Foal & Young Horse Support

Looking for everyday support for your foal or young horse? We start with ImmuBiome Lean Muscle—our go-to for growing horses—for daily nutritional support of healthy development, digestion, and everyday condition in weanlings, yearlings, and growing horses. ImmuBiome Immune is a good second option for gut–immune balance through weaning and new-herd transitions.

Please follow the feeding directions on the product label and check with your veterinarian before adding any supplement to a young horse’s diet. These supplements are for nutritional support only. They are not intended to diagnose, treat, cure, or prevent any disease, and they do not replace veterinary care.

WEANLINGS · YEARLINGS · GROWING HORSES

The first couple of years bring a lot of change—weaning, new herd mates, first trips off the farm, and a body that is still filling out. This page is for owners who want simple, everyday nutritional support for growing and young horses, not a wall of similar products. Start with ImmuBiome Lean Muscle, our go-to for growing horses. Immune is a good add-on when you also want gut–immune balance through transitions. Always check the product label and talk with your veterinarian about what fits your young horse’s age, size, and diet.

ImmuBiome Lean Muscle

ImmuBiome Lean Muscle

From $134.00
ImmuBiome Immune

ImmuBiome Immune

From $69.00

Giving young horses a great start

Everyday support for weanlings, yearlings, and growing horses as they find their feet
Healthy development — grey yearling trotting across a green paddock

Steady, healthy development

Bovine colostrum, organic Reishi, and probiotics provide daily nutritional support for healthy muscle development and a balanced frame as your young horse grows.

Weaning and new-herd transitions — three weanlings grazing together

Weaning & new-herd transitions

Weaning, new pasture mates, and first trailer rides can be a lot for a young horse. Probiotics, prebiotics, and beta-glucans help support digestive balance and natural defenses through routine changes.

Everyday condition — bright-eyed bay young horse at the barn door

Everyday condition & coat

Support for a bright, well-conditioned young horse—helping them get more from good forage, turnout, and a feeding plan built with your veterinarian.

Why Lean Muscle for young and growing horses

Our go-to for growing horses

We start with ImmuBiome Lean Muscle because it’s our go-to for growing horses. It pairs bovine colostrum and organic Reishi mushrooms with 3 billion CFU of probiotics, prebiotics, and beta-glucans per serving—nutritional support for healthy muscle development, digestion, and nutrient absorption while a young horse fills out.

Want added support through weaning and new-herd changes? ImmuBiome Immune is a good second option, built on Turkey Tail and Lion’s Mane with probiotics and colostrum for everyday gut–immune balance.

Follow the directions on the product label for amounts, and confirm with your veterinarian before adding any supplement to a young horse’s diet. These supplements do not replace veterinary care, a balanced ration, or a vaccination and deworming plan.

Shop Lean Muscle

Why horse owners choose ImmuBiome

Trusted by riders every day

Owner-trusted

Lean Muscle averages 4.95★ across 850+ owner reviews

Equine-focused

Formulas designed around the horse microbiome

Ships from Idaho

UPS from Eden · free shipping on US subscriptions

30-day returns

Hassle-free returns if it is not the right fit

Foal & young horse support FAQ

Clear answers for horse owners
Does ImmuBiome replace veterinary care?
Who is this a good fit for?
Is this suitable for my foal?
How much should I feed a young horse?
How is this different from the Muscle Building hub?
When does it make sense to add Immune?
How do I get started?

Lean Muscle reviews from horse owners

Real feedback on condition, development, and everyday wellbeing
MuscleProductHorseLean muscleGeldingHorsesResultsProductsSupplementBarry
  • 5 stars: 847 (95%)
  • 4 stars: 39 (4%)
  • 3 stars: 2 (0%)
  • 2 stars: 1 (0%)
  • 1 star: 0 (0%)
D
Diane &.A. (United States)
What is your horses estimated workload?: Light
What is your horses discipline?: Other
What is your horses age?: 13 to 20
Lean muscle really works,

Lean muscle really works, I’m using it with Spine and Nerve for my 20 yr old who had severe Lymes Disease a few years ago that was caught early but his topline and chest weren't looking as good as I hoped. When I added Lean muscle, he was already on probiotics, it took a couple of months then I started to see a big difference now, I am reordering it -I hope this review helps someone on the fence! He was diagnosed with cushings/PPID in May and was rearing and galloping, before taking the cushings pills so Lean Muscle and Spine and Nerve are super effective.

A
Aimee W. (Canada)
What is your horses estimated workload?: Light
What is your horses discipline?: Show Jumper
What is your horses age?: 13 to 20
Helped my horse during long period off.

My horse looks fantastic. He's been off for about a year now with an injury and although still gets turnout and hand walking, he hasn't done much else. I only started the protocol in December 2025 - about 7 months into our year off and he looked better after starting the protocol. I thought he'd lose a lot of his muscle but he really hasn't and I am a big believe it is thanks to the Lean Muscle!

L
Lauri (United States)
What is your horses estimated workload?: Light
What is your horses discipline?: Other
What is your horses age?: 21+
Barry is better!

I already had Barry on Nerve and Spine and now have added Lean Muscle…he is doing so much better!

J
Jamie B. (United States)
What is your horses estimated workload?: Medium
What is your horses discipline?: Other
What is your horses age?: 13 to 20
This product is outstanding

This product is outstanding. We use it for 2 retired jumpers and an older pony. Moving them from FL to NC had its challenges for them physically and Lean Muscle has helped them every step
Of the way. Their coats, feet and most importantly their muscling is so defined. You’d think they were still show horses.

E
Erin B. (Kuwait)
What is your horses estimated workload?: Strenuous
What is your horses discipline?: Other
What is your horses age?: 13 to 20
Lean muscle added to autoship.

My daughters 16 yr old gelding suffered from EPM when we bought him. We started him on Lean muscle and we havent had any issue with EPM since. Lean muscle has become a staple on our ranch and use it with our mares that are in foal as well for a smoother birth and a healthier foal. I have referred Lean muscle to many friends who has seen fantastic results.

J
Jacqueline J. (United States)
What is your horses estimated workload?: Medium
What is your horses discipline?: Hunter Jumper
What is your horses age?: 8 to 12
Amazing

Amazing, quick results! I love immubiome lean muscle! It really works!

S
Shannon J.
What is your horses estimated workload?: Light
What is your horses discipline?: Western
What is your horses age?: 21+
Excellent for my 20 something gelding

My rescue gelding struggled with keeping on weight and muscle. He’s been on about a year of lean muscle and improves every day. The photos are about 4 bottles of lean muscle between them. He’s looking even better now and maybe I can update this later. But I would say he’s improved immensely since I’ve had him on lean muscle and strength and stamina. His joints are nice and gooey and his arthritis seems more comfortable for him even in the winter!

E
Erika G. (United States)
What is your horses estimated workload?: Heavy
What is your horses discipline?: Show Jumper
What is your horses age?: 8 to 12
Amazing product with results

Lean muscle has not only changed my horses, but my client horses as well. I love the pre and pro biotics and natural ingredients. My horses eat it right up, and they look amazing!

N
N.N. (United States)
What is your horses estimated workload?: Heavy
What is your horses discipline?: Dressage
What is your horses age?: 4 to 7
Love it so far

My 6 year old dressage mare has been on this a couple weeks. Within days her coat had visibly improved and I like how she is gaining weight/muscle. She has been in full training for 2 years but was still scrawny. The product is not cheap but glad I tried it, she was clearly missing something in her diet which this has helped fill in.

C
Casey R. (United States)
What is your horses estimated workload?: Medium
What is your horses discipline?: Western
What is your horses age?: 21+
Impressed

I am so impressed that such a small amount can do so much. My old man is vet checked at mid 20s with terrible teeth. We had been struggling to find something to help him. The video doesn’t do justice. But I’ll put a before video and an after video of him on it for 2 months. I just wish there were more coupons or better discounts.

F
Freya's M. (United States)
What is your horses estimated workload?: Light
What is your horses discipline?: Dressage
What is your horses age?: 21+
Took 10 years off my mare's age

My mare was on stall rest for 6 months (corollary desmitis) and lost every bit of muscle she had. The trainer who helped me bring her back recommended Lean Muscle Builder. Her massage therapist says Freya has never looked better. She's 26 and I ride her about 3 times a week. We couldn't be happier with the results from this supplement.

P
Pat L. (Canada)
What is your horses estimated workload?: Medium
What is your horses discipline?: Dressage
What is your horses age?: 8 to 12
Loves the taste, I like his movement

My gelding is PSSM1/px. I have noticed his body feels more supple, more forward, less attitude working. I believe his gut feels better.

K
KQ (United States)
What is your horses estimated workload?: Medium
What is your horses discipline?: Western
What is your horses age?: 13 to 20
🙌🏻 Immibiome for the Win 🙌🏻

My gelding was recently diagnosed with PPID (normal insulin & bloodsugar). You could tell that he just wasn’t feeling like himself. I had taken him off of Lean Muscle in an attempt to save money 🤦🏼‍♀️ and I got a vet bill instead. He’s been back on it a month and the improvements are noticeable; better muscle, top line, coat and improved mood. I’m buying the big tub.

C
CustomerJanet J. (United States)
What is your horses estimated workload?: Medium
What is your horses discipline?: Other
What is your horses age?: 21+
Awesome Changes

This 22 year old that I lease has struggled with weight swings, inconsistent muscle development and maintaining a topline for many years. This product has made an incredible difference in him. Here he is with his Mom!

A
Annadurham (United States)
What is your horses estimated workload?: Light
What is your horses discipline?: Racing
What is your horses age?: 8 to 12
We love lean muscle

Our thoroughbred was having trouble gaining weight and couldn’t be ridden to help build muscle. Lean muscle for 3-4 weeks had helped him fill out his top line and start to build muscle as well.

L
Laura (United States)
What is your horses estimated workload?: Strenuous
What is your horses discipline?: Other
What is your horses age?: 13 to 20
I was really worried

My pregnant mare had terrible FWS. Nothing worked, none of the supplements and tricks made for treating it. My vet suggested calling Immubiome about the "Lean Muscle" for my mare. You said it would be safe and it CLEARED up her really loose stool in a few days. And all is good and well.

M
Michelle G. (United States)
What is your horses estimated workload?: Heavy
What is your horses discipline?: Dressage
What is your horses age?: 13 to 20
Lean Muscle is amazing!

My FEI dressage horse has really firmed up his top line and strengthened through his stifles since being on Lean Muscle.
He has always struggled with a bit of stifle weakness which ultimately affected his ability to produce good top line muscle. Well, thanks to Lean Muscle, not anymore!

C
CustomerLaura L. (United States)
What is your horses estimated workload?: Light
What is your horses discipline?: Other
What is your horses age?: 8 to 12
Great Product!!!

I started my Spotted Mountain horse on this after 6 months of stall rest. He was in poor shape with no muscle mass at all. I was truly afraid that he would never come back around to what he was before his injury. He has been on Immubiome Lean Muscle for 3 weeks and the difference is amazing! He is no longer hollowed out behind his withers and he actually has muscle on his chest, no longer just flabby skin. He still isn’t back to riding but the improvement is amazing, this product works!!! Going to start my little racking pony on this too, I’m hooked.

See all Lean Muscle reviews

Ready for everyday young horse support?

Start with Lean Muscle for growing horses—or add Immune for gut–immune balance through weaning and new-herd changes.

Shop Lean Muscle

Shop Lean Muscle

Support for growing horses

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