This article has not yet been professionally approved. The information is based on the sources listed below.
Biotin for horses: what the hoof studies really show
What studies on biotin and hoof horn actually measured, why any effect becomes visible after months at the earliest, and why protein, trace elements and hoof care belong in the picture.
The short answer
Biotin is a B vitamin authorised as a feed additive for all animal species 1. In a placebo-controlled study, hoof horn was rated better after nine months on 20 mg daily 2; another study found more growth and hardness over ten months, more so with 15 mg than with 7.5 mg 3. The hoof wall takes around eleven months to grow out once 2. A quick or reliable effect in every horse is therefore not proven.
What is biotin and why is it fed for hoof horn?
Biotin is one of the B vitamins 4. Under feed law, it is a nutritional additive from the vitamin group; its authorisation for all animal species was renewed in 2025 1. EFSA assesses it as safe under the authorised conditions of use 5.
For hoof horn, the veterinary reference names sulphur-containing amino acids such as methionine, and biotin, as essential for healthy horn growth. According to the same reference, it is documented that 15–25 mg of biotin daily improved hoof quality in horses with soft hoof walls, especially after major ration changes or severe digestive disorders 6.
What do the studies on biotin and hoof horn show?
The most frequently cited studies are small and mostly date from the 1980s and 1990s. They measure different things: horn quality by visual assessment, tissue structure, hardness or growth. The overview shows what was examined in each case.
- Histological examination of the same Lipizzaners showed a small but significant improvement in horn structure after 19 months 7.
- Not every defect responded: under the scanning electron microscope, one superficial defect improved with biotin, a second only after additional feed lime 8.
| Study type | Animals | Amount and duration | Result | Limitation |
|---|---|---|---|---|
| Case series | over 40 cases with weak horn | 10–30 mg/day, at least 6–9 months recommended | Improvement of varying degree described in all cases 4 | Case observations without a control group |
| Riding horses, two doses | 24 riding horses | 7.5 or 15 mg/day, 10 months | More growth and hardness, greater with 15 mg 3 | Small group, no clinical hoof findings |
| Long-term observation | 97 horses with brittle horn, 11 controls | 5 mg per 100–150 kg, 1–6 years | Improvement after 8–15 months 9 | Small, unequal control group |
| Double-blind study | 42 Lipizzaner stallions | 20 mg/day, double-blind | Better than placebo after 9 months 2 | One breed, one location |
| Ponies, paired comparison | 8 ponies | 0.12 mg per kg, 5 months | Around 15% more horn growth 10 | Very small number of animals |
Selected biotin studies in horses. Dose and duration describe the studies, not a recommendation.
How long does it take for biotin to show in the hoof?
Hoof horn grows slowly. In the Lipizzaner study, the hoof wall grew around 7 mm in 28 days, so a completely new hoof wall took about eleven months 2. An improvement was statistically detectable after nine months and continued to increase over the following months 2.
In the long-term observation, the horn improved after 8–15 months. When biotin was then reduced or stopped, the condition deteriorated again in 7 of 10 horses 9. Anyone expecting a new hoof after four weeks of biotin is not accounting for horn growth.
Does biotin make horn grow faster?
The findings contradict each other. In two studies, horn grew faster with biotin 310. In the Lipizzaner study and in the long-term observation, the growth rate was the same with and without biotin; what had improved there was the quality of the horn 29.
To sum up honestly: in horses with poor horn quality, there are repeated indications of improvement over many months. However, the studies are small and some lack a control group 49. They do not show whether horses with unremarkable horn gain a practical benefit: the studies in animals not selected by hoof findings measured growth and hardness, not hoof problems 310.
What role do protein, zinc and the rest of the ration play?
Biotin is only one building block. A review names poor hair and hoof growth as a possible consequence of too low a protein intake 11. So first check whether the ration provides enough usable protein before relying on a single vitamin.
For zinc and the hoof, the evidence is thin: a study with seven horses found denser horn material, but no clinical endpoints 12. And hoof problems can also arise from too much. Chronic selenium poisoning shows, among other signs, as separation of the hoof wall and horizontal hoof cracks 13. So check what several products fed in parallel provide together.
How do you read the amount of biotin on a product?
You find the additives of a complementary feed and their amounts in the declaration 14. A freely chosen example, not a product declaration or dosage: 1,000 mg of biotin per kg of product at 20 g daily gives 0.02 kg × 1,000 mg/kg = 20 mg of biotin per day.
If the product also contains zinc, copper, selenium or amino acids, these contributions belong in the total ration. The maximum contents for trace elements refer to the entire ration, not to the individual product 15.
- Note the biotin content and daily amount from the declaration.
- Record the product's other additives.
- Add them up with the mineral feed and other supplements.
- Note the start date and compare the hoof only after months, ideally with photos.
When does a hoof problem belong with the farrier and the vet?
Brittle horn, cracks or breaking wall edges cannot be assessed through feed alone. Discuss changes with your farrier or hoof trimmer before buying a product, and document the condition with photos.
Key takeaways
Frequently asked questions
How much biotin does a horse need per day?
The sources reviewed here do not give a fixed daily requirement. Mostly 15–20 mg daily in adult horses was studied 23; the veterinary reference gives 15–25 mg for horses with soft hoof walls 6. These are study amounts, not a dosage recommendation for your horse.
How long do you have to feed biotin before you see anything?
In the studies, differences appeared after about 8–15 months 29. That fits with horn growth: around 7 mm in 28 days, around eleven months for a new hoof wall 2. After reducing or stopping, the horn deteriorated again in 7 of 10 horses 9.
Sources & studies
The content is based on the references listed below. It does not replace individual veterinary or feeding advice.
Show list of sources (15)
- Durchführungsverordnung (EU) 2025/1424 der Kommission vom 17. Juli 2025Renewal of the authorisation of biotin and two biotin preparations as feed additives for all animal species (identification number 3a880, nutritional additive, functional group vitamins); repeals Implementing Regulation (EU) 2015/723.
- Josseck H, Zenker W, Geyer H (1995): Hoof horn abnormalities in Lipizzaner horses and the effect of dietary biotin on macroscopic aspects of hoof horn quality. Equine Veterinary Journal 27(3):175–182Controlled double-blind study over 19 months in Lipizzaners of the Spanish Riding School; companion paper to Zenker et al. (1995), assesses the macroscopic quality of the hoof horn
- Buffa EA, Van Den Berg SS, Verstraete FJ, Swart NG (1992): Effect of dietary biotin supplement on equine hoof horn growth rate and hardness. Equine Veterinary Journal 24(6):472–47424 randomly selected riding horses, 10 months, different amounts of biotin: significantly higher horn growth rate and hardness with biotin, more so with 15 mg daily than with 7.5 mg. Small study, endpoints growth and hardness, no clinical hoof findings (PMID 1459062).
- Comben N, Clark RJ, Sutherland DJB (1984): Clinical observations on the response of equine hoof defects to dietary supplementation with biotin. Veterinary Record 115:642–645Pioneering clinical study in 40 horses on biotin supplementation of hoof horn
- EFSA FEEDAP Panel (2025): Assessment of the feed additive consisting of biotin for all animal species for the renewal of its authorisation. EFSA Journal 23(2):e9250Scientific opinion on the renewal of authorisation: biotin remains safe for all animal species, consumers and the environment under the authorised conditions of use; a new efficacy assessment was not required for the renewal.
- Merck Veterinary Manual: Nutritional Requirements of Horses and Other EquidsSummary of the NRC recommendations: water requirement 5 litres per 100 kg body mass per day at maintenance, sweat losses of around 3.1 g sodium, 5.3 g chloride and 1.6 g potassium per litre, salt recommendation 1.6–1.8 g per kg feed dry matter at a maximum of 6% of the ration; from a 50% forage share potassium is adequately covered. Also covers the selenium requirement (0.1 mg/kg feed dry matter or at least 1 mg/day for a 500 kg horse, selenium as a component of glutathione peroxidase together with vitamin E) and the strong location-dependent variation of selenium in forage (grass forage on average 0.194 ppm, range 0–1.2 ppm); some regions are markedly low in selenium and may need supplementation. Also gives the iodine requirement (0.35 mg/kg feed dry matter, mares in late pregnancy 0.4), iodine poisoning of pregnant mares from around 40 mg/day, documented goitre cases in mares and their foals associated with large amounts of dried seaweed (kelp), that iodised salt easily covers the requirement, and that iodine supplementation is usually unnecessary except in severely iodine-deficient regions
- Zenker W, Josseck H, Geyer H (1995): Histological and physical assessment of poor hoof horn quality in Lipizzaner horses and a therapeutic trial with biotin and a placebo. Equine Veterinary Journal 27(3):183–191Double-blind, placebo-controlled long-term study (19 months) in 42 Lipizzaner stallions of the Spanish Riding School
- Kempson SA (1987): Scanning electron microscope observations of hoof horn from horses with brittle feet. Veterinary Record 120:568–570 (Royal Dick Vet School)Differentiation: superficial defects respond to biotin, inner keratin layers additionally require bioavailable calcium
- Geyer H, Schulze J (1994): The long-term influence of biotin supplementation on hoof horn quality in horses. Schweizer Archiv für Tierheilkunde 136(4):137–149Long-term observation over 1–6 years: 97 horses with brittle hoof horn received 5 mg biotin per 100–150 kg body weight, 11 horses without biotin as controls. Improvement in horn quality after 8–15 months, same growth rate of coronary horn in both groups, deterioration in 7 of 10 horses after reduction or withdrawal (PMID 8202678).
- Reilly JD, Cottrell DF, Martin RJ, Cuddeford DJ (1998): Effect of supplementary dietary biotin on hoof growth and hoof growth rate in ponies: a controlled trial. Equine Veterinary Journal Supplement 26:51–57Controlled feeding trial with 8 pair-matched ponies, 0.12 mg biotin per kg body weight: after 5 months around 15% more horn growth and a higher growth rate than in the control group. Very small number of animals (PMID 9932094).
- Mok CH, Urschel KL (2020): Amino acid requirements in horses (Invited Review). Asian-Australasian Journal of Animal Sciences 33(5):679–695Review of amino acid requirements: in horses essentially only lysine is quantitatively established; there are no robust requirement figures for methionine/threonine
- Neri Basurto R, et al. (2008): Effect of zinc methionine on the equine hoof – an evaluation by environmental scanning electron microscopy. Veterinaria México 39(3):247–2537 horses, 5.4 g zinc methionine daily for 6 months: denser tubular and intertubular horn, more zinc and sulphur in the horn. Very small number of animals, no clinical endpoints – weak evidence
- Merck Veterinary Manual: Selenium Toxicosis in AnimalsStandard veterinary reference work (toxicology): chronic selenosis/alkali disease with hair loss and breakage in the mane, tail and neck, plus coronary band swelling, separation of the hoof wall and horizontal hoof cracks; notes that the neurological disease “blind staggers” historically attributed to selenium is more likely polioencephalomalacia due to high sulphur intake. The horse-specific acute single dose is documented by the primary study Miller and Williams (1940).
- Verordnung (EG) Nr. 767/2009Placing on the market and use of feed, labelling and claims; definitions of complete feed (Art. 3(2)(i)) and complementary feed (point (j)), content of feed additives (Art. 8), feeding instructions (Annex II No. 4). Link to the current EUR-Lex consolidated version (as of 26 December 2018).
- Verordnung (EG) Nr. 1831/2003Feed additives – authorisation and use; “daily ration” based on 12% moisture (Art. 2(2)(f)), renewal of authorisation and automatic continuation (Art. 14(4)), general conditions of use (Annex IV: natural plus added amount; complementary feed, diluted as specified, at most at the level for complete feed). Link to the current EUR-Lex consolidated version (as of 27 March 2021).