Exosomes
Exosomes in dogs and cats
Exosomes are tiny bubbles that cells release to send signals to other cells. They are smaller than a cell and they are not alive. The idea behind selling them is appealing: instead of inject
What it is
Exosomes are tiny bubbles that cells release to send signals to other cells. They are smaller than a cell and they are not alive. The idea behind selling them is appealing: instead of injecting living stem cells, you inject only the signals those cells were sending, which should be easier to store and ship and should not be rejected. That idea is reasonable and worth researching. It is also worth knowing that exosome is not a product description. International scientific guidance discourages using the word as a generic label, because two vials both labelled exosomes can contain very different mixtures, and FDA has stated there are no quality control standards for manufacturing these particles that would let a commercial product be validated. A vial advertising billions of exosomes has told you a number, not a specification.
What the evidence shows
There is no published clinical study showing that exosome therapy works in dogs or cats. That is the plain finding, and it is a finding rather than a gap we are glossing over. A targeted search for a randomized, placebo-controlled exosome trial in dogs with objective outcomes returned nothing. For canine arthritis, which is the biggest commercial target, the only study injected into the joint is a three-dog safety study using whole freeze-dried cell secretions rather than purified exosomes, and its authors say it showed safety, not benefit. The best-designed study in this field anywhere in companion animals is in cats, not dogs: a 30-cat randomized controlled trial for a specific eye condition, from a single centre with a company co-author. Two controlled dog studies exist in wounds, but the wounds were created surgically in healthy dogs rather than being real clinical disease. Several papers carry canine or feline in the title while actually dosing mice or rats, which is the most common way this literature gets misrepresented. A veterinary review in JAVMA chose its words carefully: recent studies have demonstrated the safety and feasibility of these products in dogs and horses, and more rigorously designed, sufficiently powered, placebo-controlled trials are required.
The most important sentence on this page is that no published in-vivo clinical efficacy study exists in dogs or cats, for any condition. No exosome product for animals is FDA-approved, none appears on FDA's short public list of risk-reviewed animal cell and tissue products, and FDA keeps a standing public notification that exosomes sold to treat disease are unapproved drugs. Calling a product acellular or cell-free does not put it outside those rules, because FDA's definition covers products derived from cells. FDA treated conditioned media, which is the closest relative of an exosome product, as a drug in a 2024 warning letter to a company selling dog and cat cell products. Two more honest details: one equine study found that whole conditioned medium worked better than the purified exosome fraction, which argues against the premise that exosomes are the active ingredient, and one controlled dog study in a nerve-damage model found the cells outperformed the exosomes. If someone offers your dog or cat an exosome treatment, reasonable questions are what published study in this species and this condition they are relying on, what the certificate of analysis says about particle count, purity and sterility, and whether an approved treatment has been tried first. We would rather you ask those questions than take our word for anything.
Two randomised, double-blinded, controlled intra-articular secretome trials in dogs with naturally occurring osteoarthritis have been published. One, in 26 dogs with an excipient control and 80-day follow-up, reported a statistically significant benefit on lameness. The other, in 20 dogs with a placebo control and 150-day follow-up, found that owner- and clinician-scored outcomes improved while accelerometry — the objective activity measure — showed no difference between groups.
That divergence is the most calibrating fact in this field. Across the canine trials that measured both, owner and veterinarian scores improved while force plates and accelerometers did not move. Either the subjective instruments are measuring expectation, or the objective ones miss the change that matters. Nobody knows which, and we will not pretend otherwise.
Results from one preparation cannot be carried to another. Micro-fragmented adipose tissue, stromal vascular fraction, platelet-rich plasma, conditioned medium, secretome, purified exosomes and culture-expanded stem cells are different products with different evidence. The two randomised canine trials are SECRETOME trials, not purified-exosome trials. In a canine demyelination model stem cells outperformed stem-cell-derived exosomes, and in equine tendon cells whole conditioned medium produced a larger response than its isolated vesicle fraction. So we do not present those trials as evidence for our own purified exosome line.
Sources
- FDA: no approved exosome products, for any species — U.S. FDA, Public Safety Notification on Exosome Products. There are no FDA-approved exosome products; exosomes intended to treat disease are regulated as drugs or biologics requiring pre-market approval. https://www.fda.gov/vaccines-blood-biologics/safety-availability
- FDA: no animal cell or tissue product is approved, and derived-from-cells counts — U.S. FDA, FDA's Role in Veterinary Regenerative Medicine, content current as of 03/31/2025. 'Currently, no ACTPs are FDA-approved.' The ACTP definition covers articles containing, consisting of, or derived from cells or tissues. https://www.fda.gov/animal-veterinary/cell-and-tissue-products-a
- Authoritative review: clinical validation lags far behind preclinical work — Zayed M, Jeong BH. Mesenchymal stem cells in veterinary clinical practice. The Veterinary Journal 2026;320:106837. PMID 42624276. 'The application of MSC-derived EVs in veterinary medicine is still very new, with preclinical results far exceeding clinical validation.' https://doi.org/10.1016/j.tvjl.2026.106837
- JAVMA review: safety and feasibility, not efficacy — Williams KB, Ehrhart NP. Regenerative medicine 2.0: extracellular vesicle-based therapeutics for musculoskeletal tissue regeneration. JAVMA 2022;260(7):683-689. PMID 35263279. Calls for 'more rigorously designed, sufficiently powered, and placebo-controlled clinical trials.' https://doi.org/10.2460/javma.22.02.0060
- The only canine intra-articular study: three dogs, safety only — Mocchi M, Bari E, Dotti S, et al. Canine mesenchymal cell lyosecretome production and safety evaluation after allogenic intraarticular injection in osteoarthritic dogs. Animals (Basel) 2021;11(11):3271. PMID 34828003. n=3, contralateral-joint control; authors conclude it is safe, not effective. https://doi.org/10.3390/ani11113271
- Review: very limited data on cell-free therapy for canine osteoarthritis — Sharun K, Muthu S, Mankuzhy PD, et al. Cell-free therapy for canine osteoarthritis: current evidence and prospects. Vet Q 2022;42(1):224-230. PMID 36336651. 'very limited data is available on the efficacy and safety of cell-free therapy... large-scale, multicentric, randomized clinical controlled trials are required.' https://doi.org/10.1080/01652176.2022.2145620
- Why exosome is not a product specification — Welsh JA, Goberdhan DCI, O'Driscoll L, et al. (International Society for Extracellular Vesicles). Minimal information for studies of extracellular vesicles (MISEV2023). J Extracell Vesicles 2024;13(2):e12404. PMID 38326288. https://doi.org/10.1002/jev2.12404
- Veterinary review: mostly preclinical, limited approved therapies, no standard methods — Gad WA, Ibrahim S, Nagdy H, et al. Bridging biology and therapy: translational advances of extracellular vesicles in veterinary clinical practice. Vet Res Commun 2025;50(1):42. PMID 41247562. https://doi.org/10.1007/s11259-025-10917-3
- FDA treated conditioned media as a drug in dogs and cats — U.S. FDA warning letter to Safari Stem Cell, LLC, 5 April 2024, MARCS-CMS 661023. Products included canine and feline stem cells, platelet-rich plasma and conditioned media, found to be unapproved new animal drugs and adulterated for manufacturing failures. https://www.fda.gov/inspections-compliance-enforcement-and-crimi