08 November, 2026
WOOFCORE editor

UC-II for dogs: what it is, how it works and what the studies found

UC-II is a type of collagen made from chicken breastbone (sternum) cartilage. Its makers say it is processed at a low temperature so the collagen keeps its natural shape, which is what "undenatured" means. In the recent dog studies, dogs got 40 mg a day, whatever their size. That is a tiny amount next to most joint ingredients, because UC-II is thought to work through the gut's immune system rather than by supplying building blocks for cartilage. Small studies found less pain and lameness in dogs given UC-II. We found no large, independent trial.

UC-II at a glance

What it is Undenatured type II collagen from chicken sternum cartilage
Daily amount in recent dog studies 40 mg, the same for every size of dog
How long the studies ran 30 days to 6 months
Side effects reported None in the dog studies that reported on safety, which were small
If you stop giving it In two early studies, every dog's pain came back within 30 days

What is UC-II?

Collagen is the main protein in skin, tendons and cartilage. Type II collagen is the kind found in joint cartilage, the smooth layer that covers the ends of bones.

Hydrolysed collagen is cut into small pieces, and the idea is that the body uses those pieces as raw material. UC-II is made differently. Its makers say a low-temperature process without enzymes keeps the collagen in its natural folded shape. That shape is the point: the theory of how UC-II works depends on the body recognising intact type II collagen.

UC-II is a branded ingredient, so you will see the same name in several dog joint products. A label that says "type II collagen" without "undenatured" may be a different kind of collagen.

How UC-II is thought to work

Your dog's gut has small patches of immune tissue, called Peyer's patches, that check what passes through and learn which proteins to leave alone. This learning is called oral tolerance. Think of a dog that meets the same postman every morning: after enough calm visits, it stops barking.

  1. A small amount of intact type II collagen reaches the Peyer's patches every day.
  2. There it is believed to turn some immune cells into regulatory T cells, a type of cell that calms immune reactions, tuned to type II collagen.
  3. These cells travel in the blood. When they meet type II collagen in joint cartilage, they release anti-inflammatory signals.

If this is right, it would explain why the daily amount is so small: the aim is to send a signal, not to deliver material. It would also explain why the natural shape matters, because hydrolysed collagen has lost it.

This mechanism comes from mouse, rat and cell research. It has not been shown directly in dogs. The authors of one dog study note that oral tolerance needs at least 2 to 3 weeks to start and can take up to three months to be fully active.

What the dog studies found

These are the published studies of UC-II in dogs that we could read. Numbers are quoted as the studies report them.

Study Dogs UC-II a day Length What it found
DeParle, 2005 15 obese dogs with arthritis 1 mg or 10 mg 90 days Pain and lameness fell on both amounts, more on 10 mg. Dogs were more active. All dogs relapsed within 30 days of stopping.
D'Altilio, 2007 20 dogs with arthritis, 5 per group 10 mg 120 days Placebo dogs did not change. On UC-II alone, overall pain fell 62%, pain when the leg was handled fell 91% and lameness after exercise fell 78%.
Gupta, 2012 Dogs with moderate arthritis, 7 to 10 per group 10 mg 150 days Pain scores fell on UC-II, on glucosamine with chondroitin, and on all three together. A force plate, which measures how much weight a dog puts through its legs, showed gains only in the UC-II group.
Stabile, 2019 60 dogs with osteoarthritis, 46 finished 40 mg 30 days The owner questionnaire score (LOAD) fell 32.7% on UC-II and 31.5% on robenacoxib, a prescription anti-inflammatory. The study could not show that UC-II was as good as the drug, and it had no placebo group.
Stabile, 2022 76 dogs with osteoarthritis 1 tablet 30 days The owner questionnaire score (LOAD) fell 31.4% on UC-II, 29.5% on cimicoxib (a prescription anti-inflammatory) and 21.1% on both together. Untreated dogs were the comparison.
Varney, 2021 and 2022 40 healthy Labradors aged 5 to 12 on a running plan 40 mg 13 weeks Compared with placebo, UC-II dogs had lower blood markers of inflammation after a 5 km run and of cartilage breakdown after a 16 km run, and lower pain scores at some points after the runs. Funded by the maker of UC-II.
Cabezas, 2022 110 dogs with mild to moderate joint disease 40 mg 6 months The median vet pain score fell from 35 to 0 by month 4. There was no comparison group, and owners and vets knew the dogs were on the product. Supported by the product's maker.
Stabile, 2024 17 dogs with mild to moderate osteoarthritis, 13 analysed 40 mg, in a chew with Boswellia and omega-3 8 weeks on each Blinded, with placebo. The owner score fell 21.4% at 4 weeks, a significant gap from placebo. At 8 weeks the gap was no longer significant. Funded by the product's maker.

How to read these results

The results point the same way, and they are encouraging. They are also limited. Every study is small, and several were paid for by companies that sell UC-II products. Only one reports both a placebo and blinding, and it tested a chew that mixed UC-II with other ingredients. We found no large, independent, blinded trial of UC-II on its own in dogs with arthritis.

How much UC-II does a dog need?

Every dog study since 2019 used 40 mg of UC-II a day. The authors of the largest study say the amount does not depend on the dog's weight. Older studies used 1 mg or 10 mg a day, and the papers do not explain how that measure compares with today's 40 mg.

Most dogs in these studies were mid to large dogs: the average or median weight was 26 to 32 kg in the studies that reported it. We found no study focused on very small or giant breeds, and none that shows more than 40 mg gives a bigger effect.

How long does UC-II take to work?

The studies suggest weeks to months, not days. In the 2007 study, overall pain was down 33% within 30 days, with bigger changes at 60 and 120 days. In the 2012 study, the biggest improvement came by day 150. In the 2022 study of 110 dogs, scores improved month by month up to month 4.

A fair trial is daily use for at least two to three months. Pick three everyday movements before you start, such as getting up from a rest, a familiar turn and the first few stairs, and film them the same way each fortnight. Our science page has a simple 60-day movement diary you can follow.

What happens if you stop?

In the 2005 and 2007 studies, every dog's pain and lameness came back within 30 days of stopping UC-II. In those studies the benefit did not last after stopping, so if UC-II helps your dog, plan to keep it in the daily routine.

UC-II vs glucosamine and chondroitin

These ingredients have different jobs. Glucosamine and chondroitin are building blocks of cartilage and are given in hundreds or thousands of milligrams. UC-II is given in tens of milligrams and is thought to work through the immune system.

Two small studies from the same research group compared them. In the 2012 study, only the UC-II group showed gains on the force plate. In the 2007 study, UC-II alone cut overall pain by 62%, handling pain by 91% and lameness by 78%, while UC-II with glucosamine and chondroitin cut them by 57%, 53% and 53%. The groups had 5 to 10 dogs each, and neither summary reports whether that gap is real or chance.

WOOFCORE combines UC-II with glucosamine, chondroitin and three other ingredients. Those two studies do not show that a combination does better than UC-II alone, and their numbers lean the other way. No larger study has tested the question.

Is UC-II safe for dogs?

None of the dog studies that reported on safety found side effects. The 2005 study found no changes in blood chemistry, the 2007 study found no change in liver or kidney markers or body weight, and in the 2024 study owners checked daily for vomiting, diarrhoea and loss of appetite and saw none. These studies were not designed to test safety and the numbers were small.

UC-II comes from chicken, so it is not suitable for a dog with a chicken allergy. If your dog takes medication, has a diagnosed condition or is pregnant, ask your vet before starting any supplement.

How WOOFCORE uses UC-II

Each WOOFCORE chew contains 40 mg of UC-II collagen, the amount used in the recent dog studies, alongside five other named ingredients. All six amounts are printed on the back of the pouch:

Glucosamine HCl 1,250 mg
MSM 400 mg
Chondroitin sulphate 200 mg
Green-lipped mussel 100 mg
UC-II collagen 40 mg
Hyaluronic acid 20 mg

Dogs up to 25 kg get one chew a day. Dogs over 25 kg get two, so they get 80 mg of UC-II a day. The chews are heart-shaped and chicken-flavoured, and are made to be eaten like a treat. They contain chicken and crustacean shellfish, so they are not suitable for dogs with either allergy.

If you want to try UC-II as part of your dog's daily routine, see the chews and serving guide. Your first order has a 60 day money back guarantee, counted from first delivery. The full terms are on the product page.

Questions owners ask

Is UC-II the same as collagen for skin and coat?

Not necessarily. UC-II is undenatured type II collagen, given in a small amount for joints. A collagen product sold for skin and coat may be a different type or form, so check the label.

Can I give UC-II with glucosamine?

Yes. Many joint products combine them, including ours. The two small studies that compared them are described above.

Can puppies have UC-II?

The studies that list ages used adult dogs. Ask your vet before giving any joint supplement to a puppy.

Does it work for every dog?

The studies report group results, so they cannot tell you how one dog will respond. Give it a fair trial of two to three months and judge by the same filmed movements, not by one good or bad day.

Where can I read the studies?

The full list is below. Several are free to read in full.

Sources

  • DeParle LA et al. Efficacy and safety of glycosylated undenatured type-II collagen (UC-II) in therapy of arthritic dogs. J Vet Pharmacol Ther. 2005. PubMed
  • D'Altilio M et al. Therapeutic efficacy and safety of undenatured type II collagen singly or in combination with glucosamine and chondroitin in arthritic dogs. Toxicol Mech Methods. 2007. PubMed
  • Gupta RC et al. Comparative therapeutic efficacy and safety of type-II collagen (UC-II), glucosamine and chondroitin in arthritic dogs: pain evaluation by ground force plate. J Anim Physiol Anim Nutr. 2012. PubMed
  • Stabile M et al. Evaluation of the effects of undenatured type II collagen (UC-II) as compared to robenacoxib on the mobility impairment induced by osteoarthritis in dogs. Vet Sci. 2019. Full text
  • Stabile M et al. Evaluation of clinical efficacy of undenatured type II collagen supplementation compared to cimicoxib and their association in dogs affected by natural occurring osteoarthritis. Res Vet Sci. 2022. PubMed
  • Varney JL et al. Undenatured type II collagen mitigates inflammation and cartilage degeneration in healthy Labrador Retrievers during an exercise regimen. Transl Anim Sci. 2021. Full text
  • Varney JL et al. Impact of supplemented undenatured type II collagen on pain and mobility in healthy Labrador Retrievers during an exercise regimen. Transl Anim Sci. 2022. Full text
  • Cabezas MA et al. Long-term supplementation with an undenatured type-II collagen (UC-II) formulation in dogs with degenerative joint disease: exploratory study. Open Vet J. 2022. Full text
  • Stabile M et al. Effects of a feed supplement, containing undenatured type II collagen (UC II) and Boswellia Serrata, in the management of mild/moderate mobility disorders in dogs. PLoS One. 2024. Full text
  • Gencoglu H et al. Undenatured type II collagen (UC-II) in joint health and disease: a review on the current knowledge of companion animals. Animals. 2020. Full text