Finding areas of hair loss along with black spots on your old dog’s skin can be concerning, especially when the changes seem to appear without an obvious reason.
Hair loss in an older dog can have many causes, and the pattern of the bald areas can provide useful clues. It is also important to look at the skin itself for redness, itching, scaling, odor, or thickening.
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Old Dog Losing Hair with Black Spots on Skin: Why It Happens
A dog may lose hair and develop black spots on the skin when chronic inflammation, hormonal changes, allergies, parasites, infection, or repeated irritation affects the skin and hair follicles.
Darkening of the skin, known as hyperpigmentation, can occur after prolonged irritation or inflammation and may become more noticeable when hair falls out.
In older dogs, new or widespread hair loss deserves attention because skin problems can sometimes be associated with underlying medical conditions.
The location of the hair loss, whether your dog is itchy, and whether the skin has changed in texture can help your veterinarian narrow down the cause.
Old Dog Losing Hair with Black Spots on Skin: Symptoms
Depending on the underlying problem, other symptoms may occur at the same time, including:
Patches of missing or thinning hair
Dark or black areas of skin
Increased skin pigmentation
Itching or scratching
Licking or chewing at affected areas
Flaky or scaly skin
Skin thickening
Unpleasant skin odor
Old Dog Losing Hair with Black Spots on Skin: Common Causes
Allergies and Chronic Skin Inflammation
Allergies can cause ongoing inflammation of the skin and may lead to itching, licking, scratching, and hair loss.
When inflammation continues for a long time, the affected skin can become darker and thicker.
Dogs may develop hair loss around the paws, belly, armpits, groin, ears, or other areas they frequently scratch or lick. The skin may also become irritated or develop secondary infections.
Allergies are often manageable, but recurring hair loss and darkening should be evaluated because several different conditions can produce similar symptoms.
Related: Old dog losing hair (Causes and treatment)
Fleas and Other Parasites
Fleas can cause intense itching in some dogs, leading to repeated scratching and chewing. This self-trauma can break hairs and eventually leave areas of thinning or missing fur.
Chronic irritation can also cause the skin to become darker. You may notice small scabs, redness, or evidence of scratching, although fleas are not always easy to spot.
Other external parasites can also cause itching and hair loss. Your veterinarian can examine the skin and determine whether parasite testing or appropriate parasite treatment is needed.
Yeast or Bacterial Skin Infection
Skin infections can develop when the normal balance of microorganisms on the skin is disrupted.
Yeast overgrowth may cause itching, redness, greasy skin, odor, hair loss, and progressive darkening.
Bacterial infections can cause similar signs and may produce crusting, bumps, discharge, or painful areas. Dogs with chronic allergies are particularly prone to secondary skin infections.
A veterinarian may recommend skin testing to determine whether yeast, bacteria, or another problem is contributing to the hair loss. Treatment depends on the specific cause.
Read more: Old Dog Hair Falling Out in Clumps (Causes and treatment)
Hormonal or Endocrine Disease
Some hormonal conditions can cause hair loss without the intense itching seen with many allergic skin disorders.
Endocrine problems may affect how hair grows and can lead to thinning or bald areas on the body.
Other changes may include alterations in body shape, appetite, thirst, urination, energy, or skin quality, depending on the underlying condition.
Because hormonal disorders can become more common considerations as dogs age, unexplained symmetrical hair loss or significant changes in the skin should be discussed with your veterinarian.
Pressure and Chronic Friction
Repeated pressure or friction can cause hair to thin or disappear from specific areas. Older dogs that spend a great deal of time lying down may develop hair loss over pressure points such as the elbows or other areas that regularly contact hard surfaces.
The skin in these areas can become darker or thicker over time. A firm or roughened area may also develop.
Providing a comfortable, supportive sleeping surface can reduce ongoing pressure, but any painful, swollen, ulcerated, or rapidly changing area should be examined by a veterinarian.
Repeated Licking or Self-Trauma
Some dogs repeatedly lick or chew one part of their body because of itching, discomfort, anxiety, or underlying pain. Constant licking damages the hair and irritates the skin.
Over time, the affected area may become darker and thicker, particularly when the irritation has been present for a long period.
Identifying why your dog is licking is important. Simply preventing the licking without addressing the underlying cause may not resolve the skin problem.
Nutritional or Systemic Illness
Hair growth depends on adequate nutrition and overall health. Certain illnesses can affect the skin and coat, sometimes resulting in thinning or poor-quality hair.
An older dog with a combination of hair loss and other changes, such as weight loss, reduced appetite, vomiting, diarrhea, or unusual tiredness, may need a broader medical evaluation.
Hair loss by itself does not identify a specific internal disease. Your veterinarian can determine whether additional testing is appropriate based on your dog’s complete symptoms.
Skin Growths or Other Abnormalities
Older dogs can develop different types of skin and subcutaneous growths. Some are harmless, while others require investigation.
A dark spot that is raised, rapidly changing, bleeding, ulcerated, or distinctly different from the surrounding skin should be examined. Hair loss directly over a skin mass can also occur.
Do not assume that every black spot is simply pigmentation. A veterinarian can examine unusual areas and determine whether further testing is needed.
Read more: Old Dog Losing Hair Loss On Back (Here’s why)
When to Call or Visit the Vet
Hair loss accompanied by skin discoloration can have many causes, so persistent or progressive changes should be assessed rather than assumed to be a normal part of aging.
Schedule an appointment if you notice:
Hair loss that continues to spread
Increasingly dark or thickened skin
Persistent itching or licking
Recurrent skin infections
Scaly or crusty skin
Unpleasant skin odor
Unexplained changes in weight or appetite
Unusual tiredness or other changes in your dog’s health
Seek emergency veterinary attention immediately if your dog develops:
Rapidly worsening swelling of the skin or face
Severe skin pain
Extensive skin damage
Sudden weakness or collapse
Difficulty breathing
Severe illness accompanied by rapidly developing skin changes
Old Dog Losing Hair Black Spots on Skin: Treatment
Veterinary treatment for an old dog losing hair with black spots on the skin starts with a thorough examination of the skin, coat, and affected areas, along with an assessment for underlying medical conditions that could be contributing to the hair loss.
The veterinarian may recommend skin tests, microscopic examination, blood tests, hormone testing, or other diagnostic testing when appropriate to identify allergies, parasites, infections, or internal disease.
Treatment may include parasite control, prescription medications, medicated skin treatments, allergy management, nutritional support, or other targeted therapy based on the diagnosis.
Recovery and Monitoring
Recovery depends on what is causing the hair loss and skin darkening. Hair may begin growing again after the underlying inflammation, infection, parasite problem, or other condition is successfully controlled, although the skin can take longer to return to its previous appearance.
Some chronic conditions require ongoing management rather than a short course of treatment.
Allergies and certain hormonal disorders, for example, may need regular monitoring and long-term veterinary care.
Monitor the size and location of bald patches, the color and texture of the skin, and your dog’s level of itching or licking.
Taking photographs periodically can help you and your veterinarian determine whether the condition is improving.
Follow the treatment plan provided by your veterinarian and avoid stopping prescribed treatment simply because the skin looks better.
If hair loss returns or new darkened areas appear, arrange a follow-up examination.
Key Takeaway
An old dog losing hair with black spots on the skin may have allergies, parasites, a yeast or bacterial infection, chronic irritation, hormonal disease, or another skin or internal health problem.
Darkened skin can develop after prolonged inflammation, but unusual or changing spots should not automatically be dismissed as normal pigmentation.
Persistent hair loss, spreading dark areas, itching, skin thickening, odor, or other changes should be evaluated by a veterinarian.
Finding the underlying cause is important because treatment needs to address the reason the hair is being lost rather than simply the appearance of the skin.
If your dog’s skin changes rapidly, becomes severely painful, or your dog develops serious signs such as weakness or breathing difficulty, seek veterinary attention immediately.
With the right diagnosis and treatment, many causes of hair loss and skin discoloration can be appropriately managed.