A Fungus Amongus

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Last Updated on Friday, 04 December 2009 16:17 Written by Kim

 

Thrush dominates the barefoot forums around the world.  It appears to be the downfall of all potentially sound horses, the reason why your horse isn't a gravel cruncher.  I'm here to tell a different story, despite what my compatriots have to say.

Yes I believe thrush exists, but not at the levels many folk seem to think.  I have come to believe what Tom Stovall, CJF has been saying for years it is a management problem way more than anything else.  Moisture in your pastures is a problem, but it isn't the cause of thrush.  Poor trimming or a horse standing in manure or urine can cause thrush.  

Dawn Saunders, AHA Member sent this email to me and with her permission I have reposted it here.

"Thrush" is an invasion of naturally occurring anaerobic fungus and bacteria.   Their job in nature is to live on dead cells (otherwise we would all be knee deep in shed cells!!), if there is an ingress point on the foot, the fungus will enter and set up house and its little bacterial pals, fusobacterium necrophorum being one, will follow as they live on the "fungus pooh" for lack of a better description.  The fungus multiplies slowly and does not like oxygenated blood so stays away from vascular tissue, the bacteria multiply faster than the immune response and will attack live tissue, which then becomes necrotic tissue for the fungus to live on and so it continues.......... working it's way into the foot.

I disagree with those who say that high blood sugar causes thrush, see Dawn's excellent explanation above, however a horse on a high carb diet is going to have an unhealthy hoof, which can create an ingress point. 

Later in this article, I'm going to include photographs of feet with actual thrush and you will see how poor the foot form is, or the housekeeping.  Fix those issues and most times, thrush goes away.  Ruth made an interesting discovery last month.  She lives in Arizona and her horses are on hard dry Arizona ground.  She keeps their living area clean, or so she thought!  One horse was starting to develop thrushy feet.  She thought it was boot related, at first, she felt the heat from the boots combined with the sweaty foot was creating a moist environment that was conducive to opening the door to fungus and bacteria.  She stopped using the boots but the problem seemed to still persist (despite the dry environment).  One day as she was cleaning his pen she discovered that he was peeing in the same place and while the ground looked dry, it actually wasn't.  She shoveled up some of the dirt to find an area wet from urine.  This is where this horse liked to stand AND by doing so he was creating his own thrush problem.  She shoveled and cleaned that area and continues to do so on a daily basis and his "thrush" has gone away. She didn't soak his feet, she didn't use any magical cream, it just went away. 

I've recently read on the internet where some trimmers, are telling people that their horses out West have "Dry Thrush".  From what I understand there is no such thing, thrush needs moisture of some sort.  Thrush is wet, not dry.  

Many people think a small, peeling frog is an indicator of thrush, it isn't.  Many of the photos I'm going to include will be of frogs in this shape.  Two important points are:  

  • The frog is an expression of the digital cushion, if it is atrophied and or weak, your frog will be too.  
  • When the frog sits in moisture for day after day and month after it month it will be shriveled - not thrush laden.

In my experience and those whose opinion I value and trust, actual thrush will go away with good hoof form and good housekeeping.  In other words, you can trim your way out of this.  But (and there is always a but, isn't there), if I have a horse that has a deep central sulcus infection (thrush) I treat it with either ToMorrow (cow mastitis treatment) or Pete's Magic Butt Creme (recipe at the end of the article)

Soaking hooves is a recipe for disaster (most times, I will not say always or never).  Soaking for months and years on end is damaging not only to the hoof but to the pedal bone as well.  I know many of you do it, but water is bad for the hoof.  I had discussed this with Monique Craig of the Epona Institute and she gave me the science behind this statement.  First let me give a description in layman's terms, why oversoaking is actually detrimental to the hoof and will cause a weaker hoof over time.

Keratin is a water un-soluble molecule.  Hydration of keratin (for instance hoof wall) only affects the disulfide crosslinks not the keratin itself.  The reason you have disulfide crosslinks between the two keratin helices is to increase the strength of the keratin molecule.

So imagine a ladder - the two pieces on the sides, that is your keratin.  Then imagine the rungs, those are your disulfade crosslinks.  In a dry hoof you have many many rungs(crosslinks), the two side pieces (the helices) are inflexible, you can't really bend them due to the crosslinks.  Hence why so many horses out West do so good barefoot and RETAIN THEIR SOLE.

Now add water and the crosslinks start to dissolve, imagine how flexible the two side pieces of the ladder will become.  Hence why there are so many horses with thin soles out in the East.  Water is the enemy to the hoof. 

Here is an excerpt from an article not related to hooves, but to shampoos and their effectiveness.  It succinctly explains the characteristics of keratin.

Hair is made from keratins. Keratin is a protein, and proteins are chains of amino acids. Different types of protein contain different amino acids, linked together in a different order. Keratin happens to contain lots of the amino acid cysteine, which contains a sulfur atom. The sulfur atoms from two cysteines join together, forming a disulfide bond. These disulfide bonds give hair fiber its strength. However, OH- can split disulfide bonds, thereby removing crosslinks between keratin molecules and weakening the hair. H+ does not disrupt disulfide bonds. As such, alkali solutions can weaken hair and strong alkali solutions will actually dissolve it. In contrast, acid solutions do not interact with disulfide bonds. 

Here is an email I received from Monique Craig, when we were first starting to discuss the chase of thrush and the soaking that so many seem to do. 

There is plenty of research on the alpha keratin behavior.  Actually it is even more complex than just the crosslinks being weakened.  Alpha keratin when destabilized change in structure from alpha helices to a beta pleated molecular form.  This can be caused by mechanical stress and/or too much moisture.

I know some of the big name hoof teachers recommend soaking based on Mustang research, ergo all hooves behave like Mustang hooves and have the same skin genetics.  Genetically, horses have different skin thickness and will also have different wall thickness.  If you have a thin skinned horse, I would say look to the hooves to be thin walled, they go hand in hand.  I have been out West and looked at feet, they are overall more sound than those I see here.

That’s what started me thinking about all this obsessive soaking.  Reminds me of when Anti-bacterial soap first came out.  I never use the stuff, it worries me how much people apply it to their skin.. Same thing.  I think humans think a little bit of a good thing means even better with a lot of a good thing :D

I would suggest to anyone who finds themselves continuously battling “Thrush” to send a sample to a lab to determine which type of bacteria or fungus you are attempting to treat. This is something that your vet can do for you. This info would help you to use the correct treatment immediately as it takes out some of the guesswork and the length of treatment. My preferred method of treatment does not involve soaking. If you remain unconvinced I suggest you try soaking only one front foot, document the changes on both feet, then take a look at the results. I have often wondered if what some people think are improvements are actually water-logged frogs and walls, combined with their knowledge of better hoof form.
 
Recently a fellow hoofcare professional started working on a horse whose hooves had been soaked for a year in an attempt to treat Thrush. The horse now has Pedal Osteitis and thin soles-which we believe to be a direct result of repeated soaking.
 
Not to beat a dead horse, but if you can take one piece of advice after your reading it would be to STOP SOAKING FEET. And IF you feel an overwhelming need to treat for CSI (Central Sulcus Infection) or Thrush, use a paste treatment and not a water-based treatment. 

Here are photos of a variety of hooves, I've listed in the description which is thrush and which isn't, along with comments about each foot.  Click on the photo box to open the slideshow, to move to the next picture, click anywhere on the picture or look to the upper right for the Next button and the upper left for the Previous button.

 

 

 

 

 

 

 

 

 

 

 

 

 

The next series of photos show a very sound, healthy horse who can do her job barefoot, indoor ring/Dressage horse.  When riding out on trail she needs boots, she uses Gloves and loves them.  Bella is a 6 year old Oldenberg mare who has never worn shoes and lives in Westchester, NY.

 

 

 

 

 

 

 

 

 

 

 

 

 

This horse is no longer a client but she came out of shoes lame, progression is from October to January.  Horse was not treated for thrush, just trimmed and ridden, owner used boots for the first few months and then went bare.

 

 
 

 

 

 

 

 

 

 

 

 

Another mare, she has been barefoot for 6 years and this is what her feet still look like.  She is trimmed every 5 weeks no matter what and most times she needs it.  She is now a pasture ornament, an OTTB, 14 years old.  She used to be ridden in Old Mac's but was retired due to mental reasons, not health.  If this had been my friends only horse she would have been driven mad by our barefoot attempts as this mare is thin skinned and thin soled, no matter what we have tried.  Her horse Bella is the shown above and is very sound.  Genetics and upbringing do play a role!

 

 

 
 
 
 
 
 
 
 
 

This horse is a new client as of this week (November 2009)  His issue is definitely trim and management related.  This is my first trim, I'll make sure to follow up with photos over the next few trims, he will not get thrush treatment so lets see what happens.

 

 

 

 

 

 

 

 

 

 

 

 

 

Pete's Magic Butt Creme.

Mix equal parts in a baggie:

Triple Antibiotic Ointment, Bacitracin, Athlete's Foot Cream and Zinc Oxide.  Moosh (yes that is a word) them all together and put into a tube that has a catheter tip, I get them from my vet.  Use that to squeeze into the CSI for 2 - 3 weeks straight and you will have a happier hoof.