Brown Spots on a Dog’s Skin: Vet Advice with Pictures

This article was updated on November 12th, 2023

Dogs’ skin can have many skin issues like lumps, bumps, and black or brown spots. As a veterinarian, I see these skin problems on a daily basis. This article will focus on brown spots, their meaning, and if treatment is necessary.

Why does a dog’s skin turn brown?

Darker brown spots can look like dirt on your dog’s skin and can happen because of the following:

• Irritation or infection
• Injury
• Hormonal changes
• Sun exposure
• Cancer
• Aging

When brown spots on a dog are less of a concern

As a dog ages, their body goes through all kinds of changes, their skin included. One of those changes that you may see is the development of age spots. These darker brown spots are typically harmless, as shown on the picture below:

Brown spots on your dog’s skin is not always alarming. In fact, some spots may be caused by sun exposure, age, or even new medications. If your furry friend has recently started a new medication or gradually developed dark spots over time due to aging, there’s likely no need to worry.

If you notice new darker spots on your dog that don’t seem to be bothering them, you may choose to watch and monitor for a few weeks to see if anything changes.

Just be sure to keep an eye on these new spots for any sudden changes in size, shape, texture, or color. See your veterinarian if you’re at all concerned, or if you see any changes.

When brown spots are a reason for concern

Changes in your dog’s skin can be tricky to deal with. This is why it’s so important to consult your veterinarian anytime anything new pops up. This is especially important with new lumps, bumps, and spots. Call your vet if you see any of the following:

• The brown spot happens to grow
• The brown spot changes in shape, texture, or color
• Your dog is showing signs of discomfort or illness (e.g. itchiness, red skin, etc)
• Your dog behaves differently (changes in appetite, behavior, or activity level that may indicate that something is off with your pup)

Top causes of brown spots

Let’s take a look at some of the major causes:

1. Natural freckles

If your pup has more than one color to their haircoat, their skin will also have more than one color. Lots of different colored spots, or dapples, mean that the skin underneath can also be spotted. This makes for natural dark spots that you may notice when you part the hair.

This will, of course, show up more commonly in spotted dogs, such as Dalmatians, Australian Shepherds, and Dachshunds, but can show up in any breed of any color. The dark spots won’t change over time, and your pup won’t even notice they have them. As long as these spots have been there during your dog’s entire life, no treatment is necessary.

2. Sun exposure

Just like people that seem to pop up with new freckles every time the sun shines, some dogs may develop brown spots on their skin after being out in the direct sun. This is because sunlight can encourage the production of more melanin.

These spots will likely show up in the lightly-haired areas of the body like the belly, nose, or ears. They may also be associated with sunburns and can turn cancerous.

If you notice new brown or black spots on your dog’s light skin, see your veterinarian. This is especially important if those spots are growing, changing shape, or if your dog is bothered by them.

3. Hyperpigmentation

Hyperpigmentation is the darkening and thickening of the skin as a dog’s body reacts to different things:

• Inflammation
• Chronic irritation
• Hormones
• Infections

Obesity is even a culprit as excess fat rolls rubbing together create irritation that can turn the skin dark. This will show up as dark spots in the affected area. You may also see redness around the edges, a thickening and hardening of the skin, and possibly some itching or licking.

Have your veterinarian check out any changes to your dog’s skin color. Since some of the causes of hyperpigmentation can be quite serious, you’ll want to seek professional treatment. Learn more about hyperpigmentation.

4. Skin infections

One of the causes of hyperpigmentation, and therefore, brown spots, is a skin infection. Whether of the fungal, bacterial, or parasitic variety, these infections can cause inflammation that could lead to color changes in the skin.

With skin infections, you will likely see other signs: dogs may be itchy, have redness bordering the brown spots, and their skin may develop an odor.

Pictures of spots due to infections:

Your veterinarian will need to look at your dog’s skin and possibly take skin scrapings to look at under the microscope to determine the cause of your dog’s skin infection. Medications, such as antibiotics, antifungals, and parasiticides, will be used to treat.
Learn more about skin infections in dogs (with pictures and veterinarian advice).

5. Skin allergies

Another cause behind hyperpigmentation in dogs is allergies. Just like humans, our pups are susceptible to all kinds of allergies. Some of those can cause chronic irritation of the skin that may lead to brown spots.

Skin allergies may be due to contacting an allergen in the environment or something they ate. Either way, you may see itching and redness with those brown spots.

Itchy, allergy skin usually shows up on feet, ears, or lightly-haired areas of the body like the belly and groin. Your vet will want to take a skin scraping to rule out other causes of your dog’s changing skin color. They will then try to treat by removing the allergen or by using topical or oral antihistamines or anti-inflammatories.
Learn more about skin allergy issues.

6. Cancer

Any lump, bump, or color change in your dog’s skin should be seen by a veterinarian solely because it could mean cancer. The most common type of cancer that causes dark spots on the skin is melanoma. This can be a very aggressive type of cancer, and so any new spots should be checked out as soon as possible, especially if the spot grows or changes in shape or texture.

These spots may show up anywhere on your dog’s body but look for them more commonly in lighter-haired parts as well as inside the mouth.

Veterinarian Tip: Because cancers can spread to organs such as the lungs, liver, and spleen, it is imperative to diagnose and treat them as soon as possible.

7. Medications and other causes

Whole-body health conditions, such as hypothyroidism, Cushing’s, and diabetes, can all result in dark or brown spots on the skin. You may also notice hair loss, a change in appetite and water consumption, and increased urination. Moreover, some medications, such as antifungals, may lead to a color change in the skin.

Your vet will want to run bloodwork and other tests if you notice any of these changes. Most of these issues that cause brown spots can be treated with medications, which are often lifelong.

How will the vet diagnose and treat brown spots?

The diagnostics for nearly every skin issue in dogs is going to involve a sample. This may be a skin scraping, fine needle aspirate, or even a biopsy of the brown spot in order to see what’s going on with your dog’s skin.

Look to spend $100-$300 for diagnostics.

Can these spots be a sign of cancer?

Most pet parents who see a new brown spot on their dog’s skin will immediately jump to the diagnosis of cancer—and with good reason. Melanomas and other skin cancers are the most commonly diagnosed tumors in dogs. But that doesn’t mean that every new brown spot is indeed cancer.

As we’ve seen, brown spots on a dog’s skin can come from a number of things, including irritation from infection, allergies, sun exposure, and being overweight. It can also be a result of parasites, age, and other health conditions.

To be on the safe side, see your veterinarian anytime your dog shows up with changes on their skin for a proper diagnosis and to start treatment, if necessary, as soon as possible.

How does a dog’s skin turn brown?

Changes in skin color are usually due to a change in the skin pigment. Dark coloring is due to pigmentation called melanin. The more melanin a dog has, the darker their skin and hair. Sometimes that melanin can clump into a group and create a dark spot.

Related Posts:

Black Spots on Your Dog’s Skin

Belly with New Black or Brown Spots