Extreme weather can increase the trend for people to add large amounts of salt to their horse’s daily feeds, despite actual requirements or what may be coming from the rest of their diet. While horses need sodium or chloride to continue to sweat, it’s important to remember that commonplace blanket recommendations like “add 10g of salt per 100kg of bodyweight” don’t take into account a horse’s specific condition.
Take this horse’s diet for example, shown in the graph below. If we add 10g/100kg of bodyweight to his diet, his sodium intake is well over 200% of what he needs. In extreme heat conditions, this may well be accurate, but once it cools off, this is way more sodium than he needs.
What does excessive salt do to the bacteria in their gut? Salt is, after all, one of the best-known and most widely used anti-bacterial agents in the world.
A paper published in ‘Nature’ (one of the most reputable journals in the world) showed that in both humans and mice, adding more salt than normal to a diet affected the gut bacterial populations – in some cases even entirely wiping out certain strains of bacteria. The researchers were then able to link those shifts in gut bacteria to high blood pressure, which may help to explain the link between high salt diets and hypertension.
For horses, feeding excessive salt is unlikely to have any benefit and may be negatively affecting the good bacteria in your horse’s gut. When using FeedXL, be sure to meet but not exceed your horse’s requirement for sodium with salt that is added to the diet. Then leave free choice salt out so that they can top up any extra requirements they may have.
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Sunbleaching in horses appears to be influenced by a combination of sun exposure and sweat.
An unintentional experiment
One of our Nutritionist’s horses lives in a region where flies are prevalent, so the horses wear fly masks during the daytime. They also experience extreme heat, reaching temperatures upwards of 40 degrees Celsius (100°F), which has caused significant sweating behind the ears where the mask straps sit.
A striking observation from this experiment is evident in a liver chestnut horse prone to summer bleaching. Areas where the horse sweated around the mask strap have bleached severely due to the combined effect of sweat and sunlight exposure. Interestingly, under the strap where no sunlight reached, the coat color remains unaffected. This phenomenon highlights the role of sweat in enhancing sunbleaching patterns.
Additional bleaching could be found around the flanks and shoulders, areas where sweating is more pronounced. This reinforces the correlation between sweat, sun exposure, and the resulting bleaching effect, despite adequate dietary intake of copper and zinc, as confirmed by FeedXL and pasture analysis.
It’s notable that another horse, with a distinct coat type characterized by different color, length, thickness, and texture, does not experience any bleaching whatsoever. This suggests that certain coat types are more susceptible to bleaching than others, influenced by both genetics and environmental factors such as climate.
In conclusion, sunbleaching in horses appears to be a complex interaction involving sunlight, sweat, specific coat characteristics, and regional climate conditions. Understanding these factors can help horse owners better manage and protect their horses’ coats during periods of intense sunlight and heat exposure
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Draught conditions seem to be more and more common these days. Less water means less grass and hay, which raises the question: how can you feed your horse properly during a draught? Many of us in Australia have been dealing with drought conditions, increasingly we are having to turn to sources of hay outside of the commonly used lucerne, grassy/meadow, rhodes, clover, oaten and wheaten hays. Not all alternative hay types are suitable for horses however so be careful when choosing an alternative hay or chaff for your horse.
Alternative Sources of Hay and Chaff
Some suitable and unsuitable alternative hays and chaffs include:
Suitable Hay/Chaff Types:
• Well cured grass or legume silage
• Pea hay or straw
• Wheat or barley straw
• Canola hay
• Teff Hay (but don’t feed as the only hay and be aware it can be high in starch and sugars)
• Sugarcane hay (avoid for Cushing’s horses or laminitic horses)
• Vetch hay (don’t feed more than 0.5kg/100 kg bodyweight)
• Barley hay/chaff (feed with caution if it has intact seed heads with long awns, avoid for Cushing’s horses or laminitic horses)
• Triticale hay/chaff (avoid for Cushing’s horses or laminitic horses)
Unsuitable Hay/Chaff Types:
• Lupin hay (may cause lupinosis)
• Sorghum/forage sorghum hay (may cause prussic acid or hydrocyanic acid poisoning)
• Red clover and alsike clover hay/chaff (may cause liver damage and photosensitisation)
Regardless of the hay type you do choose, ALWAYS make sure it is clean and free of mould. If the hay is dusty, it should be dampened down prior to feeding.
And remember, all these different types of hay will affect what else you need to feed to keep diets balanced and meeting requirements. This is where FeedXL can help. Simply enter the hay you are feeding and check that your supplementary feeds and supplements are still able to meet requirements! Even with all the changes of hay, keeping the diet balanced will keep your horse glowing and in pristine health!
Sand and Dirt Accumulation
Horses naturally eat quite a bit of soil! Under normal circumstances however the large amount of fibre moving through their gut acts to move the sand and dirt through their gut and out in their manure… so normally it won’t accumulate. When feeding your horse in a drought however, the amount of soil they eat increases due to grazing very close to virtually bare ground. And often the amount of fibre they have access to is reduced. So, it’s a double whammy… more sand and dirt in their gut and less fibre to clear it. This situation often results in accumulation of sand and dirt, irritation of the gastrointestinal tract and colic or diarrhea.
The best way to clear sand and dirt from a horse’s gut is to feed lots and lots of hay. But this isn’t always possible during a drought. An alternative and also very effective way of clearing it is to feed psyllium husk. Psyllium husk is a fibre that absorbs water in the gut and turns into a really stick goo (technical term!) that is able to shift sand and dirt out of the gut.
For those of you who would like to use psyllium without nasogastric tubing it, we have good success feeding 50 grams per 100 kg of bodyweight per day. Feed it in a single meal, for 5 days in a row, mixed with something your horse loves the taste of. Make the feed very, very slightly damp then tip the psyllium in and mix it around. Don’t wet it too much as most horses don’t like the taste and/or texture of wet psyllium. If your horse was showing signs of sand or dirt accumulation (mild colic or diarrhea), give the horse a break for 5 days and then repeat the 5 day treatment. You can continue to do this as long as you feel necessary.
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Anhydrosis, or the inability to sweat, is a serious condition that affects horses in hot and humid climates. Horses rely heavily on sweating to cool themselves down and keep their core body temperature within a normal range. Sweat wets the horse’s skin and then as it evaporates it takes heat with it, effectively creating an evaporative cooling system for the horse.
In some horses however, for reasons largely still unknown a horse’s sweat glands either partially or fully quit producing sweat. These horses find it very difficult to stay cool and need to resort to offloading heat via their lungs by breathing harder and faster than you would expect them to, which is why horses with this condition are often said to ‘have the puffs’.
In many situations though, puffing is not effective enough, so horses that can’t sweat are at serious risk of hyperthermia which wreaks all sorts of havoc in the body and if not dealt with effectively will eventually result in death.
The right feeding strategy may help
While we don’t understand what causes anhydrosis it does appear that for some horses, certain nutritional strategies can help. Tips for feeding horses with anhydrosis include:
1. Always meet electrolyte requirements in the diet
It is likely some horses stop sweating simply because they run out of electrolytes. The major electrolytes found in sweat are sodium, chloride and potassium. The two most commonly deficient electrolytes in a horse’s diet are sodium and chloride and these are the components of ordinary old salt.
Use FeedXL to assess your horse’s requirement for the electrolyte minerals and use plain salt and/or an electrolyte supplement to meet requirements. Horse’s on forage-based diets should be receiving lots of potassium from their forage so in most cases all you need to add is plain salt.
2. Always provide access to free choice rock salt
A horse will seek salt out when it knows it needs it, so providing free access to loose rock salt allows them to eat as much or as little as they need to meet their requirements.
In very hot and humid climates avoid the use of salt blocks as it is difficult for a horse to lick enough salt off to meet requirements when they need a lot of salt.
3. Feed controlled amounts of protein
Diets that are too high in protein have a couple of negative effects on horses that can’t sweat.
The first is that protein generates a lot of heat during the process of digestion and metabolism which adds to the heat load a horse needs to get rid of to keep its body temperature normal. For most horses this is usually not an issue as they are able to sweat and easily dissipate the excess heat. But when a horse isn’t able to sweat, it just makes their job of staying cool even more difficult.
The second is that when protein is fed in excess the horse needs to get rid of the excess nitrogen contained in the protein. In a healthy horse the kidneys perform this task without hassle. BUT a lot of water and electrolyte are excreted with the nitrogen, so potentially it can lead to dehydration and electrolyte deficiency, neither of which will help a horse that can’t sweat properly in the first place.
To keep protein in diets low, restrict the amount of forages and feeds that are high in protein like lucerne, copra meal, lupins, faba beans, sunflower/soybean/canola meals, pollard and rice bran and rely more on grassy pasture and hay, oils, low protein fibres like beet pulp and lower protein cooked cereal grains (where it is safe to do so). FeedXL will help you to keep track of the amount of protein in your horse’s diet.
4. For horses in work, consider using a lower forage diet
When the fibre contained in forages is fermented in the hindgut a lot of heat is produced which then increases the amount of heat a horse needs to get rid of to keep its body temperature normal. By reducing the amount of forage and therefore the amount of fibre in a diet you will reduce the heat load placed on a horse.
To maintain the horse’s required energy intake you can add oil (the best option as it produces the least heat) and/or cooked grains to the diet. It is essential that you feed well-cooked grains, with extruded grains being the best option, as the starch contained within these grains will be digested in the small intestine. Feeding uncooked or poorly cooked grains will lead to a lot of fermentation and heat production in the hindgut and should be avoided for all horses in hot climates.
Please note: Never reduce forage intake below 1 kg/100 kg of bodyweight and be mindful of the increased risk of stomach ulcers for horses on low forage diets. Using slow feeders is highly recommended. It is also essential to have your horse’s stomach full of forage before it is worked.
5. Make sure the diet you feed is balanced
There is some anecdotal evidence to suggest that some mineral and vitamin deficiencies may contribute to a horse’s inability to sweat. The best way to counteract this is to make sure what you are feeding is meeting all of your horse’s requirements for macro and trace-minerals and vitamins. FeedXL will make sure you can achieve this!
If you have a horse with anhydrosis it is strongly recommended you seek veterinary advice. Aggressive environmental management of these horses to keep them cool is the best way to manage their condition.
Useful anhydrosis management strategies include:
1. Always provide access to shade and cool to cold drinking water.
2. Keep them under fans and water misters where possible during the day.
3. Turn them out at night only if possible.
4. Only work them if your veterinarian advises it is safe to do so and then only work them during the very early morning when it is coolest and only to the level they can comfortably handle.
5. Cool them down quickly and effectively with hosing and fans post work until their rectal temperature has returned to normal.
6. If these strategies aren’t effective in keeping your horse’s body temperature within a safe range, the horse will need to be moved to a cooler climate.
Often, and again for reasons we don’t understand, horses will start to sweat again when they move to a cooler environment.
Do you have a question or comment? Do you need help with feeding?
We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!
