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

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owner looking at a dog's belly for brown spots

This article was updated on March 1st, 2023

Brown Spots: Introduction

With skin being a dog’s largest organ and it having many important jobs, it should be no surprise a dog’s skin isn’t without its issues. From lumps and bumps, and injuries, to new brown or black spots, a veterinarian’s day rarely goes by without seeing a skin issue or two.

This article will focus on brown spots on the skin, what they could mean, and if treatment is necessary. We want to help you get the jump on any emergent brown spot so that your dog’s skin can be the healthiest it can be.

Why 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 call 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. These darker brown spots can happen because of:

  • irritation,
  • infection,
  • injury,
  • hormonal changes,
  • sun exposure,
  • or even cancer.

When Brown Spots on a Dog are Less of a Concern

Since some brown spots can show up on your pup due to sun exposure, age, and even new medications, seeing one shouldn’t always be alarming. If your dog recently started a new medication or if you’ve noticed a gradual increase in dark spots as they got older, these are more than likely not a cause for concern. Just be sure to keep an eye on these new spots for any sudden changes in size, shape, texture or color and see your veterinarian if you’re at all concerned.

brown spots on dog's skin due to aging
Normal brown spots on dog’s skin due to aging

When Brown Spots on a Dog are a Reason for Concern

On the other hand, changes in your dog’s skin can be a little 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. If you notice a new brown spot on your dog that doesn’t seem to be bothering them, you may choose to watch and monitor for a few weeks to see if anything changes.

If that spot happens to grow, change in shape, texture or color or if your dog is bothered by it, see your veterinarian. Also, note any changes in appetite, behavior, or activity level that may indicate that something is off with your pup.

WATCH: 3 Important Tips To Care For an Old Dog [VET VIDEO]

Top Causes of Brown Spots in Dogs

Let’s take a look at some of the major causes of brown spots on a dog’s skin. Not only will we show you what they can look like, we’ll also go through a bit on what to do with them.

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, means 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 may be any shape and size, they won’t change over time and your pup won’t even notice they have them. As long as these are spots that have been there your dog’s whole life, no treatment is necessary.

colors on skin

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 just 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.

Brown spots on dog’s nose due to sun exposure

3. Hyperpigmentation

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

  • Inflammation
  • chronic irritation,
  • hormones, or
  • 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 to 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.

black spots on a dog's belly
Brown and black spots with redness

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. Also, infections may cause clogged pours, scabs, or dark exudate that will look like black spots. A tell-tale sign of fleas is black spots that are actually flea dirt, or the digested blood. Dogs may also be itchy, have redness bordering the brown spots, and their skin may develop an odor.

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.

Disclaimer: This content is not a substitute for veterinary care. Always consult with your vet for health decisions. Learn more.

Dark brown spots on dog skin due to infection

Learn more about skin infection in dogs (with pictures and veterinarian advice).

5. Skin Allergies

Another cause behind hyperpigmentation in dogs is allergies. Our pups are unfortunately susceptible to all kinds of allergies, just like humans are. 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 due to 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 again want to take a skin scraping to rule out other causes of your dog’s brown spots. They will then try to treat by removing the allergen or by using topical or oral antihistamines or anti-inflammatories.

Brown spots on dog skin due to allergies

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.

Melanomas may be removed if caught early enough, however, these cancers can spread to other organs within a short amount of time. Melanomas are often found in a dog’s mouth – see example pic here from or picture below:

melanoma in dog's mouth

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. Also, 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, often lifelong.

How Will the Vet Diagnose and Treat Brown Spots on Your Dog?

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. From there, treatment will be started, if necessary, depending on the cause.

Some issues, including allergies, hypothyroidism, Cushing’s and diabetes will require lifelong medications and monitoring. Other causes may clear up with a short course of antibiotics or antifungals. Cancers may require surgical removal +/- chemotherapy or radiation.

Look to spend $100-$300 for diagnostics and then anywhere from $50 to $200 per month for medications. Surgery may run you $500-$1,500 or more.

Can New Brown Spots on a Dog’s Skin be a Sign of Cancer?

Most pet parents that 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 tumor in dogs. But that doesn’t mean that every new brown spot is indeed cancer.

As we have 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 a new brown spot for a proper diagnosis and to start treatment, if necessary, as soon as possible.

Related Posts:

Black Spots on Your Dog’s Skin

Belly with New Black or Brown Spots


  • Dr Chyrle Bonk, Veterinarian

    Dr. Chyrle Bonk received her Master in Animal Science from the University of Idaho and her Doctorate of Veterinary Medicine (DVM) from Oregon State University in 2010. She has over 10 years of experience in small animal veterinary practice, working for a veterinary clinic in Idaho.

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