If you’ve read my previous blog, you now have a better understanding of hoof biomechanics. Having a healthy frog is a key component of proper biomechanics and one of the secrets to being able to perform well barefoot.

Is poor frog health responsible for lameness?

According to the American Farriers Association, 80% of horses would fail a lameness exam (2). Quite the statement but, regrettably, it’s probably true. I regularly encounter horses with short choppy ‘toe first’ strides. Although these horses show no obvious ‘head bob’ when trotted out, they are lame – it’s just that they’re equally lame on both feet. If a vet applies a nerve block in one foot, they begin to show lameness on the opposite foot, thus exposing their pain.

I also agree with the opinions of Drs. Bowker and Taylor that many vets, farriers and horse owners don’t recognize underdeveloped frogs. We commonly see weak, diseased frogs but ‘common’ does not equal ‘normal’ or ‘healthy’. It only means that most horses have never had the chance to build an adequate frog. I certainly didn’t know what a good frog was 10 years ago. The best frogs I ever saw were on wild horse specimens during an anatomy workshop at Auburn University in Alabama. Those hooves taught me what a good frog should look like and I now strive to achieve such frogs both on my clients’ horses and my own.

Examples of good frogs on domestic horses:

wide healthy froghealthy frog wide heels

Examples of poor frogs:

deep thrush

navicular

Navicular

This was a horse with navicular problems that obviously was not using the back part of his foot. The unhealthy frog was undoubtedly a contributing factor to his lameness issues.

How do wild horses develop such good frogs?

Simply put: movement. Lots and lots of correct heel first movement on hard and varied terrain. Not standing in urine, manure and mud doesn’t hurt either. As trimmer K.C. Lapierre explains, proper stimulation promotes proper growth (3). Get your horses outside, people! No matter how clean your stalls are, they confine your horse (less movement, less blood circulation) and the cushy stall mats and shavings inhibit the frog tissues from toughening up. Remember that hooves adapt to their terrain. That same rule applies to their frogs. Domestic horses ridden and living on soft ground may never develop the massive tough frogs of wild horses living in arid rocky areas. That being said, they may not need them either if they are ridden in fluffy indoor riding arenas. Still, the better their frogs, the sounder they will remain over their lifetime.

Proper nutrition is also critical. When horses suffer from Equine Metabolic Syndrome (translation: they are fat!) and/or lack balanced vitamins and minerals in their diet, they often seem to struggle to fight off infections such as thrush (just like human diabetics struggle with foot infections for that matter). If you seem to be constantly fighting thrush despite good hoof hygiene, I would suggest reviewing your horse’s nutrition.

Understanding the frog inside and out

We all know how to locate the frog from the outside, but have you ever thought of which areas it helps protect inside the hoof? The frog sits under the digital cushion and between the lateral cartilages. It reaches forward towards the toe and helps cushion the area where the deep digital flexor tendon attaches to the coffin bone (P3). Let’s not forget that the navicular bone, proximal suspensory and impar ligaments sit just above where the frog narrows. This is a fragile area of the foot, and the frog plays a critical role in protecting it. Research from Dr Bowker (1) has shown us how excessive stress to the navicular area can lead to damage to the delicate impar ligament that attaches the navicular bone to P3.

hoof anatomy

Now that we know all of this, we can better understand why a thick healthy frog will help accomplish four things:
● better biomechanics as a horse will want to land on the frog as opposed to the toe
● cushioning of the delicate navicular region
● improved shock absorption and, more than likely,
● less lameness
Next time I will give you strategies to improve, maintain and develop a healthy frog.
(1) Robert M. Bowker, VMD, PhD, The concept of the good foot, it’s evolution and significance in a clinical setting, Care and rehabilitation of the Equine foot 2-35, 2006
(2) American Farrier’s Journal Nov. 2000, v.26 #6
(3) Biomechanics to a better hoof, The Horse’s Hoof, issue #31, summer 2008

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