Skin conditions should not be underestimated; they can be highly emotive for horse owners, not only because looking at your horse or pony’s skin can be a constant reminder when there is a problem, but also because it can prevent getting the horse out to training sessions or competitions. If severe, skin disease may even prevent ridden exercise at home.

How will I know if there is a problem with my horse or pony’s skin?

One of the most important factors in identifying equine skin disease is early recognition of a problem so that prompt management or treatment can be initiated. The key to this early recognition is a regular and thorough grooming regime or at least a regular examination of your horse or pony’s skin with your eyes and hands in good light. You might also detect skin or coat changes at other times such as bathing before a competition, or during routine clipping.

My horse or pony is very hairy, so how will I be able to assess their skin?

The health of your horse or pony’s skin is likely to be reflected in their haircoat condition overlying the skin, and therefore coat changes are important to watch for when monitoring skin health. There will be some non-haired areas e.g. inner thighs, around the sheath of geldings/stallions and the teats/udder of mares where examination of the skin will be even easier. Assessment of the skin is also easier in fine-haired horses and ponies vs. native types and hairy cobs, whose thick coat and feathering may delay detection of any problems – or even completely prevent detection of these until the hair is removed through clipping.

What types of skin changes should I be looking out for?

Skin conditions can be grouped together in many different ways – infectious/non-infectious, their location, their underlying causes etc. However, as there can be considerable cross-over of clinical signs between different types of skin diseases, as an owner it is most useful to think about what clinical signs and symptoms skin disease is likely to cause so that you can identify when there is a problem. This means you will then be able to seek appropriate veterinary input and advice, to guide any investigations, treatment or ongoing management required.

Signs and symptoms you should be on the lookout for include:

Itchiness (pruritus) – if severe, this can lead to self-inflicted trauma

Hair loss (alopecia), or broken hairs

Changes in the appearance of the haircoat e.g.

colour

the angle of the hairs

thickness

speed of shedding (this would be delayed with Cushing's disease)

Thickening of the skin (hyperkeratosis)

Reddening of the skin (erythema)

Skin lumps – tumours/warts/nodules/blisters

Scaling/crusting/oozing – often leads to the development of scabs

Pain on skin palpation, or even lameness if skin disease is affecting the limbs

Common equine skin diseases

Below are some common skin conditions you may want to be able to recognise (this is not an exhaustive list). Regular use of an anti-bacterial and anti-fungal shampoo may help to prevent and manage some of the bacterial/fungal/parasitic conditions listed below.

Lice infection

This is most commonly seen in stressed, young, malnourished, or diseased horses and ponies. It causes generalised itching of the body, with adult lice and eggs being found most commonly under the mane or forelock (they hide away wherever is warmest, but are visible to the naked eye). Hair loss is usually worst in areas which can be self-traumatised e.g. the face, underside of the jaw, neck and sides of the body/limbs. 

Leg mites

Also known as chorioptes or chorioptic mange – this is another parasitic infection but is typically limited to the lower limbs. The choropties mite burrows deep under the surface of the skin in the pastern and lower limb regions – most commonly in heavily feathered horses. These mites are rarely seen with the naked eye, but examination of skin debris or skin scrapes under the microscope can be successful for identification. Infection often results in severe itchiness of the limbs – with stamping  and self-trauma commonly seen in affected horses and ponies. Infestation can also lead to excessive scale production, dried crusts in the feathers, matting of the hair and severe skin thickening – which in the worst affected individuals can lead to the development of skin folds which are then prone to secondary bacterial infection, or worse still maggot infestation in the warm summer months.

Bacterial dermatitis i.e. mud fever or rain scald

These are both frequently seen skin conditions, but they affect different parts of a horse or pony’s body. The term mud fever is used when the condition affects the lower limbs, especially the back of the heels, pastern and cannon regions. By comparison, rain scald is used to describe a similar skin condition affecting the back, neck or hindquarters. The problem occurs when the skin’s normal defence mechanisms have been compromised in some way, e.g. broken skin, or constant wetting of the skin/hair. Dermatitis refers to inflammation of the dermis (skin), however, in these situations, it is typically seen hand-in-hand with a local bacterial infection. Clinical signs include scabs, serous discharge, crusting, redness, tufty hair or open sores – this is often combined with swelling, especially if the deeper tissues or lymphatic vessels are involved (which is then referred to as cellulitis or lymphangitis respectively).

Ringworm

The most common fungal infection of horses and ponies, and more correctly referred to as dermatophytosis. Ringworm has a very characteristic appearance; initially circular patches of hair will tuft, stick up or change direction – this is followed by loss of hair in the centre of these lesions and reddening/oozing of the underlying skin. It is important to remember that ringworm is highly contagious to other horses and ponies, and even to their human handlers – so you should be particularly suspicious if several horses and or ponies are displaying similar signs.

Sarcoids

These skin tumours come in all manner of shapes and sizes – there are six different types of sarcoids described – varying from subtle haircoat changes, through wart-like lesions (which can sometimes be hard to differentiate from viral warts) and small nodules, to large fleshy and sometimes ulcerated tumours. The take-home message for sarcoids is that early detection and treatment are key. The longer any sarcoid is left untreated, potentially the harder it will be to treat; and due to fly transmission, it is possible it may have already spread to other parts of the same horse or pony, or other in-contact horses and ponies.

Melanomas

Another type of skin tumour, however, these are generally only seen in grey horses and is typically benign. Some can become ulcerated on the surface and discharge their contents (melanin/blood), or interfere with tack or the passage of droppings if they grow to a reasonable size and depending upon their location. Early removal of all suspected melanomas whilst small is advised.

Allergic skin disease

Again, this is relatively common amongst our equine population, albeit with varying severity between individuals. Allergic skin disease typically results in pruritus (itchiness), hives (allergic bumps similar appearance to if you had been stung by a stinging nettle), hair loss (alopecia) and skin thickening due to the allergic response and self-trauma. Secondary bacterial infection is common.

Skin wounds

Unfortunately, horses and ponies tend to be rather accident-prone (some more than others!) and will frequently sustain wounds when we are not looking! Daily checks and grooming are golden opportunities for identifying wounds as quickly as possible and subsequently being able to treat/manage them appropriately to optimise healing. Some small inconspicuous wounds can present more of a problem than larger more obvious wounds, so make sure you are familiar with situations when a wound is likely to be of concern, such as:

wounds near joints or eyes

wounds associated with severe swelling, bleeding or lameness

puncture wounds – including nail penetrations of the foot

very large wounds

kick wounds

wounds involving bones or tendons

the presence of infection or maggots

Take home messages about equine skin disease

Equine skin conditions can occur anywhere on your horse or pony’s body; in fact, it can be said that the skin is the biggest organ in a horse or pony – and when you think about it, one of the easiest organs to examine because you can see and access it easily. Do not underestimate the value in regular examination of your horse or pony’s skin and haircoat during grooming, clipping or bathing etc. The sooner you find any abnormalities, the sooner you will be able to treat the condition, and keep your horse or pony’s skin looking its best. Unless you are absolutely certain what you are dealing with, early veterinary examination is encouraged to ensure accurate diagnosis and prompt appropriate treatment.

Dr Jessica Putnam BVMedSci(Hons) BVM BVS(Hons) MRCVS. February 2023