What to Avoid With Red Light Therapy

The safety record for veterinary photobiomodulation is reassuring. The systematic review covering 45 studies reported no significant safety signal, and the common problems with home use are misuse rather than harm from the light itself.

There are still situations where the device should not be used, and they are worth knowing before the first session rather than after.

Do Not Skip the Safety Glasses

The single firm rule, and the one most likely to be ignored because the glasses feel like packaging.

This is a Class 3R laser device under IEC 60825-1. That is a low risk classification rather than an alarming one, and it specifically means direct viewing of the beam is potentially hazardous to the eye. The glasses are supplied for that reason rather than as a formality.

Put them on before the device goes on, every session, including the short ones.

The same care applies to the dog. Never aim the head at the eye, angle the device away when treating anywhere near the face, and do not look into the emitter to check whether it is running, which is a surprisingly common reflex.

Do Not Treat Over a Known or Suspected Tumour

Photobiomodulation works by stimulating cellular activity, which is the mechanism you want in healing tissue and precisely the mechanism you do not want in a mass.

That means any lump you have not had identified is a reason to stop and ask your vet rather than to treat and see. It is not a small caution.

Do Not Use It on a Pregnant Animal

Standard contraindication, and there is no reason to test it at home.

Do Not Use It Instead of Seeing a Vet

The most likely real harm from a home device is not the light. It is a fortnight spent treating a limp that turned out to be a cruciate rupture, or a swelling that needed investigating.

New lameness, a new lump, heat or swelling in a joint, or a dog that is suddenly worse all need a diagnosis first. The device is for a condition you already understand, not for one you are hoping to avoid investigating.

Do Not Treat Over Broken or Infected Skin Without Asking

Wound healing is the area where the evidence for this therapy is actually strongest, so this is not a blanket prohibition.

It is a reason to have the wound assessed first. An infected site or a surgical incision that is not healing normally needs a vet involved, and treatment over it should follow their advice rather than a general article.

Do Not Assume Longer Is Better

The most common misuse, and it comes from an intuition that does not apply here.

Dose in photobiomodulation is not additive in the way people expect, and running double sessions because a normal one seemed to do nothing is not a reasonable response. The doses used across the published veterinary studies sit mostly below 50 J/cm².

The timer defaults to ten minutes and there are four power levels, which is the range to work within rather than around. If nothing has changed after a defined trial, the answer is to stop rather than to escalate. Our guide to using the device at home covers how to set that trial up.

Watch for Heat on the Skin

These devices are not designed to heat tissue, but the head rests against skin and vents warm air, and a long session in one spot can become uncomfortable.

Check the area with the back of your hand partway through. A dog that starts shifting away mid session may be telling you about warmth rather than boredom.

Do Not Buy a Device That Will Not Tell You What It Does

This is the one that costs owners money rather than causing harm.

Wavelength and output power determine what a device actually delivers, and they are the difference between something that might do what the studies describe and a red LED torch. A large share of what is sold for pets publishes neither figure.

The figures to look for are the diode type, the wavelengths in nanometres, the optical output in milliwatts, whether that output is peak or average, and the laser class. Ours are GaAlAs diodes at 650 nm and 808 nm, peak output around 500 mW, Class 3R.

That peak and average distinction is worth insisting on. A pulsed device quoting only its peak figure can look several times more powerful than it is over a whole session, and a seller who will not tell you which number they are quoting has told you something anyway.

If a specification sheet lists none of that, there is no way to relate the product to any published protocol and no way to know what dose you are giving. That is a reason not to buy it.

Do Not Let It Replace What Works

For an arthritic dog, weight loss of 6 to 9 percent produces a measurable reduction in lameness, and appropriate structured exercise maintains the muscle around the joint. Those two outperform anything else available.

Our guide to strengthening a dog's back legs covers the exercise side properly.

The order matters. Get the weight and the exercise right first, then add anything else on top of them.

A red light therapy device is worth adding to that, and it is not worth substituting for it.

The Short Version of the Rules

• Glasses on, every session, and never at the eyes
• Not over a lump you have not had identified
• Not on a pregnant animal
• Not instead of a diagnosis
• Not longer than the schedule says
• Not on a device that hides its specification

Everything else is ordinary use. The Whisker Bark red light therapy device has a session timer on the display so the last of those rules is easy to keep to, which is the one owners break most often.