25/09/2025
Thrush and Frogs
Frog
If the frog is atrophied, small or misaligned, the fundamental issue usually involves the frog and the heels of the hoof capsule, not being on or close to the same plane.
It is not always to do with the frog being out of alignment or encased by the collateral grooves, it can also be to do with bars, sole, hoof wall and heel height.
Correct all those things and the frog, with its amazing elasticity, will realign itself, often within a matter of days.
Every part of the hoof matters, regards balance and correct movement.
The horses frog is similar in its cellular makeup to skin and therefore undergoes a process, whereby older cells shed naturally over time.
The process involves the outward migration of epidermal cells that slowly die and accumulate keratin.
Keratin holds the dead cells together into a structural, protective, tough covering.
The frog is a structure made up of tissue, with a dermis and epidermis and exfoliates naturally.
Shock Absorption
When the hoof lands, the frog helps dissipate some of the force away from the bones and joints.
Blood Flow
The frog plays a major role in pushing blood up out of the foot.
There are no muscles in the lower leg or hoof and the venous plexus, right above the frog, plays a huge part in pushing blood back up to the heart.
The venous plexus is a vast network of veins, located on both sides of each of the lateral cartilages and in the sensitive structures of the foot.
The compression of these veins by the plantar cushion (same structure as digital cushion), against the lateral cartilages and the coffin bone, against the hoof, all act as a pump, to force the blood up the leg and back to the heart.
When the horse puts a hoof down, this dissipates concussion, the blood is squeezed out with the impact and travels back up the leg.
Protection
The frog helps shield the sensitive digital cushion, the soft tissue beneath the sole, that separates the frog and the heel bulb, from the underlying tendons and bones and the deep digital flexor tendon above it.
The horse’s heels have sensory nerve endings, similar to those of the human finger tips and the frog likely has a role with proprioception, that is the awareness of where the horses feet and body are.
How the horse actually puts it’s hoof down, may be partly due to the frog feeling the ground conditions, regards how it will land, a concept researchers are currently studying.
Traction
The frog also provides traction on various surfaces.
We see this in snowy and icy conditions, when barefoot horses have better grip than shod horses, the same on the roads, unless the shod horse has special traction devices.
The frog corium produces the frog.
The frog calluses, adapts and exfoliates itself.
The frog is used for proprioception, as a shock absorber, brake and weight bearing surface.
The whole hoof, frog, soles, bars, heels and the heels, quarters and toe of the hoof wall, are all weight bearing surfaces of the hoof.
Break over happens the second the heels leave the ground and occurs all round the hoof.
Thrush:
Thrush is a bacterial infection, that occurs in the tissue of the frog.
Some horses are more predisposed to it than others.
To cure and prevent thrush, you need to trim in a way that promotes healthy frog growth and remove any dead frog, that’s causing an issue or harbouring any bacteria.
Here’s How It Happens:
The disease begins, when bacteria penetrates the outer horn (epidermis of the frog).
As it progresses, the frog tissue deteriorates, looking uneven, ragged, smelly and possibly with a cheesy like substance.
In severe cases, the bacteria can reach the inner dermis (frog corium that grows the frog), the sensitive tissues beneath the frog.
This causes pain and lameness, it can also affect the digital cushion, P3 and other structures within the foot and produce a black paste like substance.
Contrary to popular belief, thrush is not caused directly by wet, muddy conditions, such conditions just aggravate the original cause.
Thrush often develops in horses with unhealthy frogs and compromised hooves.
You can put a horse with healthy frogs in the worst possible conditions, for example, excessively damp or wet, muddy conditions and they will rarely get thrush.
On the other-hand, some of the most pampered horses get thrush (despite their immaculate surroundings), because the frogs aren’t healthy.
A healthy well-formed frog is usually broad and well callused, sharing the load-bearing function with the other structures of the hoof, this helps to absorb concussion (think of the tyres of your car).
The frog also aids traction (acts as a natural brake).
This in turn stimulates continued good frog health.
A healthy frog also has a natural self-cleaning mechanism and when it comes into contact with the ground it expands, pushing accumulated dirt and debris out of the central sulcus and the collateral sulcus on each side of the frog (making up one side of the collateral groove).
You can see this in action, when the hoof leaves behind its own round compacted clump.
An unhealthy frog, often recesses or disappears from the surface level of the rest of the hoof and is often smaller in size than it should be.
This can also occur from trimming issues, such as really high heels, therefore the caudal (back) part of the hoof, is not engaging with the ground, peripheral loading (weight only being loaded onto the outer hoof wall) and genetics such as a clubfoot.
The unhealthy frog does not share the horses weight load, so it shifts too much of the load back onto the heels of the hoof capsule, this then limits the frogs contact with the ground, thus reducing stimulation from the ground and causing the frog to atrophy.
It can also be caused by over trimming the frog, therefore stripping it of it’s natural protective callous.
Different treatments seem to work in different places and no one cure suits all, it can vary.
You can treat mild thrush with a solution of apple cider vinegar and water, soak the hoof 20-30 mins each day and apply solution a couple of times a day, into all the creases and grooves, with a spray or syringe.
You can also use green clay with tea tree oil, eucalyptus oil and honey, making sure it’s packed well into grooves and creases.
You can make a dressing with honey or make a eucalyptus and tea tree oil solution.
Soak the hoof in salt water and apply dressing.
Honey, is a favourite of mine and also good for burns and wounds, it prevents blistering and scars and for wounds it prevents white hair from growing back.
As with every hoof, the cause of the issue needs to be addressed correctly and prevention is always better than cure.
Check your horses hooves regularly.
