Should I give my dog peptides?
27 August 2026 // Originally posted on X
There has been a lot of chatter on the timeline recently about peptides for dogs - mostly orthopedic uses, and also some for longevity! Until now I’ve stayed out of it as it’s a loud but small subset of the population that is interested/able to buy peptides for their dogs, and I’m extremely empathetic to the desire of dog owners to do anything to help their pups live longer and healthier lives.
However given the emerging popularity I figured now was the right time to share my current thoughts here.
What is a peptide?
A peptide is simply a small protein. Your body uses them for local and systemic signaling between cells. Most peptides have extremely short half lives (how long it lasts in the blood before being broken down by the body), which is by design as they are supposed to be transient signals. Other well known peptides include insulin, oxytocin, growth hormone(1), and GLP1s! Peptides are certainly an efficacious and validated drug class.
The class itself is not magical - it’s simply another tool in the biological toolbox. For context, an equally broad category is small molecules (which can be as safe as ibuprofen or as destructive as chemotherapy).
For conciseness, I’ll refer to research-grade and non-FDA-approved peptides as just “peptides”, but please know these comments do not apply to FDA-approved peptides like insulin!
Will peptides help my dog?
Popular peptides include:
BPC-157 - stimulates angiogenesis (new blood vessel formation by upregulating VEGF/VEGFR)
TB-500 - stimulates angiogenesis, reduces inflammation (thymosin beta-4 fragment)
Sermorelin/Ipamorelin - muscle growth (Ghrelin receptor agonist and GHRH analogs)
MOTS-c - mitochondrial function (via folate pathway and AMPK)
Semaglutide/Tirzepatide/Retatrutide - weight loss (GLP-1/GIP/Glucagon) FDA approved (sema/tir), positive Ph3 (reta)
In dogs, the majority of anecdotal evidence has been generated with BPC-157 for joint issues. My sweet senior Rottie Della suffered from debilitating degenerative joint disease before passing; mobility issues are one of the saddest and most visible signs that your dog is aging, and the options available are suboptimal (none are disease modifying, some are rather controversial).(2) Some of the videos are quite striking,(3) and anecdotal data like these can absolutely be where discoveries start.
However, there are notable caveats:
Orthopedic disorders wax and wane dramatically day to day and week to week - dogs often have bad days and good days regardless of the treatment. This was certainly true for my pup and is also true for my creaky left knee!
In addition to intra-dog variability, there is also significant inter-dog variability: data generated in a border collie may not be representative of the effect in your chihuahua. This intra-species variability is unique to dogs and adds significant complexity to developing and testing dog drugs (and is another reason our longevity trial is so large).
These drugs are extremely prone to placebo effect and statistical noise due to the aforementioned disease variability - this is a known challenge in clinical trials for new orthopedic drugs.
Dogs are in fact prone to placebo effect (well, their owners are) when assessing behavioral/functional benefit. This is actually a significant challenge for our clinical trial, where we rely in part on dog-owner reported outcomes to quantify the hopeful healthspan extension benefits of our drug LOY-002 for senior dog longevity.(4)
Simply put, BPC-157 may be effective for orthopedic conditions in dogs, but we really have no idea until someone runs a proper clinical trial that accounts for the above.
It may not work, but will it cause harm?
For many dog owners, they are willing to take a risk on efficacy as long as they will not cause harm. Unfortunately we cannot be sure peptides (especially BPC-157) are safe:
1. Questionable manufacturing standards mean you do not know what you are injecting into your dog.
It is extremely difficult to manufacture a drug consistently at scale. Loyal itself has been in “manufacturing hell” while we work to increase our manufacturing scale(5) - and this is for a drug that is much simpler than a peptide. Minute changes drive crucial variables like purity, sterility, and consistency.
Peptide manufacturers are unregulated and therefore have no independent body verifying that their processes are sufficiently rigorous to deliver a safe product. Unlike a car or a t-shirt, a drug manufacturing error doesn’t mean a slightly less aesthetic product or delayed timelines - it can, God forbid, hurt your dog.
2. BPC-157 stimulates angiogenesis (blood vessel formation) which is also a key cancer mechanism.
BPC-157 triggers new blood vessel formation by upregulating VEGF and its cellular receptor. Blood vessel formation is thought to help arthritis by introducing more nutrients and oxygen to degrading tissue. Healthy angiogenesis absolutely decreases with age and restimulating it may very well improve osteoarthritis.
Unfortunately, angiogenesis also plays a key role in propagating cancer. Tumors often have mutated angiogenesis allowing it to grow new blood vessels rapidly to feed its unchecked growth. By giving BPC-157 to an old dog, you may be inadvertently facilitating or accelerating an unknown cancer.
Looking at humans, there are no FDA approved pro-VEGF drugs for any use case; trials showed inconsistent benefit and significant risks. Anti-VEGF drugs are an FDA-approved category for cancer.
3. Biology is extremely complex - second and third order effects are only possible to characterize over time and with lots of data.
Every biologist has the Roche biochemical poster depicting the inner workings and signaling cascades in a cell.(6) Biology is unbelievably complex and we understand so very little of it.(7) Let's say peptides do indeed clinically improve osteoarthritis, and let's say the cancer side effect doesn’t occur. There are so many other ways that a drug can cause harm. It may increase the risk of developing another disease. It may be fine for Border Collies but harmful for Great Danes. It may counteract the benefits of another drug. Clinical trials and post-approval marketing are key to understanding what a new drug does in the body acutely and over time - one-off data is simply too weak and too noisy. The complexity of biology is exponentials on exponentials and multi-dimensional. It is not to be underestimated!
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While I am unlikely to personally inject myself with unvalidated peptides, the decision to do so is different for a human versus their dog. A human can understand the risk:benefit profile and make an educated decision for themselves. Additional scrutiny is prudent when it comes to your dog - they can’t consent to the same risk. If you do give your dog peptides, diligence the manufacturer and work with a veterinarian who can ensure there are no warning signs clinically or in their bloodwork from the drug. Often the success or failure of an experimental therapy is very hard to quantify or see until significant harm has occurred, so it is crucial to proactively monitor for side effects, especially with the potential pro-cancer mechanism of BPC-157.
Disclaimer: Loyal is not developing drugs for osteoarthritis in any species, but longevity interventions (specifically caloric restriction, which LOY-002 mimics) have indeed shown significant delay of osteoarthritis in dogs, so it’s reasonable to hypothesize we may eventually be tangential to it.
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(1) A peptide that we are working on lowering in big dogs to extend their lifespan, due to its correlation (in dogs + humans) and causation (worms + mice) with shorter lifespan.
(2) First line tends to be pain medicines, which certainly help your dog be more comfortable but can have long term side effects and do not slow disease progression. The injectable monoclonal antibody Librela has shockingly impressive efficacy for some dogs (including my Della), but there have been reports of neurological side effects that, causative or not, have spooked dog owners and vets off the drug.
(3) https://x.com/999TeddyB/status/2091630799145652558?s=46, https://x.com/morellifit/status/2090909241200799747?s=46
(4) We are running a 1,317+ dog study that is FDA-concurred, placebo controlled, double-blinded, and run independently by 70+ veterinarians across the USA. Even with such a large and rigorous study, we are still worried about the placebo effect nullifying the actual benefit of the drug.
(5) When discussing our “year of manufacturing hell” with investors, the metaphor I’ve used is Tesla’s infamous challenges with reliable Model 3 production early on, which led to many jokes and complaints about door gaps, uneven paint, delayed deliveries, etc. While extremely challenging to overcome, they had one saving grace: they could still sell the cars, just more slowly than they liked until the processes were perfected. Unlike the Model 3, Loyal and all other drug companies must perfect their manufacturing process before a single bottle may be sold.
(6) https://www.roche.com/about/roche-global-citizenship/science-education/biochemical-pathways
(7) Which is why even with 100% focused resources, Anthropic will not cure all disease in the next 10 years. It will be genuinely impressive and meaningful if it cures one.