Gut, skin and nutrition – when environment, nutrition and the skin barrier interact

Mange is one of the most common skin challenges in horses during the fall and winter seasons.
But muk is rarely just about “mud”.
It is also largely about the skin's ability to protect itself from the inside — and here, the diet, the fatty acid balance, vitamins and minerals, and the quality of the roughage play a crucial role.

What exactly is muk?
Pastern dermatitis (also called rasp or pastern dermatitis) is an inflammatory condition of the skin, often around the hocks and pipes.
It is typically triggered by a combination of:

• Moisture and mud that soften the skin and make it vulnerable

• Mechanical wear (e.g. from long strands of fur, soil or grains of sand)

• Bacteria and yeasts, especially Dermatophilus congolensis , which thrive in moist conditions

• Reduced barrier function in the skin, allowing microorganisms to penetrate more easily

This means that two horses in the same paddock may have very different risks of developing mange — depending on the skin's resistance.

The skin's barrier function – the horse's "invisible raincoat"

The skin's surface acts as a barrier that protects the body from moisture, microorganisms and chemical influences.
This barrier consists of, among other things:

• Dense skin cells that lie like bricks

• The skin's own fat film (lipid layer), which acts as "mortar" between the cells

• A healthy microbiome that keeps unwanted bacteria and fungi at bay

When skin is healthy and strong, it can withstand moisture and mud for periods without problems.
But if the barrier is weakened — for example, due to a lack of essential fatty acids, repeated irritation, micronutrient deficiencies or a suppressed immune system — the skin becomes more vulnerable and dirt can take hold more easily.

Omega-3 and Omega-6 – both are important

The skin barrier depends on the body having sufficient amounts of essential fatty acids – both omega-3 and omega-6.

Omega-6 fatty acids (e.g. from grass, roughage, hay, wrap and rapeseed oil) are a natural part of the horse's feed and play an important role in the structure of the skin, the immune system and inflammatory processes.
Omega-3 fatty acids (e.g. from flaxseed and algae) have a balancing and supporting effect, including on the flexibility and repair mechanisms of cell membranes.

The skin does not distinguish between omega-3 and omega-6 as “good” or “bad” – it needs both, in sufficient quantities and in an appropriate balance, to function optimally.

Many horses get a basic supply of omega-6 through roughage, but with increased work levels, coat shedding or skin challenges, it may be relevant to add extra rapeseed oil as an energy source and omega-6 supplement.
At the same time, supplementing with RC O3 Algae Oil ensures that there is also enough omega-3 to support the skin's and body's natural regulatory mechanisms.

Rapeseed oil and RC O3 Algae oil – hand in hand

Rapeseed oil is a stable and readily available source of omega-6, which also provides the horse with concentrated energy for maintenance or work.
RC O3 Algae Oil supplies the active omega-3 fatty acids DHA and EPA in a pure, vegetable and heavy metal-free form that the body can easily use.
By combining rapeseed oil and RC O3 Algae Oil, the horse gets a solid foundation of both types of essential fatty acids – something that supports skin, coat, cell function, immune system and performance.

Recommended quantity

To ensure an adequate supply, we recommend:

• Rapeseed oil: approx. 30–50 ml per 100 kg horse per day

• RC O3 Algae oil: approx. 10 ml per 100 kg horse per day

For a 400 kg horse, this corresponds to 120–200 ml of rapeseed oil and 40 ml of RC O3 Algae Oil daily.
These amounts are within the documented recommendations for horses and provide a moderate, stable supply of energy and fatty acids that support skin, coat and the body's biological functions without burdening digestion.

Roughage – the foundation for healthy skin and a strong immune system

At RC, everything starts with the roughage.
A horse with too little or too poor-nutrient roughage has a harder time maintaining healthy skin, coat and immune function – no matter how many supplements you add.

In order for the body to defend itself and repair tissue, roughage must supply:

• Sufficient quantities (min. 1.5–2 kg dry matter per 100 kg horse per day)

• Sufficient, good quality protein

• A sensible structure (NDF 50–65%) for healthy digestion and microbial balance

• A low to moderate sugar content, depending on the type of horse

Many Danish forage analyses show that the protein content in particular is often too low to meet the horse's needs — especially during the winter period and at low harvest times.
When protein intake is not sufficient, skin, fur, hoof growth, immune system and tissue healing are negatively affected.

Vitamins and minerals – small nutrients, big effect

The skin's and the body's defense systems depend on a steady and correct supply of vitamins and minerals — especially microminerals such as zinc, copper, manganese and selenium, which play important roles in the skin's barrier function, immune response and repair processes.

Roughage rarely covers the need for these micronutrients alone.
Therefore, RC recommends supplementing with a balanced vitamin and mineral supplement, e.g.:

• Every Day Happy – for most horses

• Peak Performance – for horses in higher training, coat shedding, tissue building or special needs

A stable level of vitamins and minerals helps the skin form new cells, protect itself against microorganisms and withstand stress from moisture and cold.

What you can do in practice

To help the horse as best as possible through autumn and winter:

• Keep skin as dry and clean as possible – without overwashing. Use a gentle cleanser when needed.

• Trim long hairs on the joints of the tail if they collect a lot of moisture and mud.

• Strengthen the skin from within:

  • Ensure a good balance between omega-3 and omega-6 in the feed

  • Add RC O3 Algae Oil as an omega-3 source

  • Use canola oil as a stable energy source and omega-6 supplement

  • Give the body the right building blocks through abundant, protein-rich roughage and a balanced vitamin and mineral supplement.

• Keep an eye on weight and coat quality — changes can be early signs of nutritional imbalances

In short

• Acne occurs when the skin's barrier function weakens and moisture + microorganisms take over.

• The strength of the skin also depends on nutrition – especially the fatty acid balance, protein, vitamins and minerals.

• Both omega-6 and omega-3 are necessary, and a good balance supports skin, coat and immune function

• Rapeseed oil provides energy and omega-6

• RC O3 Algae Oil ensures active omega-3 supply

• Good quality roughage and correct mineralization are the foundation for skin health

• Good skin care + proper nutrition = strong skin and fewer acne problems

📚 Academic basis
Calder PC (2017). Omega-3 fatty acids and inflammatory processes. Biochem Soc Trans, 45(5):1105–1115.
Bailey SR et al. (2007). Seasonal changes in carbohydrate metabolism in equine laminitis. Equine Vet J, 39(1):43–48.
Harris PA & Geor RJ (2013). Equine Applied and Clinical Nutrition , Chapter 8.
Ziboh VA et al. (2000). Essential fatty acids and the skin barrier. Prostaglandins Leukot Essential Fatty Acids, 63(1–2):63–69.
Proksch E et al. (2008). The skin: an indispensable barrier. Exp Dermatol, 17(12):1063–1072.
Dodson & Horrell. "Equine Shine Rapeseed Oil" product sheet.
Equine Oil Supplies UK – feeding recommendations for rapeseed oil.