Dry and brittle hooves: understanding horn quality and moisture
Dry hooves are usually caused by the alternation of wet and dry conditions as well as hard ground. Since measurements show that water does not soak into the hoof wall, the key to care lies in consistent keeping conditions and regular trimming intervals.
Close-up of a horse's hoof being professionally examined by a farrier to assess brittle horn, cracks and the moisture content of the hoof wall. · AI-generated
This article was created with the help of AI.
How to recognise brittle horn
Brittle hoof horn shows itself primarily through irregular breaking out at the weight-bearing edge, fine longitudinal cracks in the hoof wall, frayed edges around the nail holes, and horn material that crumbles when the sole is picked out. It differs from normal wear through a progressive weakening of the horn substance. A uniformly even wall thickness around the entire hoof is not a physiological health criterion, as the hoof wall naturally varies depending on the hoof region.
For horse owners and hoof care professionals, distinguishing between natural horn wear and structural weakness of the horn substance is the first essential basis for assessing the hoof. While a healthy hoof retains a smooth, load-bearing wall structure even under daily stress, brittle horn tends to splinter even under slight mechanical strain. The fine cracks usually run parallel to the growth direction of the horn tubules and widen under the lever effect of the break-over. The problem becomes particularly visible at the nail holes of older shoes, when the material around the nail channels crumbles away and no longer provides sufficient hold for the new shoeing.
- Breaking out at the weight-bearing edge: irregular, fraying horn loss along the main load zone.
- Longitudinal cracks and sand cracks: fine vertical separation lines in the outer wall layer that can widen under load.
- Nail hole breakouts: widened, crumbly nail channels that impair the secure fit of the horseshoe.
- Crumbling sole and bars: horn substance in the sole area that already breaks down under slight pressure.
The assumption that a healthy hoof must have a completely uniform wall thickness around its entire circumference does not correspond to the anatomy of the horse. The toe wall is physiologically broader than the side and heel walls in order to withstand the impact forces that occur when the hoof lands. A variation in wall thickness is therefore normal at different hoof sections. Only when the horn loses its elasticity at the bearing edge and splinters off in small particles on ground contact is there an impairment of horn quality.
Moisture distribution in the healthy hoof
The healthy horse's hoof shows a physiologically uneven moisture distribution that follows clear anatomical segments. In measurements of 110 horn samples from six warmblood horses, the water content was 34.6% in the frog horn, 31.5% in the sole horn and 22.7% in the hoof wall. These values define the specific tissue structure and elasticity of each hoof region.
A precise look at hoof hydration requires distinguishing the individual hoof segments. In biomechanical studies of 110 horn samples from six warmblood horses, researchers found that the three main segments, frog, sole and hoof wall, show clearly differing physiological water contents. One anatomical clarification matters here: these values refer to distinct hoof segments, not to outer, middle or inner layers of the hoof wall. The measurement series compares segments with one another; it does not describe a moisture gradient within the wall.
| Hoof segment | Physiological water content | Modulus of elasticity (E-modulus) | Primary anatomical function |
|---|---|---|---|
| Frog horn | 34.6% | 9.9 N/mm² | Shock absorption and pressure distribution in the frog area |
| Sole horn | 31.5% | 230.0 N/mm² | Protection of the inner hoof structures against ground pressure |
| Hoof wall (dorsal) | 22.7% | 761.8 N/mm² | Weight-bearing function and mechanical stability |
| Hoof wall (lateral) | 22.7% | 708.0 N/mm² | Lateral load bearing and capacity for deformation |
These measurements illustrate the functional differentiation of the hoof: with its high moisture content and a low modulus of elasticity of 9.9 N/mm², the frog horn is extremely deformable, which is essential for the hoof mechanism and shock absorption. The hoof wall, by contrast, is many times stiffer at roughly 708 to 762 N/mm², a stiffness needed to carry the horse's entire body weight. The hoof is therefore naturally neither uniformly wet nor uniformly dry, but clearly segmented.
The great misconception: soaking and greasing
For soaking, the widespread assumption that the hoof wall can be enriched with moisture this way has not been confirmed by measurement. A two-hour soaking does not change the water content of the hoof wall, but it does lead to water uptake by the sole. Fatty products deposit on the horn surface. Whether they transport moisture into the interior of the wall was not examined in the studies consulted.
In a foundational study on hoof hydration, researchers examined wild horses from three very different habitats, wet marshland, partially flooded terrain and permanently dry desert, as well as six domesticated Quarter Horses. The surprising result: the water content of the hoof wall was almost identical in all three wild horse groups, at around 29.5%. The two measurement series give different absolute values for the hoof wall, 22.7 percent in Hinterhofer's work on six warmblood horses and around 29.5 percent in the wild horses, which is due to different populations and measurement methods. What matters is the finding that holds regardless in this study: a two-hour foot bath did not change the moisture content of the hoof wall in the six domesticated horses, but it did change that of the sole.
- Water content of the hoof wall: in all three environments, from the flood zone to the desert, around 29.5%.
- Response to soaking: no difference in water content was found between dry wall samples and those soaked for two hours.
- Response of the sole horn: soaking for two hours significantly increased the water content of the sole.
- Limits of the evidence: only water was tested. This study provides no measurement on the effect of hoof oils and greases on the water content of the hoof wall.
These findings have clear consequences for daily horse care. Applying fatty hoof creams or oils to the wall cannot supply the horn with water from the outside. A film of grease simply sits on the horn wall as a physical barrier. Whether external greasing changes the internal tissue hydration of the wall was not examined in the studies consulted. Care products serve their purpose by keeping the horn clean and protecting it from external influences, not by increasing the water content of the hoof wall from the outside.
What actually makes hoof horn brittle
Brittle hoof horn rarely results from a single cause, but from the interplay of several external and internal stresses. The repeated alternation between wet and dry environmental conditions, mechanical wear on stony ground, delayed trimming intervals, an unsuitable hoof balance, and the relationship between nutrient supply and horn integrity are examined in the literature.
Examinations of horn samples from brittle hooves under a scanning electron microscope described two different defect types, so brittle hoof horn is not a single uniform condition. The first defect showed a loss of structure and horn in the stratum externum, the second a poor adhesion of the horn scales. One key environmental factor is the constant alternation between moisture and dryness: when the horn softens it swells, and as it dries out again it contracts. These microscopic volume changes gradually loosen the cohesion of the keratin cells.
| Influencing factor | Mechanical and physiological effect | Consequence for the hoof horn |
|---|---|---|
| Wet-dry cycles | Alternating swelling and shrinking of the horn cells | Cracking and loosening of the intercellular substance |
| Hard and stony ground | High peak loads and point abrasion at the bearing edge | Chips and mechanical horn defects |
| Overly long shoeing intervals | Leverage from overlong toes and altered loads | Overloading of the hoof wall and wall separations |
| Trace element status of the horn | Defective horn showed significantly lower zinc levels than intact horn, despite identical zinc levels in the rations | Observed correlation, not a proven cause |
In addition, levering forces act on the hoof wall when trimming or shoeing intervals are chosen too long or a conformational fault is present. When the toe becomes too long, the pulling force on the white line and the outer wall layer increases with every breakover. Combined with abrasive surfaces such as gravel or hard ground, this inevitably leads to the weakened material chipping away.
What feeding can and cannot do
Targeted nutrition secures the necessary building blocks for newly growing hoof horn, but it cannot retroactively repair existing horn damage at the bearing edge. Zinc is one of the trace elements with a clear link to horn hardness. Feeding adjustments act exclusively on the horn newly formed at the coronary band and require months of visible development.
An adequate supply of essential trace elements is an important prerequisite for keratin synthesis. Research at the Tierärztliche Hochschule Hannover on horn, hair and blood samples from 63 horses showed that defective hoof horn with reduced hardness has significantly lower zinc levels than intact horn. It is also remarkable that the low zinc levels in the horn were not accompanied by zinc-poor rations, so a single measurement says little about the supply of the hoof tissue. If a nutrient deficiency is suspected, a well-founded ration review with your vet or an equine nutritionist is therefore always advisable.
- Zinc supply: Zinc requirements are met through the total ration and belong in feeding consultation, not in external hoof care.
- Biotin effect: In a controlled double-blind study of 42 Lipizzaner stallions, long-term biotin supplementation significantly improved the macroscopic horn quality.
- Growth rate: The horn growth rate remains unchanged at around 7 mm per 28 days even under supplementation.
The use of biotin to improve horn quality has also been scientifically studied. In a controlled double-blind study of 42 Lipizzaner stallions, 26 in the biotin group and 16 in the control group, nine months of continuous biotin supplementation showed a significant improvement in the macroscopic horn quality of the hoof wall and white line, with further improvement over the following five months. Importantly, however, the supply of nutrients does not accelerate the growth rate of the horn: it remained unchanged at 7 mm in 28 days in both the test group and the control group. Feeding measures therefore require patience and do not resolve acute hoof problems at the bearing edge.
The role of the farrier
The farrier or hoof trimmer is the central partner for maintaining the mechanical hoof balance and the stability of the bearing edge. According to the animal welfare guidelines, the regular trimming or shoeing interval is 6 to 8 weeks. Since hoof horn grows at around 7 mm in 28 days, renewing the entire hoof wall takes about 11 months.
The physical relief of the hoof wall through professional trimming and balancing cannot be replaced by any external care or feeding. The BMEL guidelines for the assessment of horse keeping under animal welfare aspects of 9 June 2009 specify an interval of usually 6 to 8 weeks for the control and care of the hooves. When these periods are exceeded, the load-bearing point shifts forward, which leads to increased lever forces on the toe walls and to cracking of the bearing edge.
- Regular trimming: an interval of 6 to 8 weeks prevents unphysiological lever forces on the toe wall.
- Even growth rate: hoof horn grows at a constant rate of around 7 mm per 28 days.
- Long-term perspective: a complete renewal of the hoof wall, from the coronet to the sole, takes about 11 months.
Given the growth rate of roughly 7 mm per 28 days, it becomes clear that the horn touching the ground at the bearing edge today was formed at the coronet around 11 months ago. Measures to improve horn quality, whether dietary adjustments or optimised trimming, therefore need almost a full year before their result has fully arrived at the bearing edge. Patience in hoof care is thus not merely a recommendation, but a biological necessity.
What care can achieve for horn
Topical care protects the outer horn structure from moisture-related leaching and soiling, without altering the internal tissue hydration of the hoof wall. It is applied sparingly and in a thin layer to clean, dry horn. With deep hoof cracks, structural instability or lameness, the farrier or vet should be consulted immediately.
In the daily routine, external hoof care is primarily about cleanliness, hygiene and protecting the horn surface. To support the care of the hoof and frog region, equion® Hoof and Skin Gel offers a well-considered option. The underlying Multi-Ion Technology uses zinc and silver ions that are stored in an inert carrier material. On contact with the natural ambient moisture, the charged ions are released from the particles in a controlled way, without any prior chemical reaction being required. The low-viscosity, paraffin oil based gel is applied in a thin layer to clean, dry horn and remains there as a fine film. This gel does not supply the hoof wall with water either, and it is not designed to. Its purpose is a different one: the gel matrix keeps the particles with their stored ions on the horn for as long as possible, while the ions gradually move out on contact with moisture.
equion® Hoof and Skin Gel is a care product for external use and not a veterinary medicine; it serves to cleanse, care for and protect the horn, but does not constitute medical treatment. If the changes to the hoof go beyond superficial care, deeper wall cracks appear, or the horse shows pain on turning or lameness, the assessment must always be carried out by a vet or farrier.
Note: These explanations describe the properties of the ingredients and how the technology works. They are not statements about the healing or treatment of diseases.
- Surface cleansing: thoroughly clean the hoof of dirt and bedding residue before application and allow it to dry.
- Sparing application: apply the care gel in a thin, even layer to the affected horn areas.
- Professional boundaries: always seek the advice of a farrier or vet in cases of open wounds, deep horn fissures or impurities in the frog area.
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equion Hoof & Skin Gel – 10 ml Sample
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All you need to know
Brittle horn is often caused by constant alternation between wet and dry conditions, hard ground, unsuitable mechanical loading or overly long intervals between farrier visits. It is not a disease with a single cause, but usually the result of several factors, to which feeding deficiencies may also contribute.
No benefit for the hoof wall has been demonstrated. In a measurement series on six horses, even two hours of soaking did not change the moisture content of the hoof wall. Only the softer sole horn measurably absorbs water in the process.
Since the hoof wall does not absorb any significant moisture from the outside, a thick fatty layer of hoof oil or hoof grease does not supply the wall with water. Instead, the fat merely sits on the surface. Sensible care products should be applied in an ultra-thin layer to the clean, dry hoof.
In a controlled double-blind study, biotin supplementation improved the macroscopic horn structure. The growth rate remained unchanged, so it takes many months before new horn arrives at the bearing edge. Discuss any supplementation with your vet.
With very fine, purely superficial cracks, an adjustment of housing conditions and daily care is often sufficient. However, if the crack is deep, destabilises the bearing edge or extends up to the coronet, you must consult your farrier or vet to correct the mechanical loading professionally.
The farrier should generally come regularly every 6 to 8 weeks to keep the horn in balance and prevent mechanical overload. You need the vet for lameness, deep fissures, moist, greasy patches that indicate thrush, or if the horn does not improve despite adjusted care.