Hair loss in dogs: normal shedding and alopecia

Overview

The amount of shedding varies with coat type. Many breeds with a thick undercoat have two heavy shedding seasons each year. Some short-haired dogs shed small amounts throughout the year. Karelian Bear Dogs can naturally shed very heavily.

Normal shedding does not usually cause obvious bald patches. Alopecia can be confined to one spot or affect several areas. Sometimes hair loss is similar on both sides of the body. Hair loss is a symptom, so the same appearance can be associated with different underlying diseases.

Damage can affect the hair-producing follicle or the hair shaft itself. Alopecia does not always involve itching or visible inflammation. Broken hairs can also make a coat look thin.

Causes

Itching makes a dog scratch or lick hairs away. Allergies are among the common causes of itching. External parasites can also trigger itching that damages the coat. Bacterial and fungal infections can directly damage hairs or follicles.

Severe skin inflammation can damage the structures that produce hair. A burn can cause localised coat loss. Constant rubbing from a poorly fitting collar can wear away hair locally. A coat change over a painful joint may reflect excessive licking. Hair may thin or calluses develop at pressure points such as the elbows and hocks.

Hypothyroidism can slow hair growth without initial itching. Nutritional deficiencies, particularly inadequate protein, can also disrupt follicle function. Pregnancy and nursing may be associated with temporary hair loss. Temporary hair loss can also begin after severe illness or fever.

In congenital hairlessness, hair follicles may not develop normally. A congenital disorder is not always inherited. Some inherited hair growth disorders only become apparent as a dog born with a normal coat grows. Colour dilution alopecia is an example of an inherited follicular disorder.

A follicular disorder can sometimes affect only the black hairs of a black-and-white dog. Some congenital coat development disorders also involve missing or abnormal teeth.

Risk factors

The risk of inherited follicular disorders depends on the particular disease and the dog's genetic background. In colour dilution alopecia, thinning affects blue or fawn areas of the coat. Signs can become apparent before one year of age. This form occurs particularly in Dobermanns.

Hypothyroidism underlying hair loss is most often diagnosed between four and ten years old. The average age of affected dogs is six to seven years. Thick-coated dogs may be more prone to slow regrowth after close clipping. These predispositions concern different causes, whose significance is assessed according to the symptoms.

Typical symptoms

The appearance of hair loss and accompanying symptoms depend on the underlying cause. Some dogs also have discharge from inflamed skin.

• A thin coat: the skin shows more clearly between the hairs.
• Bald patches: hair may be missing from one or several separate areas.
• Itching: the dog may scratch or lick the area becoming hairless.
• Scaling: more shed skin cells than usual may be visible on the skin and coat.
• Colour change: the skin may darken with long-standing inflammation.
• Odour and greasiness: dermatitis may cause an unusual smell or greasy skin.

With hypothyroidism, the coat may be dry, brittle and dull. Weight gain can occur in the same disease. Tiredness and reduced activity may also form part of its symptoms. Poor tolerance of cold is another general sign worth noting.

Small raised bumps, or papules, may appear early in inflammation. Pustules and small blisters can also occur with dermatitis. Crusts may accumulate as inflammation progresses.

Complications and consequences

Skin inflammation can lead to secondary bacterial overgrowth. A yeast infection may also develop. Such infection can increase itching even if the original cause of hair loss was not itchy. Persistent dermatitis can thicken the skin.

Inherited follicular development disorders may be associated with blocked follicles, called comedones. Bare skin needs protection from the sun. Genetic hairlessness cannot always be cured. Care then focuses on protecting the skin. Colour dilution alopecia does not itself impair general health.

Redness from chronic dermatitis may lessen while skin thickening and scaling persist. Follicular development disorders can also involve inflammation of the follicles themselves.

Chronic inflammation can also dry the skin.

Diagnosis at the vet

Investigation starts by establishing when hair loss began, how long it has lasted and how it has progressed. Itching before hair loss particularly directs attention to the cause of scratching. The vet assesses general health as well as the skin. The location and distribution of hairless areas are recorded.

Hair examination distinguishes hairs shed whole from broken hairs. A fine comb looks for fleas and other external parasites in the coat. Skin scrapings help investigate parasites living on the skin or in follicles. Skin cytology can look for bacteria and yeast.

Fungal or bacterial culture may form part of further investigation according to the suspected infection. A skin biopsy is sometimes needed to identify an inflammatory or tumour-related cause. Microscopic examination shows follicle structure and numbers. Blood and urine samples may be tested if hormonal disease is suspected.

Blood thyroid tests investigate hypothyroidism. Other illness can alter thyroid results without true hypothyroidism. Coat appearance is therefore assessed alongside other symptoms and test results.

An itchy dog's ears are examined even if the owner has not noticed ear symptoms. Superficial and deep skin scrapings look for mites living in different skin layers. Hair samples may help find Demodex mites in areas sensitive to handling. An improvement in itching with corticosteroids does not identify the disease originally causing hair loss.

Treatment

Treatment depends on the cause

The vet treats the identified underlying disease to control the cause of hair loss. Secondary skin infections are treated while the primary cause is investigated. Medication may relieve severe itching while investigations continue. Skin treatment may include veterinary-prescribed bathing.

Concurrent parasites in a dog with allergic skin disease are treated alongside itch relief. Confirmed Malassezia infection may need a topical or systemic antifungal. If anti-itch medication is insufficient, repeat skin cytology may reveal persistent infection. The first response to treatment for allergic skin disease is often assessed at 14 days.

Confirmed hypothyroidism is treated with synthetic thyroid hormone. Replacement treatment usually continues for life. Its effectiveness is monitored with further examinations and blood samples. Skin and coat recovery may take several months after other symptoms have already improved.

Managing inherited hairlessness focuses on protecting the skin and preventing infection. In colour dilution alopecia, dryness and excessive scaling are also treated. With post-clipping hair growth arrest, new growth can be delayed for up to two years. This lengthy regrowth time applies to that particular post-clipping disorder.

Coat care without further damage

Extensive or tight mats may need professional attention. If matting has irritated the skin, a vet needs to assess skin treatment requirements. Cutting mats out with scissors can injure the skin beneath. Mats are dealt with before bathing, as wetting can make them harder to remove.

Grooming a dog that is difficult to handle may sometimes be performed under sedation at a veterinary practice. The need for therapeutic bathing varies with the skin disease and individual needs.

Prevention

Regular brushing removes loose hairs and dead skin cells. Checking the coat helps detect parasites and sore skin areas early. Brushes and combs must suit the coat type. Handling should be gentle, without pulling hard on mats.

Brushing also helps distribute the skin's natural oils along the hairs.

Daily brushing reduces the amount of hair swallowed during grooming.

Use shampoo intended for canine skin. Human shampoo, including baby shampoo, may be too harsh for a dog's skin. Rinse shampoo thoroughly from the coat after washing. Protecting genetically hairless skin from sunlight and mechanical injury also helps prevent damage.

Important for dog owners

Record when hair loss began and how the area has changed. Note whether it is itchy. Other health problems also belong in the history. Mention if the coat fails to regrow after clipping.

Karelian Bear Dogs are brushed daily during shedding. Long, silky or curly coats may need daily brushing to prevent mats. Short-haired dogs may need brushing less often. Check particularly the armpits, groin and behind the ears for mats.

Twigs and burrs caught in the coat after walks can irritate the skin. Bathing needs depend on coat type, lifestyle and skin health, among other factors. Changing shampoo alone does not resolve hair loss caused by another treatable disease.

Licking, chewing, rubbing and rolling can indicate itching even without obvious scratching. Tell the vet if other household animals or people are itchy at the same time. Previous treatments and their effects help plan further investigations.

Frequently asked questions

How can I distinguish normal shedding from alopecia?

During shedding, old hairs fall out as new ones grow. Clear bald patches or marked coat thinning suggest abnormal hair loss. Investigation also includes assessing itching and skin changes. Many breeds with thick undercoats have heavy shedding twice a year.

Can a dog lose hair without itching?

Yes: not all causes of hair loss produce inflammation or itching. Hypothyroidism can be associated with non-itchy hair loss. Inherited hairlessness can also occur without inflammation. The vet also assesses hair loss distribution and general health.

Why is my dog's coat not growing back after close clipping?

Some thick-coated dogs develop delayed regrowth after clipping. This disorder can delay growth for up to two years. Slow growth can also be associated with hypothyroidism, so the cause is investigated according to the symptoms. Blood tests may be needed to investigate a hormonal cause.

Can I wash my dog with human shampoo?

Choose shampoo intended for canine skin. Human and canine skin differ in thickness and acidity. Even baby shampoo may be too harsh for a dog's skin. A vet plans therapeutic bathing for skin disease. Rinse shampoo thoroughly from the coat afterwards.

Does hair always grow back?

Recovery depends on the cause of hair loss. Skin and coat recovery during hypothyroidism treatment can take months. Genetic hairlessness cannot always be cured. Care then focuses on skin protection and preventing secondary infections.