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Mild Mud Fever & Rain Scald: Symptoms, Causes & Prevention | Probiotic Spray | MicroMed

(Also known as (Rain Rot, Pastern Dermititis, Dermatophilus congolensis,  Equine Dermatitis,  Lumpy Wool, Greasy Heel, Mycotic Dermatitis, Cracked Heel) & Streptothricosis).

Hose Mud Fever Treatment | NZ | Probiotic Spray | MicroMed

Description: The usual signs of mud fever begin with damage to the skin or cracking of the skin, in the lower limbs, that then allow detrimental bacteria access to the lower layers of the dermis or skin where the infection is able to begin.  The area then becomes inflamed and thickens, before forming a crusty scab.   These scabs can travel from the pastern and up through the cannon bone, with the hair becoming matted with exudate, and often the horse will suffer associated hair loss.  If at this point your mud fever has not resolved it is important your horse is under the care of a vet.  As the condition progresses, it can result in a pus discharge and can cause the horse discomfort as the lower leg swells and becomes hot, resulting in lameness.

Mild mud fever is usually more common, but not restricted to, feathered breeds of horses and it also occurs in ponies and donkeys.  When the crusted scabs appear on the back, rump and face, this is called Rain Scald.

Rain Scald Treatment NZ | Probiotic Spray | MicroMed

Rain Scald appears as crusted, moist mats of hair, where underneath there can be pus which is exudative.  The bacteria can actually remain behind the scabs for up to 42 months if not treated. 


Mud fever and rain scald are caused by a number of factors, most of which can be minimised or eradicated. 

  • Opportunistic bacteria and fungi : It was traditionally thought that mud fever was only due to the bacteria Dermatophilus congolensis, however now it is more accepted that there can be a number of different bacteria and fungi that can become involved in mud fever such as Staphylococcus and Pseudomonas species.  Dermatophilus congolensis is actually a bacteria and a fungus due to the fact that it is an actinomycete, which behaves as both, so a powerful probiotic blend of both beneficial bacteria and fungi can be a truly effective remedy in mild mud fever and rain scald.   
  • Moist conditions are usually a prerequisite to the proliferation of the detrimental bacteria however crucially there are usually insufficient beneficial bacteria present both on the horse and in the environment.   If it is possible to avoid or minimise exposure to mud, morning dew in paddocks, heavy rainfall and even excessive leg washing if your horse is susceptible to mud fever and rain scald then this is helpful.  Interestingly, you often find leg washing recommended for mud fever however, heavy leg washing can remove the protective oil barrier on the skin, worsening the likelihood of succumbing to mud fever.  If a stall is an option, that would be preferable during the mud fever season, to enable a clean, dry and well-ventilated area for your horse.  The Hagyard Equine Medical Institutes, Dr. Luke Fallon, says, Horses that are constantly standing in a moist environment can develop defects involving the soft tissues associated with the hoof, heel bulbs, and coronet band. Defects of this nature can become an entry point for bacteria. 
  • Insect bites from ticks and flies, allow detrimental bacteria to gain access through the damaged epidermis - the protective outer layer of skin.   
  • Ringworm, the equine form usually contracted is Trichophyton equinum, however there is also a soil-borne ringworm fungi Microsporum gypsum that horses can also often contract.  All of these are highly contagious so isolation while treating the animal is advised.  If the vet has diagnosed which genus species it is, and its the soil-borne family Microsporum gypsum, we recommend liberally spraying Micromed for Horses Acute Care where the horse stands, roots around or rolls, to re-establish the healthy organisms on and in the soil, as well as using on the horse, and liberally spraying equipment and bedding areas.  All of these fungi are parasitic, eating the keratin of the skin, the protein that forms the structure of hair and epidermal skin cells, which is why there can be bald patches with this condition.   
  • UV damage either in the form of sunburn or photosensitisation can often occur, particularly in non-pigmented skin, however liver disease should be ruled out by your vet as a causative factor, as should grazing on clover, perennial ryegrass, and alfalfa (also known as lucerne). 
  • Liver disease in horses will be either acute or chronic; In acute liver failure, horses will become icteric (jaundiced) and if your horse exhibits yellowed mucus membranes such as the eye sclera and gums, it could well be the first sign they are in acute hepatic jaundice. Accompanying this there can be neurologic signs of the damaged livers inability to clear ammonia from the blood, causing hepatic encephalopathy, with symptoms such as depression, lethargy, persistent yawning, pica, or aggressiveness.  Urgent medical attention must be sought to avoid coma or death.  Horses experiencing chronic liver problems will lose weight and develop photosensitivity or sunburn on the non-pigmented areas of their body, often initially perceived as mud fever. 
  • Mites - If it is a mite infestation, your horse will be stamping or rubbing themselves against things due to the itch, and although technically the mites do not pierce the skin and tunnel in as was previously thought, they instead create an allergic reaction, due to contact of their faeces on the skin.  This in turn creates an exudate which the mite then feeds on, the horses skin subsequently forms scabs, and secondary infection often results.   
  • Rough or spiky vegetation and stubble fields, that may cause injury to the hoof or skin, giving rise to a bacterial or fungal infection.  
  • Physical or chemical irritants such as straw bedding can aggravate some horses, particularly if there are certain allergens within the bedding and/or high ammonia within the deeper layers of the bedding.  Spraying with a powerful probiotic solution can offset this becoming a problem and not only is the ammonia broken down, the associated odour is decomposed into organic by-products, by the powerful nitrifying bacteria in MicroMed for Horses.  


  • Pastern and cannon leukocytoclastic vasculitis can look very much like mud fever, and can subsequently give rise to secondary bacterial infection and pastern dermatitis.   
  • Equine Cushings Disease, also known as Pituitary Pars Intermedia Dysfunction, is where you may see mild coat changes initiallythat can progress over time to more severe symptoms such as laminitis, recurrent infections and lethargy, so be vigilant when mud fever is recurring over time, to have Cushings ruled out by a veterinarian. 
  • Pemphigus foliaceous (PF), is a fairly rare auto-immune condition where the horses immune system starts to react to and break down its own skin.  Symptoms are crusting and scabby legs with or without itching and hypersensitive skin, initially mimicking mud fever.  Lesions can also appear on the face and abdomen with lower abdomenal swelling, over a period of around three months. If your horse becomes reluctant to move combined with a fever, depression, lethargy, anorexia, appears in pain and suffers weight loss, please do seek veterinarian advice.  Interestingly, although the cause of PF remains unclear, there are some veterinarians who believe drugs such as antibiotics, dewormers, vaccines, and some supplements have triggered a number of PF cases. 

TREATMENT:  chlorhexidine is often used, as is iodine, sudocream or antibiotics 


5 Top Tips for Mud Fever Prevention and Treatment 

  • Re-establish the healthy microbial balance on your horse, and in their environment, by spraying your horse and the areas they most often frequent, or stand around in, with MicroMed for Horses.  This is particularly recommended after a course of antibiotics or strong medications or where bleaches or disinfectants or anti-bacterials have been used, all of which impair or kill naturally occurring micro-organisms on your horse and/or in its environment. 
  • Try to remove your horse from muddy environments where possible, as moisture is the key to thriving detrimental organisms 
  • Spot the signs of mud fever or rain scald early by checking your horse daily if possible, in mud fever season.  This is best performed by running your hand over their skin, and especially in places where mud fever may be hiding, such as the feathers or folds of skin.  Im sure youll agree your horse will let you know if there is a problem area! 
  • Try to clear your horses daily environment from all sources of detrimental grazing plants such as, buttercup, clover - in particular white clover, perennial ryegrass and alfalfa, (lucerne). 
  • Remove rough or spiky vegetation that may harm your horse and do not graze in stubble fields, as these may cause injury to the hoof or skin, giving rise to a bacterial or fungal infection.  

Please note mud fever and rain scald is contagious and can be transmitted  through flies, ticks, grooming equipment or tack, as well as between horses.