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11 Clinical Causes of Black Spots on Dogs (2023)

If you’ve recently noticed black spots on your dog’s fur, you may be wondering what they are. 

Have you tried brushing them away only to discover they’ve come back hours later? Have you noticed skin discoloration that seems to be changing appearance?

Those black spots could be caused by flea dirt (we’ll explain later in this post), a yeast infection, secondary skin infections, or worse.

In this blog post, we delve into the world of black specks on dogs.

As a caring pet parent, you need to know the possibilities so that you can take appropriate action. Understanding the reasons for dark spots on a dog is the first step!

11 Clinical Causes of Black Spots on Dogs

The following list consists of the most common causes of black spots on dogs.

You’ll also notice we’ve added the causes of skin discoloration and other abnormalities of the skin. The reason for this is so that you can have a well-rounded understanding of possible scenarios.

Some dogs naturally have darker patches of skin and other dogs are prone to allergies that can leave their skin vulnerable to infections. It all boils down to the long-term health of your dog.

The more you understand what to look for, and where to look, the better off your dog will be.

The following list covers everything from fleas (the most common cause of black spots on dogs) to skin cancer, and everything in between.

Flea dirt on a dog infographic.

1. Fleas

The most common cause of black spots on dogs is the presence of fleas or flea dirt. 

Fleas are small, parasitic insects that infest the dog’s fur and feed on their blood. The life cycle of a flea consists of four stages: 

  • Egg
  • Larva
  • Pupa
  • Adult flea

Adult fleas lay eggs on the dog’s fur, and these eggs eventually fall into the environment. 

The eggs hatch into larvae, which feed on organic matter found in their surroundings. After going through the pupal stage, adult fleas emerge and jump onto a dog, seeking a blood meal.

​Flea bites can lead to itching and discomfort for the dog. Additionally, excessive scratching can cause breaks in the skin. This creates an opportunity for bacteria to enter, possibly resulting in underlying bacterial infections. 

You can usually find these black spots around the base of the tail, on the dog’s belly, and in areas where the fur is especially thick. 

As fleas feed, they excrete digested blood. That excrement appears as black specks or “flea dirt” on the dog’s skin and coat.

Flea Prevention

Fleas can cause more than an intense itch. They can also transmit diseases and parasites including tapeworms, Bartonella, and certain types of bacteria.

Some dogs develop an allergic reaction to flea saliva and this leads to flea allergy dermatitis. The result is a highly uncomfortable dog with severe itch, hair loss, and secondary skin infections.

The best thing dog owners can do for their dogs is maintain regular flea prevention. You can use flea collars and flea comb to pick fleas from your dog. Flea shampoo can also be used to help lower infestations as well.

The best intervention is flea prevention. Flea collars, flea shampoo, and other similar products have limited results. Ultimately, it’s hard to stop the flea life cycle using these methods.

You might think you’ve caught all the adult fleas only to discover the eggs they’ve left behind have begun to hatch. By the time you get around to catching all of the new adult fleas, those fleas have left even more eggs behind!

It’s a vicious cycle best stopped in its tracks through the use of prescription topical or oral treatment. Commonly used brands include:

  • NexGard
  • Bravecto
  • Simparica Trio
  • Trifexis
  • Sentinel
  • Simparica

Non-prescription flea and tick prevention can also be used successfully.

However, be sure to read the instructions carefully. Some products may not be suitable for dogs that are pregnant, lactating, or that have underlying health conditions.

In addition, some products can be toxic or fatal to cats. Speak to your veterinarian for the best advice.

2. Ticks

When ticks attach to a dog’s skin and feed on their blood, they can leave behind dark, tiny specks that look like dirt. 

That “dirt” consists of dried blood or feces from the tick. That doesn’t sound pleasant, but it’s not the worst thing to come out of a tick. Tick-borne diseases are common in areas where ticks are endemic.

Without appropriate tick prevention measures in place, your dog is at risk of contracting tick-borne diseases. See above for information on flea and tick prevention.

​Read more about tick-borne diseases and how to best prevent tick bites in dogs.

Read: 11 Early Signs of Rocky Mountain Spotted Fever in Dogs

3. Allergies 

Allergic reactions themselves typically don’t cause the formation of black specks on a dog.

It’s the excessive scratching, licking, or rubbing of the affected area that can lead to secondary skin issues and potential skin discoloration.

Excess licking and scratching, for example, leaves your dog’s skin moist and vulnerable to yeast infections. If the skin cracks open, it then becomes vulnerable to secondary bacterial infections.

Common allergens for dogs include:

  • Food allergies
  • Pollen
  • Plants
  • Dust
  • Mold spores
  • Flea saliva
  • Dust mites
  • Insect bites or stings
  • Certain medications
Black spots on dogs can be caused by tick bites, tumors, or skin conditions.

4. Seborrhea

Dogs with seborrheic dermatitis or seborrhea can have oily, flaky skin that may appear discolored. Dogs can have seborrhea sicca (dry skin) or seborrhea oleosa (oily skin). Most dogs have a combination of the two.

The condition causes red and inflamed patches of skin with lesions that either feel dry or oily. These tend to be worse in places where there are skin folds (neck folds and armpits, for example).

Dogs can develop primary or secondary seborrhea. Primary seborrhea is inherited where as secondary seborrhea (the most common type) is often related to underlying medical problems.

5. Mites

Certain types of mites, such as demodex or sarcoptic mites, can cause black specks on a dog’s skin, particularly in their ears.

These mites can lead to skin irritation, hair loss, or crusty, scaly skin.

Read more about Mites in dogs and watch the video below:

6. Skin Cancer

​There are different types of skin cancer than manifest in dogs. These include, melanoma, squamous cell carcinoma, and mast cell tumors, among others.

Causes of skin cancer in dogs can be related to sun exposure, genetics, and environmental toxins. 

These tumors can present as irregularly shaped spots or growths on the skin.

They may vary in color, including shades of brown, black, or even reddish tones. Of course, not all brown spots on a dog’s skin indicate cancer. There are many other benign conditions or harmless pigmentation that can leave the skin discolored.

That said, if you notice any suspicious spots or growths on your dog’s skin, contact a veterinarian.

A veterinarian can perform a thorough physical examination and, if needed, recommend further diagnostic tests. 

​7. Natural Skin Pigmentation

Natural skin pigmentation in dogs can result in the presence of brown spots or black spots on the dog’s skin. The amount and distribution of melanin (the pigment responsible for skin and hair color) varies among different dog breeds. 

The following are examples of dog breeds more prone to having pigmented spots on their skin:

Not all breeds with pigmented skin will have visible spots. In most cases, the presence of pigmented spots are considered normal. However, if you notice any changes in the size, shape, and color or texture of the spots, contact your veterinarian.

8. Hyperpigmentation & Secondary Hyperpigmentation

Hyperpigmentation is the excessive production of melanin.

It can cause areas of the dog’s skin to become darker than the surrounding skin, and is usually seen on the legs and groin area. Hyperpigmentation can occur in any dog breed, but is especially common in Dachshunds.

Dogs with hyperpigmentation usually show signs by one year of age.

Secondary hyperpigmentation is usually caused by friction or skin inflammation, and is always suggestive of an underlying disease.

9. Age Spots

Age spots, also known as solar lentigines or liver spots, are pigmented areas that may appear on the skin of aging dogs. These spots are typically flat, small, and can range in color from light brown to black. 

The development of age spots is often a result of long-term exposure to the sun’s ultraviolet rays. Spots commonly occur on areas such as the nose, ears, belly, or areas with sparse fur.

Contact a veterinarian if you notice any changes to the size, shape, color, or texture of age spots.

10. Sun Spots 

Sun spots are pigmented areas that develop on the skin due to chronic sun exposure.

They are very similar to age spots but are specifically caused by the sun’s UV rays. Young dogs can also develop sun spots, which resemble freckles.

​Dogs most vulnerable to sun spots and potential sun burns are those with pink skin and minimal fur. Some breeds more at risk include:

  • Hairless breeds (Dog breeds with hairless skin include the Chinese crested, Mexican hairless, and Peruvian Inca Orchids.) 
  • Boxers
  • Greyhounds
  • Dalmations
  • Bull Terriers

The best way to protect your pet’s skin is to limit sun exposure, provide shade, apply pet-safe sunscreen, and consider protective clothing. 

11. Bruising

When a dog experiences trauma or injury that damages blood vessels under the skin, it can result in bleeding or hemorrhaging.

The accumulation of blood in the affected area can appear as a black or dark-colored spot. Bruising can occur from a fall, blunt force trauma, excessive scratching or biting.

Dogs with natural hyperpigmentation infographic.

​Diagnosis and Treatment of Black Specks on Dogs

It’s important for a veterinarian to diagnose black spots on a dog because these spots can indicate the presence of underlying health issues.

While some causes of black spots may be harmless, others can be more serious and require appropriate diagnosis and treatment.

Ultimately, treatment options will depend on the underlying cause. If there have been any changes to the texture, color, size, or shape of the skin, it may be necessary to surgically remove a sample of tissue with a biopsy.


The most common cause of black specks on a dog is from flea dirt.

If fleas are detected, your veterinarian will recommend the best treatment plan for your dog. Topical or oral flea and tick preventatives are common, but only your veterinarian can offer the best advice on which one is best.

Ultimately, black specks on a dog can have a variety of causes. It’s essential for pet owners to pay attention to any changes in their dog’s skin and coat and to report these to a licensed veterinarian.

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“Bruising in Dogs: Ecchymosis.” Pet Health Network, 5 June 2014,

“If You See a Black Spot on Your Dog’s Tongue, This Is What It Means.” Reader’s Digest, 14 Mar. 2023,

MORIELLO.KAREN. “Hyperpigmentation (Acanthosis Nigricans) in Dogs – Dog Owners – Merck Veterinary Manual.” Merck Veterinary Manual, Accessed 8 June 2023.

“Seborrhea in Dogs | VCA Animal Hospital | VCA Animal Hospitals.” Vca, Accessed 8 June 2023.

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