This article was updated on October 13th, 2023
One condition that I commonly see in my veterinary practice is discolored, dark or black spots 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.
These dark spots are referred to as hyperpigmentation, which simply means “increased pigmentation.” The good news is that these findings are usually benign. As a matter of fact, the pigmentation helps the skin be less predisposed to solar damage from the sun and UV rays.
When Black Spots are Likely NOT a Reason for Concern
If the darkened areas are flat, mild and slowly darkening to black, with no change to the texture of the skin, it is likely that the dog has benign hyperpigmentation of age. This can be a normal part of the aging process for your dog. Below is a picture of normal hyperpigmentation on the abdomen of a 5-year-old dog:
Learn more about black “Age Spots” on Dogs.
Dogs may also have natural black spots or patches on their skin. These spots are called macules. When many macules start to overlap and become large areas, they are called patches. The picture below shows black spots as a normal part of the dog’s skin coloration:
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 (as shown on the picture below).
If the spots are black and loose on your dog’s hair and skin, it could also be fleas or flea excrement, as shown below. Your number one clue that your dog has fleas is that your dog will likely chew, lick or scratch themselves more than usual. If this is the case, read our article: Easy Ways to Tell if Your Dog has Fleas.
When Black Spots Are a Reason for Concern
Dark spots are a reason for concern when the affected skin also changes texture or becomes itchy. The skin with the dark spots may become:
- Itchy. A dog will show they are itchy by scratching, rubbing, licking or chewing at their skin. Read our article about Itchy Black Spots.
- Red around the area. In the picture below, dark spots on this Shih Tzu can be seen with a red rash:
- Thickened (lichenification). This occurs when dogs have an overgrowth of yeast on their skin and the result can be what many owners refer to as “elephant skin“.
The picture below shows a dog with dark black patches, as well as other signs of disease including redness, hair loss, and a rough skin appearance:
Many of these changes can be the result of a medical condition that needs veterinary attention, so we recommend that you consult with your veterinarian to discuss these changes.
Let’s now review the top causes of dark or black spots on a dog, and figure out how to help your dog.
Top Causes of Black Spots (Hyperpigmentation) in Dogs
Most commonly, dark spots, along with the other signs of redness, scaling, crusting, and itchiness, are a result of:
Allergies resulting in black spots will typically be accompanied by licking of the feet, red skin, and itching. The spots themselves will be flat and not raised off the skin’s surface, as shown in the picture below. Learn more: Dog Skin Allergy Issues (with pictures and comments from our veterinarians.)
Parasites, such as fleas and ticks, will typically cause itching as well as biting of the skin. The parasites themselves are often visible on the pet. These dark spots, like allergy spots, will be flat on the skin.
Learn more about Skin Flea Allergies and Mites.
Any irritation or injury (e.g., self-induced from scratching, post-vaccine/needle, burns, etc.) to either the skin, or even the underlying bones, joints, and muscles, can result in hyperpigmentation & dark spots. Typically, these black spots will also be flat on the skin’s surface and will be over or near the injury.
Upon closer inspection, it is common for these spots to be scabs or darker spots that are a result of the skin’s healing. Because they are due to a break in the skin’s barrier, these dark spots will shrink and then usually disappear with time. Click here to see dark spots on skin as a result of a burn (warning: graphic image).
4. Bacterial infections
According to Banfield Pet Hospitals, skin infections are one of the top 5 reasons for veterinarian visits. Skin infections can lead to skin irritation and black spots. These spots will lie flat as part of the skin and will not have a mass-like appearance.
Bacterial skin infections (usually Staphylococcus sp.) cause black spots on the skin in the same manner as injuries: the infection ends up damaging the skin’s barrier, as shown on the picture below.
Learn more about Bacterial Skin Infections.
5. Fungal infections
Yeast infections (Malassezia sp.) are the most common type of fungal infection in dogs. They typically present as itchy, red, and inflamed skin, as shown on the pictures below. If a yeast infection is left untreated for a long time, it can lead to black spots, and thickening of the skin.
The dog’s immune system response to the yeast overgrowth can lead to increased production of melanin, the pigment that gives skin its color. This protective response can lead to darkening on the skin.
Learn more about Black Spots from Yeast Infections.
6. Autoimmune diseases
Autoimmune disorders occur when the body’s defense mechanisms overreact and attack part of the body thinking it is a foreign invader. If the condition involves the skin, the result can be hair loss, lack of pigmentation, or hyperpigmentation as the body attacks cells in the skin. With proper treatment, these spots should be resolved.
The symptoms of autoimmune diseases in dogs vary widely depending on the type of disorder, but often include lethargy, weakness and loss of appetite.
Learn more about Autoimmune diseases.
7. Comedones (Blackheads)
Comedones are what we often refer to as blackheads. These occur when the hair follicle becomes blocked with bacteria, dead skin cells, dirt, and oils. Blackheads can be secondary to other skin conditions or a stand-alone issue. See this picture of comedones on Animal Allergy Colorado, or the picture below:
Comedones are pores or hair follicles that have gotten blocked with bacteria, oil (sebum), and dead skin cells (keratin) to form bumps on the skin. They are not inflamed or painful.
9. Hormone Changes
Rarely, a hormone change due to aging or sterilization surgery (spay or neuter), can cause areas of the skin to become darker. This may also occur with some endocrine diseases such as hypothyroidism, hyperadrenocorticism, and diabetes. With hyperadrenocorticism, calcium can build-up under the skin (calcinosis cutis). This can also happen from corticosteroids administered at high doses.
These changes are benign and will not be raised, scaly, or itchy. The most common place to see this is trunk of the dog.
Two conditions worth noting are cyclical flank alopecia and alopecia X. You can read about these conditions (with more pictures) in this article: Cyclical Flank Alopecia and Alopecia X.
10. Other conditions leading to skin irritation and itching
Food allergies, mange, and other disorders can all lead to skin irritation that may result in hyperpigmentation and black spots or black patches on a dog’s skin. As hyperpigmentation results from chronic irritation, these spots will lie flat as part of the skin and will not have a mass-like appearance.
What About Spots on a Dog’s Belly?
Black spots on a dog’s belly can be perfectly normal. Some dogs are born with dark spots on the skin as a normal part of their skin coloring. Others tend to develop dark spots on their bellies as they age. The pictures below show two examples of normal black spots or normal dark areas on a dog’s belly:
However, there is a possibility that the spots are a sign of an underlying condition such as skin infection, allergies, endocrine disease, or even cancer, so newly noticed spots should always be brought to the attention of the dog’s veterinarian.
Can Black Spots on a Dog’s Skin Be a Sign of Skin Cancer?
Dark or black spots on a dog’s skin can be an indication of cancer: 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.
Learn more about Melanomas on Dogs.
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.
Treatment Options for Hyperpigmentation in Dogs
The first step in treatment is diagnosing the underlying cause. This process can be aided by examining 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.
- 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.
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.
Frequently Asked Questions
Why does a dog’s skin turn black?
The most common causes include:
There are other causes, including:
- Specific breed characteristics (e.g., Black Labradors, Scottish Terriers, etc.)
- Endocrine disorders:
- Cushing’s disease (hyperadrenocorticism)
- Estrogen-producing tumors (Sertoli cell – testicular)
- Medications (e.g., corticosteroids – oral or topical)
- External environment changes (UV light exposure)
What is hyperpigmentation?
Most instances of dark or black colored spots on the skin of dogs are hyperpigmentation. As previously mentioned, 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. Hyperpigmentation in dogs is usually more of a symptom than a disease in and of itself.
What does it mean if my dog has black spots that are itchy?
Black spots, or areas of hyperpigmentation, will not cause your dog to itch. It is more likely that your dog has another condition, such as a food or environmental allergy, or parasites, that is causing them to be itchy. The spots could also be the result of the same condition. Read our article about itchy black spots in dogs.
What does it mean if my dog has black spots near her privates?
Black spots near a dog’s genitals have the same causes as black spots in other areas. If the skin’s appearance is changing suddenly and if the dog is licking that area, it is essential to determine the underlying cause. It could have something to do with their urinary or reproductive tracts. The genitals often have skin folds and are also frequently moist, and are ideal places for a skin infection to arise.
Can a dog yeast infection cause black or dark spots?
Yes, yeast infections of the skin can result in black or dark 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 happen as a result of allergies. It is imperative to not only treat the skin infection but also to address and control the allergies to prevent a recurrence.
- Brown Spots on the Skin: Veterinarian Advice with Pictures.
- Spots on a Dog’s Belly: What Do They Mean?
- Pictures of Common Skin Conditions in Dogs.
Disclaimer: This website's content is not a substitute for veterinary care. Always consult with your veterinarian for healthcare decisions. Read More.