You Are Here: Home > Hoofcare > Articles > Thrush Infection in Equine Hooves
Thrush Infection in Equine Hooves
Notes from the Jan 2005 Thrush Busters Meeting
*** PLEASE FEEL FREE TO PRINT, COPY AND DISTRIBUTE THIS DOCUMENT.
*** This document was created by the Thrush_Busters hoofcare study group. For
*** information about joining Thrush_Busters, or for information on additional
*** topics, visit: http://groups.yahoo.com/group/thrush_busters
*** For a plain text version (for printing), Click Here
*** THIS DOCUMENT WAS CREATED ON: 1/8/2005
*** THIS DOCUMENT WAS LAST UPDATED ON: 1/1/2007
This paper was created as a result of the discussion on thrush in the equine hoof
at the January 8th, 2005 "Thrush Busters" hoofcare study group meeting.
The information provided on this page is a combination of the study group
member's research, experience, and discussion. This information is not meant to
diagnose, treat, cure or prevent disease. Please consult with your veterinarian
if your equine is sick, injured or otherwise unhealthy.
For many years, thrush was believed to be caused by a fungus. However, research
now shows that this condition is not a fungus, but rather an anaerobic bacterial
infection. Since many hoof infections contain more than one type of pathogen (bacteria,
fungus, yeast, etc.), determining which type a horse has can be difficult. See the
article Hoof Infections for more information
on the other types of infection.
Although there are many bacterium that cause thrush infection, the
bacteria commonly responsible is fusobacterium necrophorum. The fusobacterium
necrophorum bacteria is a normal inhabitant of the gastrointestinal tracts of
animals and humans. Since this bacteria is present in animal feces and most soil
samples, the horse's hooves will likely have regular exposure to it. The
fusobacterium necrophorum bacteria is anaerobic, which means it thrives in dark,
moist environments that have minimal or no exposure to oxygen.
Thrush most often infects the central sulcus of the frog, the collateral grooves
and along the frog/sole junction. Although not as common, thrush has also been
seen to infect the white line and sole of the hoof.
Signs and Symptoms of Thrush
The fusobacterium necrophorum bacteria causes a black, odorous, oily discharge
which is often seen in and/or around the frog, central sulcus and collateral
grooves of an infected hoof. Thrush infection often causes a foul odor, which
can be noticed when picking out the hooves or while trimming. A hoof that has
become infected with thrush may also be tender around the frog and collateral
grooves. Also commonly seen is a disintigration of healthy frog tissue.
When left untreated, thrush infection can cause bleeding, pus, inflammation and
lameness. In rare cases, thrush infection can spread to internal tissues,
sometimes requiring internal antibiotics to eliminate. If you think thrush
has spread to internal tissues (common signs are heat and inflammation in
the hoof and/or leg), contact your veterinarian immediately.
Test Your Hoof
Find A Local
IL Study Group
Thrush has commonly been associated with dirty or unhygienic living conditions.
However, this does not explain how some horses get it and others don't when
they are kept in the same living conditions (same soil, feed, management).
Improper Hoof Trimming
The equine hoof, when naturally worn or trimmed properly, is inherently capable
of self-cleaning. When proper hoof form is achieved, the heels of the hoof will
spread upon weightbearing, which will allow the coffin bone (P3) and sole of the
hoof to descend. This motion aids in the expelsion of any material which has
accumulated in the hoof. Many sources believe that the main cause of thrush is
impairment of this natural self-cleaning mechanism of the equine hoof. Most (if
not all) of the "Thrush Buster" members in attendance at this meeting agreed, based
on experience in dealing with thrush. This would also explain why thrush can be
found both in animals who are kept in healthy, clean conditions and in animals
kept in unhygienic living conditions.
When accumulated material is not normally expelled from the hoof, it prevents
oxygen from reaching the tissues of the hoof. Since we know that the bacteria
that causes thrush lives in environments that have increased moisture and decreased
oxygen, accumulated material in the hoof is likely to encourage rapid spreading
of the thrush bacteria.
The study group members agreed that the following deformities or problems will
increase the liklihood of thrush infection: contracted heels, underrun heels,
impacted bar, overlaid bar, too-high heels, untrimmed/tattered frogs.
Insufficient Natural Movement
It made sense to our members that the self-cleaning mechanism of the hooves cannot
function properly without movement. If the horse is not continually moving about,
any accumulated material in the hoof cannot be expelled normally. In addition,
without sufficient movement, bloodflow to the hoof will be compromised, which often
results in slower tissue recovery when thrush has previously "eaten away" healthy
Unhygienic Living Conditions
Horses that are kept in small enclosures or stalls have no where to walk except
on their own manure. The bacteria that causes thrush infection is found in manure
and in some soils. Neglecting to keep your horse's living environment clean can
cause more exposure to the thrush bacteria than normal.
Weakened Immune System
In the case of a weakened immune system, be sure that you are feeding a good
quality hay, and any supplements necessary to boost your horse's immune system.
Check with your veterinarian and think about doing hay analysis, water analysis
and blood work to determine any system deficiencies. Vitamins A, C, E and others
as well as echinacea and homeopathic remedies can help to boost the immune system.
Prevention of Thrush
The members of the study group agreed that the most important aspect to preventing
thrush is to maintain proper hoof form to allow for the self-cleaning mechanism of
the hoof. Most (if not all) of the members further agreed that the application of
horseshoes to the equine hoof prevents proper hoof form and/or self-cleaning
For a list of hoofcare practitioners who have been trained to trim to
achieve proper form and self-cleaning mechanism, please visit the Hoofcare Practitioners page.
To promote sufficient movement, the members of the "Thrush Busters" study group
recommended 24/7 turnout on clean, firm, unsoiled ground, preferrably with
In addition, it is also recommended that pastures, paddocks, stalls and all other
enclosures be kept clean and free from manure and urine. The smaller the enclosure,
the more frequently it should be cleaned. All enclosures should be cleaned daily,
at a minimum.
As a topical preventative, one study group member shared that she uses a mixture of
8 parts water, 1 part apple cider vinegar, and 1 part tea tree oil. She mixes the
ingredients in a sprayer bottle and sprays the hooves once per day. This spray can
also be used for abscesses and other minor injuries.
Another study group member recommended picking the hooves out daily to expose the
collateral grooves and frog sulcus to oxygen. Yet, other study group members
commented that picking should be unnecessary if the hoof's natural self-cleaning
mechanism is functioning properly.
Treatment of Thrush
If you suspect your horse has a thrush infection, the members of the study group
recommend first following the "Prevention of Thrush" advice shown above, or
treatment may be completely ineffective and/or recurring bouts of thrush may be
experienced. Then, you should discuss with your veterinarian the proper topical
and/or internal treatment necessary for your case. Below, we have listed the
topical and internal treatments that were discussed at our meeting. Please
note: it is possible that some of the topical treatments below may react if
used at the same time as another topical. For this reason, it may be wise to
use only one topical treatment at a time.
It must also be noted that the hoof may be considered by some professionals as a
metabolic organ, which excretes metabolic waste. If this is the case, it would
probably be wise to avoid applying harsh chemicals, toxins and irritants to the
hoof. It is recommended to try some of the less harmful treatments before
resorting to anything that may be harmful to living tissue.
Thrush does not clear up instantly and it may take days to weeks depending on the
severity of the infection. The most obvious sign that the thrush infection is
clearing up is the disappearance of foul odor and black, oily secretions. If the
thrush bacteria or treatments have destroyed any living tissue, the hoof may also
be tender or sore until healthy tissue is regenerated over time.
Proper trimming will allow for expansion and contraction within the hoof
capsule, and will allow the self-cleaning mechanism of the hoof to function.
When treating thrush, your hoofcare practitioner should trim away as much of
the infected tissue possible.
Promote sufficient movement in your horse by allowing for as much turnout on
clean ground as possible. Additional ways to promote more movement are to
pasture your horse with herd-mates, spread hay around, and place hay and
watering areas far enough apart to encourage natural movement to eat and drink.
Exercising and hand-walking may also be helpful.
Clean manure and urine from all living areas, and keep the horse's living areas
as clean as possible.
The mildest and seemingly most effective topical treatment is to wash the
hooves in water with a mild soap. Be sure to use a toothbrush to scrub the
crevices well, and be sure to rinse the hoof well afterwards. This cleaning
can be performed as often a needed. Some sources recommend using an
antiseptic cleanser such as Betadine.
This solution can be made from providone iodine and table sugar. Mix them
together until a paste-like texture is achieved and apply to areas of the hoof
that are infected by thrush. This can be applied daily or twice daily. It
may be beneficial to clean the infected tissue with a mild soap prior to
application. This solution has been used for years in human medicine to treat
burns and wounds. The logic behind it is that the iodine will kill off the
bacteria, and the sugar will help to suspend the iodine. It is also said to
reduce swelling and nourish surface cells. One of the study group members also
mentioned that the bacteria feeds on sugar, and that the sugar is so plentiful
that if any bacteria are not killed by the iodine, they "eat themselves to
death" or explode. WARNING: make sure that what you're treating is thrush,
and not a yeast... yeast thrives on dead thrush cells and sugar!
Apple Cider Vinegar
One of the study group members has experienced that hoof soaking in a mixture
of 8 parts wate to 1 part apple cider vinegar helps to keep bacteria from
breeding in the hoof. The logic behind this is that the pH of the apple cider
vinegar kills bacteria. Apple cider vinegar is also gentle on living tissues
and will not harm the hoof. Additionally, apple cider vinegar can help to
harden the hoof, and while soaking may help to expel any abscesses that may be
Tea Tree Oil
Tea tree oil is an essential oil that is highly anti-bacterial, anti-fungal and
anti-septic. It can be purchased at most health food stores. It can be applied
topically to the infected areas. The hoof can also be soaked in water with a
few drops of tea tree oil. In addition, tea tree oil is excellent for cuts,
scrapes, wounds and fungal infections that may exist on the horse's body.
Before applying hydrogen peroxide, wash the hooves well in water with mild soap.
Rinse well, then hold the hoof up and pour hydrogen peroxide onto the infected
tissues. The logic behind this treatment is that hydrogen peroxide will
oxygenate the tissues and kill bacteria. However, one study group member
expressed concerns that hydrogen peroxide can destroy and/or burn living
tissue. Many people have used this treatment successfully without noticeable
burning or destruction, but as a precaution, if you choose to use hydrogen
peroxide, carefully observe the tissues throughout treatment.
This product is a very powerful disinfectant, as powerful as Lysol, but is
less destructive to the tissues. It works well on bacteria, yeast and fungus.
So, if the less expensive treatments above are not working, or you aren't sure
whether you horse has a bacteria, fungus or yeast, you might want to try using
CleanTrax, as it works on all three types of hoof infections. The ingredients
in CleanTrax are unknown, however, it is possible the company may tell you if
you call and ask.
Formalin is used in a few of the commercial products available. The most well
known is Thrush Buster. Formalin, however, is classified as a carcinogen,
biohazard, and irritant so most of the study group members agreed that this
definitely should not be used on the horse's hooves. Formalin can cause
excessive hard soles, peeling, cracking and irritation. Although it is one of
the strongest disinfectants known, it literally kills living tissue. Formalin
also releases harmful fumes, which should be avoided by humans and animals.
The members of the study group seemed to be in agreement that copper naptherate
can be very highly toxic. A majority of the commercial thrush products contain
it (Coppersept, Kopertox, Coppernate, ThrushXX). Most (if not all) study group
members agreed that products containing copper naptherate should be avoided.
This ingredient is often used as a disinfectant, and is commonly found in
waterless hand sanitizers and surgical wipes. It is the main ingredient in
Hooflex thrush Remedy. Our search for information about this ingredient
yielded very limited results.
Gentian violet is an anti-fungal medicine found in many of the commercial
thrush treatments. It is used to treat thrush, candida, and other fungal
infections in humans. Although thrush is not a fungus, some believe that
the hoof becomes secondarily infected with a fungus after thrush infection.
Gentian violet is a known carcinogen, and can cause burning and irritation.
Chlorine bleach is known as the "universal disinfectant". Chlorine bleach will
irritate and burn skin, and bleach fumes can be very dangerous and may burn the
respiratory tract. It is also potentially fatal if ingested. Never mix
chlorine bleach with other cleaners, as this may create a very deadly gas.
Of the study group members who have at one time used chlorine bleach to treat
thrush, few said it actually worked. Although chlorine bleach is often
recommended by horseshoers to treat thrush, all members of the study group were
strongly against the use of chlorine bleach for thrush treatment.
Your veterinarian might prescribe oral antibiotics for your horse if the thrush
has invaded living tissue and has been introduced into the inner tissues. If
you think this has happened, contact your veterinarian immediately.
Although we all learned a lot about thrush through our discussions and research,
there are still a few questions that the study group members presented of which we
have yet to find answers for:
- Can the thrush bacteria be spread to humans? (I know some of us have
accidentally flung a piece of hoof or dirt into our mouths while trimming and
talking at the same time)
- How long can the thrush bacteria live (on and off the horse)?
- Should we (as trimmers) sanitize our hands and tools after working on thrushy
horses? In other words, can thrush be spread through our tools?
After searching the internet to attempt to find answers to our above remaining
questions, we found several documents that state that the fusobacterium necrophorum
bacteria is present in all mucous membranes in humans. Despite our search, we
were unable to find information that stated how tissue actually becomes infected.
The best we found was: "Virulence factors and pathogenic mechanisms that contribute
to the transition of this otherwise commensal organism to a pathogen are poorly
understood". However, several sources linked the infection to gingivitis,
menengitis, and abscesses of the mouth. Below are a few of the links we read:
For additional information about bacteria/thrush, fungus and yeast infections in
horse's hooves, view the article Hoof Infections.
Thrush_Busters Yahoo! Group
Illinois Barefoot Hoofcare Study Group Homepage
Much thanks to all the members of the Thrush Busters study group who attended the
January 2005 Study Group Meeting! This information would not be here without you!
NaturalHorseTrim Yahoo! Group
Group with over 2000 members (horse owners, veterinarians, hoofcare specialists)
Search the group messages for the word "thrush" and you'll find a lot of
information that is based on practical experience
Northern Virginia Equine, Stephen E. O’Grady, DVM, MRCVS
"Background on Thrush and the Hoofs Self-Cleaning Mechanism"
American Farrier's Association, Danvers Child, CJF
"Thrush: Beyond Cleaning Stalls"
Horsekeeping Books & Videos, Cherry Hill
The Horse, Michael Ball, DVM
"Phew! Stinky Feet!
Horse Illustrated, Kara L. Stewart
"Something Foul Afoot"
The information on this site is not meant to diagnose or prescribe for you. This information is not intended to be used as medical advice and is for informational purposes only. Cheryl McNamee-Sutor is a certified mentor hoof groom, wholistic bare hoof specialist, horse trainer, reiki practitioner, and an educator and distributor of therapeutic-grade essential oils; NOT a licensed doctor or veterinarian. If you are sick, injured or otherwise unhealthy, please consult with a licensed doctor.