Peptides — the evidence audit

Swaim et al. 1996, Am J Vet Res 57(3):394-9 (PMID 8669775). Twelve mature English Pointers; full-thickness 6x8 mm wounds in the metatarsal and third and fourth digital pads were injected at days 0, 3 and 6 with a tripeptide-copper complex, an immunostimulant, or physiologic saline. Type-I collagen was higher in the copper-complex wounds at 6 days and significantly higher at 14 days. This is the only controlled administration study of a copper tripeptide in a pet species that we located. FDA lists this substance in category 2 of its interim compounding policies — bulk drug substances that "may present significant safety risks."

Species with data: Dog (one controlled study, 12 dogs, surgical pad wounds, 1996)

• The endpoint was the type of collagen in a biopsy — not healing time, not lameness, not anything an owner would see. The paper attributes the first-week improvement in healing rate to the immunostimulant arm, not to the copper tripeptide.
• One study, twelve dogs, one wound type, delivered by injection into the wound itself. Nothing in it supports systemic, subcutaneous or oral dosing, and nothing in it is about joints, skin disease or ageing.
• Copper is the specific risk in this species. Copper-associated hepatitis is a recognised and increasingly diagnosed canine liver disease with breed-linked genetic susceptibility — COMMD1 in Bedlington Terriers, ATP7A and ATP7B in Labrador Retrievers — and in Labradors dietary copper intake strongly drives the disease phenotype (PMID 28063745). Deliberately injecting a copper complex into a dog is not a neutral act.
• FDA places GHK-Cu (for injectable routes of administration) in category 2 of its interim compounding policies, citing immunogenicity risk from aggregation and peptide-related impurities and limited human safety data.
• The review most often cited for the canine claim (PMID 26236730) is written from the research department of a company that sells GHK-Cu skincare, and its dog sentence traces back to this same 1996 study.
• No approved product in any species.

He et al. 2022, Front Pharmacol 13:1026182 (PMID 36588717). Single intravenous and intramuscular dosing in rats and beagle dogs: linear kinetics, elimination half-life under 30 minutes, absolute intramuscular bioavailability about 45-51% in beagles, excretion in urine and bile, rapid breakdown into small peptide fragments and free amino acids. That is a disposition study — it reports where the molecule goes, not whether it does anything. FDA's own July 2026 briefing document to the Pharmacy Compounding Advisory Committee puts the intravenous half-life in beagles at 5.3 minutes. A PubMed search crossing BPC-157 with dog, cat and horse returns two records: this one, and a rat study that matches only because "wet dog shake" is a rat behaviour term. FDA lists this substance in category 2 of its interim compounding policies — bulk drug substances that "may present significant safety risks."

Species with data: Dog (pharmacokinetics and toxicology only — no efficacy endpoint)

• There is no efficacy study in dogs, cats or horses. Every therapeutic claim made for BPC-157 rests on rodent models, a large share of them from a single research group.
• An elimination half-life measured in minutes is hard to reconcile with the dosing schedules sold to owners.
• FDA states that BPC-157 is a common name and not a United States Adopted Name, and that it "has encountered multiple salts, and derivatives, including different active moieties, sold commercially under the same common name" — so two vials labelled BPC-157 need not contain the same substance.
• In July 2026 FDA proposed NOT adding BPC-157 to the 503A Bulks List, citing poor physicochemical characterisation, a lack of safety and immunogenicity information, and insufficient evidence of effectiveness.
• FDA has received adverse-event reports involving compounded BPC-157 injections, including one patient who developed significant adverse reactions after a BPC-157 and TB-500 product labelled "research purposes only".
• No approval in any species, human or animal.

TB-500 is the N-acetylated fragment LKKTETQ, residues 17-23 of thymosin beta-4. The published horse administrations are doping-control method development: a single 10 mg subcutaneous dose to two thoroughbred geldings, to validate detection in plasma and urine down to 0.01-0.02 ng/mL (PMID 23084823 and PMID 23318763, Hong Kong Jockey Club Racing Laboratory). A 2024 French racing-laboratory population study describes thymosin beta-4 as being of "yet non-authorized use as a medicine and being forbidden by the IFHA, the FEI, and the WADA" while noting the numerous online products claiming to contain it (PMID 39314109). FDA lists this substance in category 2 of its interim compounding policies — bulk drug substances that "may present significant safety risks."

Species with data: None — the horse administrations are detection studies, not efficacy studies

• Zero efficacy evidence in any pet species. The marketing claims — angiogenesis, keratinocyte migration, collagen deposition, reduced inflammation — appear in the analytical literature as claims being quoted, not as findings being reported.
• Banned in competition by the International Federation of Horseracing Authorities, the FEI and WADA. Administering it to a competition horse ends that horse's eligibility, and the assays to catch it are published and validated to 0.01-0.02 ng/mL.
• FDA places thymosin beta-4 fragment (LKKTETQ), also known as TB-500, in category 2 of its interim compounding policies and states it has not identified any human exposure data for products containing it.
• Thymosin beta-4 is endogenous and highly conserved across mammals, so a measured level proves nothing on its own — and it rises as an artefact in plasma left in contact with blood cells at 4 degrees C (PMID 39314109).
• The analytical literature describes TB-500 as "a veterinary preparation" that "has emerged" — sold for animals, approved for none.