Common causes
| Cause | Typical picture | How it is confirmed |
|---|---|---|
| Flea allergy | Itching and hair loss over the back and tail base | Fleas or black flea dirt on combing |
| Mites (sarcoptic, demodex) | Intense itch on ear edges and elbows; patchy loss in puppies | Skin scrape under the microscope |
| Ringworm (fungus) | Round bald patches, scaling; can spread to people | Wood's lamp, fungal culture |
| Bacterial or yeast infection | Red rash, pustules, greasy smelly skin in folds and between toes | Tape impression under the microscope |
| Environmental allergy (atopy) | Seasonal itch of feet, armpits and face, recurring ear infections | Diagnosed once other causes are ruled out |
| Food allergy | Year-round itch, ear infections, gut upsets | 8 to 12 week prescription-diet trial |
| Hormonal disease (hypothyroid, Cushing's) | Symmetrical hair loss without itch, thin dark skin | Blood tests |
What happens at the visit
- History: how long, seasonal or not, diet, whether other pets or people are affected.
- Skin scrape, tape impression and ear swab examined under the microscope on the spot.
- Fungal culture, blood tests or allergy testing where needed.
Most dogs start targeted treatment the same day.
Treatment
- Parasites and infections first: flea control, antibiotics or antifungals, medicated shampoo.
- Itch relief: modern dog-specific anti-itch drugs have fewer side effects than steroids and can be used long term.
- Allergy: identify and avoid the trigger, diet trial, or a long-term control plan.
- Ear infections must be treated at the same time, or the skin keeps flaring.
At home
- No human creams, essential oils or antiseptics; they make things worse.
- Monthly flea and tick prevention all year, for every pet in the home.
- Keep the skin dry; dry folds and toes thoroughly after bathing.
- Use only the shampoo the vet recommends, and not daily.
See a vet promptly if
- Large areas are red, bleeding or smell
- The face swells or hives appear suddenly (acute allergy can affect breathing)
- The itch stops your dog sleeping or causes self-injury
- Family members develop round red patches (possible ringworm)