8 Common Skin Allergies in Dogs — What to Watch For

> Vet-noted reminder: This article is educational and not a diagnosis. If your dog shows concerning symptoms, call your veterinarian.

Dogs itch for lots of reasons—but when scratching becomes constant, you could be looking at an allergy. Here are the most common culprits, what they look like, and simple next steps you can take at home before (and while) you work with your vet.

1) Flea Allergy Dermatitis (FAD)

What it is: A hypersensitivity to flea saliva.
What you’ll see: Intense tail-base itching, scabs, hair loss on rump and back legs; you may never see the flea.
What to do: Start fast-acting oral or topical flea prevention for every pet in the household and deep-clean bedding. Wash with warm water weekly for a month.
Pro tip: One bite can set off a 2–3 week flare—keep prevention monthly, year-round.

2) Environmental Allergies (Atopy)

What it is: Allergies to pollens, molds, dust mites—similar to human hay fever.
What you’ll see: Face rubbing, paw licking/chewing, recurrent ear infections, seasonal flares (often spring/fall).
What to do: Rinse off pollen after walks (wipe paws/belly or quick shower), use vet-approved medicated shampoos weekly during flare seasons, discuss antihistamines or prescription therapies with your vet.
Pro tip: Track flare timing in your calendar to spot patterns and plan bathing/meds ahead of peak seasons.

3) Food Allergy / Adverse Food Reaction

What it is: Immune reaction (or sensitivity) to a food protein—often chicken, beef, dairy, or egg.
What you’ll see: Year-round itch, ear infections that keep coming back, bum scooting, and sometimes GI signs (soft stool, gas).
What to do: Ask your vet about a strict 8–12 week elimination diet with a hydrolyzed or novel-protein food (no treats/table scraps). Rechallenge to confirm.
Pro tip: Photograph every label and build a “safe foods” album so family members don’t accidentally break the trial.

4) Contact Dermatitis

What it is: Skin reaction to what the dog touches—grasses, cleaning products, shampoos, certain plastics/metals.
What you’ll see: Red, itchy belly, armpits, groin, or muzzle that improves when indoors; sudden flares after yard time or a new product.
What to do: Rinse after outdoor play, switch to fragrance-free detergents/cleaners, try a barrier balm on the belly/paws before walks.
Pro tip: Test changes one at a time (shampoo → detergent → cleaner) so you know what helped.

5) Yeast (Malassezia) Overgrowth

What it is: Yeast taking advantage of inflamed or oily skin—common secondary to allergies.
What you’ll see: Musty “corn chip” odor, greasy/flaky skin, red or darkened areas, itchy ears with brown debris.
What to do: Use vet-recommended antifungal shampoo or wipes; treat ears as prescribed. Address the underlying allergy to prevent repeat flares.
Pro tip: Dry thoroughly after baths; residual moisture feeds yeast.

6) Bacterial Pyoderma (Secondary Infection)

What it is: Bacterial infection that follows scratching/irritation.
What you’ll see: Pimples, crusts, circular “collarettes,” oozing hot spots, and tenderness.
What to do: See your vet for cytology and targeted treatment (topicals or antibiotics). Keep an e-collar on to stop self-trauma.
Pro tip: Clip long fur around lesions to let medicated sprays or wipes actually reach the skin.

7) Mite-Related Itch (Sarcoptic or Demodex)

What it is: Parasites that inflame skin; sarcoptic mange is very itchy (and contagious to other dogs), demodex often in pups or immune‑stressed dogs.
What you’ll see: Sudden, severe itch; ear edges, elbows, belly; patchy hair loss. Sometimes humans in the home develop itchy bumps.
What to do: Vet visit for skin scraping; many modern preventives (isoxazolines) treat mites quickly. Wash bedding and limit dog-to-dog contact until cleared.
Pro tip: If humans are itchy too, mention it—helps your vet prioritize scabies testing/treatment.

8) Hot Spots (Acute Moist Dermatitis)

What it is: Rapid, painful skin lesions triggered by allergies, fleas, moisture, or stress/licking.
What you’ll see: Raw, wet, hair-matted patches—often on neck, cheeks, or thighs. They enlarge fast.
What to do: See your vet to clip/clean, treat infection/inflammation, and manage the trigger (fleas, atopy, anxiety). Keep an e-collar on.
Pro tip: After swimming or rain, towel-dry and brush out dense coats to prevent trapped moisture.

 

Quick Buyer’s Notes (What Actually Helps)

– Year-round parasite control for every pet in the home (tablets or spot-ons).
– Medicated shampoos/wipes (chlorhexidine, ketoconazole, selenium sulfide per vet advice).
– Hypoallergenic diet trials (hydrolyzed or novel protein) for 8–12 weeks when food allergy is suspected.
– Topicals (sprays, mousses) to calm skin and support the barrier (ceramides, essential fatty acids).
– Allergy control plan: wiping paws, weekly baths in season, air purifiers, washable dog beds.

At-Home Checklist

– Track itch: “itch score” 0–10 nightly for two weeks.
– Note pattern: seasonal vs year‑round; body areas most affected.
– Confirm preventives: last flea/tick dose date; apply now if overdue.
– Switch to fragrance‑free laundry and cleaning products.
– Rinse paws/belly after outdoor time; dry thoroughly.
– Book a vet visit if no improvement in 7–10 days or sooner if worsening.

When to Call the Vet

– Open sores, oozing “hot spots,” or your dog seems painful.
– Ear infections (head shaking, odor, discharge) or repeated ear flares.
– Sudden, severe itch disrupting sleep/appetite.
– Hair loss spreading in patches; people in the home becoming itchy.
– Any rash plus lethargy, fever, vomiting, or swelling of the face.

 

SOURCES & NOTES

– American Kennel Club (AKC) — Atopic dermatitis overview; seasonal patterns; common signs.
– VCA Animal Hospitals — Food allergy in dogs; elimination diet best practices; signs and management.
– Merck Veterinary Manual — Flea allergy dermatitis pathophysiology and management.
– Cornell University College of Veterinary Medicine — Otitis externa/ear infections linked to allergies.
– Royal Veterinary College (RVC) — Hot spots (acute moist dermatitis) first-aid and prevention.
– Medical disclaimer: This content is for education, not medical advice. Always consult your veterinarian for diagnosis and treatment.