Horses’ performances and skin conditions

In France, 1 horse out of 10 suffers from Recurrent Equine Summer Dermatitis (REED), a very disabling and mentally challenging for horses skin disease. If a single skin disease, among dozens of others, can affect 10% of the whole French herd, just imagine the total amount of horses suffering from skin disorders only in Europe...

Horses suffering from that on a daily basis is a subject that is too little discussed in the equestrian literature, in the same way that the management of pain itself was little mentioned before the end of the 2010s. However, all sports doctors are formal: pain affects performance. If it is the case for humans, why should it be different for horses?

Understanding the pain mechanisms for horse

According to the definition given by the (International Association for the Study of Pain (IASP) ) in 1979, pain is an "unpleasant sensory and emotional experience related to actual, potential or self-described tissue damage"

Pain induces an analgesic physiological response: the body struggles to reduce the pain, releasing molecules such as enkephalins for example. Pain induces behavioral changes to in order to avoid it or to protect the affected areas.

Your osteopath has probably already told you about the famous "analgesic positions" or "compensations", that's what we are talking about here.

IIt is absolutely natural, instinctive and necessary for an animal (just like for us) to avoid pain.

Performance factors in equestrianism

• the physical factor,

• the technical factor,

• the “tertiary” factors such as tactics, mental and luck

If the Cadre Noir de Saumur's rider notes that the horse must be in perfect health to perform, the notions of pain are not explored among the performance factors. Yet this is the nerve of the war.

How can I know my horse is in pain

Horses naturally hide their pain: they remain silent and quiet, and their behavioral changes are very discreet in order to protect themselves from potential predator attacks. The use of a pain assessment grid allows a simplified approach to this notion of pain.

Calm Horse :

• Directed ears : towards the point of interest (food, human being, fellow horse, any other animal, noise. They remain tensionless

• Opened eyes : sharp and calm watching, ocular muscles unsolicited

• Mouth at rest : If the horse is not eating at the moment, the lips are unclenched, the lower one may even be loose.

• Soft neck : It is relaxed and mobile, naturally oriented in the continuation of the body

Although discreet, changes in behaviour should be monitored as they represent clues on the « level » of suffering of your horse. In France, Léa Lansade, IFCE researcher in Ethology at the INRAE (National Institute for Research in Agronomy) regularly conducts research on this subject. The grid proposed by Léa Lansade, like most other pain evaluation grids for horses, mentions :

• changes in feeding behaviour: the horse feeds less or not at all or, on the contrary, gorges itself.

• changes in locomotor or physical behaviour: the horse changes its stance, stands in an unusual position, limps, scratches, rolls, yawns, grinds its teeth, bites, licks itself, waddles, etc.

• the appearance of facial expressions of pain: backward or drooping ears, sunken eye muscles, wrinkled eyelids, glassy eyes, tense jaw, pinched or dilated nostrils.

• changes in the classic physiological observables: white mucous membranes, reddened eyes, fever, etc.

Pain signals of horse :

• Low ears : the distance between the ears increases related to the growing pain

• Strained gaze : ocular muscles contract due to pain

• Pinched mouth : the lips are pressed together, the chin is tucked in, it looks flattened

• Facial muscles tension : clenched jaw, facial muscle appear under the skin out of contraction.

• Dilated nostrils : from the middle of the nostril outwards

• Contracted neck : The tension of facial muscles can also create a contraction of the neck.

Do skin conditions cause pain?

Outright : yes, they do.

Atopic dermatitis, summer dermatitis, contact dermatitis, mud scabies, mite infestations, fungal infestations, bacterial infestations... whatever! Skin discomfort causes obvious and sometimes violent physiological reactions.

Scratching, bloodletting, facial pain signals (see diagram), changes in eating or physical behaviour... there is no doubt: a skin problem always brings with it its share of suffering, both physical and mental.

When they face pain, horses look for solutions, but when they don't find them, it can quickly turn into a nightmare. Studies also show that if pain is not treated, the prolonged stress it generates can lead to a more or less profound impairment of the horse's quality of life and well-being, sometimes with serious consequences:

• Self-injurious, aggressive behaviour; some horses may injure themselves - hoping to relieve themselves, this is a normal physiological reflex (although impressive) which should alert the owner immediately

• A state of depression which results in a decrease in appetite and activity, and consequently a loss of weight and muscle mass in the horse

• A drop in immunity; the horse falls ill more easily (runny nose, crying eyes, difficult moult...)

Do horses feel more pain?

The horse’s skin : (from left to right, counter-clockwise)

• Sebaceous glands

• Blood vessels

• Hair follicle

• Hypodermis.

• Dermis

• Epidermis

The skin of horses is thicker than the humans’ one. However (and this is where it gets very interesting) the horse's epidermis is thinner than the human's. l’épiderme du cheval est plus fin que l’épiderme de l’humain.

The nerve endings are located at the junction between the dermis and the epidermis (between red and green on the diagram), so the thicker the epidermis, the longer it would take for pain to travel to the nerve.

According to the report on a pilot study conducted in 2015 by veterinary doctor Lydia Tong: for horses, as the epidermis is thinner, the pain on the surface of the skin would reach the nerve more quickly. In simple terms, this means that for the same amount of force (e.g. the pain felt after a slap), the horse would hurt more quickly than a human.

Following these initial hypotheses, veterinary surgeon Lydia Tong, supported by Professor of Veterinary Medicine Paul McGreevy of the University of Sydney, conducted further research. The results, published at the end of 2020 in the scientific journal Animals, established that given their physiological attributes, horses feel pain at least as well as humans.

The second study validates the first part of the hypothesis of veterinary doctor L. Tong's hypothesis: the horse's epidermis is thinner than humans'. It remains to be seen whether the nerve travel time is (or is not) significant in the estimates of pain sensation.

Do skin condition affect the horses’ performances ?

Let’s summarize all the facts above : :

1. Pain is a restricting factor in sports performances

2. Skin conditions cause pain

3. Horses feel pain at least as intensively as we, human, do

In conclusion, the link between performance and skin disorders seems obvious: yes, our horse’s performances can be strongly affected by skin condition.