Red Alert: 9 Types of Red Lumps on Dogs [With Pictures]

This article was updated on February 13th, 2024

Seeing a new red lump or bump on your dog can be scary. But don’t jump to conclusions just yet. Our veterinarians Dr. Chyrle Bonk and Dr. Jamie Whittenburg have treated hundreds of dogs with a red lump. In this article, they will provide important information you should know as well as 9 types of red lumps that are most commonly found on dogs (with images).

9 common types of red lumps in dogs (with images)

The most likely causes of red lumps and bumps in dogs are:

1. Histiocytomas

Histiocytes are cells that work surveillance for the immune system. Occasionally, especially in younger dogs, these cells can over-reproduce and create small, red lumps. These bumps are fast-growing but are benign.

Treatment and prognosis: Histiocytomas often go away on their own, usually within a few months. However, if your dog is bothered by it or has caused ulceration or an infection, surgical removal may be necessary.
Learn more about Histiocytomas.

2. Warts

Warts are very frequent in dogs, especially senior dogs. They are caused by an infection with the papillomavirus. While warts are typically a darker color, they may also appear pink/reddish, as shown in the pictures below.

Treatment and prognosis: Warts are most often benign. Occasionally, they can become cancerous, so any wart that is a long-term issue or that changes in color/size/look needs to be investigated by a vet.
Learn more about Warts.

3. Skin tags

Skin tags are another benign growth in dogs that typically occurs as dogs get older. They are usually fairly small, soft, and the color of a dog’s skin. Occasionally, they can become red and inflamed if your dog scratches them, as shown below.

Most skin tags won’t require treatment and generally don’t get big enough to become problematic.
Learn more about Skin Tags.

4. Mast cell tumors

Mast cell tumors come in very different shapes and sizes—including red lumps or bumps, as pictured below.

These tumors are more often seen in middle-aged and older dogs but can affect younger dogs, too. Mast cell tumors are not always malignant, but it’s impossible to know which ones are and which aren’t without a fine needle aspirate or biopsy.

Treatment and prognosis: If caught early on, mast cell tumors have a high success rate with removal. If caught later, these tumors may spread to local lymph nodes and other organs, requiring surgical removal as well as chemotherapy.
Learn more about Mast Cell Tumors.

5. Squamous cell carcinomas

Squamous cell carcinomas in dogs are fairly rare, and they vary in their levels of aggressive cancerous behavior in terms of spreading.

These types of malignant tumors are usually found on areas of skin that are bare or have little hair. They are more common in dogs with light-colored skin. Squamous cell tumors in dogs can be raised lumps or nodules, or flatter areas of ulcerated skin. They sometimes resemble warts. The growth pictured below is one example:

Treatment and prognosis: The most common treatment for squamous cell carcinomas is surgical removal.
Learn more about Squamous Cell Carcinomas.

6. Skin rashes and red bumps (allergies)

Dogs also develop bumps or rashes as a result of allergies or other irritants. This may appear as many small bumps or just a few larger bumps. The cause can be an allergy to fleas, pollens, or chemicals in the environment. Red bumps can also be a sign of mites. The bumps may also be itchy, which can cause bleeding, oozing, and secondary infections.

Treatment and prognosis: We treat most skin rashes in dogs by dealing with the underlying cause. For allergies, we start by trying to remove the allergen from the dog’s environment or treating with antihistamines or anti-inflammatories is usually helpful. When mites are present, we will treat the issues with an anti-parasiticide. Secondary infections may require antibiotics.
Learn more about Skin Allergy Rashes.

7. Foreign objects

Any dog that’s out and about may come in contact with things that are sharp and prickly. Sometimes, those things can become lodged in a dog’s skin, where they will become inflamed and develop a red bump. Grass seeds, thistle stickers, and slivers are common culprits. Dogs may lick at these bumps, causing them to become raw and ooze. They may grow very quickly and be quite alarming.

Treatment and prognosis: Veterinary treatment is usually recommended: leaving a foreign body can make it worse and increase the likelihood of complications. Surgical removal is usually all it takes. Sometimes, those objects can be too small to see. Soaking the area in Epsom salts and getting antibiotics from your veterinarian (to control secondary infections) can get rid of most foreign body issues. Learn more.

8. Cysts

Interdigital cysts, also known as interdigital furunculosis, are typically small, firm bumps between the toes, usually on the front feet (see picture below). They are usually red and inflamed, sometimes oozing discharge or pus.

Treatment and prognosis: Home treatments include bathing with Epsom salts. However, this is unlikely to fully resolve the cyst, and veterinary treatment is recommended to address the underlying cause (for example, a foreign body or an allergy). Treatments may include antibiotics, bathing, anti-inflammatory medication, and management of any underlying allergies. Learn more about Interdigital Cysts.

Other types of cysts can also become infected and look like red bumps, as shown in the image below (pearly, red, and raised bump that has slightly bruised and ulcerated on the surface):

9. Melanomas

Melanoma tumors are dark and can be small, or large, flat, or raised. They can be either benign or malignant, so they shouldn’t be ignored. If a dog has malignant melanoma, it’s usually an aggressive cancer that recurs even after removal and may spread throughout the body quickly, so the lesion needs to be surgically removed as quickly as possible.

Treatment and prognosis: Malignant melanomas are very aggressive, and prompt treatment is required for the best outcome. Surgery is required to remove the initial tumor, and radiation may be necessary to deal with any spread. Chemotherapy generally isn’t very successful.
Read more about Melanomas.

Important: It is often not possible to diagnose a lump just by looking at it. Diagnosis often involves taking samples and analyzing them under a microscope or sending them to a laboratory for analysis. Learn more.

A red lump can be cancerous, but most are harmless

A raised red lump on a dog is usually the skin’s way of showing inflammation. It can be as benign as a wart or an irritated cyst. As Dr. Bonk clarifies, many are benign so it’s important not to jump to conclusions:

On the other hand, a red color, as well as ulceration and a firm, irregular texture, are all common properties of a cancerous growth. The picture below shows a red cancerous growth:

Should I take my dog to the vet?

When to call your veterinarian:

1. The bump changes size, shape, or color. Taking pictures and measurements every couple of days can really help you get an idea of whether the lump is changing or not.
2. The bump oozes, bleeds, or ruptures.
3. Your dog constantly licks or chews on the bump.
4. Your dog develops any new similar lumps.
5. Your dog is showing other signs of illness.

When you can monitor the lump at home:

1. The lump stays a uniform size, shape, and color.
2. Your dog isn’t bothered by it.
3. It appears to be getting smaller/better.

If you choose to monitor your dog’s lump at home, it still may be a good idea to get in touch with your vet just so that they know what’s going on if you end up bringing them in. Also, keep in mind that any changes in a lump, no matter how small, can be significant.

How is a new red bump diagnosed?

There is no surefire way to diagnose a lump with full confidence just by looking at it. It is important to get a biopsy done to know what you are up against. A biopsy is a medical procedure to extract and examine a small tissue sample. Our veterinarian director Dr. Whittenburg, explains:

Diagnostic tests typically cost $300-$500, but biopsies done under anesthetic may cost $600 or more. Learn more about biopsies to diagnose lumps.

Other less common causes

Hot spots, ulcers, and lick granulomas

Things like ulcers or erosions of the skin, a raised hot spot, or a lick granuloma can all take on the appearance of a red bump. They will usually be hairless, red, and could be bloody or moist.

Dogs often lick them, which usually makes them worse. Pictured below is a cancerous bump that has become ulcerated, most likely due to the dog licking or scratching it:

Causes:

1. Hot spots are often due to allergies or excessive moisture trapped in a thick hair coat.
2. Ulcers can be due to a wound or self-inflicted by the dog licking or scratching at a different kind of bump or lump.
3. Lick granulomas are another self-inflicted issue where a dog excessively licks because of arthritis pain in a joint, allergies, or anxiety.

Treatment and prognosis: Ulcers, hot spots, and granulomas are best treated by treating the underlying condition. This often includes antibiotics, anti-inflammatories and creating some kind of roadblock to prevent licking. Lick granulomas may also require behavior modification or medication to treat.

Insect or bug bites

Bug bites or stings can potentially cause red bumps on your dog’s skin, especially if you’re dealing with an external parasite like fleas or mange. Below is a picture showing an insect bite on a dog’s lip.

Dogs may also be itchy with these types of bumps, and you may see other evidence, like flea dirt on their fur.

Treatment and prognosis: A veterinarian will be able to diagnose bug bites and treat them accordingly.

Related posts:

Red Skin Issues and Rashes in Dogs

Images of Skin Problems in Dogs

Common Lumps and Bumps on Dogs

Red Bumps or Spots on the Belly