Probiotics for horses come in three main formats: powders that are mixed into a feed, pellets that are fed by the scoop, and pastes given from an oral syringe. The live micro-organisms inside may be similar across all three, but the format decides how easily the product gets into your horse, how much is wasted, how it travels and how it should be stored. This comparison sets out the practical differences so you can match a format to your horse and your routine. For background on what probiotics are designed to do, start with our guide to equine probiotics.
The three formats at a glance
Powders
Powders are the most common format for daily gut balancers and straight probiotics. They are measured with a small scoop and stirred into a bucket feed, usually a chaff or a dampened fibre feed so the powder clings to the feed rather than settling at the bottom. Many powders combine live yeast or bacteria with prebiotic fibres, and some add vitamins, minerals or other ingredients. Because the daily dose is small, a single tub can last a long time.
Pellets
Pellets carry the active ingredients in a larger, more palatable base, so the daily serving is bigger and is often fed straight from the scoop or on top of a feed. Pelleted gut balancers tend to suit horses that already have a feed each day and owners who want something quick to measure. The carrier ingredients become part of the ration, so check what they are if your horse is on a restricted or low-sugar diet. A larger serving also means more product to store and carry for each day of feeding.
Pastes
Pastes come in a pre-measured oral syringe and are squeezed onto the back of the tongue. They are usually intended for short courses: around travel, competitions, a change of yard or another period of upheaval. A paste does not depend on the horse eating a bucket feed, which is its main advantage. The trade-off is that a syringe holds only a few doses, so check the cost per dose carefully before relying on paste for anything beyond a short course.
Side-by-side comparison
| Factor | Powder | Pellets | Paste |
|---|---|---|---|
| Ease of feeding | Needs a bucket feed to mix into | Fed from the scoop or added to feed | Given by syringe, no feed needed |
| Fussy feeders | Can be noticed in a small feed | Often palatable, though some horses sort them out | Bypasses fussiness, but some horses resent syringes |
| Forage-only diets | Needs a small carrier, such as a handful of low-calorie chaff | Can be fed alone as a handful | Works without any bucket feed |
| Travel and competition | Pre-weigh into labelled bags | Take up more space on longer trips | Very convenient for short courses away from home |
| Waste | Powder left in the bucket or blown away outdoors | Low, if dropped pellets are not lost | Low, if the full dose goes in |
| Cost per day | Small daily dose; work it out from tub size | Larger daily serving; work it out carefully | Work it out per dose; designed for short courses |
| Storage | Sealed, cool and dry | Sealed and dry; larger tubs or bags | As stated on the pack; check the expiry date |
Ease of feeding and fussy feeders
For a horse that eats everything put in front of it, the format matters very little. Powders mix best into a damp fibre feed, and pellets can go into the same bucket or be offered on their own. Fussy horses are a different story. A powder can change the smell or taste of a small feed enough for a suspicious horse to leave it, so introduce it gradually, starting with a fraction of the dose and building up over several days.
Pellets are usually made to be palatable, but a determined horse can still pick around them. Paste avoids the problem altogether because it does not rely on appetite, although horses that dislike being handled around the mouth may need patient practice with an empty syringe first. If a horse that normally eats well suddenly refuses its feed, treat that as a possible health sign rather than a palatability problem; our article on the signs of poor gut health explains what else to look for.
Horses on forage-only diets
Many good-doers live on hay or grass with little or no hard feed, which makes powders awkward. A powder needs a carrier, so keep it to a small handful of low-calorie chaff or soaked fibre to avoid adding unwanted calories. Pellets can be fed alone as a handful, and a paste needs no carrier at all. World Horse Welfare points out that overweight horses fed only forage may fall short on protein, vitamins and minerals and recommends a balancer, so for many owners that daily balancer becomes the natural carrier for a powdered probiotic.
If you are trimming rations for weight loss, the forage itself still has to meet a sensible minimum. Our guide to how much forage a horse needs sets out the figures used by UK welfare charities.
Travel, competition and short courses
Travelling, stabling away from home and changes to routine are the situations where owners most often reach for a probiotic. A paste fits neatly when a horse may not finish its usual feed at a show or a new yard. Powders travel well too if you pre-weigh each day's dose into labelled bags. Whichever format you choose, start it at home before the trip rather than on the day, so you know the horse accepts it and you are not introducing something new at a stressful moment. Our page on travel and competition covers the wider management picture.
If you compete, check your governing body's rules on prohibited substances before you travel. The British Equestrian Trade Association runs the NOPS scheme (Naturally Occurring Prohibited Substances), which applies to the company rather than to individual factories, and BETA provides a webchecker so you can confirm whether a brand is a member.
Waste and dosing accuracy
Waste matters for two reasons: it costs money and it means your horse receives less than the intended dose. Powders stick to the sides of a bucket, sink to the bottom of a wet feed or blow away when fed outdoors on a windy day. Pellets are easily dropped in a field or bedding when fed by hand. Pastes are only wasted if the horse spits part of the dose out, which usually happens when the syringe is emptied onto the front of the tongue rather than the back. Our guide on how to feed a probiotic has practical tips on getting the full dose in.
Working out cost per day
Pack prices are misleading because servings vary so widely between formats. Work out how many days a pack lasts by dividing the pack weight by the daily dose for your horse, then divide the pack price by that number of days. A 1kg tub fed at 10g a day lasts 100 days; a 3kg bag fed at 50g a day lasts 60 days. For a paste, divide the price by the number of doses in the syringe and multiply by the length of the course.
Check whether the label sets a higher loading dose for the first week or two, and whether the dose rises with bodyweight. A product that looks economical for a pony may cost far more per day for a 600kg horse. Compare products on cost per day at the dose your horse actually needs.
Storage and shelf life
Live micro-organisms are sensitive to their surroundings, which is why manufacturers give storage instructions and a best before date. Reseal tubs and bags after every use, keep them out of direct sun and away from damp, and follow any temperature guidance on the label. Feed rooms and horseboxes can get hot in summer, so avoid leaving pastes and opened tubs in a lorry for long periods. Keep products in their original packaging so you always have the batch number and expiry date.
What the format cannot tell you
Format is about convenience; it says nothing about whether a product contains what it claims or whether it works. A review of probiotic use in horses by Schoster and colleagues in the Journal of Veterinary Internal Medicine (2014) concluded that the evidence for controlling disease with probiotics in horses was weak, and that quality control of commercial products was not tightly regulated. One study cited in that review found that only 2 of 13 veterinary and human probiotic products contained the specified organism at the concentration stated on the label.
In Great Britain, micro-organisms used to influence the gut flora of animals fall within the gut flora stabilisers group of zootechnical feed additives, and the Food Standards Agency publishes a register of authorised additives and their terms. Look for products that name the strain, state a guaranteed count and give clear storage advice. Our best horse probiotics in the UK comparison and the reviews hub set this information out product by product.
Which should you choose?
- Choose a powder if your horse already has a small daily bucket feed, eats reliably and you want a compact, long-lasting daily product.
- Choose pellets if you want quick measuring, your horse is a little picky with powders, or you need something that can be fed alone as a handful.
- Choose a paste for short courses around travel, competitions or other upheaval, or for a horse that will not eat a bucket feed reliably.
- Consider combining formats only after checking with your vet or a nutritionist, for example a daily powder at home and a paste on travelling days, so you are not doubling up without reason.