In summer the horse’s body takes in less feed, because digestion generates extra metabolic heat. In hot weather its priority is to keep its thermal balance, not to process large volumes of food. In addition, the loss of electrolytes in sweat can lead to mild dehydration, and one of the first signs of dehydration is precisely a reduced interest in eating. Heat stress also affects gut motility, slowing it down, which can cause a feeling of heaviness and a reluctance to eat.
A drop in appetite is one sign that the horse is coping less well with high temperatures. Other signs are lethargy, drinking less, dry and hard droppings, faster breathing, and skin that is slower to return to its normal position after the “skin tent” test. The longer this goes on, the more dehydrated the horse is – 5 seconds means things are not right and we need to act as quickly as possible.
Electrolyte levels have a large effect on appetite in hot weather. In sweat the horse loses sodium, potassium, chloride and magnesium, and a shortfall of these lowers thirst and reduces the desire to eat. It is then worth using electrolyte supplements to prevent this. Electrolytes are best given after training, when the body is starting to return to normal. Constant access to a salt lick is just as important, although most horses stop using it as soon as the salty taste has satisfied them. A salt lick alone is often not enough in hot weather to replace mineral losses fully.
On hot days it is best to feed horses at the cooler times, that is morning and evening. It is also a good idea to give smaller but more frequent meals, so as not to burden a digestive system that is already working more slowly. It is worth limiting concentrates that are rich in starch, because digesting them increases heat production. Better choices are feeds high in fibre – hay, grass nuts, a mash or sugar beet pulp. When appetite is lower, additions that improve the taste and structure of the meal, such as vegetable oils, also work well. A fresh smell and a slightly moist consistency are often enough to overcome a summer reluctance to eat. It is also worth checking hay quality regularly, because in high temperatures it quickly loses its freshness and aroma, which can put the horse off still further.
For a horse to reach for its feed more willingly, it has to feel comfortable, especially when temperatures are high. The right environmental conditions matter enormously here. In hot weather the horse must have access to a shady, airy place where it can rest out of the blazing sun. Fresh water at 8–15°C is just as important. Water that is too cold can cause discomfort, and water that is too warm puts the horse off drinking, which further reduces appetite.
To sum up, a reduced appetite in hot weather is a natural response of the body, but the right feeding, proper supplementation and attention to thermal comfort can limit it considerably. A well-planned summer diet based on fibre, electrolyte replacement and fresh, palatable feeds will help your horse stay healthy, energetic and willing to eat even on the hottest days! ☀️