What are Mallanders and Sallanders in Horses?
Mallanders and Sallanders stem from hyperkeratosis, where the body produces excessive amounts of keratin, a protein present in the skin, hair, and hooves. The excess keratin production results in dry, scaly and itchy patches of skin forming on the front of the hocks on the hind legs (Sallanders) and behind the knees on the front legs (Mallanders).
Causes of Mallanders and Sallanders in Horses
Genetic Predisposition
Mallanders and Sallanders almost always occur in heavier breeds with leg feathers. Breeds most at risk of developing these conditions include cobs, clydesdales, shires and drafts. The exact reason as to why these breeds are put at an increased risk is unknown however it is thought to be linked to genetics as these breeds will typically produce greater levels of keratin.
Feather Mites
The presence of feather mites is also thought to be associated with the condition. Feather mites are microscopic parasites which feed off dead skin cells, this often compromises the skin and may trigger a flare up of hyperkeratosis. As the name suggests, feather mites can be found in leg feathers, normally seen in heavier breeds.
Symptoms of Mallanders and Sallanders
Visible Signs on the Skin
Lesions are often easy to identify due to their location on the body, the skin will appear thickened, crusted and scabby, in milder cases this may be disguised by feathering however in some lesions will protrude through the hair. Hair loss as a result of the condition can result in bald patches on the knees and hocks developing. In more severe cases, the skin may crack and lead to the development of sores, swelling in the lower leg and lameness may also be seen.
Behavioural Changes
Due to the intense discomfort caused by the condition, affected horses will often display behavioural changes, these include stamping, head shaking and scratching. Horses may also appear to become lethargic.
Treatment Options for Mallanders and Sallanders
Veterinary Consultation
If you suspect your horse has Mallanders or Sallanders it is important to contact your vet as soon as possible. A vet will be able to confirm a diagnosis and advise on the best course of treatment depending on the individual case.
Common Treatments
Unfortunately there is no known cure for hyperkeratosis. Topical washes and ointments formulated to soften and protect the lesions are the most commonly prescribed treatments for Mallanders and Sallanders. For cases of secondary infections, an antibiotic may be required. As tempting as it may seem, scabs should not be picked off, this can be uncomfortable for your horse and increases the risk of infection.
Dietary Management
Horses with Mallanders and Sallanders can benefit from having increased levels of omega 3 in the diet to help maintain and strengthen the skin barrier. One of the best sources of Omega 3 fatty acids for horses is linseed oil or micronised linseed. If wanting to avoid linseed due to its calorie content, chia seeds are another valuable source of Omega 3 fatty acids that can safely be fed to horses.
As high amounts of sugar and starch can exacerbate inflammation in the body. Horses with Mallanders and Sallanders should be fed a low sugar and starch diet. Ideally the combined sugar and starch content of the diet should not exceed 10%. Due to the fact it is essentially pure sugar, any feeds containing molasses should also be avoided. Other inflammatory ingredients that owners may want to avoid include soya (especially soya oil), high sugar and starch grains such as oats, maize and barley and oils with a higher ratio of Omega 6 than Omega 3 (vegetable oil, rapeseed oil and olive oil to name a few).
Many owners will report flare ups of Mallanders and Sallanders during the Spring months when the grass sugar content is at its highest so it is a good idea to limit grazing during these periods.
It is a common misconception that biotin in the diet can be detrimental to horses with hyperkeratosis however there is no real scientific evidence to suggest this is true. In fact studies in other animals have also shown links between biotin deficiency and hyperkeratosis. Biotin is present to some extent in grass and forage so is impossible to remove from the equine diet entirely. Failure to supply horses with adequate amounts biotin in the diet can actually be detrimental as it may result in deterioration of hoof quality.
Preventing Mallanders and Sallanders in Horses
As feathered legs create the ideal environment for feather mites which may be linked to the development of hyperkeratosis, it is a good idea to keep your horse’s feathers trimmed or clipped to minimise their risk of becoming infested. Extra care should always be taken when trimming a horse with Mallanders or Sallanders lesions however as the thick scabs can alter the leg shape and easily become injured during the clipping process. In some cases of hyperkeratosis, clipping is not advised.
Whilst there is no indefinite way to prevent hyperkeratosis, measures can be taken to minimise the risk of secondary infection. It is important that owners ensure their horse’s legs remain clean and dry whenever possible. Daily mucking out and avoiding turn out on wet muddy ground will minimise exposure to bacteria that may result in secondary infection. If your horse has been treated for mites it is important that their stable and any equipment that has come into contact with their legs is thoroughly disinfected otherwise they can reoccur.
If your horse is at risk of developing hyperkeratosis, it is important to regularly examine their legs for signs of Mallanders and Sallanders. The earlier the condition is picked up on, the sooner it can be treated and the chances of secondary infections occurring are minimised.