Your cat is not going to tell you she is in pain. She is going to stop jumping onto the windowsill. She is going to groom a little less. She is going to sit somewhere slightly different, and you are going to think she has picked a new favourite spot.
That is the part that keeps me up at night about cats. With dogs, you usually get a limp. With cats, you get a quiet, gradual editing of their own life, and most of us read it as ageing.
I have been using red light therapy with my French Bulldog Milka for years. But when we sat down with Donna Woods of Photonic Health for this episode of the Next Level Pet Parent Podcast, the story that stayed with me was not about a dog at all. It was about a cat whose back legs had stopped working, and whose pet parent had been told there were no options left. So let's talk about what red light therapy is, what the evidence actually shows in cats specifically, and where it is not the right call.
The short version
Red light therapy, known clinically as photobiomodulation, uses red and near-infrared light to influence activity inside the cell. The Merck Veterinary Manual lists it as showing value for arthritis and degenerative joint disease, post-surgical musculoskeletal pain, wound healing and tissue repair.
It matters more for cats than for dogs, because according to the FDA, no veterinary NSAIDs are currently approved for safe, long-term control of osteoarthritis pain in cats.
It is not right for every cat. An overactive thyroid, which is common in senior cats, is on Merck's contraindication list. That single detail is why this conversation starts with your vet, not with a device.
In this article
What red light therapy actually is
Why cats have fewer pain options than dogs
The signs of pain cats actually show
What the research shows in cats specifically
What Donna Woods has seen in 15 years
When it is not the right call for your cat
How to choose a device (more powerful is not better)
Running a session with a cat who will not sit still
What to pair it with from the inside
Questions pet parents ask us most
Sources
What red light therapy actually is
The clinical name is photobiomodulation. The Merck Veterinary Manual describes it as the effect of light on mitochondria, cells and tissue, and it is explicit that this covers light-emitting diodes and other light sources, not only lasers.
Here is the mechanism in plain language. A molecule inside the cell called a chromophore absorbs the photon. In this case the main one is cytochrome c oxidase, which sits in the mitochondrial respiratory chain. Merck describes the downstream effects as increased ATP production, modulation of reactive oxygen species, cell proliferation and migration, normalised cytokine concentration, modulated inflammatory mediators and improved tissue oxygenation. Light therapy may also cause vasodilation, which improves oxygen delivery and supports immune cells moving into the tissue.
The wavelengths that matter sit in two bands. Merck gives red at roughly 630 to 680 nanometres and near-infrared at roughly 700 to 1100 nanometres, and notes that molecules such as melanin and haemoglobin preferentially absorb light in the 630 to 670 range, while longer wavelengths like 810 and 980 pass through the surface layers to reach deeper structures.
One clarification worth holding onto, because the marketing muddies it constantly: "cold laser" is not an accurate description of every device sold under that name. Merck notes that Class IV devices routinely heat tissue, which makes the term inaccurate for them. Home LED units and clinic Class IV lasers are not the same category of thing.
Why cats have fewer pain options than dogs
This is the part most pet parents are never told clearly, and it is the reason a cat article deserves to exist separately from a dog article.
The FDA states that many veterinary NSAIDs are approved for long-term use in dogs to control osteoarthritis pain and inflammation, but that no veterinary NSAIDs are currently approved for safe, long-term control of that same pain in cats. It adds that cats are especially sensitive to NSAID side effects. There is an approved monoclonal antibody injection for feline osteoarthritis pain, and the FDA describes the non-drug side of the picture as weight management, rehabilitation and environmental changes such as litter pans with lower sides, raised bowls, ramps and soft bedding.
Read that again. For the single most common chronic pain condition in older cats, the drug shelf is genuinely shorter than it is for dogs.
That is not an argument for skipping your vet. It is the opposite. It is an argument for walking into your vet's office already knowing that the non-drug side of the plan carries more weight for a cat than it does for a dog, and asking what belongs there. Rehabilitation guidance from the American Animal Hospital Association lists photobiomodulation therapy among the modalities used to reduce pain and improve quality of life in senior pets, alongside exercise therapy, hydrotherapy, acupuncture and manual therapy.
The signs of pain cats actually show
Before any device, the honest first step is recognising what you are looking at. The FDA is blunt about how hard this is: cats tolerate bone and joint problems because of their size and agility, they hide pain very well, and they generally dislike being handled during a physical exam, so your observations at home may be the most useful information your vet receives.
| What you notice at home | What it may be telling you |
|---|---|
| Not jumping as easily, or jumping a shorter distance | In a study of 28 cats with osteoarthritis cited by the FDA, almost three-quarters did not want to jump and two-thirds jumped a shorter distance |
| Limping | Less than half of those same cats limped, which is why waiting for a limp misses most cats |
| Grooming less, or a coat that looks unkempt | Listed by the FDA among the signs of osteoarthritis in cats |
| Urinating or defecating outside the litter pan | Also on the FDA's list, and often misread as a behaviour problem |
| Grumpier or quieter than usual, less active, off her food, losing weight | All listed by the FDA as signs of the disease in cats |
The FDA also notes that the most commonly affected joints in cats are the elbows and hips, with shoulders, hocks and knees also involved, and that arthritis in the backbone and sternum is common too.
What the research shows in cats specifically
Here is what the research tells us, and I want to be straight with you about where it is strong and where it is thin.
Post-surgical comfort. Two feline studies from the same research group are worth knowing about, because they speak directly to the spay and neuter moment. In a 2015 study published in Evidence-Based Complementary and Alternative Medicine, twenty cats undergoing ovariohysterectomy were randomised, and supplemental analgesia afterwards was needed by five of ten cats in the control group compared with one of ten in the laser group. A 2019 follow-up in the Journal of Veterinary Medical Science ran thirty cats across laser, electro and control groups and again found the need for rescue pain relief significantly higher in the control group. Both used infrared light delivered at acupoints rather than a pad over the whole body, so this supports the principle rather than any specific home device.
Oral inflammation. Low-level laser therapy has been studied as an option in feline chronic gingivostomatitis, one of the most painful conditions a cat can live with. A 2024 study in Veterinary World looked at 24 healthy cats and tested how well 830 nanometre light applied from outside the cheek actually penetrates through to the inside of the mouth, along with how contact, distance and transmission medium change the result. That is the kind of unglamorous work the field needs more of.
Joints, wounds and recovery. Merck's indications list includes arthritis and degenerative joint disease, musculoskeletal pain including post-surgical and fracture, wound healing, tissue repair across many tissue types, and peripheral nerve injury. Those indications are written for veterinary patients broadly rather than cats alone.
And that is the honest summary. The mechanism is well described, the veterinary indications are recognised, and the feline-specific clinical literature is smaller than the canine and equine literature. Anyone telling you the feline evidence is settled is selling you something.
Merck is also candid about what remains open. It notes that questions remain about whether laser therapy can stimulate neoplastic growth, and lists the long-term safety of high-powered devices, particularly in patients with a history of cancer, among the field's live controversies. You will see claims online that red light therapy protects against cancer. I am not going to repeat those claims here, because the reference veterinarians actually use says the opposite of settled.
What Donna Woods has seen in 15 years
Everything in this section is Donna's own account from our podcast conversation, shared as her experience rather than as clinical evidence. She co-founded Photonic Health with her husband Brian in 2009, and they were, by her description, roughly the second light therapy company in the United States.
The cat story is the one that turned a hobby into a company. A woman in their town had a cat who had lost the use of his back legs, with his paws curled under. Her stated options were to try this or to have him put to sleep. Donna and Brian went over, illuminated him, and left their only device behind. Two days later the woman called to say the paw had started to untwist. Within two weeks, by Donna's account, the cat was up and walking.
The other example she gave was quieter and, honestly, more useful for most of us. Their ragdoll kitten went in for spay surgery, and the clinic called afterwards to say there was some internal bleeding and they wanted to keep her overnight for observation. Brian drove down and illuminated her. Two hours later the clinic called back to say she was ready to go home.
Her framing for routine surgeries stayed with me. Every cat she has is spayed or neutered, and every one of them gets light on that incision, because she is thinking about inflammation, comfort and scar tissue in the fascia rather than about a crisis. She also described using it for small things that never became big things: an upset tummy, a wasp sting, an infection in a Frenchie's facial fold.
"It's about having the right tools in your toolbox so that, when that situation comes up, you can respond quicker and more effectively than if you weren't prepared." Donna Woods, Photonic Health
I want to be careful here, because I love a good recovery story and I know how easy it is to hear one and expect the same outcome. Individual accounts are not clinical evidence, and Donna owns the company, which she said openly on the episode. What I take from her account is not a promise. It is a question worth putting to your own vet.
She is also, for what it is worth, a strong advocate for partnering with your veterinarian rather than working around one. So am I.
When it is not the right call for your cat
If you take one section away from this article, make it this one. Merck's contraindication list is short, but two entries on it are unusually relevant to cats, and I have never once seen them mentioned in a consumer article about red light therapy for cats.
| Merck lists as an area to avoid | Why this matters for a cat |
|---|---|
| A hyperactive thyroid gland | Overactive thyroid is one of the most common conditions in senior cats, and the neck is exactly where you might place a device for a stiff cat |
| Areas of neoplasia or malignancy, and patients with lymphoma | Lymphoma is among the more common feline cancers, and any lump needs your vet's assessment before light goes anywhere near it |
| Patients on immunosuppressant medication | Merck notes the immunostimulatory effects may counteract those drugs, and steroids are common in feline care |
| The retina, and direct eye exposure | Merck names retinal damage as a main risk. Never work near your cat's face without proper eye protection guidance |
| Areas of active bleeding, and a pregnant uterus | Relevant for any fresh injury or an unspayed queen |
| Over long bones in animals under one year old | Merck cautions that higher powered devices may cause premature closure of growth plates. This is a kitten consideration |
Merck adds that for patients on photosensitising medications or botanicals, intensity should be lowered, and names thermal burns from improper application as the other main risk alongside retinal damage.
None of this means red light therapy is dangerous. It means your senior cat needs a thyroid check and a proper physical exam before you point anything at her, which she probably needs anyway.
How to choose a device (more powerful is not better)
Donna told us a story about a woman at a horse clinic whose animal had a swelling that had not shifted in eight months. She had bought a very powerful device online and got nothing from it. Brian swapped her their least powerful handheld overnight, and by morning the swelling was down by more than half. His explanation was that when a device is too powerful, the light goes straight through without doing the work.
I went looking for whether that holds up outside a company founder's story, and the principle is supported. Merck's guidance on device power says that in general, a more intense beam relates to stronger pain relief, while less intense light applied for a longer period gives better tissue healing results. Different goals, different settings. Bigger is not automatically better, it is a different tool.
Merck is equally useful on the depth claims you see in advertising. It explains that spot size changes the intensity per square centimetre even when the power is identical, and that delivering a large amount of light to a tiny area increases the risk of overheating and burning tissue. It also states plainly that the ideal dose of light for specific conditions remains controversial.
So what would I actually ask before buying anything for a cat?
- What wavelengths does it emit, in nanometres, and does the company publish them?
- Is the coverage area sensible for a four-kilo animal, or was it designed for a horse?
- Is there a human being I can call who will help me work out placement and session length for my cat?
- Is there a return window long enough to find out whether my cat will tolerate it?
- Does the device have a visible indicator when it is emitting? Merck notes that light longer than 760 nanometres is invisible to the human eye, so a device without a finder beam or audible signal creates a real safety hazard.
Red light therapy devices are the one category we point pet parents outside PAWDEGA for, because we do not stock them. The company we use with our own animals, and the one Donna co-founded, is Photonic Health.
Affiliate links. We earn a commission at no extra cost to you.
Photonic Health Essential Back Pad
This is the one I would start a cat parent on, and it is the device we bought first. It delivers red and near-infrared light, and because it lays over the animal like a blanket, it covers a broad area without you holding anything in place or pinning your cat down. For an animal who decides how long she is staying, that is the whole game. It is also the device Larry reached for on the flight with Milka when nothing else was within reach.
See the Essential Back PadThe full Photonic Health range
If your cat has one specific area you are working on, a paw, a spot along the spine, the side of the face, a handheld gives you far more precision than a pad does. Browse the range, and if you are stuck between two devices, their team will talk you through placement and which one suits your cat before you buy. That conversation is the reason we send people there rather than to a marketplace listing.
Browse Photonic HealthI want to be plain about the arrangement, because you deserve to know it before you click. We earn a commission if you buy through those links. We also bought our own devices before any of that existed, we travel with three of them, and I would tell you the same thing about them if we earned nothing.
Running a session with a cat who will not sit still
This is the part nobody warns you about. A dog will lie under a pad because you asked. A cat will decide.
What has worked for the pet parents in our community, and what Donna described from her own household, is going to the cat rather than bringing the cat to the session. She sleeps in the same spot every afternoon. That spot is where the session happens. Sitting on the floor beside her, letting her stay where she chose, is worth more than any technique, because the session that actually happens beats the perfect session she walks away from.
On frequency and duration, protocols are specific to the condition and to the device, which is why I am not going to invent numbers for you. Donna's own example was a senior terrier with an acute back injury: two to three sessions daily in the first five to seven days, once daily for the following week, every other day for the two weeks after that, then once a week for ongoing maintenance once she was comfortable again. Ask the manufacturer for the feline protocol for your cat's specific situation, and tell your vet what you are running.
One practical note from that 2024 Veterinary World study: contact and the medium between device and tissue changed how much light got through. Fur, distance and angle are not trivial details.
What to pair it with from the inside
Light works on the tissue you point it at. It does not change what is arriving in the food bowl. Everything comes back to inflammation, and inflammation is driven from the inside, which is why the pet parents who see the most change tend to be the ones doing both. These three are the ones we most often talk cat parents through, and all three are suitable for cats.
Jump for JOYnts
A joint support tincture that supports mobility and helps address inflammation, formulated for dogs and cats. This is the one I reach for first for a stiff senior, and it can go straight into the mouth or onto food, which matters when you are dealing with a cat.
See Jump for JOYntsInflapotion
A 100% organic herbal powder for dogs and cats, made to help address inflammation, discomfort and stiffness. Useful for the senior cat who has quietly stopped doing one of the things she used to do.
See InflapotionYou can browse everything we stock for cats on our cat collection, and the wider joint and mobility range if her comfort is the main thing on your mind.
Not sure where the foundation goes?
A device is a tool, not a plan. The Holistic Pet Wellness Blueprint is our free guide to the foundations underneath everything else: diet, gut health, reducing the toxin load and building a routine you can actually keep. Start there, then layer the tools on top.
Questions pet parents ask us most
Is red light therapy safe for cats?
It has a recognised place in veterinary rehabilitation, but it is not free of restrictions, and anyone describing it as completely without risk is overstating things. The Merck Veterinary Manual names areas to avoid including an overactive thyroid gland, areas of malignancy, lymphoma, patients on immunosuppressant medication, the retina, active bleeding and a pregnant uterus, and names retinal damage and thermal burns as the main risks when it is applied improperly. Given how common thyroid and lymphoma concerns are in cats, a veterinary check before you start is not optional.
Does red light therapy help cats with arthritis?
Merck lists arthritis and degenerative joint disease among the conditions for which photomedicine has shown value in veterinary patients, and AAHA rehabilitation guidance includes photobiomodulation among modalities used to reduce pain in senior pets. Most of the published clinical work has been done in dogs and horses rather than cats, so this is best discussed with your vet as one part of a plan rather than as a replacement for one.
What is the difference between an LED device and a clinic laser?
Photobiomodulation covers both, but the light itself differs. Merck describes laser light as monochromatic, coherent and collimated, meaning it sits in a narrow band and travels in parallel, while LEDs scatter more. It also notes that Class IV devices routinely heat tissue, which is why calling every device a "cold laser" is inaccurate, and that debate continues about the relative value of laser light versus LEDs.
How long should a red light therapy session be for a cat?
There is no single answer, and I would be suspicious of anyone who gives you one without asking about your cat. Merck says the ideal dose for specific conditions remains controversial and that both power and duration change the outcome, with more intense light relating to stronger pain relief and gentler light over longer periods relating to better tissue healing. Follow the protocol for your specific device and condition, and tell your vet what you are doing.
Can I use red light therapy after my cat is spayed or neutered?
This is the application with the most direct feline research behind it. Two randomised studies in cats undergoing ovariohysterectomy found that fewer cats in the light therapy groups needed rescue pain relief afterwards compared with controls. Both delivered infrared light at specific acupoints before surgery, so talk to your vet about whether it fits your cat's recovery plan rather than assuming a home device reproduces the study conditions.
Does PAWDEGA sell red light therapy devices?
No, and we are not planning to. We use them with our own animals and we are asked about them constantly, but devices are not our range, so we refer pet parents to Photonic Health instead. That is an affiliate link, meaning we earn a commission if you buy through it at no extra cost to you. If you want to talk through which device fits your cat before you decide, their team will do that with you, and so will ours.
Where I would start
Not with a device. With a notebook.
Write down the things your cat has quietly stopped doing. The counter she no longer jumps onto. The patch of coat behind her hips that has gone a bit rough. The litter tray accidents you had put down to attitude. Take that list to your vet, because the FDA says outright that your observations at home may be the most useful thing your vet receives, and cats are notorious for freezing on the exam table.
Then ask the question this article was really written to hand you: given that the medication options for feline osteoarthritis pain are more limited than they are for dogs, what should the non-drug side of her plan look like, and does photobiomodulation belong in it?
You are not powerless here. You are the person who notices, and with a cat, noticing is most of the work.
Much love, Larry
Listen to the full conversation
Donna Woods joined us on the Next Level Pet Parent Podcast to talk through how red light therapy works, what she has seen across cats, dogs and horses in 15 years, and how to choose a device. We also open the episode with what happened to Milka on an 11 hour flight, which I still think about.
Watch the episodeSources
- Robinson, N. G. Photomedicine in Veterinary Patients (Laser Therapy, Light-Emitting Diode Therapy). Merck Veterinary Manual, full review September 2022, last updated October 2025. merckvetmanual.com
- U.S. Food and Drug Administration, Center for Veterinary Medicine. Osteoarthritis in Cats: More Common Than You Think. Content current as of 18 February 2025. fda.gov
- American Animal Hospital Association. 2023 AAHA Senior Care Guidelines for Dogs and Cats, pain management section. aaha.org
- Marques, V. I., Cassu, R. N., Nascimento, F. F., et al. Laser Acupuncture for Postoperative Pain Management in Cats. Evidence-Based Complementary and Alternative Medicine, 2015. pubmed.ncbi.nlm.nih.gov/26170879
- Nascimento, F. F., Marques, V. I., Crociolli, G. C., et al. Analgesic efficacy of laser acupuncture and electroacupuncture in cats undergoing ovariohysterectomy. Journal of Veterinary Medical Science, 81(5), 2019. pubmed.ncbi.nlm.nih.gov/30905889
- Assessing the potential efficacy of 830-nanometer low-level laser therapy in cats: extraoral applications. Veterinary World, 2024. pubmed.ncbi.nlm.nih.gov/38911083
Warmly,
Charly
Please keep in mind that I'm not a veterinarian, and this isn't medical advice. Every pet is unique, so I always recommend working alongside your vet, ideally a holistic or integrative vet, especially for anything ongoing or serious. If you would like help finding one, we keep a holistic vet directory here.
Affiliate disclosure: PAWDEGA does not sell red light therapy devices. The Photonic Health links in this article are affiliate links, which means we earn a commission if you buy through them, at no extra cost to you. We bought and used these devices with our own animals before that arrangement existed, and it does not change what we recommend or what we tell you about the evidence.
