Half of Dogs Get Supplements: What 40,367 US Owners Reported
In a US survey of 40,367 dogs, about half got supplements, most often fish oil and glucosamine. Some owners listed prescription medicines as supplements.
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If your dog takes supplements, tell your vet, especially before surgery or a new medicine. Don’t stop or start a prescribed medicine without asking your vet.
Our note: This advice is ours. The paper says vets should discuss supplements with owners, but gives no owner instructions.
In a US survey of 40,367 dogs, owners of 52% said they gave their dog supplements (O’Brien et al., American Journal of Veterinary Research 2026). Fish oil and glucosamine were the most common.
While supplements feel like a harmless extra, the authors note they “are not required to demonstrate safety or efficacy through clinical trials”. Some owners also listed prescription medicines as supplements.
→ Glucosamine and Chondroitin: The Meta-Analysis Says No
1. The study
The dogs. Owners enrolling in the Dog Aging Project, a large US study of pet dogs, answered questions on supplements from 2020 to 2022.
What they reported. Owners ticked supplement types from a list and could write in others.
Funding. The Dog Aging Project is funded by a US government ageing research grant, plus other grants and donations. The authors have nothing to disclose.
2. What owners were giving
| Supplement | Share of dogs getting supplements |
|---|---|
| Omega-3 (fish oil) | 57% |
| Glucosamine | 56% |
| Chondroitin | 45% |
| Vitamins | 38% |
| Probiotics | 37% |
Written-in extras. The most common write-ins were CBD or hemp, turmeric, liver support and dental supplements.
By age. Senior dogs were the most likely to get a daily supplement, at 61%, and puppies the least, at 37%.
→ Fish Oil for Arthritis: What the Trials Show
→ Probiotics for Dogs: What the Trials and Label Checks Found
3. Supplements and conditions
Joints. Dogs with joint conditions were the most likely to get supplements. Glucosamine was the most common.
Skin and heart. About four in ten dogs with skin allergies got omega-3, and so did 45% of dogs with heart murmurs or valve disease.
Bladder stones. Only 25% of dogs with stones got a urine-changing supplement.
Our note: The paper describes use, not benefit. Our other pages cover the evidence for each supplement.
→ CBD for Dogs: The Legal Position, and the Unknowns
4. Medicines listed as supplements
What happened. Among the written-in answers, some owners listed prescription medicines as supplements. A few combined joint supplements with a prescription anti-inflammatory.
Why it matters. The authors say this is a reason for vets to discuss supplements in more depth.
Our note: The paper names the medicines, and we leave them out. Tell your vet about every supplement your dog takes.
5. What the study can’t tell you
Owner reports only. The survey asked what owners gave, not what vets recommended or whether it helped.
Big numbers, small gaps. The authors note that with so many dogs, small differences are often statistically significant without mattering in practice.
Small slips. The abstract calls the 56% figure “joint supplements”, but the results show it is glucosamine alone. The discussion says “so many medications” were confused with supplements, but only 156 of 3,995 written-in answers were medicines or foods.
Our note: “So many medications” may overstate what the paper’s own numbers show.
6. What we could not verify
| Commonly said | What we found |
|---|---|
| “Few owners give supplements” | No. About half of the dogs in this survey got them. |
| “Supplements are tested like medicines” | No. The authors say supplements don’t have to prove safety or benefit in trials. |
| “Owners know what counts as a medicine” | Not always. Some owners listed prescription medicines as supplements. |
Sources
- O’Brien JS, Dog Aging Project Consortium, Tolbert MK, Ruple A. Supplement use is common in Dog Aging Project participants, especially among dogs with orthopedic conditions, and varies by life stage. Am J Vet Res 2026. ⚠️ survey, owner reports for 40,367 US dogs. US government-funded
Always confirm with your vet before acting on anything on this page.