When you notice your dog losing hair in spots, it can be alarming especially when the bald patches appear quickly or look irritated, flaky, or inflamed.
We outline the common causes of hair loss in spots on dogs, what you can do, and when to seek veterinary help.
Dog Losing Hair in Spots — Why It Happens
Dogs lose hair in spots when the skin becomes irritated, infected, inflamed, or damaged from parasites, allergies, excessive licking, or fungal infections. These conditions disrupt normal hair growth, causing round or irregular bald patches that may or may not itch. Some causes develop suddenly, while others progress slowly over weeks.
Because spotty hair loss can have many different triggers — from minor irritations to more serious skin conditions — understanding what the bald patches look like is an important first step.
Some spots appear smooth and round, others are scabby and crusted, while others come from repetitive licking or scratching. The pattern helps guide the likely cause.
Dog Losing Hair in Spots: Common Causes
Ringworm
Ringworm is one of the most well-known causes of spotty hair loss in dogs. Despite the name, it is a fungal infection, not a worm. It causes round, sharply defined bald patches that may look scaly, dry, or slightly red.
Typical features of ringworm spots include:
• Perfectly rounded or oval bald areas.
• Dry, flaky skin at the center.
• Broken hairs around the edges.
• Mild itching (sometimes no itching at all).
Because ringworm spreads through spores, dogs can develop multiple spots across the body — head, legs, tail, or trunk. It is contagious to other pets and humans, making early treatment important.
Read more: Dog Losing Hair in Patches and Scabs (Common skin causes explained)
Hot Spots
Hot spots can cause dramatic sudden bald patches that appear within hours. They occur when dogs lick or scratch one area so intensely that the skin becomes moist, inflamed, and infected. These spots are typically painful, red, and warm to the touch.
You may notice:
• A raw, oozing bald patch.
• A foul smell from the infection.
• Constant licking at the site.
• Discomfort when you touch the area.
Hot spots often start from a small irritation (flea bite, allergy flare, tangled hair, insect bite) but quickly become large patches of hair loss if not treated promptly.
Flea Allergy Dermatitis
Dogs with flea allergies often bite specific areas of their bodies aggressively, causing localized bald spots. Even a single flea bite can lead to days of itching and localized hair loss, especially around the tail base, hips, thighs, or lower back.
Signs include:
• Scattered bald spots or thinning patches.
• Red bumps or scabs in the itchy areas.
• Constant nibbling at specific spots.
Many owners never see fleas — allergic dogs remove them quickly. But the pattern of hair loss in spots strongly suggests fleas, especially if the bald areas are near the rear end.
Mange (Localized Mite Infestations)
Both demodectic and sarcoptic mange can create bald spots, but localized demodectic mange often starts as small, isolated patches with:
• Thin or missing hair.
• Dry or mildly inflamed skin.
• Occasional scabs or crusting.
• Minimal itching at first.
Sarcoptic mange causes intense itching and hair loss in scattered spots. Dogs with mange often develop bald patches around the eyes, mouth, elbows, or legs.
Mange is common in puppies, stressed dogs, or those with weakened immune systems.
Allergies Targeting Specific Body Areas
Environmental or food allergies sometimes cause generalized itching, but for many dogs, the irritation clusters in specific zones — creating patchy bald areas.
Localized allergy-related spots may appear on:
• Paws
• Belly
• Armpits
• Tail base
• Inner thighs
These areas are prone to friction or contact with allergens (grass, pollen, mold, cleaning products), making them susceptible to hair loss in repeated spots.
Self-trauma from licking or scratching is often the main reason the bald patches appear.
Bacterial or Yeast Skin Infections
Localized infections can cause irregular bald patches surrounded by redness, swelling, or flaky skin. These infections may be secondary to allergies, scratching, or moisture buildup.
You may see:
• Greasy or oily skin.
• Round or uneven bald spots.
• A yeasty or sour odor.
• Darkened or thickened patches.
These infections worsen quickly without treatment and may appear in multiple small clusters across the dog’s body.
Over-Grooming from Pain or Stress
Some dogs lick or chew a specific area obsessively, leading to self-inflicted bald spots. This may be due to:
• Anxiety or boredom.
• Joint pain or arthritis.
• Nerve irritation.
• Compulsive grooming tendencies.
The bald patches produced by licking often appear smooth and shiny with little to no redness, especially in chronic cases.
Read more: Dog Losing Hair Near Tail (Why the tail base is a hotspot)
What to Do If Your Dog Is Losing Hair in Spots
Start by gently parting your dog’s fur and examining each bald area. Look for redness, dryness, scabs, crusting, circular borders, or signs of infection. The appearance helps differentiate fungal infections from hot spots, mange, fleas, or allergies.
If the patches are round and smooth, ringworm is a strong possibility. If they look raw, moist, or painful, a hot spot is likely. If your dog seems extremely itchy, fleas, allergies, or mange rise to the top of the list.
Avoid shaving or trimming the area unless your vet advises it — cutting the hair can irritate the skin more. Keep your dog from licking or chewing the bald spots by providing enrichment, using a recovery cone if necessary, or distracting with toys and treats.
If fleas are possible, start or update flea prevention promptly. For suspected allergies, bathing with gentle, fragrance-free shampoo and reducing exposure to known triggers may help soothe irritation.
When to Call or Visit Your Vet
Seek veterinary care if:
• The bald spots are spreading.
• The skin looks red, painful, infected, or moist.
• The patches are circular (possible ringworm).
• You see scabs, crusting, or thickened skin.
• Itching is severe.
• Fleas or mange are suspected.
• Hair loss returns after treatment.
Ringworm, mange, and infections require prescription therapies, and early treatment prevents complications or spreading to other pets or people.
Read more: Dog losing hair in patches on back (Here’s why)
Key Takeaway
Spotty hair loss in dogs is often caused by fungal infections, fleas, mange, hot spots, allergies, or over-grooming. Identifying the appearance of the bald patches — round, moist, scabby, or smooth — is one of the best clues to determine the underlying cause.
With proper care and veterinary guidance, most dogs recover fully and regain normal hair growth.