In The Media

English translated version: DOSSIER YOUNG HORSE REARING Thursday, June 5, 2025 Looking for Rearing: Between Practice and the Ideal World “Young horses that grow up only with peers learn to survive, but not how to behave socially with ease.” After weaning, many foals go to a rearing facility—a place where, ideally, they grow up safely and healthily until the age of three and are ready for the rest of their lives. What considerations can you make when choosing a rearing facility? We have created a checklist and asked experts for their views from both science and practice. According to Kerry M. Thomas, a ‘suitable family unit’ is the ideal place to grow up. In such a mixed herd, horses learn things they can only learn from other horses. “Don’t be afraid to let horses just be horses,” says Kerry M. Thomas. Unlimited roughage of good quality is very important during rearing. The type of concentrate feed should ideally be determined based on the composition of the roughage. Contact with older horses is important for young horses during rearing. “That works better than a ‘kindergarten class without a teacher’,” says Machteld van Dierendonck. Rearing Checklist Ideally, rearing provides the following elements (in random order): Sufficient free movement Social contact Good nutrition Adequate supervision Proper worm management Rest & cleanliness Up-to-date vaccinations Interaction with humans Notes from Experts Sufficient Movement: Movement is essential for a growing horse. Preferably, pasture year-round, supplementing with group housing and paddock time in winter. Science tells us there is a balance: too much movement can cause early injury, too little can hinder the development of joints and tendons. Social Contact: Mixed groups with adults work best; it helps develop healthy social behavior. One or two social adults without offspring in the group provide stability. Nutrition: Young horses have different nutritional requirements than older horses. Unlimited good roughage is crucial; concentrate feed must be tailored. Supervision: Regular checks prevent many developmental problems. Increasingly, surveillance cameras let owners monitor remotely. Worm Management: Essential for young horses’ development. Sufficient pasture is helpful. Cleanliness & Fresh Air: Important since young horses’ immunity is still developing. Keep their environment as clean and fresh as possible. Vaccinations: Most facilities require core vaccinations (such as strangles, influenza, and rhinopneumonitis) to keep infection pressure low. Human Interaction: Exposure to humans should be gradual and not overwhelming; regular short interaction is beneficial for preparing for training later in life. For 1: What is ‘sufficient exercise’? We now know that exercise is essential for a growing horse. In the Netherlands, day and night in the pasture is common in the summer, but in the winter this is usually not possible. Many young horses are then kept in a loose stable during rearing and are also put in the paddock. But how often, how long and how much do they exercise then? And how much exercise is necessary? Harold Brommer, professor of equine surgery and orthopaedics at the Faculty of Veterinary Medicine, Utrecht University: “The question ‘what is sufficient exercise for an animal in rearing’ is not so easy to answer. It is a balance in which too much exercise during rearing can cause premature damage to injury-sensitive tissues (articular cartilage, tendons) and too little exercise provides insufficient conditioning of these tissues, making them more susceptible to injury later in life. But what exactly and concretely the balance should be translated into practical implementation, science does not tell us.” Pasture Brommer continues: “In general, pasture is the best. If there is a bit more exercise than pasture, so pasture with a few extra sprints in the pasture, then the conditioning process of cartilage and tendon tissue proceeds faster without necessarily causing premature damage. However, if the number of sprints is too many or too intensive, damage can occur. But when the number of extra sprints is too many or too intensive, no one can substantiately indicate.” No less “ On the other hand: if a young, growing animal gets less exercise than pasture, the conditioning process is slower. This can be made up for to a certain extent/age, but after three to four years, hardly anything happens in terms of conditioning of cartilage and tendon tissue. But if it is asked how much less exercise from pasture then causes how much delay in the conditioning process, then no one can substantiate this either. The age of the horse is also important in this. The metabolism of tissue is much higher in the newborn foal compared to, for example, a two-year-old. Deviating from ‘the ideal amount of exercise’ will therefore have more impact on a foal of five or six months old than on a two-year-old.” Compromising on hardness René van Weeren, emeritus professor of equine musculoskeletal biology, also emphasises the importance of sufficient exercise: “Exercise is very important, especially for young horses during rearing, because the musculoskeletal system is still developing. In fact, the ideal standard is: 24/7 free movement. This is difficult to achieve in Dutch conditions in the winter, and a loose stable is better than a box, but you can say that once or twice a week in a paddock (and how big is it?) is far from ideal. I understand that it is not always easy from a business perspective, but I really think that with such a regime you compromise on the hardiness of the horse you are rearing, which means that (on average of course, there are always exceptions) the susceptibility to injury is greater than when you make the extra effort – and incur costs – to give them more exercise.” Re 2: How do you organise ‘social contact’? At most rearing farms, foals of the same age and sex are grouped together. After weaning, the foals are often first given a buddy, after which they enter the larger group in pairs. Is that the best way to lay the foundation for a social horse? Machteld van Dierendonck, clinical ethologist and animal welfare expert: “In rearing, science advocates mixed age groups with adult animals. That works better than a ‘kindergarten class without a teacher’. An additional advantage is that the horse that is initially at the bottom of the pecking order will automatically move up when young animals join. This prevents horses that are dominant for three years and are not used to being counterbalanced, and horses that are the loser of the group for three years. One or two social animals without offspring in the group also provide stability and peace here. An ideal task for a horse that can no longer be used in sports due to an injury or age, for example.” American Kerry M. Thomas, who specializes in horse behavior and the application of cognitive theory to training, selecting, and breeding horses, agrees. “The first years of a horse’s life are crucial. From a herd dynamics and psychological development perspective, there are things that only other horses can learn – such as true communication and life skills that come from the laws of nature, where mutual dependence is central. The balance between innate strength and vulnerability is a binding factor in herd psychology.” According to him, a ‘suitable family unit’ is the ideal place to grow up. “Suitable means: emotionally connected in a proper hierarchy – because in nature a herd is not counted in numbers, but in emotional connections.” Sufficient space is very important. “That is important to be able to move freely and to be able to separate from each other when desired. This reflects nature, in which the stallion rarely stays close to the family group all the time. In cases where the ‘men’ are geldings, that is less of an issue, but even then I recommend building in sufficient space.” No negotiation or nuance When it comes to growing up with peers, Thomas says, “This is common in the domesticated world, but it’s far from ideal. An immature brain that naturally relies on older family members to develop suddenly becomes isolated without them—as if it’s been put on an island. Of course, they’re still developing, but their psychological growth patterns are interrupted. Young horses that grow up only with peers learn to survive, but not to move smoothly socially. They don’t learn negotiation or nuance like horses that grow up with adult peers. It’s like putting a six-year-old in a group of other six-year-olds on a playground with only one teacher. They learn, but based on the environment they’re in. Horses, like us, are very susceptible to their emotional environment.” Re 3: Does the owner understand horse feed? Young horses have different nutritional needs than older horses. A lack of essential nutrients can seriously hinder the horse’s development and health. Knowledge of feed is therefore essential at a rearing location. Unlimited good roughage is very important, in addition the type of concentrated feed must be determined. In this way the ratio between the different nutrients such as proteins, vitamins and minerals is consciously coordinated, so that the young horse can develop optimally. At 4: Is there sufficient supervision? With good supervision and regular (preventive) checks, many problems in the development can be prevented. Regular checks on the hoof development and timely involvement of the farrier, for example, prevent abnormal hoof shapes and can contribute to the prevention of problems with the foot axis. More and more companies work with camera surveillance, whereby owners can also watch. At 5: Is the worm management under control? In foals and young horses, worms can cause growth retardation, weight loss, severe colic or diarrhoea with possible death as a result. Good worm management (manure examination, deworming) is therefore a must. Sufficient available pasture land also plays an important role in connection with the possibility of grazing horses sufficiently. At 6: Is it clean and fresh? Cleanliness and fresh air are important because the young animal still has to develop its immunity. By building up this system as gradually as possible, the young horse will remain as healthy as possible. At 7: Are the vaccinations in order? Most rearing companies require a number of vaccinations. Vaccinating against strangles, influenza and rhinopneumonia before and during the rearing period helps to keep the infection pressure on the company low. An outbreak of strangles or rhino, for example, cannot always be prevented in this way, but it will be less severe. At 8: Is contact with people important in the first three years? Because of exercise, space, grass and social contact with other horses, rearing in a nature reserve, for example in Germany or France, is attractive. But is it also important that horses are regularly handled by people in those first years? There are rearing companies that pay special attention to this, by occasionally taking a horse out of the group and getting it used to certain ‘human things’. Machteld van Dierendonck is in favour of this. “As far as I’m concerned, the horse stays in a group until it’s about three years old. But in the meantime, you can start with simple exercises in hand, in or next to the group, or games with objects (a tarpaulin!) and, for example, short periods of getting used to the stable (with friends and food), etc. Do it gradually and over a longer period in preparation for saddle breaking.” Not pushy Kerry Thomas also thinks that’s a good idea, as long as it’s not too much. “Human physical contact can be very healthy, as long as it’s never pushy or too demanding – especially in early life. The duration of physical interaction is also important. Spending too long on a physical exercise to ‘learn’ something can quickly be experienced as negative by the young horse. A natural rule of thumb is: too much time = too much emotional pressure.” “It’s very valuable to expose young horses to different stimuli, even if it’s just on the same terrain. Move them around, let them explore. It enriches their lives enormously.” But ‘just being a horse’ is the most important thing in those first years. “Don’t be afraid to let horses just be horses. They will play, fuss, fight, learn from different surfaces, smells, environments, etc. – all by just being horses.” More from Kerry M. Thomas American behavioral scientist Kerry M. Thomas will come to the Netherlands later this year. Stay informed via www.paardenluisteren.nl from Nieske Pohlmann-Fles or visit his website: www.kerrymthomas.com.