Seasonal Flank Alopecia in Dogs: Light Therapy & Winter Hair Loss Guide
Symptom Checker
Hair loss on both flanks [moderate]
Balding patches that are roughly symmetrical, often the size of a hand on each side.
Skin appears normal (no redness, bumps, scales) [mild]
The underlying skin looks smooth and healthy — just hair missing.
Winter seasonal pattern [mild]
Hair loss starts in late fall or early winter and improves in spring.
No itching or scratching [mild]
Dog doesn't lick or bite at the bald spots.
Hair loss limited to flanks [mild]
Only the sides of the body (flanks) are affected — not back, belly, or legs.
Frequently Asked Questions
My dog's flanks are bald and the skin looks a little pink — should I freak out?
That's scary, I get it. Pink skin without itching or redness is normal — just the skin showing through thin hair. If it's hot to the touch, red, or your dog can't stop scratching, then call your vet. Otherwise, it's likely just seasonal flank alopecia. Start light therapy and watch it over a week.
How do I know for sure it's seasonal flank alopecia and not something like mange?
Great question. Seasonal flank alopecia is two-sided, smooth bald patches with no skin changes — like someone shaved your dog's sides. Mange is usually patchy, itchy, and causes red bumps. If your dog is scratching like crazy, that's not seasonal flank. Otherwise, a quick vet check with a skin scrape gives you peace of mind.
I've been using the light therapy for three weeks and see no hair growth — am I doing something wrong?
Patience, friend. Hair growth takes 2-3 months, sometimes longer. Keep the lamp on 8-12 hours daily. You might not see baby hairs for another month. Take a photo today and compare in 30 days — you'll probably notice the difference. If after 3 months nothing changes, talk to your vet.
Will buying a light therapy lamp hurt my dog or my wallet?
Your wallet's safe — good full-spectrum lamps are under $100. Your dog is safe too, as long as you use a lamp designed for indoor plants or humans (no UV). Don't use reptile basking lamps — those can burn. Your dog can be near the lamp but doesn't need to stare at it. Just place it where they nap.
Will my dog be permanently bald on the sides?
Deep breath — no. Seasonal flank alopecia almost always grows back in spring. Some dogs may have thinner fur every winter, but they won't be bald forever. Light therapy can help it grow back faster. The only permanent situation is if another condition is missed, so a vet check is a good idea if you're worried.
My dog's skin is now red and he's scratching the bald spots — what do I do?
That's not typical for seasonal flank alopecia. It could be a secondary infection or a different skin issue. Call your vet today. In the meantime, put a cone on your dog to prevent licking. Don't apply anything to the skin. Your vet might need to do a skin scrape or prescribe antibiotics if there's an infection.