The trouble with Friesians
With its jet-black coat, powerful frame and signature high-stepping gait, the Friesian horse has become increasingly popular over the past 20 years. A Friesian named Othello played the prominent role of the stallion Goliath in the 1985 film Ladyhawke. Friesians have increasingly been favorites of Hollywood with roles in Conan the Barbarian, Eragon, The Mask of Zorro, Alexander, The Chronicles of Narnia, Clash of the Titans and The Hunger Games. This familiarity and growing popularity mean that practitioners are likely to see even more Friesian horses in their practices.
A purebred population leads to problems
With their recent popularity leading to greater demand and increased breeding with restricted bloodlines, Friesian horses are facing some significant problems that all practitioners should be familiar with. A number of suspected genetic disorders affect the Friesian horse. Identifying these problems early will aid clinicians in prompt, accurate treatment and, equally importantly, will possibly help remove these animals from breeding programs. This may be the single best step toward eliminating these problems from the breed.
Roughly 7 percent of the Netherlands' horse population is Friesians. So it's no surprise that from 1995 to 2003, 7 percent of the caseload at Utrecht University's College of Veterinary Medicine in the Netherlands and Ghent University's College of Veterinary Medicine in Belgium was composed of Friesian horses.1 What was surprising, however, was that veterinarians at these two schools began to notice a high incidence of certain clinical problems among Friesian horses—much higher than the 7 percent population should predict. Researchers from these institutions have subsequently joined with a number of private clinics in these countries and are now trying to document problems in Friesians and educate veterinarians worldwide about these conditions.
One of the best-known disorders in the Friesian breed is dwarfism. The condition manifests with growth retardation mainly in the limbs, which are 25 percent shorter than normal. A Friesian dwarf is about 50 percent smaller than an age-matched normal Friesian foal.1 This condition is easily observed because of the larger head, broad chest and disproportionately long back with short limbs.
Hyperflexion of the fetlocks and narrow, long-toed hooves are also seen in these animals. Tendon and ligament laxity varies greatly between dwarf Friesians and normal ponies, with dwarfs showing excessive looseness to these structures and, often, resultant load failure. Normal Friesians have tendon and ligament stretch properties in between those of dwarfs and normal ponies.2 Some researchers think the Friesians' increased laxity is what creates their characteristic high-stepping, dancing gait. Many of the problems currently being investigated in the Friesian breed also stem from abnormalities in ligaments, or, more specifically, from a systemic collagen-linked disorder. It would be ironic if the condition that allowed the Friesian breed to exhibit its signature movement were also shown to be behind many of the devastating problems that threaten this breed.
The Friesian registry is no longer allowed to breed dwarves, and hopefully this problem will eventually disappear. But because this condition was tolerated and dwarves were still used as broodmares until relatively recently, dwarfism is likely to remain a part of the breed's genetics for some time.