When you give your dog a belly rub, or brush their coat after a bath, you may see something odd. What are those black spots on my dogs skin? Is it normal for a dog to have black spots on the skin? Read on to learn more about black spots on the skin, what they mean, and what you can do.
What Are Black Spots on a Dog’s Skin?
Black spots on the skin can show up in a number of different ways. This can include flat, pigmented parts of the skin that are level with the regular lighter pigmentation. Other forms can include raised bumps or growths and scabs. The spots may also change over time, especially in older dogs, however, these changes are usually very slow.
General Signs to Watch Out For
In many cases, spots on the skin can be normal and can change some over time. However, there are some general signs to watch out for. Rapid changes can indicate that something more serious is ongoing and should be checked out by your vet. Signs of an issue include the spot becoming raised when it wasn’t previous, or is suddenly changing in size. Irritation such as itching, redness, or oozing debris are also signs that something is wrong.
If the spot appears to be irregular in shape, or suddenly appears, this can also be a cause for concern. It’s best to keep an eye on any spots that do appear so you can note any changes over time. Track the overall size, how quickly it changes, and any other symptoms in addition. This can help your vet determine the best course of action.
Black Spots on the Skin — Causes
Normal Skin Pigmentation
In most cases, black spots on the skin can be part of normal skin pigmentation in dogs. Many breeds, especially lighter-coated breeds such as Maltese and Shih Tzus, or multi-pigmented breeds like Chows, have naturally pigmented skin intermixed with non-pigmented skin. Your dog’s nipples may also appear as raised black spots on the skin. These are usually in a line of 6-8 total (even on male dogs) divided equally on both sides, and are not cause for concern unless they are irregular in shape, size, or rapidly changing.
It’s still important to regularly monitor these spots for any changes to ensure the pigmentation isn’t caused by another issue. Checking regularly after grooming, bathing, or outings in the sun can alert you more quickly to problems.
Another normal body process is that of healing scabs. As the body heals from a minor scratch or wound, the skin will fill in with scab material. Scabs are filled with a multitude of cells and enzymes that help facilitate this process. They should not be disturbed to allow for healing.
If the wound is more than a few centimeters in size, however, it should be seen by your veterinarian. They can determine if it needs to be sutured or closed differently. Large wounds can be harder to scab over, or may not be able to fully scab for healing. It is also best to keep your dog from scratching and chewing at scabs as they heal. Repeated bumping and irritation can lead to secondary infection and inflammation which will slow healing. An Elizabethan (cone) collar or T-shirt sized to your dog can help prevent scratching and biting.
If you notice your dog has many scabs forming suddenly, the skin around it looks red or inflamed, the scabs do not heal, or your dog has additional symptoms, this is a sign of something more serious that should be checked out by your vet. Keeping your dog safe, on preventive parasite medications, and quickly treating any cuts and scratches can help prevent excessive scratching and scabbing.
Fleas, Ticks, and Other Parasites
Many parasites, such as fleas, ticks, and lice can sometimes appear as black spots on your dog’s skin. Fleas may also leave behind “flea dirt”. This shows up as little black flecks on the skin or at the base of the hair follicle. Ticks will bury their heads under the skin, leaving their body to stick out as a raised “spot” on the surface. Other parasites, such as some types of biting lice, may also appear dark brown or black against the skin.
Your dog may itch or scratch at areas these parasites bite. In some cases, an allergic reaction, called flea allergy dermatitis, may also cause hair loss and red inflammation at the affected area. Diagnosis can usually be done at home if you can identify the parasite embedded in the skin. You can also gently flick any black flecks onto a paper towel that is then moistened. If the flecks turn red or “bleed”, this is a sign of flea dirt and a flea infestation.
Treatment involves the removal of any parasites manually. Flea treatments such as oral or topical medications, sprays, shampoos, and collars can also help. Treating the environment by washing bedding, baseboards, and removing brush or heavily wooded portions of the yard can prevent fleas and ticks. Since fleas and ticks can transmit many severe diseases such as tapeworms, intestinal parasites, Lyme disease, and more, it’s important to both prevent and treat any infestations immediately.
Not a condition in itself, hyperpigmentation can be a sign of other underlying problems, and is a cause of blacks spots forming on the skin. Hyperpigmentation involves the thickening or darkening of the skin, sometimes in a specific pattern. It most often occurs on the lateral (outer) parts of the thigh, and can happen on both at the same time. The skin may also lose hair and become velvety. While any breed can have hyperpigmentati
on, some breeds, such as Dachshunds, are more prone.
Your vet will perform several tests to determine the cause of hyperpigmentation. These include skin scrapings of the affected area to check for parasites, bacteria, and yeast infections. Blood work to check for metabolic illnesses is also a good idea. In most cases, if the hyperpigmentation is secondary to another illness, treatment will resolve the issue. However, in the case of primary hyperpigmentation, such as with Dachshunds, it can remain permanently. Treatment involves medications such as anti-parasitics, antibiotics, or medication for underlying illness.
There isn’t much prevention that can be done for hyperpigmentation, since it often happens in conjunction with other illnesses. However, regular treatment of parasites, and watching for any signs of bacterial or yeast infection and treating it in its early stages may help.
Metabolic Disease (Cushing’s, Thyroid Disease)
As part of the disease process, metabolic, or hormonally caused illnesses, can cause skin pigmentation and texture changes as well. Often, these are a key indicator of issues such as Cushing’s disease, especially when the changes are bilateral, or affecting both sides of the body equally. For Cushing’s, skin changes can include black spots, hair loss, and “velvety” skin along the flank and back legs. In thyroid diseases, such as hypothyroidism, skin changes occur on the chest and front legs, and can include pigment changes such as black spots, hair loss, and thickening of the skin.
Diagnosis of metabolic diseases involves several tests in addition to checking symptoms. Blood work such as T4 and Free Thyroid tests can check for hypothyroidism. ACTH Stim tests and Low-dose Dexamethasone Suppression tests are used to rule out Cushing’s disease. Treatment such as thyroid medications like levothyroxine and steroids for Cushing’s can resolve symptoms. In many cases, the skin will return to normal, however, if the symptoms were long-term, the changes may be permanent. Since these are often diseases of older dogs, regular blood work and physical exams can catch these illnesses before they become too severe.
Bacterial Infections (Seborrhea)
While bacterial infections more commonly cause redness or wounds to appear on the skin, they can sometimes cause pigmentation or skin changes that look like black spots. Bacterial infections occur when bacteria that naturally occurs on the skin or elsewhere in the environment makes its way under the protective skin barrier. There, the bacteria can flourish, leading to symptoms such as redness, inflammation, oozing of pus and debris, heat, and pain. Your dog may lick or bite at the affected area, leading to further inflammation, hair loss, and even skin changes.
Bacterial infections are often diagnosed by visual symptoms, such as the appearance of pus. Blood work to rule out systemic infections, and skin scrapings are also useful tools. A skin scraping can be monitored for bacterial growth over time, and sent to a lab to determine the type of bacteria present. The infection can then be treated with specific antibiotics targeted to that type of infection if regular medications aren’t working.
Most skin infections are treated by gently trimming and cleaning the affected area, and then with a course of antibiotics. If the infection is severe, or covers a large area, pain medications and drains inserted under the wound can be used. Keeping any wounds clean and dry, and monitoring for sudden changes to your dog’s skin can prevent infection. If the wound is beginning to change in color, size, shape, or appears infected, a vet visit ASAP is best to prevent further issues.
Like bacterial infections, allergic inflammation can cause changes to the skin, including the appearance of dark spots. However, like bacterial infections, the most common appearance change is reddening skin. Allergies may also cause darkened red or brown bumps to appear on the body. Most sites for these reactions include the armpits, belly, face and neck, or along the back. However, an allergic reaction can happen anywhere. Dogs will often scratch, lick, or chew at affected areas, leading to more swelling and irritation at the location.
Allergies are often determined by ruling out other issues like infections, and by case history such as looking for triggering environmental contact or food ingredients. Depending on the cause of the allergies, treatment can vary. For environmental allergens, treating with medicated shampoos, and changing the environment can help. More severe allergies may also be treated with oral medications such as antihistamines and anti-inflammatory drugs like Benadryl, Zyrtec, or Temaril-P (a steroid). Elizabethan (cone) collars and T-shirts are also useful to prevent scratching.
For food allergies, a food trial over a period of 6-8 weeks can be used to remove potential triggers and find an appropriate diet. Allergies can be hard to prevent, but keeping the environment clean, treating any reactions, and feeding a hypo-allergenic food can help.
Another non-medical cause, aging can be a reason behind black spots forming on your dog’s skin. As your dog ages, they experience many changes to the skin and coat,
including graying of the fur and darkening of skin pigmentation. This may appear in random spots on your dog’s body, or in a pattern over time, usually over the flank, on the face, or on the chest. However, as with any other change to your dog’s body, new pigmentation on the skin should always be checked out by your vet.
Your vet can take a look at any changes for signs of an issue, such as a raised appearance, irregular pattern or shape, or irritation. Other issues such as sudden changes, or new symptoms in addition to the skin changes can indicate more than aging is going on.
Excessive sun exposure, especially in short-haired or no-haired breeds like Chinese Crested Dogs can lead to black spots on the skin. This can cause a range of problems, from the benign natural tanning of the skin, to severe burns and injuries to the skin that may lead to blisters, cancers, and tumors later on in life. Just like people, it is important to protect your dog from excessive sun exposure.
Signs of severe exposure can include visible blisters forming on the skin, black spots or reddening of the skin, heat or pain, and changes in appearance. Your dog may also be painful to the touch in the affected area, attempt to hunch or protect affected areas, or seek out shade to try to get away from the sun. If the skin is affected enough to have visible blistering or changes, it should be seen by your veterinarian right away.
Your vet will treat sunburn like other burns, and may recommend topical creams, pain medications, or oral antibiotics to prevent infection as the area heals. Just like with people, sun protection can help prevent burns. For light-coated or hairless breeds, coats, sunhats, and applying sunscreen is the best preventive. Avoid going out during the height of the day when the sun is at its highest, and seek out shade when you know you’ll be in a sunny location for a long period of time.
Black spots on the skin caused by bruising can be a serious cause for concern. Small bumps and bruises can be caused by trauma, such as an injury. Bruises that form across large parts of the body or in multiple spots are concerning. Severe bruising can indicate issues such as bleeding disorders, blood platelet dysfunction, or even toxic ingestion. Other symptoms can also appear with bruising, such as vomiting and diarrhea, lethargy, and increased heart and respiration rate. If you see sudden bruising, suspect your dog ate something toxic, or they were recently injured, veterinary attention is needed immediately.
Your vet will help to determine the cause of your dog’s bruising. If there was trauma involved, checking for internal injuries, blood loss, and bone breaks are important to treat the underlying problems. If toxic ingestion is suspected, treatment to improve blood clotting such as vitamin K, blood transfusions, and IV fluid flushing of toxins can help. In the case of bleeding disorders, determining the type of disorder is done through blood tests and clotting tests. Causes such as low platelets, loss of clotting factors (due to blood loss), or genetic disease such as Von Willebrand’s will determine the course of action needed.
Prevention of bruising is hard, especially if secondary to an issue like toxicity. However, knowing your dog’s genetic history and preventing traumatic injury can help reduce the chances of a bruise forming.
Skin Growths and Tumors
Skin growths and tumors can create a raised, black, spotted appearance on the skin. Often, these issues won’t be flush with the regular skin pigmentation and can have an irregular shape to them. They may also rapidly change in size and shape, or cause irritation and redness around them. Skin growths, such as skin tags or cysts can be benign, but may still be unsightly or need to be removed if they appear in problem areas such as on the joints. Tumors can be more serious, though some skin tumors, such as lipomas, are usually benign.
Changes to the skin from growths should always be checked out by your vet. It is impossible to determine if a growth is benign or cancerous without having the growth evaluated. This generally involves either taking a biopsy of the area (called a punch biopsy), an aspirate of the cells within the growth with a needle (fine needle aspirate). These are then looked at under a microscope or sent off to a lab to determine the cell type present.
Treatment varies depending on what is causing the growth. For benign growths, they may just be left alone and monitored, especially if they aren’t causing any other issues. For cancerous growths, removal is the best option. Your vet will likely remove both the growth itself, and some surrounding skin and tissue to make sure all sections are removed.
Your vet will also likely want to check the rest of your dog’s body via physical exam and X-ray. This will determine if the tumor has spread. If it has, additional treatment, such as chemotherapy may be needed. Tumors and growths are hard to prevent, but monitoring any changes and early detection is the best way to prevent and remove growths before they spread.
In addition to regular growths and tumors, a type of skin tumor called nodular dermatofibrosis can cause several pigmented masses to appear on the skin (often called nevi). This disease is most common in breeds such as German Shepherds. These tumors can progress to lesions on the feet or limbs that open and bleed, and can also metastasize to other areas of the body such as the kidneys.
Like most tumors, diagnosis involves taking a biopsy of the mass to check for cancerous cells. Additional testing such as X-rays of the chest and abdomen can check for the spread of tumors to these areas. A referral to an oncologist for treatment such as removal of external masses and chemotherapy may help. As with most tumors, prevention can be difficult as the masses may appear suddenly. However, early detection and treatment can improve prognosis.
Familial Dermatomyositis is a rare condition of collie breeds such as Collies and Shetland Sheepdogs. This condition causes severe changes to the skin, including black spots. This often occurs in young dogs and puppies, and can cause spots, crusting, and wounds to appear on the face, ears, and legs. In addition to skin changes, other body changes such as muscle wasting may occur. Affected skin areas can worsen with sun exposure. Diagnosis involves ruling out other causes of skin changes via blood work and skin scrapings, as well as taking a full breed and family history.
Treatment depends on the severity of the condition, with less severe cases responding better. Vitamin E and steroids can help resolve skin issues and reduce symptom severity. This condition is likely genetically caused. Prevention involves spaying affected litters and parents to prevent passing on the disease.
Black Spots on Dogs Skin – Wrap Up
A new black spot on your dog’s skin can be concerning. By monitoring any changes to your dog’s skin and coat on a regular basis, you can catch irregular changes to the skin earlier. This makes it easier to prevent and treat serious conditions. While skin spots can just be a normal part of your dog’s body, it’s always best to consult your veterinarian if you have questions or notice any odd changes.