Sebastiaan Donker

Sebastiaan Donker is an FEI veterinarian and the founder of Synovium.

Anouk Frieling

Anouk Frieling works as a nutritionist (MSc Equine Sciences).

Stal Houtzager-Kayser 

Marc Houtzager and Julia Houtzager-Kayser are the owners of the showjumping stable Stal Houtzager-Kayser. Since 2000, Stal Houtzager-Kayser has been located on Holtrustweg in Rouveen, Netherlands. Marc and Julia have been using Synovium supplements for many years.

Veronique Swagemakers

She graduated in 2004 from the Faculty of Veterinary Medicine at Utrecht University. She spent several years as co-owner of an equine clinic in Mol, Belgium, specialising in equine medicine. Since 2008, she and her colleague Sebastiaan Donker have owned a dressage training yard, where they have successfully trained many horses from a young age up to PSG and Inter II level. In 2009, she started her own equine sports medicine practice: Equine Performance Center. The combination of rider and equine sports veterinarian is ideal.

Alizée Froment

Alizée was active for 15 years in the French pony showjumping team and later in (youth) dressage, always driven by excellence and a strong connection with her horses. She spent five years as the national coach and selector of the French pony dressage team, where she taught young riders values such as respect, perseverance, and empathy.

As an artist, she created poetic horse shows and authored three books; her latest, The Horses Who Made Me, has been translated into five languages and won the Fernand-Méry Prize in 2024.

Worldwide, she develops new equipment and natural care products in collaboration with specialists. Together with Synovium, she focuses on the physical and mental well-being of horses, enabling them to perform at their best.

Stal Sprengerhorst

We are Rien, Inge & Romy van der Schaft, and together we run Stal Sprengenhorst in Apeldoorn. Here, we train dressage horses ranging from just backed to Grand Prix level and coach riders from both the Netherlands and abroad. In addition, Rien is the national coach for Spain, and Inge is the national trainer for Greece. Every day, we work to train and care for our horses in the best possible way. That’s why we want to use products that help us bring out the best in our horses. This is the reason we have been so enthusiastic about Synovium supplements for many years. Whether it’s an older horse that could use support for its tendons and joints, or a more stress-prone horse whose stomach needs extra attention, Synovium offers a suitable product for every horse, made from the highest quality ingredients. For us, the most important thing is that our horses feel their best both physically and mentally—and Synovium helps us achieve that.