Biotin

Biotin is vitamin B7, occasionally still called vitamin H. It is a water-soluble B vitamin that works as a cofactor for carboxylase enzymes involved in fat metabolism, gluconeogenesis and amino acid breakdown. For our purposes the relevant consequence is keratin — the structural protein that makes up hoof wall, claw, hair and the outer layer of skin. Biotin is required to build it, which is why this vitamin is sold almost entirely for hooves and coats.

Horses: the Use With Real Evidence

Equine hoof supplementation is where biotin earns its reputation. Controlled studies in horses with poor hoof horn quality have shown that biotin supplementation improves hoof horn quality and growth rate. This is not extrapolated from human nail research — it was studied in horses, in the species where it is sold.

The effective amount is 15 to 20 mg daily for an average riding horse. Lower amounts are common in general-purpose supplements and are unlikely to achieve much; check the actual milligrams rather than assuming a hoof product contains a useful dose.

Now the part that is nearly always understated: the timeline. Hoof wall grows roughly 6 to 9 millimetres a month, and replacing the entire hoof capsule from coronary band to ground takes around nine to twelve months. Biotin cannot improve horn that has already been made. It only affects horn produced from the day you start. So the honest expectation is:

• Nothing visible for the first two to three months.

• New growth at the coronary band looking better from around three to five months.

• A genuinely different foot at nine to twelve months.

Owners abandon biotin at eight weeks constantly, having concluded it does not work, when the trial simply has not run long enough to produce an answer. If you are going to do this, commit to a year and take photographs at the start. And be clear that biotin addresses horn quality, not the shoeing, trimming cycle, nutrition, moisture management or underlying laminitis that may be the real problem.

What the Horse Studies Actually Found

It is worth knowing what the individual trials showed, because they do not all say the same thing. As summarised by Kentucky Equine Research:

• Buffa and colleagues, 1992 — 15 mg daily for ten months produced statistically significant improvements in both hoof growth rate and hardness (Equine Veterinary Journal).

• Josseck and colleagues, 1995 — 20 mg daily for nine months in Lipizzaners improved hoof wall integrity, but not growth rate.

• Geyer and Schulze, 1994 — 97 horses given 5 mg per 100 to 150 kg of body weight for one to six years showed better horn condition, again with no change in growth rate.

The honest reading: better horn quality is the consistent finding, faster growth is not. That fits the practical advice above — you are buying a stronger wall that takes most of a year to show, not a quicker one.

Does Every Horse Need It?

Probably not. KER notes that microbes in the horse’s hindgut make biotin in sufficient quantities that no documented biotin deficiency has been reported in horses, and Central Gippsland Equine Vet says most horses on a balanced, forage-based diet with healthy hindgut function do not need extra. Alfalfa and good pasture are natural sources, and oats, barley and soybean meal contain modest amounts.

Where it earns its place, per KER: horses with compromised hoof walls, high-performance horses on a regular trimming and shoeing cycle, and horses going through nutritional, climatic or athletic stress. If a horse’s gut is disrupted — after colic, a diet change or antibiotics — sort the gut out alongside the supplement, since that is where the horse’s own biotin comes from.

Dogs and Cats

Biotin deficiency is genuinely rare in dogs and cats. Complete commercial diets contain it, and gut bacteria synthesise more. But there are two specific and well-defined ways an animal becomes deficient, and both are worth knowing because both are avoidable.

Raw egg whites. Egg white contains avidin, a protein that binds biotin extremely tightly and prevents its absorption. Feeding raw egg whites regularly — not occasionally, but as a habit — can produce genuine biotin deficiency, showing up as a dull brittle coat, hair loss around the eyes and muzzle, and scaly skin. Cooking denatures avidin completely, so a cooked egg is not a problem, and the yolk is itself a good source of biotin. This matters most to raw feeders, and the fix is simple: cook the whites, or feed whole eggs rather than whites alone.

Prolonged antibiotic courses, which suppress the gut bacteria that make biotin. Relevant for animals on long-term antibiotic therapy.

Beyond genuine deficiency, biotin is widely given for coat condition and brittle claws. It is harmless and the mechanism is real, though the evidence in dogs with normal biotin status is weak. It is often paired with the B vitamins in brewer's yeast, which is itself a decent biotin source.

Biotin in a Dog’s Diet

Before reaching for a supplement, it helps to know where biotin already comes from. Chewy’s vet-reviewed guide lists organ meats, eggs, fatty fish and some root vegetables such as sweet potato as natural sources, and notes that a dog on a complete and balanced diet should already be getting enough.

The canine evidence is thin and old. In a 1989 Swiss clinical study of dogs with skin conditions, biotin was given for three to five weeks and owners reported all signs resolved in 60 percent of cases and improvement in another 31 percent. Chewy points out there has been little dedicated follow-up since. If you try it, use a dog-specific product or one your vet recommends, avoid stacking several skin and coat products at once, and give it several weeks before judging. Pairing it with fish oil covers the fatty acid side of the coat that biotin does not.

How Much to Give

Animal · Daily amount

• Cat — 1 to 2 mg

• Dog under 20 lbs — 1 to 2 mg

• Dog 20 to 50 lbs — 2 to 5 mg

• Dog over 50 lbs — 5 mg

• Horse, hoof support — 15 to 20 mg

• Pony or small horse — 10 to 15 mg

Note the scale difference between species. A horse needs several times what a large dog does, and an equine hoof product dosed at 2 mg is not going to reproduce the study results.

How to Give It

Biotin is water-soluble, odourless and tasteless, and mixes into food without complaint. Give it daily with a meal. Because it is water-soluble there is no loading phase and no storage depot — consistency is what matters, and a missed week is a missed week of horn production. For horses it goes into feed as a powder or pellet; for dogs a capsule can be opened into wet food.

What to Look For When Buying

• The actual milligrams of biotin per serving. This is the whole decision for a horse product. Many hoof supplements contain a token amount.

• Supporting nutrients for hoof work — methionine, zinc, copper and lysine all contribute to keratin structure, and a well-built hoof supplement includes them rather than biotin alone.

• Single-ingredient biotin if you are already feeding a balancer and only want to top up, so you are not double-dosing minerals.

• No added sugar or xylitol in any chewable format.

• A date and sealed packaging, and third-party verification where offered — the same standard behind our own certificates of analysis.

Side Effects and Cautions

Biotin is one of the safest supplements in common use. It is water-soluble, excess is excreted in urine, and no toxicity has been established in dogs, cats or horses even at high intakes. There is one caution that matters and it is not about safety at all.

• Biotin interferes with laboratory tests. Many clinical immunoassays use biotin-streptavidin binding as part of their chemistry, and high circulating biotin can distort the result — thyroid hormone assays are the classic example. A dog or horse on high-dose biotin can produce misleading thyroid values, which could mean an incorrect diagnosis in either direction. Tell your vet the animal is on biotin before any blood test, and ask whether to stop it beforehand. This is real, documented and widely unknown among owners.

• Mild digestive upset occasionally, usually from the carrier rather than the biotin.

• It does not fix mechanical problems. A horse with poor hooves because of an overlong shoeing cycle, wet-dry cycling, or a metabolic condition like insulin dysregulation will not be rescued by biotin.

When to Talk to Your Veterinarian

Before any blood test, as above. For horses: sudden lameness, heat in the foot, a bounding digital pulse or a reluctance to walk on hard ground needs a vet and a farrier now, not a supplement — those can be laminitis. For dogs and cats: hair loss around the eyes and muzzle, scaly skin or a coat that has changed markedly warrants investigation, because the common causes are allergic, parasitic or endocrine rather than nutritional. Our article on allergies in dogs covers that workup.

How It Fits With Hemp

Coat and skin is the shared ground, and they work from different directions, which is the point. Biotin supplies the cofactor keratin production depends on. The fatty acids in hemp seed oil contribute to the lipid barrier of the skin itself, and collagen and fish oil address yet other parts of the same structure. Stacking those is not duplication.

The timeline lesson from hooves applies to coats too, if less dramatically: hair grows slowly, and any coat intervention needs six to eight weeks before it is fair to judge. Our serving guide covers hemp amounts by weight, and for horses the 5,000mg concentration in our equine range is the practical choice at equine body weight.

Frequently Asked Questions

How much biotin does a horse need for hooves? 15 to 20 mg daily is the amount used in the studies that showed improvement. Lower amounts in general supplements are unlikely to do much.

How long does biotin take to improve hooves? Expect nothing for two to three months, better new growth at the coronary band by three to five months, and a genuinely different foot at nine to twelve months. Hoof grows 6 to 9 mm a month and biotin only affects horn made from today.

Do dogs need biotin supplements? Rarely. Complete diets contain it and gut bacteria make more. The exceptions are dogs fed raw egg whites regularly and dogs on long antibiotic courses.

Why are raw egg whites a problem? Egg white contains avidin, which binds biotin and blocks its absorption. Cooking destroys avidin, so cooked eggs are fine and whole eggs are better than whites alone.

Can you give too much biotin? No toxicity has been established, since it is water-soluble and excess is excreted. The real issue is that high biotin can distort laboratory tests, particularly thyroid assays, so tell your vet before bloodwork.

Will biotin help my dog's brittle nails? It may, and it is harmless to try, but evidence in animals with normal biotin status is weak. Give it eight weeks before judging.

For the equine hoof research, the study on biotin supplementation and hoof horn quality in horses is the reference point. For the laboratory interference issue, the American Association for Clinical Chemistry has published on biotin interference in clinical immunoassays.

Do all horses need biotin?

No. Hindgut microbes make biotin, and Kentucky Equine Research notes no documented biotin deficiency has been reported in horses. Supplementation is for horses with poor horn quality or under heavy work or stress.

What feeds contain biotin for horses?

Alfalfa and good-quality pasture are natural sources; oats, barley and soybean meal contain modest amounts. None of them reliably delivers the 15 to 20 mg used in the hoof studies.

Does biotin make hooves grow faster?

Sometimes, but not consistently. One study found faster growth at 15 mg a day; two others found better horn quality with no change in growth rate. Quality is the reliable effect.

Can I give my dog human biotin?

Use a dog-specific product or one your vet recommends. Human chewables and gummies can contain xylitol, which is toxic to dogs, and human doses are not scaled for pets.

Does biotin help with shedding?

It is not shown to reduce normal seasonal shedding. If your dog is losing noticeably more coat than usual, or has bald or scaly patches, see your vet — the common causes are allergic, parasitic or hormonal.