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Thrush, Solar Abscesses and Bruises; A Pain in the Foot

The equine foot is one of the most common sources of lameness, often contributing up to 80% in most cases.  Many times, the pain originates in the foot or hoof, then transfering up the limb to create secondary lameness concerns.  Three of the most common sources of frustration and lameness in the foot are abscess conditions, bruises and thrush, not excluding white line disease.  They are very common but continue to plague many horses on a daily basis, proving difficult to remedy at times.  As with most cases, with a better understanding of the conditions, we stand a better chance of success in regards to management.

Lameness is one of the most common presenting conditions in the horse, originating from a variety of locations and causes.  In a high percentage of those cases, the foot is tightly connected, either primarily or secondarily.  As the saying goes, ‘no foot, no horse.’  Foot lameness can be very frustrating to contend with for all of us, myself included, but with a better understanding as to why these things are happening, we can do more to prevent and even manage. Unfortunately or fortunately, dependent on how you look at it, the foot is a live, growing piece of tissue with many working parts.  On the downside, this means that in order to improve certain conditions, we need growth, which takes time. On the upside, this growth is a fantastic thing as it allows us to remedy and improve that situation.  In all too many of these cases, we get in too much of a hurry to remedy the problem at hand, instead of giving it the proper time and approach that is truly required.

The hoof is a living structure, composed mainly of proteins in the form of keratin and also fatty acids, which provide a layer of moisture protection. The hoof tissue is not far removed from our own finger nails, with our cuticle region being analagous to the coronary band region, in regards to new hoof growth moving downward in direction.  The newest hoof tissue is located at the top of the hoof, while the oldest is at the bottom.  The average time for complete hoof regrowth is on average 4-6 months, dependent on certain variables.

In order to have a strong, healthy foot there are really four main factors at play, from my point of view.

  1. Proper diet and nutrient provision
  2. Proper gastrointestinal health for digestion and nutrient absorption
  3. Proper blood circulation for tissue health and nutrient delivery
  4. Proper hoof trimming, balance and load bearing

All these factors play a role in hoof health and if even just one of them is out of balance, the foot can be compromised, opening the door for lameness issues. The foot is so important, that I cannot over emphasize this enough. It should be evaluated in every case of lameness and ruled out as a contributor, but sadly, the foot is often overlooked.  Even when we do ‘see’ the foot as the cause, finding weaknesses and even sources of pain, we don’t always approach the problem in the best manner, often applying ‘bandaids’ to quickly cover up the problem.  In fact, what we need is time and the right approach to allow that foot to heal and to grow, becoming stronger and healthier.

The three main problems impacting the equine foot; abscesses, bruises and thrush.  They can be frustrating to manage and I am not immune to this frustration in my own horses or patients.  Sadly, many horses have had these problems for years and that ‘stage’ has been set for quite some time. As much as we want these patients to improve overnight, many do not. We may be able to quickly resolve the immediate concern but more importantly, we have to see the reasons as to why this happened.  Resolving those underlying factors is the challenge and what takes time.  If we truly want to improve the situation, we have to take the time that is needed.  If we do not, then likely those problems will recur for most. Unfortunately, in many cases, we have permanent challenges which often include decreased blood circulation to the foot for various reasons or even impaired GI health.  This can slow and even deter our chances of recovery, but despite these contributors, there are ways we can improve that situation.  There are always answers and solutions for better management.  We just have to keep seeking and knocking on doors.

One of the most important things that I can tell you, as a horse owner, is that there is a reason for the condition you are dealing with, often over and over. We can’t just think that thrush, an abscess or even a bruise develops, like catching a cold.  This simply is not true.  There is a ‘weakness’ that is present that is opening the door for that problem, especially if the problem is ongoing.  It is that ‘weakness’ that we must see and address through the best means possible, to improve the situation for the long term.

Solar Abscesses:

An abscess is simply an accumulation of bacteria, generally in a pocket of sorts, creating a localized infection.  Often, the body will recognize the infection and create a ‘wall’ around the infection to prevent further spread.  This is common in other areas of the body, such as in puncture type wounds.  The wall is the body’s defense mechanism, helping to protect the rest of the body from the infection.  As a result of an abscesss, discharges are produced, bacteria multiply in number and inevitably, pressure is produced due to the confinement.

Horse hoof with wall separation
Horse hoof with wall separation

Hoof abscesses may also be referred to as solar abscesses or even subsolar abscesses.  Simply put, they are an abscess, a bacterial infection that has developed and creating pressure within the hoof capsule.  This pressure then leads to pain for the patient, often pretty severe to the point where they are barely willing to put weight on the affected foot.  The bacteria generally enter at the white line region, usually at the sole level.  In order to do this, the white line must be ‘open’ or weakened to some degree. This is common post trimming as the white line is ‘opened’ due to passing of the rasp. A horse that develops a significant lameness within a 7-10 day window post trimming should have an abscess ruled out.  Other contributors are weakness of the hoof integrity and white line due to too much moisture exposure.  This is noted in horses that are kept in wet conditions, either inside or outside.  Horses that are constantly exposed to mud due to heavy rains or snows are at higher risk of abscessation.  Likewise, horses that are stall bound are at higher risk due to being exposed to urine and even fecal material.  The hoof is ideally meant to be dry and with dryness, strength and integrity are improved.  However, moisture is also needed, so essentially we have to have a balance between the two.

Abscess will form and are very common in the horse.  A one time occurrence is something that is managed and resolved, almost expected in many horses. However, when we have a repeat offender, with ongoing abscessation problems, it is a sign we need to look deeper.

When I have continual abscess problems in a horse, I first look at the environment.  Is there a problem there and if so, can we change it?  Are the paddocks too wet?  Are they spending too much time in a stall?  Should we put them out on pasture or should we maybe add some pea gravel to the paddocks around the water trough and feeding area?

After evaluating the environment, I then turn to the foot itself.  How is overall hoof health?  How is balance? Are the heels under-run or too long of a toe? Is there laminar separation present, which is very common not just in laminitic patients.  If the foot has problems, is this just due to improper trimming or is there a deeper problem?  How is the diet for this patient?  If it is good, then how about GI health?  Maybe there is a reason they are not assimilating the nutrients in that diet and supporting a healthy foot?

How do we resolve the immediate problem and improve that patient’s comfort level? First, we need to evaluate that foot and find that abscess location if possible.  The abscess is usually originating around the white line region, but can also be in the heels around the bars or even in the frog.  We need to locate the source of pain and investigate.  I will often use the hoof knife, paring gently at sole tissue to find ‘black’ marks or tracks, then explore them. We don’t want to go too deep as that can create more problems in regards to sole integrity.  In many cases, with light exploration and early timing, we can find the abscess, open it and drain it, which will relieve pressure quickly.  In other cases, that track goes pretty deep and over time, the abscess may work its way up the white line, towards the path of least resistance, progressing towards the coronary band region.  We can often detect this by palpation of the coronary band, locating a swelling or painful region upon pressure.

Antibiotics are generally not helpful in cases of hoof abscesses, mainly because the pocket of infection is located in a region of the foot where there is little blood circulation.  In order for antibiotics to work, we need blood circulation to deliver them in high levels.  Most of the time, the infection is walled off, isolated between layers of the hoof wall and not accessible by antibiotics.  However, if the infection goes deeper, or involves a puncture wound, then of course, antibiotics are warranted.  Most abscesses are managed supportively, first by exploration and opening them if possible.  We have to remember that we do not want to do damage to the hoof capsule or sole.  I am not in favor of digging too deep, nor am I in favor of opening the hoof capsule itself.  These methods create more harm than good and can often put us further behind the 8 ball in regards to recovery.  Foot soaking is commonly used but is a two edged sword.  The purpose is to open the abscess, draw it out either at a sole or coronary band level.  However, we have to remember that continuous soaking can actually further weaken the hoof integrity, creating more problems.  Personally, I will try to open an abscess in the acute stage and then use soaking in Epsom salts for 3-4 days to futher allow it to come to a head.

We can get through an acute hoof abscess in most cases, but the ongoing ones create challenges.  This is where we must dig deeper, look at the foot and the patient.  Through this, we can improve outcomes for the long term.

Solar Bruises:

A bruise is simply excess pressure applied to a region, resulting in tissue trauma and usually blood vessel (capillary) damage.  This blood vessel damage leads to leakage of fluids and blood into the surrounding region, creating the typical dark color we associate with a bruise.  The tissue is damaged and painful, but over time, it will repair and recover.  The lost blood in the tissue is broken down and reabsorbed over time, resolving the ‘bruise’.

A solar bruise in the equine hoof usually happens as a result of stepping on something hard, hard enough to create internal hoof capsule damage within the sole.  This could be a rock or some other object in most cases.  A solar bruise is very common, but in reality, it is a sign of a sole that is too thin, too weak to stand up to the normal every day traumas that a hoof should encounter.  These bruises can be very painful and acute in nature.  Again, here we must investigate the foot, removing debris, using hoof testers and localizing the source or location.  The bruise can really be anywhere on the foot, from the toe region to the heels.  Many times, with light paring of the sole, we can actually see the bruise as an obvious red area on the sole.

So, how do we manage these cases?  First, the bruises will resolve but takes time, no different than someone punching you in the arm, leading to a bruise. Time will heal those tissues.  In severe cases, the blood and fluid accumulation may mimick an abscess, creating excessive pressure and pain. Here, we may need to gentlly open the region for drainage and pressure relief.  Otherwise, it is mainly supportive care that is needed, using protection such as hoof boots if needed.

Any horse can develop a foot bruise, even those with healthy hooves.  What we have to determine is whether this is an isolated incident or is there an underlying problem that needs to be addressed.  In the recurrent cases, we often have inferior hoof growth and sole thinness that is to blame.  Those horses are often the ones that are also generally sensitive when walking on firmer ground or gravel.  This indicates sole pain, linked back to a thin sole.

Here again, like the abscess situation, we have to see what is present, recognize those contributors and do our best to remedy them.  We can’t grow a thick sole overnight and many horses, due to poor diet or circulatory issues, fail to grow a thick sole no matter what we do.  I am not a fan of shoes, as I feel the shoes are more often a cause of thin soles than a remedy.  They offer protection, but that protection leads to tissues not being exposed to factors that they should, and likewise they become weaker, not stronger.  I tend to look at the patient as a whole in these situations.  If I can go barefoot, I will, making balance adjustments to strengthen hoof tissues hopefully in the long term.  I will also look closely at diet, GI health and influence of inflammation on circulatory problems which may impairing proper hoof growth.

In the long term, we deal with and contend with solar bruises in our patients and in our own herd.  They can be frustrating, especially in the TB breed, but through the right approach, we end up with better overall management for the long term.

Thrush and White Line Disease:

Both thrush and white line disease are infections of sorts, not far removed from solar abscesses in my opinion.  Thrush is an infection usually involving the collateral sulci or grooves next to the frog, while white line disease is involving the white line structure of the hoof wall.  Both conditions can involve bacteria of non-specific types, but also commonly involve various fungal pathogens.

Here again we have predisposing factors that open the doors for these problems.  The first contributor is often environmental, meaning too wet or overall just filthy, such as standing in mud or manure constantly.  As with solar abscesses, these conditions weaken the hoof structure and act as mediums for bacteria and fungal infections.  Not all horses exposed to these factors develop thrush or white line disease, so this tells us there is variability.  In most, the ones that have problems have underlying contributors such as laminar separation, improperly maintained feet, dietary concerns or underlying health issues.  Solar abscess, thrush and white line disease are very common in horses with metabolic syndrome, insulin resistance and laminitis….for a reason.  That reason is that the overall hoof is unhealthy, not as strong as what it should be for a variety of reasons. If the hoof is unhealthy, the opportunity exists for infections to occur.  Another example is a hoof with heel contraction, which creates deep sulci which tends to accumulate debris.  These factors set the stage for recurrent thrush and white line conditions.

How do we manage these problems?  First and foremost is hygiene.  We must improve the environment and reduce contributors.  In cases of white line disease, the infection can extend up the hoof wall to variable heights, which is dictated by the degree of laminar separation present and overall poor hoof health.  White line disease can be very frustrating to contend with and a light tapping with a hammer to the hoof wall will often yield a hollow sound, sometimes all of the way up to the coronary band.  This is a sign of separation and a dictator of the level of work that lies ahead.  Many will pare out the white line region and even perform hoof wall resections, in hope of getting control of the infection.  Some will soak the feet in various solutions or even medications.  Bottom line is that we don’t want this to get too far advanced.  The other is that in order to resolve the problem, we not only have to clean up wht environment, but we need to get that hoof wall to grow in a healthier fashion, attached in the laminar region.  All too often, new hoof is formed, well attached at the top, but becomes separated as it grows down.  This then allows the infection to spread further.  We have to allow for time in these matters, but also try to figure out why that hoof capsule may not be growing properly.  Is it due to improper trimming?  Improper load bearing?  Is diet a factor? Is GI health a factor?  Does this patient have underlying inflammatory and/or immune problems?  All of these things must be addressed if we are to make positive ground in these cases.

Thrush is not far removed from white line disease, and is essentially an infection that develops in the collateral or central frog sulci.  In many, this is due to excessive heel height and likewise deep sulci development which then accumulates debris.  In these cases, the heels are not able to expand upon landing and self clean, not too mention support healthy circulation.  There is often a black, odorous discharge in the region with associated pain or discomfort.  The infections can be superficial but in some can extend rather deep over time, creating some serious situations.  Like white line disease and other hoof conditions, we first must realize contributors and address them properly.  As part of our therapy with thrush, we may clean up or debride the frog region, removing dead frog tissue and opening up the region to function better.  Some will use foot soaks, while I prefer to use topical remedies in conjunction with other ‘whole horse’ approaches.

Concluding Thoughts:

Hoof abscesses, bruises, white line disease, and thrush are all very common problems that we encounter in the horse.  Many times, the problems may seem minor or superficial, but in reality, their presence indicates a potential problem in that foot or even in the health of that animal.  If we can see and recognize these signs for what they are, hopefully sooner than later, we can better manage these patients for the longterm.

Foot balance, diet, GI health, inflammation and immune support are some of my main focus areas in all of these cases, as each plays a vital role.  It is not uncommon to consult with an owner that has battled abscesses or even white line disease for many years, only to realize that the foot is not being addressed in regards to balance with obvious laminar separation and flares being present.  In other cases, we may have applied the right approach to the foot and even corrected environmental problems, however we continue to struggle.  This may then indicate that there is a dietary problem or even underlying health inflammatory issue that may be present.

Most of these conditions develop over time and time is what we need to help resolve them.  With the right approach, we can make positive progress every day!

 

Tom Schell, D.V.M

Nouvelle Research, Inc.

www.nouvelleresearch.com

 

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