Quick answer
The collagen types that matter for dogs are Type I, Type II (including UC-II), and Type III. Type I is the most abundant and supports skin, coat, tendon and bone; Type III works alongside it in skin and gut; Type II is joint cartilage — and its undenatured form, UC-II, has the strongest joint evidence in dogs. For skin and coat, look for hydrolyzed Type I & III; for joints, look for UC-II.
The collagen types, by job
| Type | Main role | Form to look for |
|---|---|---|
| Type I | Skin, coat, tendon, bone (most abundant) | Hydrolyzed peptides (marine or bovine) |
| Type II | Joint cartilage | Undenatured (UC-II) for joints |
| Type III | Skin, gut lining, blood vessels (with Type I) | Hydrolyzed, usually paired with Type I |
| Types V & X | Minor structural roles (from eggshell membrane) | Bonus, not a primary target |
UC-II vs hydrolyzed — the key distinction
Evidence: Two mechanisms, two dosesUndenatured type II (UC-II) is left intact so the gut immune system can ‘learn’ from it and calm the attack on joint cartilage (oral tolerance; Bagchi 2002). It works at tiny milligram doses and has the best canine joint evidence (Gupta 2012). Hydrolyzed collagen is broken into peptides used as building blocks for skin, coat and connective tissue, and is dosed in grams. Neither replaces the other.
Which type does your dog need?
- Joints / arthritis / senior mobility: UC-II (undenatured type II).
- Skin, coat, shedding: hydrolyzed type I & III.
- Both: a product that combines UC-II with hydrolyzed type I & III.
Read alsoUC-II collagen for dogs — a deep dive on the joint form with the best dog evidence.
Pure Majesty Pets Liquid Collagen for Dogs — actives per 2 mL serving
| Active ingredient | Per 2 mL |
|---|---|
| Hydrolyzed collagen peptides (Type I & III) | 462 mg |
| Undenatured type II collagen (UC-II) | 48 mg |
| Micro-emulsified salmon oil (omega-3 EPA/DHA) | ~126 mg |
| Pork bone broth concentrate | ~126 mg |
| MSM (methylsulfonylmethane) | ~63 mg |
| L-glutamine | ~52 mg |
| Tyndallized S. boulardii postbiotic | ~21 mg |
| Low-molecular-weight hyaluronic acid | ~8.4 mg |
| Vitamin C (sodium ascorbate) | ~4.2 mg |
| Ginger root extract | ~4.2 mg |
| Natural astaxanthin | ~0.5 mg |
Manufacturer-published formulation, current as of July 2026, per 2 mL daily serving. Ingredient amounts describe the contents; the individual actives have published evidence (below), but this exact multi-active blend has not been tested as a finished product in a controlled canine trial. Introduce gradually and check with your vet if your dog has kidney disease or a protein-restricted diet.
Frequently asked questions
What type of collagen is best for dogs?
It depends on the goal: undenatured type II (UC-II) for joints — it has the best canine evidence — and hydrolyzed type I & III for skin and coat. Products that combine both cover the most ground.
What is the difference between Type I, II and III collagen for dogs?
Type I supports skin, coat, tendon and bone; Type II is joint cartilage; Type III works with Type I in skin and gut. Type I & III are used hydrolyzed for skin/coat; Type II is best as undenatured UC-II for joints.
Is UC-II the same as type II collagen?
UC-II is a specific undenatured form of type II collagen that stays intact so it can modulate the joint immune response. Ordinary (hydrolyzed) type II is broken down and works differently.
Sources
- Gupta RC, Canerdy TD, Lindley J, 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. Journal of Animal Physiology and Animal Nutrition. 2012;96(5):770–777. doi:10.1111/j.1439-0396.2011.01166.x
- Bagchi D, Misner B, Bagchi M, et al. Effects of orally administered undenatured type II collagen against arthritic inflammatory diseases: a mechanistic exploration. International Journal of Clinical Pharmacology Research. 2002;22(3–4):101–110. PMID:12837047
- Varney JL, Fowler JW, Coon CN. Undenatured type II collagen mitigates inflammation and cartilage degeneration in healthy Labrador Retrievers during an exercise regimen. Translational Animal Science. 2021;5(2):txab084. doi:10.1093/tas/txab084
Veterinary disclaimer. This article is educational and is not a substitute for professional veterinary advice, diagnosis, or treatment. Collagen is a supplement, not a drug, and is not a treatment for arthritis or any disease. Talk to your veterinarian before starting any supplement, especially if your dog has kidney disease, is on a protein-restricted diet, is pregnant, or has food allergies.