Raising a healthy equine: How does my young horse grow? *H&H Plus*

On a hilly wilderness in southern Sweden, a group of warmblood fillies is busy growing up under the distant but watchful eye of former equine vet and biomechanics expert Professor Ingvar Fredricson. Free to roam over an area the size of 70 football fields, the youngsters are monitored daily, in person and with drones, and have been fitted with HoofStep sensors on their halters that measure their movement patterns and health status. The study, known as the Brösarp Project, is small-scale yet should offer an insight into how growing sport horses develop under different management systems. [subscriber-content]According to Ingvar, it has long been known that optimum movement during foalhood and beyond can contribute to long term soundness. “My main goal is to make horse breeders aware that young horses who are able to move over large areas, with different footing, grow up to be strong and durable individuals,” he explains, contrasting this upbringing with the more “static” lifestyle typical of a big breeding barn. “At auction you can buy a foal, filly or colt with an interesting performance pedigree that moves and jumps brilliantly, without knowing anything about how it has been reared. If you invest years of training in a very expensive young horse, you must be pretty sure that its performance career does not end too early due to lameness.” Ingvar points out that the window for development of quality joint cartilage closes when a foal reaches three months old, and for robust bones, tendons and ligaments at between two-and-a-half and three years – after which we can only “preserve, not improve”. His Olympic showjumping silver medallist son, Peder, shares his father’s belief that this is the way to raise horses for athletic longevity. The project is ongoing, but has already produced interesting findings. Even though grass is currently in abundance, the HoofStep app reveals the yearlings are moving between 8km and 18km per day, up and downhill, of their own accord – a far greater distance than a reference group of yearlings living on similar-sized yet largely flat pasture, and considerably further than horses kept in stables and paddocks. The Brösarp horses are chewing grass for around 11 hours per day, which is also closer to the habits of the truly wild horse than the average youngster. Such free-range management is not practical for all, of course, but the findings may add to our understanding of the optimum feed-to-exercise ratio from foalhood onwards. Just as children who sit around too much are thought to be weaker as adults, Ingvar believes that the same phenomenon exists in equines. “Foals, colts and fillies should be outside in a group, with the ability to move,” he says. “Otherwise, we will see the same decline in soundness.” Firm foundations Healthy habits lay the right foundation for the next phase of development, when a horse nears the end of what would be our teenage years. “There are so many changes after the age of three,” says Gil Riley MRCVS, pointing out that a youngster of this age equates roughly to an 18-year-old human. “A horse’s musculoskeletal system is still growing and developing; he is fully under the influence of reproductive hormones, and there is a lot of activity in his mouth with tooth development.” Gil explains that musculoskeletal development depends very much on breed. “A racing thoroughbred bred for speed at two to three years of age will be expected to perform much earlier than a warmblood, where there is not the same pressure to mature early,” he says. “The growth of bones is largely a result of elongation of areas of cartilage called growth plates, the closure of which is a measure of skeletal maturity. “The growth plates of the lower limbs close earlier than those of the long bones of the limbs, the pelvis and the vertebrae of the spine,” adds Gil. “At around three years, the growth plate in the ulna and femur in the section just above the knee and hock closes, roughly six months before the lower growth plate in the humerus and femur – the weight-bearing areas just above the elbow and stifle. “At approaching four years, the lower weight-bearing growth plate in the scapula (shoulder blade) closes. The small bones of the hock and the growth plates between the tibia and fibula, above the joint, then follow. Not without good reason did literature as early as the 18th century advise against ploughing, crossing deep mud and jumping for youngsters. “Finally, between five and eight years, the growth plates in the bones of the spine and neck (the vertebrae) close,” he says. “The larger the horse the later this happens: a warmblood horse of around 17hh will not be ‘fully grown’ until he is eight.” It has been demonstrated, adds Gil, that exercise at a young age may be safely performed and can be protective to joints. “Young horses that are exercised show an advanced and beneficial degree of joint and osseous [bony] maturation, compared those just turned out in a paddock,” he explains. “Should a young horse resist exercise, however, consider that the difficult behaviour may be a response to pain – and not purely temperament. “Lesions on the surface of joints, known as osteochondritis dissecans (OCD), are common in young sport horses and have been linked to fast growth,” adds Gil. “Pain can originate from areas including the growth plates or the mouth, from OCD in the joints, or hock or knee pain due to deformation of the small bones of these joints. “Slowly, slowly is the philosophy with regards to exercise,” he concludes, stressing the importance of an appropriate diet, regular farriery and dental checks to prevent problems later in life. One of the gang Alongside physical development, a young horse will undergo significant behavioural changes. Equine behaviourist Professor Jan Ladewig explains that in a domesticated foal, this process encompasses both natural behavioural responses and those related to husbandry. “The primary goal for the development of most behaviour patterns, both inherited and acquired, is to prepare the foal or young horse for his adult life,” says Jan. “Undoubtedly, the most important aspect of this is socialisation. Horses are social animals whose survival and reproduction depends on their belonging to a herd. “During the socialisation process, young horses learn to communicate with their peers. To maintain herd cohesion, group members need a means to solve conflicts and also to strengthen bonds with each other. Most of this communication is based on body language, a language the young horse must learn. “The learning primarily happens through interaction with herd mates during the socialisation period, which starts in the second to third week of a foal’s life. Some of the cues used in social interactions are easily discernible, such as ear direction or tail swishing, while others, such as eye direction or body orientation, are more subtle. Interestingly, unfriendly cues are easier to observe than friendly cues. “Socialisation is also important for domesticated horses, who need to habituate to being handled and touched and must become familiar with a halter and other equipment. Studies have shown that horses that are handled regularly also learn to notice peoples’ body language. “As with the development of natural behaviour, learning the right responses to handling is a matter of exposure at the right time. The advantage of socialisation this early in the horse’s life is that it is easier to teach him the correct responses before he has had a chance to develop bad habits. “Additionally, since a foal or a young horse is not as strong as an adult horse, it is possible to train him in a calmer and gentler way,” Jan concludes. “He is then more likely to develop trust in people, rather than mistrust.” Ref Horse & Hound; 25 June 2020 [/subscriber-content]