon facilities, horses can be cooled and walked, a cooling collar can be used also, cooling units with water and fans which will increase the airflow thus increasing evaporative and convective cooling.
It is important horses are monitored; secondary hyperthermia may occur, thus they must be kept close to veterinary supervision and monitored carefully in case further cooling is necessary. Horses can also be overcooled which can cause cramping up.
There is much information concerning cooling methods for horses;
Marlin et al, 1998 carried out a study whereby horses were worked in hot and humid conditions and cold water cooling improved heat removal by increasing the cooling of circulating blood which provides a greater capacity of heat transfer between muscle and circulation. As with Kohn et al, 1999 who carried out a study on exercising horses in hot and humid conditions and compared active water cooling and no active water cooling, the pulmonary artery temperature was significantly lees in actively cooled horses within 4 minutes of the recovery period and the heart rate and rectal temperature were significantly less for actively cooled horses by 15 minutes of the recovery period. The cooling technique did not effect hydration status, muscle health, or serum electrolyte concentrations, thus indicating that active cooling did not cause obvious adverse effects and active cooling by washing with cold water is a safe, and a effective means for facilitating heat dissipation of horses after exercise in a hot, humid environment.
It has previously been found that Aggressive cooling measures have been proven to cool equines core temperature effectively compared to applying warm water to the quines neck and back (Williamson etal., 1995). This study was completed several years ago; however, principals are still the same now, however there have been adaptations made in present time. Limitations of this study include only 16 horses being studied and only 2 types of cooling being used.
DeleteExpanding further Ting etal., (2013) found that using ice cold water was the most effective way of cooling in Malaysia. They also looked at the effects of cooling gels and water was the most adequate way of cooling. However, they did not look at other aspects therefore causing limitations of the study.
DeleteIn a similar, more recent study, Kang et al. (2022) found that continuous monitoring of body temperature immediately post-exercise is crucial in determining whether more aggressive intervention to cool horses is required, however, measuring rectal temperature did not show a good relationship to core body temperature post-exercise hence PTSM technology was used as an alternate option for monitoring the body temperature of exercised horses. In this study, the authors evaluated three cool-down methods which were used to observe their effects on body temperature at each of the PTSM implantation sites (right pectoral muscle, right gluteal muscle, right splenius muscle and nuchal ligament). Even though the statistical analysis showed no significant differences between the cool-down methods on TCV during the first 10 min post-exercise, the application of cold water (6 °C) with 1 min intervals between reapplication resulted in a faster cooling effect during the first two minutes, than just walking without the application of cold water. Furthermore, although statistically not different, the cold-water application itself exhibited a slightly further cooling effect on the central venous temperature than scraping the cold water from the body suggesting that constant water application is more effective in cooling horses than the use of scraping. The different cooling effects observed may be attributable to heat transfer by conduction from the skin to the cold water, which is more effective at dissipating body heat than evaporation from sweat after scraping. The main limitation of this study was that it was conducted in a controlled indoor setting in only a few horses, that were not physically active in racing or other competitions. Future research needs to be conducted in a larger number of trained horses, in outdoor field conditions, frequent measurement of climate conditions, and under environmental conditions of heat and humidity.
ReplyDeleteJanczarek et al. (2022) compared cooling treatments and how they affect and change rectal temperatures and skin body temperature. 19 warmblood geldings (Anglo-Arabian half-breed horses weighing 523 ± 28.7 kg and aged from 10 to 15 years) were used for this study and each of them took part in four repetitions of the experiment. All of the experimental horses were regularly trimmed and not shoed, they were clinically healthy and did not exhibit any behavioral anomalies. The horses had summer hair (not clipped) and were brushed vigorously for 30 min every morning for 10 days prior to and during the study.
ReplyDeleteThe experiment was conducted in the summer (between 23 June and 12 August). In order for the conditions of the experiment to be optimized, exercise was started early in the morning on hot days and later in cooler weather. Moreover, horses were exercised inside a 17 × 55 m indoor arena (riding hall) with a professional riding ground and with identical schemes of work. The conditions inside the arena were estimated using the psychrometric method.
Cooling of lower, upper, and lower and upper body parts was performed. In each variant, the rectal and body surface temperatures were measured five times: before; immediately after; and 10, 20, and 30 min after effort.
The results showed that using water cooling under the studied conditions did not influence a post-exercise decrease in the rectal temperature and that the decrease in body surface temperature depended on the used variant of cooling down the horse. Cooling the limbs by pouring water several times changed the surface body temperature from 34.2 ± 0.37 °C to 32.0 ± 0.32 °C and was more efficient than the repeated application of cool water on both the upper and lower body parts.
The analysis of the post-exercise rectal and surface temperature, in this study, indicates that spraying a horse with water once does not cool it down. For recreational horses, the application of cold water on the limbs only is sufficient for cooling the horse after medium-intensity exercise under moderate air temperature. Since the repeated application of cool water on the horse’s upper and lower body parts after medium-intensity work seems to be less effective than the application of cool water on limbs, it should not be recommended after medium- or low-intensity effort for leisure horses.
A limitation to the study by Ojima et al., (2022) was that the limbs could not be effectively cooled. Therefore, further research is required in order to produce a similar study that includes correct and efficient ways of cooling the limbs.
ReplyDeleteAnother limitation is that, this cooling method may be costly in comparison to others, thus determining further research is also required to compare the cost of cooling ice packs with other methods (Ojima et al., 2022).
The paper discussed above (Janczarek et al., 2022) is a very good paper which backs up earlier research by Wilk et al., (2020) by looking at both rectal and superficial body temperature. Both parameters increased in a response to exercise and then decreased during the restoration period.
ReplyDeleteLimitations to the study by Janczarek et al., (2022) include the fact that the workload of horses was evaluated on the basis of the increase in rectal temperature only. Other exercise parameters, such as heart rate and blood lactic acid concentration, were not registered during this study. Therefore, their term of 'medium intensity effort' varies however, it only applies to leisure horses and not to sport or racehorses. Further research should be completed to see if these results match high-intensity workload horses such as event and racehorses (Janczarek et al., 2022).
ReplyDeleteThe study by Wilk et al., (2020) looked at the distribution of superficial body temperatures in horses ridden by two riders with varied body weights. Body weights (BW) were 20% and 10% of the horses BW (about 470KG each). The study was carried out on 12 leisure horses, 10-15 year old warmblood geldings. Both riders rode each of the 12 horses for 13 minutes walking and 20 minutes trotting. An infrared thermography camera was then used to analyse the superficial surface temperatures, then the rectal temperature was taken after.
ReplyDeleteResults found that the rider of 20% of the horses BW cause significant increases in superficial temperatures of the neck, front, middle and back parts of the trunk. In contrast, the 10% BW rider did not cause a significant increase in temperature of the horses. Therefore, a horse’s load above 20% of its body weight, even with little effort, affects changes in surface temperature and the activity of the autonomic nervous system (Wilk et al., 2020).
As a result of understanding this, for the welfare of horses, it is important to ensure horses are not loaded above 20% of their body weight to help minimise the risk of horses overheating.
ReplyDeleteLimitations to this study by Wilk et al., (2020) are the fact they only used two riders of a 'similar ability'. Further research could look at multiple riders of similar weights but different abilities to see if this would have a different effect on horse temperature.
Another limitation was that the authors did not mention the behaviour or physiological effect each rider had on the horse. Horses are known to prefer certain riders and it is possible one rider may have caused the horses to get wound up or stressed due to their way of riding. This could have had an effect on the overall results. So again, using a multiple variety of riders would help to back this study up.
There are multiple limitations in the study completed by Takahashi et al., (2020) which include the fact they only used 5 horses which is a small scale study. They also only used thoroughbreds which is only one breed out of many. Further studies should look into other breeds and those with different coat types and skin thicknesses.
ReplyDeleteAnother limitation of this study was that, in the shower method, the horse remained standing throughout the post-exercise period. During the other four protocols, the horses kept walking on the treadmill. It is possible that the difference in results may be due to the difference in experimental conditions. Ideally, the horse should continue walking even with the shower method to remove bias (Takahashi et al., 2020).' Comment from Jaymee
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ReplyDeleteThe cause of overheating is detrimental, like previously mentioned over heating can cause dehydration and therefore the start of the body and organs to shut down, but also, tendons can break down, therefore causing lameness issues (Yamasaki etal., 2001), and because of this potential long term impacts effecting performance and then quality of life.
DeleteIn 1995, it was found that equines were more likely to go lame when competing in hot humid conditions then compared to cool conditions (Kohn and Hinchcliff, 1995). This could be due to the harder ground conditions typically found due to hot weather conditions and the deuteriation of soft tissues that are most commonly causing by excessive heat and lack of cooling down.
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ReplyDeleteAs a concluding remark, from the overviewed literature and by the comments made it appears that costant application of cold water is generally accepted as the most efficient cooling method, though the efficiency of cooling depends on three factors: 1) the temperature difference between the horses’ surface and the water applied; 2) the area of body surface that is covered by the water; 3) the volume of water applied. Possibly coat colour and density have an impact on how fast the horse cools down, though further studies are needed.
ReplyDeleteEfficient in reducing hyperthermia are also pre-cooling strategies and ice blankets, in combination with "under the skin microchips" to monitor efficiently changes in body temperature, as rectal and termography may be less precise and not corrispond to internal body temperature. Jennifer's comment that I deleted