Easy on the system.
Fermentation breaks down plant cell walls before the bowl, so the nutrients are easier for an older gut to absorb.
Formulated with Dr. Ian Billinghurst
Shop by concern · Senior dog
For the dog who's been there for all of it.
Energy, appetite, coat, comfort. The things you watch more closely now start in the gut.
- 14,500+ Happy Customers
- 18 fermented superfoods
- 30-Day Taste Guarantee
From our blog: Senior Dogs and Gut Health: The Whole Picture →
You notice everything now.
How long it takes him to get up. Whether he finishes breakfast. The gray around the muzzle that showed up sometime last year.
You want the years ahead to be good ones. Supporting the gut is one quiet, daily thing you can do, right from the bowl.
Sound familiar?
- Less interest in food
- A coat that's lost its shine
- Softer or less regular stools
- Less bounce on walks
What changes in an older gut
Research in dogs suggests the variety of gut microbes tends to drop with age, absorption becomes less efficient and digestion can slow down, so the same bowl may deliver less. An old dog can eat a good diet and still get less out of it, which touches everything from energy to coat.
That makes two things matter more: variety in the bowl, and food that's easy to absorb. Rather than a separate fix for the stiffness, the fog and the fading coat, you tend the gut that decides how much of every meal gets used. What owners tell us they notice most is the joy of life coming back, the joie de vivre: more interest in the walk, the toy and the family.
Where to start
Your starting point
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Step 1
Boost™
Ground it.
Why it helps here: Older guts absorb less from the same food. Fermentation does part of the digestive work in the jar, so 18 superfoods arrive already broken down and there's less for an older gut to do. The start is extra slow on purpose.
Start at ⅛ to ¼ tsp and build up over two to three weeks.
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Step 2 · with Boost™
Youthful Grasses & Sprouts™
Optimize it.
Why it helps here: Seven young grasses and sprouts, fermented, add the variety a long-settled gut community may be short on. Used with Boost™, more kinds of plants means more kinds of microbes fed, which is where an older dog's energy and coat start.
From week 4, 1 tsp per 20 lb.
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After 90 days
Sustain™ + Youthful Grasses & Sprouts™
Why it helps here: Every day, for the rest of the long walk. Sustain™ keeps fermented foods in the bowl at the everyday price.
See Sustain™ →
What to expect over 90 days
Every dog is different. If you see blood in the stool, stop and call your vet.
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Weeks 1–3 · The slowest start.
Older dogs ease in over two to three weeks. ⅛ to ¼ tsp to begin, building gently. Keep notes on getting up, finishing breakfast, and interest in the walk.
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Weeks 4–6 · Boost™ + Youthful Grasses & Sprouts™.
Full dose, and the young greens go in. Stool and appetite usually settle first.
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Weeks 7–12 · The joy of life.
With more of every meal absorbed, this is when owners tell us they see the joie de vivre coming back: more spring on the walk, the toy picked up again, the greeting at the door.
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Day 90 · Look back, then decide.
Compare with week one. Many owners move to Sustain™ to keep the garden going, year after year, and keep Youthful Grasses & Sprouts™ in the bowl.
Real dogs, real results
How it's helped other dogs
Reviews from owners who started where you are, straight from our review app. We've opened it on this concern; pick All to read everything.
Browse by topic
No reviews on this one yet.
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Coat
Lindsay "It's been life changing"
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Itching
Diana "Healthy gut microbiome equals healthy skin microbiome"
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Poop Eating
Veronica "Her poop eating has definitely decreased"
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Energy Levels
Becky "Her energy levels are crazy!"
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energy levels
Tracey "He was happier, his entire demenour changed"
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Stool Quality
David "I immediately noticed stronger consistency with stool quality"
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Stool Quality
Dana "His poop is consistently good"
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Grass Eating
Emma "She hasn't eaten grass in months now"
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Grass Eating
Lauren "I gave it a week and they stopped eating grass"
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Itching
Theresa "She's not scratching anymore!"
Formulated with Dr. Ian Billinghurst, B.V.Sc.Veterinary surgeon · Creator of the B.A.R.F. diet · Author of four books on natural pet nutrition
Why 90 days? An older gut gets the slowest start and the slowest change. Give it the full season, and watch for the joy of life coming back: the walk, the toy, the greeting at the door.
14,500+ Happy Customers
Turn your senior dog's gut around
Your dog's 90-Day Gut Reset
Boost™ sized to your dog's weight, delivered every 90 days.
- 18 Fermented Superfoods
- 100-Day Guarantee
Tell us the weight and we'll send the right number of 7.5 oz bags of Boost™ for 90 days, every 90 days, with Youthful Grasses & Sprouts™ as the add-on for variety an older gut may be short on.
We ask for 90 consistent days before you judge it. If you're not willing to give it 90 days, this may not be right for you.
GutAbles® treats
Reward them, and treat their gut between meals.
Every reward is a chance to keep the gut going. GutAbles® are one animal protein, a blend of Gussy's Gut® fermented organic superfoods and organic Manuka honey, dehydrated and never cooked, baked or extruded.
They work alongside the powder in the bowl, so the gut support carries on between meals, one treat at a time.
- Dehydrated, never baked
- One protein + fermented superfoods
- Organic Manuka honey
- For dogs
Awarded the 2025/2026 Treat List by Susan Thixton. See the list
How Gussy's helps
The science, in plain words
Variety, every day.
18 Fermented Superfoods in Boost™, plus seven young grasses and sprouts in Youthful Grasses & Sprouts™.
Built for the long run.
After 90 days, Sustain™ keeps the garden going at about 40% less per bag than Boost™.
Read the research
These studies explain the mechanisms. None of them tested Gussy's Gut® products.
Our Chief Veterinary Advisor & Formulator
Dr. Ian Billinghurst
“Sustain is a game changer for dog's gut health maintenance.”
Dr. Ian Billinghurst, Chief Veterinary Advisor & Formulator
- Veterinary surgeon
- Creator of the B.A.R.F. diet
- Author of four books on natural pet nutrition
- Founder of the Billinghurst Institute
- Decades of species-appropriate nutrition work
Dr. Billinghurst formulated Sustain™ for exactly this: keeping the gut garden going, year after year.
Meet Dr. Billinghurst →Questions
Common questions
Is my dog too old to start?
No. Start low and build up slowly. Older dogs just get a gentler start.
She's on medication. Is that OK?
Gussy's Gut® is a whole-food supplement. If your dog has a diagnosed condition or takes medication, check with your vet first, and use Gussy's to support nutrition alongside their care.
What about joints?
We don't make joint claims. Many owners of older dogs tell us they notice more energy, but every dog is different.
How do I give it?
Mix about 1 teaspoon per 20 lb of body weight into your dog's food with a splash of water, once a day. Never serve the powder dry. Start with a quarter of the dose and build up over one to two weeks. Don't cook it; heat breaks down what fermentation built.
What if my dog won't eat it?
Stir it into something they love with a strong smell, like fish oil, tuna water, plain yogurt, kefir or coconut milk. If they still won't eat it, the 30-Day Taste Guarantee covers your first pack (see below).
What's the 30-Day Taste Guarantee?
If you're a new customer and your dog won't eat it, the first package you buy of any product gets a no-questions-asked refund, including shipping. Return it within 30 days of delivery with at least 50% still in the package. If your first order has more than one pack, only one pack can be returned, so we suggest starting with one.
Read the full guarantee →
Good years, and the joy in them, from the bowl up.
Start Boost™ gently. Keep the garden going with Sustain™.
