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Black Spots on Dog Skin: Common Causes and What to Do

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black spots on dog

Dogs are such an important part of our lives and our families. It can be scary when a pet parent finds a new lump, bump, or black spot on their dog’s skin. One condition that I commonly see in my veterinary practice is discolored or black areas on the skin. This often happens on a dog’s belly or near their genitals but could also happen anywhere on your dog’s skin.

Most instances of dark or black colored spots on the skin of dogs are hyperpigmentation. Hyperpigmentation occurs when there is an increase in dark pigmentation of the skin.

The pigment of skin cells is what gives the skin its color. The substance in these cells that make this color is called melanin. Specialized cells in the skin produce melanin. If these cells become damaged, it may affect melanin production.

Black Spots and Hyperpigmentation in Dogs

black spots on dog's belly
Credit: VeterianKey.com

Hyperpigmentation is the medical term used to describe an increase of the pigmentation on a dog’s skin when the amount of color is more than what is normal for that dog – often describing black spots on a dog’s skin.

If your dog has hyperpigmentation or black spots, you may notice other changes to the skin in this area as well. Though hyperpigmentation can be seen as the only change, often the affected skin will change texture.

The skin may become rough, scaly, red around the area, itchy, or crusty. Many of these changes are caused by the affected skin thickening.

Causes of Black Spots / Hyperpigmentation in Dogs

Hyperpigmentation on vet dog

Hyperpigmentation in dogs is usually more of a sign than a disease in and of itself. Most commonly, the dark or black spots, along with the other signs of redness, scaling, crusting, and itchiness, are secondary to trauma.

Allergies, parasites, injuries, and other things may all cause skin irritation and itching, leading to hyperpigmentation.

When the dog’s skin is traumatized, for whatever reason, the skin cells go into repair mode. In this process, the melanocytes produce and release more melanin than normal in an effort to protect the damaged and more vulnerable skin. As the melanin accumulates in the skin, the result is dark or black colored spots.

Though trauma is the most common cause of hyperpigmentation in dogs, there are other causes. These include aging, specific breed characteristics, endocrine disorders such as hypothyroidism or Cushing’s disease, medications, external environment changes, and cancer.

Hairless dogs like the Chinese Crested and Mexican hairless will often show hyperpigmentation due to exposure of the skin that is not protected by hair.

Any changes in your dog’s skin should be brought to the attention of your dog’s veterinarian immediately. In many cases, prompt treatment of the underlying cause will cure both the cause and resolve the hyperpigmentation.


WATCH: 3 Important Tips To Care For an Old Dog [VET VIDEO]


Can Black Spots Be a Sign of Cancer?

Dark or black spots on a dog’s skin can be an indication of cancer, as well. Termed melanoma, these skin masses may be malignant (cancerous and apt to spread) or benign. These are cancers of the melanocytes in the skin that produce melanin.

Though not the case 100% of the time, malignant melanomas most commonly occur in the mouth, around the lips, or on the gums. They can also be found surrounding the toe nails and on the pads of the feet. Malignant melanomas are more commonly found in non-haired areas; however, they can be found in areas of haired skin as well.

Malignant melanomas grow extremely quickly and have the ability to spread to other organs (metastasize). Malignant melanomas usually metastasize to the liver and the lungs in dogs.

The most common breeds to be affected by malignant melanomas are Schnauzers and Scottish Terriers. Being black in color is also a risk factor.

As with all cancers, it is not clear why some dogs develop malignant melanoma. Genetics, skin color and trauma to the area are all thought to play a role.

Benign melanomas (also known as melanocytomas) are typically found in areas of haired skin. They may be black or any shade of darker color than the dog’s normal skin. A melanocytoma may be very small or multiple inches in diameter. They tend to grow and change slowly in comparison to the malignant version.

Benign melanocytomas are most commonly diagnosed in Schnauzers, Vizslas, Doberman Pinschers, terriers, and Labrador Retrievers. They are also more commonly diagnosed in older dogs.

Treatment Options for Hyperpigmentation in Dogs

The first step in treatment is diagnosing the underlying cause. This process can be aided by examining all of the dog’s skin as well as obtaining a thorough medical history. Any itching, licking, parasites, or injuries should be noted.

Skin infections, whether bacterial or fungal, must be identified and treated. Many dogs with these skin ailments also have underlying skin allergies, either to something in the environment or food allergies, and these must be controlled.

Allergies in dogs are just like allergies in people – they cannot be cured. However, they can be managed. If a treatment is started and later stopped, the allergic response will often recur, which in turn leads to a recurrence of the hyperpigmented or dark skin.

Endocrine disorders, such as hyperadrenocorticism (Cushing’s Disease) and hypothyroidism, are also lifelong health issues that need to be treated and controlled. These illnesses, if left untreated, will have significant adverse effects on the dog’s health and will drastically shorten their life span.

Malignant melanomas are aggressive tumors and need to be removed surgically. Many cases will require post-surgical cancer care, including chemotherapy, immunomodulation, or radiation.

Preventing Hyperpigmentation & Black Spots in Dogs

Due to the many varying causes of hyperpigmentation in dogs, prevention is difficult. Owners should always treat any allergies, infection, or injuries to the skin promptly and continue treatments as necessary.

UV damage may also play a role in hyperpigmentation, so it is prudent to keep dogs out of the sun as much as possible and when not, to utilize dog-safe sunscreen such as zinc oxide on non-haired areas of skin.

Disclaimer: This website's content is not meant to be a substitute for veterinary care. Always consult with your local veterinarian for health decisions. Learn more.

Frequently Asked Questions About Black Spots on Dogs

1. What if black spots are near a dog’s genitals or on the dog’s belly?

Black spots on a dog’s skin near their genitals or on their belly have the same causes as all black spots on dogs. The genitals often have skin folds and are also frequently moist, and are ideal places for a skin infection to arise.

2. Does dog yeast infection cause black spots?

Yes, yeast infections of the skin can result in black spots. This is due to the chronic irritation of the skin from itching, licking, and the organism living on the skin. Most dogs with yeast skin infections have the infection secondary to allergies. It is imperative to not only treat the skin infection but also to address and control the allergies to prevent a recurrence.

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Author

  • Dr. Jamie Whittenburg is the Director and Owner of Kingsgate Animal Hospital, a a full-service animal hospital providing comprehensive pet healthcare services in Lubbock, TX. She graduated from Kansas State University's College of Veterinary Medicine (DVM).

Disclaimer: This website's content is not meant to be a substitute for veterinary care, diagnosis, or treatment. Always consult with your veterinarian to determine the best course of action. Read More.

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