The Functions of Skin 

Skin is a very complex organ and performs many tasks, many of which we don't even really think about.  First off, it creates an internal space for the internal structures and organs.  By doing this, it protects all of these structures from the outside environment.  It is involved in the production of hair and hooves, and helps to regulate the temperature of the body.  Nerve bundles located in the within the dermis allow for the perception of even the lightest of touches.   

One of the biggest jobs the skin has is immuno-surveillance.  Skin is our first line of defense against many harmful bugs.  If anything penetrates the upper layers of the organ, then the white blood cells monitoring the area jump into action and defeat it before there is a problem.  This is occurring constantly and we have usually have no idea or sensation of it.  You can see why it's so important to maintain the health of skin.      

So with that in mind, let's take a look at some problems we may encounter in the horse world! 

Severe Scratches

Scratches, otherwise known as "Greasy Heel" or "Mud Fever" is a dermatitis of the pastern area.   It generally presents as inflam-mation or scabbing of the caudal pastern area.  Redness, swelling, itchiness and pain can all be seen initially.  These signs can worsen to skin crusting/oozing and can progress to lameness or cellulitis. 

Causes of this disorder are numerous and include contact dermatitis (caustic or abrasive substances), bacterial infection, mange or fungal infections.  Typically, it's a combination of factors that are a result of compromised skin due to wet and/or muddy conditions and the presence of opportunistic bacteria and fungi.  

Simple cases of scratches can be treated by removing the horse from the wet environment and gentle cleaning of the area.  We really like daily cleaning with betadine or chlorhexidine for this.  If signs continue, we my need to proceed with a topical steroid in combination with an antifungal/antibacterial.     

In more severe cases, as seen above, further diagnostics such as a skin scraping or biopsy may be necessary to find an underlying cause.  Once determined, the treatment can become more directed.  In some instances, systemic antibiotics and/or steroids may be necessary to alleviate the issue completely.   

  Also known as rain scald, this actual name of this problem is "Dermatophilosis".  

This is due to the bacteria that causes it which is Dermatophilus congolensis.  This is a potentially contagious disease, so be sure not to share any blankets between horses.  D. congolensis is an opportunistic bacteria that requires skin damage and moisture to take hold.  This leads to superficial, pustular lesions that are quite crusty and uncomfortable.  Horses with poor immune systems, such as undernourished or those with Cushings disease, are predisposed as their immune system is reduced.  (Remember when we mentioned immuno-surveillance?)

Treatment of rainrot begins with keeping the horse dry, if possible.  Remember that blankets can trap moisture, so removing them may actually be better.  Removal of the crusts and disposing of them can allow the area to dry better, but remember this may be a bit painful.  Once the wounds are open, topical treatments can usually get rainrot under control. You can use betadine scrub, shampoos or one of our new favorites - a spray on Chlorhexidine Rinse.   This attaches to your hose, spray for 5-10 seconds, and let it dry.  Whatever topical you choose, we recommend daily washing for 3-5 days then weekly until heeled.  If issues continue, systemic treatment may be necessary.   

Beyond treating the horse, be sure to disinfect all tack, brushes and blankets that may have come into contact with the infected area.  As with any infection, bio-security is important to prevent further spreading.           

 Believe it or not, ringworm is not actually a worm - it's a fungus.  I know - your world just came crashing down.  But that doesn't mean it's any less of a problem.  The technical name for ringworm is "dermatophytosis" and is caused by various species of fungus.  It is easily transmitted from horse to horse (or horse to human!) by direct contact or via contact with contaminated tack.   The fungal spores can remain viable in the environment for months to years.   

Ringworm causes circular patches of hair loss, leaving a classic "ring" appearance of crusted, raised skin with central healing occurring.  It is not usually itchy, and if it is, it's very mild.  Lesions are commonly found on the face, neck, sides or girth area.  Based on this appearance, we can usually diagnose ringworm.  If further diagnostics are needed, a fungal culture can be performed or microscopy of hairs may give an answer as well.   Unlike the fungus that affects small animals with ringworm, equine ringworm does not fluoresce under a Wood's lamp.   

Spontaneous remission will occur in a healthy horse in about 3 months.  The key to treatment is disinfection of everything that you can.  Bleach can be one of your best friends, just don't use it on the horse!  Some items, such as girth covers, may need to be  thrown away.  Topical treatments can help slow the progression of the disease and for this we recommend creams such as miconazole, chlorhexidine rinses or even just plain betadine.   

 There are many types of tumors that can affect the skin of horses, but the most common ones are sarcoids, squamous cell carcinomas and melanomas. 

Sarcoids, the most common skin tumor in horses, is locally invasive but don't metastasize.  They can occur anywhere on the body and are believed to be caused by Bovine Papillomavirus

Flat Sarcoid

.  Sarcoids can present in various forms, including flat, nodular, verrucous (wart-like), fibroblastic or a combination of these. 

Location and size can affect the outcome of treatment of sarcoids.  Removal is best, however if it is not removed entirely they can regrow and sometimes become more aggressive.  Other options include cryotherapy (freezing) or chemo-therapeutics which can be applied topically or injected into and around the mass.     

Squamous cell carcinoma is the second most common tumor in horses.  It is typically locally invasive and while it does metastasize, it does so slowly.  It is most commonly seen on the eyelid and prepuce, and tends to be more common in light colored breeds.  Treatment of SCC is similar to that for sarcoids, however a multimodal approach tends to be the most successful.  Early detection and treatment are also paramount as these need to be taken care of before they metastasize. 

Probably every horse person knows an old grey horse with melanomas.  They most commonly arise under the tail and around the anus, but they can also appear in the throatlatch, and around the eyes and lips.  These tumors can be locally invasive, and some may metastasize.  Depending on the tissues they invade, other signs may appear.  A cure for melanoma is not easily obtained, but local chemotherapeutics or drugs such as cimetidine may slow the progression.  Typically, these have to be managed long term.