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Dog Hair Loss in the UK: Common Causes and Treatments

Hair loss in dogs (alopecia) is a common presenting complaint at UK vet practices and has many possible causes. Some are simple and treatable; others indicate underlying conditions requiring investigation. Here's what commonly causes hair loss in dogs and what treatment involves.

Allergic Skin Disease

Allergic skin disease (atopy) is one of the most common causes of hair loss in dogs in the UK. Atopic dogs develop hypersensitivity to environmental allergens — house dust mites, grass and tree pollens, mould spores — and respond with intense itching. It's the repeated scratching, licking and chewing that causes hair loss, not the allergy itself.

Affected areas typically include the paws, face (muzzle and around the eyes), ears and belly — all areas where allergens make skin contact and where dogs can reach to scratch. A patchy, symmetrical pattern of hair loss with reddened, thickened skin underneath is characteristic.

Management involves allergy testing, allergen avoidance where possible, and medical management with prescription medications including Apoquel, Cytopoint injections or allergen-specific immunotherapy. A UK vet consultation to investigate atopy typically runs £40–£65 plus the cost of diagnostic tests.

Parasites: Fleas, Mites and Mange

Fleas cause intense itching, particularly around the base of the tail and lower back, leading to hair loss through scratching and chewing. Even dogs not visibly infested with fleas may react to a single flea bite if they've developed flea allergy dermatitis (FAD) — the most common skin allergy in UK dogs.

Mange comes in two forms: sarcoptic mange (caused by Sarcoptes scabiei, highly contagious to other animals and humans) causes intense itching with hair loss on ear margins, elbows and face; demodectic mange (caused by Demodex mites present in normal skin) causes non-itchy patchy hair loss and is related to immune dysfunction.

Diagnosis involves skin scrapes, tape preparations and sometimes skin biopsy. Treatment depends on the cause — mange is treatable with prescription parasiticides. Don't confuse mange with other skin conditions without veterinary confirmation.

Hormonal Causes

Hormonal conditions cause bilaterally symmetrical (same on both sides) hair loss, typically without associated itching — this pattern is a diagnostic clue that the cause is systemic rather than local.

Hypothyroidism (underactive thyroid) in dogs causes progressive hair loss, weight gain, lethargy, and skin thickening. It's most common in middle-aged to older dogs of larger breeds. Diagnosis is via thyroid hormone blood tests; treatment is daily oral thyroid hormone supplementation.

Cushing's disease (hyperadrenocorticism) causes a characteristic pot-bellied appearance, increased thirst and urination, muscle wasting and bilaterally symmetrical hair loss. Alopecia X (a pattern of hair loss related to sex hormones, common in Pomeranians, Chow Chows and Keeshonds) produces truncal hair loss with normal skin.

Oestrogen-related alopecia can occur in entire (unspayed) female dogs around oestrus. Neutering often resolves this.

Ringworm and Fungal Infections

Despite the name, ringworm (dermatophytosis) is a fungal infection, not a worm. It causes circular areas of hair loss with scaly or crusty skin, typically without significant itching. It's more common in puppies, immunosuppressed dogs and dogs from rescue environments.

Ringworm is zoonotic — it can spread to humans, including children, causing characteristic circular red patches on the skin. This makes prompt diagnosis and treatment important both for the dog's welfare and household safety.

Diagnosis involves Wood's lamp examination (some species fluoresce green), fungal culture and sometimes PCR testing. Treatment involves antifungal shampoos, topical antifungal creams and in some cases oral antifungal medication. Treatment is prolonged — typically 6–8 weeks — and all contact animals and environmental decontamination should be addressed.

When Hair Loss Is an Emergency

Hair loss on its own is rarely an emergency. However, it warrants prompt veterinary attention when: accompanied by open sores, severe redness or skin infection; spreading rapidly; occurring alongside systemic signs like lethargy, weight change, increased thirst; or when the dog appears in discomfort.

For isolated patchy hair loss in an otherwise well dog, a vet appointment within a week or two is appropriate. Bring photos of the affected areas taken at different times to show progression — this can be very helpful for diagnosis.

Management of skin conditions in dogs is frequently a long-term commitment, often involving prescription treatments and regular follow-up. Understanding this before starting treatment helps owners plan the financial commitment involved.

Find a Vet Near You

Investigating hair loss usually starts with a vet consultation. Use CompareMyVet at app.comparemyvet.uk to find and compare vet practices near you, including consultation costs, to get your dog the assessment they need.