This article was updated on September 17th, 2023
Does your dog have a new black or very dark bump, lump, or growth? They can be concerning, particularly because in human medicine black growths may mean cancer.
I encountered various causes for black bumps on dogs when I was in practice. Some were cancerous, but other growths were benign.
In this article, we’ll discuss what makes lumps or bumps on dogs turn dark, the top causes for black bumps, how they can be diagnosed, and the cost of treatment.
Why are some lumps black?
Black bumps or growths on dogs can be blood-filled lumps called hematomas. When a dog’s skin experiences trauma, blood may collect at the point of injury. Over time, the blood dries and turns reddish-brown or black, like a scab. Some blood-based tumors also develop black coloration.
Black lumps can also be tumors. Whether the growth is benign or malignant, it may collect pigment granules known as melanin that turn the bump black. They often appear in response to skin inflammation, but the cells that produce melanin sometimes turn cancerous, causing malignant black tumors known as melanomas.
Top causes of black lumps, bumps, or growths on dogs
In this section, we will review black raised lumps, bumps, and growths and discuss if anything needs to be done to help your dog.
1. Black warts or adenomas
Warts, caused by canine papillomavirus, and adenomas are one of the most common types of small lumps on dogs. These masses are benign, irregularly shaped like cauliflower, and usually pale in appearance. However, when they become inflamed or infected, blood or pigment can turn the bumps dark.
Although they’re not a major concern, they can become infected or ulcerated. When warts are problematic, the treatment of choice is surgical removal. Below are two examples of black warts. Notice the irregular, raised shapes:
2. Black skin tags
Skin tags are benign fibrous growths that usually occur in high-friction areas on your dog’s skin. With a variable appearance, tags may look like raised bumps or attach to the body on a narrow stalk. They appear with or without hair. Skin tags are very common in dogs and can sometimes be black.
Although you find a skin tag suddenly, it usually takes time to develop. They can become irritated and painful from constant rubbing, but they are generally harmless. However, contact your veterinarian if you notice any changes in color, shape, or size. He may want to examine the black lump and take a biopsy.
As long as your dog isn’t bothered by skin tags, they can be left alone. However, if they become painful from repeated irritation, they have to be surgically removed. View more pictures of skin tags.
3. Histiocytoma turning black over time
Usually occurring in younger dogs (up to about 3 years old), histiocytomas are benign, dome-shaped lumps that arise when immune cells (histiocytes) overgrow. They suddenly appear on the face, ear flaps, or legs, can grow rapidly, and may ulcerate. Although histiocytomas are normally pinkish to red in color, they can turn black over time. This happens because dogs lick or scratch and irritate the growths, which causes pigmentation.
If you have a young dog that develops a histiocytoma, discourage him from licking, chewing, or scratching the bump. This will help to prevent inflammation, infection, and ulceration. Keep ulcerated growths clean until your veterinarian can treat it.
Histiocytomas usually resolve spontaneously in a month or so. However, if they ulcerate, become infected, or bleed, your veterinarian can surgically remove them. On rare occasions, older or immune-compromised dogs have multiple histiocytomas. These may become malignant if left untreated. View more pictures of histiocytomas.
Melanomas are malignant black growths that usually occur in older dogs. When pigment-producing cells known as melanocytes grow proliferatively, they usually create brown or black lumps because the cells contain melanin granules. Your dog may have tumors anywhere on his body, including the nail bed, mouth, and lips. These tumors often grow rapidly and spread quickly to other parts of the body.
Early diagnosis and treatment are important because they significantly impact your dog’s diagnosis. The primary method to treat melanomas is the surgical removal of the tumor along with surrounding tissues that may be affected. There is also a vaccine that can help to shrink the tumor. It’s usually used in combination with radiation or surgery when the tumor spreads to other tissues.
Disclaimer: This content is not a substitute for veterinary care. Always consult with your vet for health decisions. Learn more.
5. Darker ticks
Some embedded ticks can mimic black bumps when you see them on your dog’s skin. Depending on where you live, some common ticks on dogs include deer ticks, American dog ticks, and Lone Star ticks. If you find an embedded tick on your dog, you may remove it at home or have your veterinarian extract the parasite.
To remove a tick, use fine-tipped tweezers and grasp the pest as close to your dog’s skin as possible. Pull the tick straight out with gentle, steady pressure. Avoid twisting, as you may break off the head, which can cause infection. Once the tick is out, examine it to make sure you have the entire body, then disinfect/wash the bite area. You may want to preserve the tick in rubbing alcohol or bring it to your veterinarian for identification.
Hygromas typically form on the bony prominences of large dogs who lie on hard surfaces like pavement or tiles. They form in an effort to protect the dog’s skeleton and to minimize friction. In the photo below, the dog has a hygroma on the elbow and the fur above it is missing; this would be quite typical:
Hematomas are blood-filled sacs caused by trauma. When these appear on the surface of the skin, they may also be referred to as blood blisters. Ear hematomas are a common type of hematoma in dogs. When the pinna experiences trauma such as bites, scratching, or head-shaking, blood vessels may burst and fill the space between the ear cartilage and the skin.
Ear hematomas present as swollen pockets of fluid that are more visible on the inside of the ear. Early on, the blood blisters are soft and may feel warm. Later, the ear may have the appearance of cauliflower.
Treatment for ear hematomas includes needle aspiration, drainage tubes, or tacking sutures to prevent recurrence. During recovery, the ear is usually bandaged to prevent further trauma from scratching or head shaking.
Conditions causing black spots or scabs on the skin
Below, we’ll look at various reasons that black spots, scabs, or raised, itchy patches of dark skin may suddenly appear on your dog.
When your dog’s skin is traumatized, melanocytes produce extra pigmentation to protect the damaged areas – resulting in black spots on your dog’s skin. Common causes of hyperpigmentation include injuries, allergies, parasites, aging changes, cancer, or endocrine disorders like Cushing’s disease or hypothyroidism. If your senior dog develops black patches or spots on his skin but there aren’t any other changes, it’s probably age spots. However, you should contact your veterinarian if there are other changes to the skin like:
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- redness around the margins
These symptoms often indicate an underlying condition that requires treatment.
Injuries such as scrapes or cuts are the most common cause of black scabs in dogs. When the skin surface is traumatized, it seeps blood and platelets. A clot forms and dries to form a protective covering over the skin. Over time, the scab turns dark brown to black.
As long as the scab doesn’t turn yellow or become infected, and your dog leaves it alone, you can let the skin heal naturally. If your furbaby continually licks and abrades the area, you may need to use an E-collar to protect the wound from further irritation.
When your dog reacts to a food-based or environmental allergen, he can develop an allergy skin rash or hives. At first, the skin will be red and irritated, but if the inflammation is chronic, the area may become thickened, darkly pigmented, and form black or dark scabs from incessant itching.
If your dog has chronic allergies, consult with your veterinarian. He may benefit from steroid treatment or a hypoallergenic diet.
External parasites like fleas and mites can cause black scabs or spots on your dog. Fleas usually jump on your dog to feed and often leave behind flea dire (feces) that resemble tiny black scabs. Additionally, their bites can trigger an allergic reaction known as flea bite dermatitis that can leave black scabs.
On the other hand, mites tend to burrow under your dog’s skin, causing inflammation and irritation. As a result, your pup will scratch or chew the area continuously and cause skin trauma and scabbing.
To prevent skin issues from external parasites, keep your dog up-to-date on preventative treatments for parasites. If you suspect that your dog has mites or fleas, contact your veterinarian.
5. Skin infections
Skin infections in dogs are usually caused by Staphylococcus spp. bacteria or fungal infections(most commonly ringworm or yeast). These conditions irritate the skin and cause inflammation that can lead to scabbing or hyperpigmentation.
Skin infections should be examined by your veterinarian to properly diagnose the underlying cause and administer the appropriate treatments. Depending on the type and severity of the infection, your veterinarian may prescribe topical treatments, antifungal medication, or antibiotics.
Will a vet be able to recognize a black bump or lump through a video call?
Black lumps and bumps that appear suddenly may be difficult to differentiate over a video call because many black growths, such as warts, hemangiomas, and melanomas, can closely resemble one another. Your doctor will need to closely examine the bump and run diagnostic tests to determine the underlying cause.
Figuring out the cause of your dog’s black lumps
When you bring your dog to the clinic for black lumps, the veterinarian will perform a physical examination and run tests that may include:
- evaluating the characteristics of the mass including size, shape, depth, and more
- taking a fine needle aspirate and submitting it to the lab for cytology
- taking a biopsy or removing the lump and submitting it for pathology
- running bloodwork to check for endocrine disorders or signs of infection
- skin scrapings to check for mites or infections
- hair samples to check for ringworm and other issues
- impression smears to help diagnose the cause of black scabs
Estimated cost of diagnosis
- office visit and initial exam – approximately $50-100
- bloodwork – $150-300
- aspirate, skin scrapings, or impression smears with cytology – $25-200
- biopsy with pathology – $300-600
- bacterial or fungal cultures – $300-400