Mallenders & Sallenders – when skin, fur, environment and feed meet

protein, soy, alfalfa, sainfoin and the feed's saponins

Brief conclusion (for the busy reader)

• Mallenders and salenders are skin changes in which skin keratinization and connective tissue play the main role – not a classic food allergy [1–3].
• Genetics and age play a significant role: some horses have a hereditary predisposition , and the condition often gradually worsens with age [2–4].
• Environment and fur often play a crucial role: warm skin, moisture and dense fur can cause fungal and bacterial growth , which worsens skin changes.
• Mowing the area provides better ventilation and care and can be an important part of management [1,3].
• Saponins in feed (e.g. soy, sainfoin and alfalfa), rather than the proteins themselves, can affect the intestinal environment and immune response , but only a few individuals react pathologically , and there is no evidence that saponins systematically trigger mallenders/sallenders [5–10].
• If an owner experiences deterioration in connection with certain feed materials, a low-saponin feeding strategy with, for example, green pellets and roughage can be used during a controlled elimination period [11].
• The focus should primarily be on skin care, environmental management, clipping of affected areas, and the quality and stability of the feed – not on demonizing individual feed ingredients [1–3].

What are mallenders and sallanders?

Mallenders (behind the knee, front legs) and salenders (in front of the hock, hind legs) are particularly common in heavy breeds and feathered types , such as cold blooded horses, Friesians and some ponies [1,2]. Clinically , thickened, scaly skin and crusts in the flexural grooves are seen; the condition is associated with hyperkeratosis (excessive keratin production) and changes in the connective tissue , often with secondary infection [2,3].
Skin changes often worsen with age – the skin’s repair capacity decreases, and small cracks can become chronic, especially if the skin is moist or covered with thick scales [4].

Genetics play a role

There is probably a genetic component , with some horses having inherited variants that affect the skin's regulation of keratinization and connective tissue [2]. This does not mean that the disease is "inherited" in the classical sense, but that some individuals have an increased vulnerability . Therefore, two horses on the same feed may react differently — and only a few individuals develop an actual pathological condition.

Saponins in feed – what do we know?

Saponins are plant-based triterpenes found in, for example, soy, alfalfa, other legumes and some grasses . They can:
• Bind cholesterol in cell membranes , change intestinal permeability and influence microbiota [5–7],
• Activate mucosal immunity in the intestine (including via M cells and dendritic cells) [6,7],
• In experiments on other animal species, they cause changes in the intestinal environment and low-grade immune activation [7–9].

👉 In horses, there is no evidence that saponins in normal feed quantities directly trigger skin problems . However, it is biologically plausible that some individuals with an already sensitive skin/immune profile may react to changes in the gut environment [6–10].

Saponin content in selected feed materials

📌 Note: Most common grasses contain very low levels of saponins. Soybean, sainfoin, and alfalfa have significantly higher levels , but still well below the levels used in experimental studies [5–8].

Feeding strategies in practice

Most horses tolerate soy, alfalfa, and other saponin-containing feeds without problems [5,8,9]. However, if an owner experiences skin problems that worsen with, for example, alfalfa or soy, one can:

1. Conduct a controlled elimination period of 4–8 weeks.
   – Remove suspect ingredients at the same time.
   – For example, use green pellets (grass-based pellets) as a source of protein and fiber instead of alfalfa, sainfoin or soybean meal to minimize saponins [11].
   – Record skin status weekly (possibly with photos).

2. Reintroduce the ingredient after the period and observe. Only if the reaction recurs is there a real connection. (optimally test over 3–4 days and in two periods, to be sure, but stop when there is a clear reaction)

3. If necessary, choose low-saponin soy sources (SPC/SPI) rather than soy meal if soy is to be retained in the diet [5].

The most important thing: Skincare and the environment

Food may be one piece of the puzzle — but mallenders and sallanders are primarily a skin and connective tissue problem , which typically requires:
• Gentle removal of crusts and hyperkeratosis
• Good hygiene and drying in the bending grooves
• Treatment of any mites or secondary infections
• Clipping the area to ensure air circulation and reduce heat/humidity — especially important in horses with a lot of fur or feathers during hot periods [1,3]
• Systematic care for CPL and heavy breeds [2–4]

Conclusion

• Mallenders/sallenders are primarily caused by the skin's own processes , influenced by genetics, keratinization, connective tissue, fur/environment and age [1–4].
• The saponins in the feed may theoretically contribute to immunological irritation, but only a few individuals react pathologically , and there is no evidence that soy or alfalfa in normal feed amounts generally “cause” skin diseases [5–10].
• A low-saponin strategy with green pellets and roughage can be used as an elimination tool in suspected cases [11].
• Clipping the area and reducing heat/moisture are often essential in practical management. Skin care, environment and prevention of secondary problems are key [1–3].

📚 Sources and literature

1. Tribute Equine Nutrition. Mallenders & Sallenders. Online article.

2. White et al. (2019). Chronic progressive lymphedema and keratinisation disorders in draft horses. Vet Dermatol.

3. Naylor's Horse Care; Equiderma. Practical descriptions.

4. Merck Veterinary Manual. Hyperkeratosis and chronic skin disorders.

5. Guang et al. (2014). Soyasaponins: chemical structure and biological effects. J Agric Food Chem; USDA ARS Phytochemical Database.

6. Zhang et al. QS-21 activates the NLRP3 inflammasome. Nature Immunology (PMC).

7. Knudsen et al. Soyasaponin Bb and intestinal permeability. Br J Nutr. (salmon model).

8. Field studies in Medicago sativa. tandfonline.com. Total saponin 6–11 mg/g DM.

9. ETH Zurich Dissertation. Secondary metabolites in sainfoin (Onobrychis viciifolia).

10. acsess.onlinelibrary.wiley.com. Switchgrass saponins (protodioscin); other grass species low/not detectable.

11. Regulator Complete practice experience; elimination strategies recommended by Tribute Equine Nutrition / Optim Equine.