Hyperpigmentation in Dogs—How to Manage It

Hyperpigmentation, as the name suggests, describes a condition in which the skin or fur increases in pigmentation, making it appear darker. This most commonly results in patches or focal areas of skin that change from a lighter color to grey or black. It can also happen to the fur itself.

Hyperpigmentation in dogs is a sign of an underlying skin problem, most often related to inflammation. While not typically dangerous, it can indicate underlying issues like allergies, hormonal imbalances, or skin infections that need medical attention. The good news is that most of the time, when the underlying cause is treated, the skin and fur will return to their original appearance. Be sure to consult a veterinarian to determine the cause and start an appropriate treatment plan right away.

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What does hyperpigmentation look like?

Hyperpigmentation is a darkening of the skin or fur in a focal area of the body. This can happen anywhere on the body, but tends to occur in areas where the fur is more sparse, like the belly, armpits, or groin areas. Depending on what is causing the hyperpigmentation, there may be other changes in the skin too, including hair loss, redness, thickening of the skin, dry skin, scabs, or bumps on the skin.  

What are the symptoms of hyperpigmentation?

The main symptom of hyperpigmentation is the change in the color of the skin or fur in certain areas of the body. Depending on the underlying cause of the hyperpigmentation, there may be additional signs including: 

• Discoloration: Skin or fur becomes darker in focal areas of the body.

• Change in skin texture: Skin may become thickened or feel dry or crusty.

• Hair loss: Areas of hyperpigmentation may also have thin or missing fur.

• Odor: In cases of skin infections, the skin may also have a bad smell.

• Itchiness: You may notice your dog is especially itchy and scratches or licks at the areas with hyperpigmentation.

• Systemic signs: Some causes of hyperpigmentation, like hormonal imbalances, may also cause other changes in the body like lethargy, weight gain, increased thirst, or increased urination.

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What causes hyperpigmentation?

Hyperpigmentation can be caused by many different underlying medical conditions. Most of the time, this is considered a secondary problem, meaning that something else is the main cause and hyperpigmentation is a symptom of that problem. However, there is a unique condition in Dachshunds that causes a primary hyperpigmentation. Some of the most common causes of hyperpigmentation include: 

Primary hyperpigmentation

Acanthosis nigricans of Dachshunds is a unique condition that only affects this breed. In these cases, Dachshunds will have darkened skin, most often in their armpits and groin areas. This is a genetic condition and does not have another underlying cause.

Secondary hyperpigmentation

• Inflammation of the skin: This is the most common reason for hyperpigmentation in dogs. Anything that causes long-term inflammation of their skin can lead to this kind of discoloration.

• Skin allergies: Skin allergies and the allergic condition known as atopy cause ongoing inflammation and itchiness of the skin. When this is not well-controlled, it may lead to hyperpigmentation.

• Contact dermatitis: Anything that comes into contact with the skin and directly irritates it can cause inflammation that could eventually lead to hyperpigmentation. This can happen when dogs are allergic to grasses, plants, dust, or other materials in direct contact with their skin.

• Skin infections: Infections including fleas, skin mites, bacterial, yeast, or fungal infections can all cause lots of inflammation which may lead to hyperpigmentation. 

• Hormone imbalances: Certain systemic diseases, like Cushing’s disease and hypothyroidism can also cause changes in the skin, including hyperpigmentation.

• Friction: Areas of friction on the body can also lead to inflammation and secondary hyperpigmentation. This sometimes occurs in places where a collar or harness rubs against the skin. It can also occur in obese dogs that may have excessive skin folds creating friction. 

What breeds are especially at-risk

Hyperpigmentation can happen in any breed of dog; however, some breeds are more predisposed to it. Most of the breeds that are predisposed to hyperpigmentation also tend to have other skin problems since this condition is usually a result of skin inflammation. This list includes: 

• Dachshunds

• Yorkshire Terriers

• Australian Shepherds

• Pugs

• Bulldogs

• French Bulldogs

• Staffordshire Terriers

• Boston Terriers

• Shar Peis

• Cocker Spaniels

• Shih Tzus

• Poodles 

How to diagnose hyperpigmentation

Hyperpigmentation is a visual change in the skin that your vet can diagnose during an exam. In order to determine the underlying cause for the hyperpigmentation, your vet will consider the history of what you observed at home along with other physical signs your dog may exhibit including itchiness or systemic changes. Your vet may recommend some of the following tests to assist in making a diagnosis: 

• Skin tests: Tests like skin scrapes, tape cytology, or impression smears are often part of the diagnostics to look for skin disease like parasites, bacterial infections, fungal infections, or yeast overgrowth. 

• Allergy testing: For dogs that seem to be chronically itchy and have other signs consistent with allergies, allergy testing can be very helpful. It is important to know that only skin testing is considered an effective way of testing for allergies as blood tests are notoriously inaccurate.

• Blood and urine testing: Routine blood and urine testing is a helpful way to look for systemic changes that may be consistent with an infection or hormonal disorder.

• Response to treatment: The way a dog responds to medical treatment can also help to confirm the underlying cause of their hyperpigmentation. For example, if your dog is treated for a skin infection and their hyperpigmentation resolves, it confirms that this was the underlying cause.  

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How to treat hyperpigmentation

The most effective way to treat hyperpigmentation is to identify and target the inciting cause. Once your vet determines the underlying cause, the treatment will likely be a combination of the following approaches: 

• Treat underlying medical conditions: If your vet identifies a specific medical condition that is causing your dog’s skin problems, be sure to follow the recommended treatment plan as directed. This may include topical treatments or medications given by mouth for conditions like skin infection, allergies, or systemic conditions like hypothyroidism or Cushing’s disease. Be sure to confirm with your vet whether these are short-term treatments versus medications they may need to stay on long-term and when follow-up exams will be needed. 

• Reduce skin inflammation: Hyperpigmentation is a response to inflammation. The more you can reduce skin inflammation, the better. The most effective way to do this will be to target the exact cause of the inflammation, whether that is an infection, allergy, or other condition. At the same time, treatments like soothing shampoos and essential fatty acid supplements can also help to reduce inflammation. Be sure your dog is on regular flea preventative year-round as well to protect them against highly irritating flea bites. 

• Eliminate sources of friction: As much as possible, try to reduce friction where materials rub against your dog’s skin. If they are getting hyperpigmentation in the site of their harness or collar, try a different style temporarily and make sure to remove it whenever it is not needed. If your dog is overweight, work with your vet on a safe and healthy weight loss plan to reduce friction from excessive skin folds. 

The bottom line

• Hyperpigmentation is a sign of inflammation within the skin.

• There are many possible causes for hyperpigmentation including skin infections, allergies, or systemic conditions.

• The good news is that hyperpigmentation can be cured if the underlying cause is identified and treated.

References

• Bajwa, Jangi. “Cutaneous hyperpigmentation in dogs.” The Canadian Veterinary Journal, vol. 63, no. 1, January 2022, pp. 85-88. 

• Kim, Ha-jung, et al. “Melanotrichia in Poodles: Clinical and Histopathological Findings.” Journal of Veterinary Clinics, vol. 22, no. 2, 2005, pp. 153-156. 

• Moriello, Karen. “Primary Acanthosis Nigricans and Postinflammatory Hyperpigmentation in Dogs.” Merck Veterinary Manual, January 2025.