Blood Blisters in Dogs: Causes, Symptoms, and Treatment

Vet checking out a golden retriever

Blood blisters in dogs can be a cause for concern. If you’ve noticed a red, fluid-filled area on your furry friend’s skin, it’s essential to understand its causes and the best course of action to take. In this article, we’ll dive into the most likely causes of blood blisters in dogs, provide pictures for reference, and explore effective treatment options.

What’s a blood blister and is it serious?

A blood blister is an area of the skin that contains a bubble filled with blood. It typically appears on the outermost layer of the skin, known as the epidermis. While blood blisters in dogs can be a result of skin trauma and may resolve on their own, they can also indicate more serious medical conditions, including cancer. Therefore, it’s crucial to consult a veterinarian to determine the underlying cause.

Skin abnormalities that cause blood blisters

There are various skin conditions that can resemble a blood blister in dogs. These conditions manifest as circular or oval lumps or bubbles with red fluid or bleeding. However, they are not always harmless blood blisters. To accurately diagnose the condition, it’s best to make an appointment with a vet. Here are some examples of these skin abnormalities:

Collage of pictures of blood blisters in dogs

1. Mast cell tumors

Mast cell tumors account for nearly 18% of tumors found in dogs. They often appear as raised bumps with redness or bleeding and can vary in size. Diagnosis of mast cell tumors involves fine needle aspirates, and treatment outcomes depend on the tumor’s behavior. Surgical removal is usually recommended.

Lump looking like mast cell tumor

2. Cutaneous hemangiosarcoma

These masses typically occur on a dog’s belly, affecting the outer layer of the skin. While they are not as quick to spread as other types of hemangiosarcoma, they still require surgical removal and possibly additional treatments like chemotherapy.

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Hemangiosarcoma cutaneous blister on a dog

3. Hemangioma

Hemangiomas are benign cancers that can cause dark purple blisters on the skin. They arise from blood vessels and are more common in dogs with short fur and light skin, especially in areas exposed to sunlight. Surgical removal is typically recommended.

Tick on a dog

4. Ticks

Feeding ticks can sometimes resemble blood blisters. It’s important to be aware of this possibility and consult your vet for proper identification.

Histiocytoma turning black over time

5. Histiocytomas

Histiocytomas make up 15.9% of tumors found in dogs. They are small, benign lumps commonly seen in young dogs. Treatment usually involves regression of the histiocytoma within three months. However, in rare cases, multiple histiocytomas can indicate a more dangerous skin disease called histiocytosis.

Hematoma symptoms on a dog

Remember, a proper diagnosis by a veterinarian is essential to determine the appropriate treatment for your dog’s condition.

When to contact your veterinarian about blood blisters

If you notice a swollen ear or a firm, fluid-filled sac in the ear region, your dog may have an ear hematoma. While it’s not life-threatening, it can be uncomfortable, so it’s important to contact your vet for an appointment within a few days. If there is active bleeding, seek emergency veterinary care immediately.

For any area or lump on your dog’s skin that appears red, contains blood, or bleeds, it’s advisable to schedule an appointment with your vet, especially if the condition persists after a few days. These types of lesions can be caused by various conditions that may not be easy to diagnose visually.

If your dog displays additional symptoms such as loss of appetite, lethargy, pain, or changes in behavior, it is always best to have them evaluated by a vet urgently.

What you can do at home while waiting for a vet appointment

For other skin problems that resemble blood blisters:

  • Prevent access and trauma to the affected area without applying pressure. You can use an e-collar or a loose t-shirt to prevent your dog from licking or scratching the area.
  • Monitor the affected area once or twice daily and note any changes in size, shape, or color. Taking photos to show the vet can be helpful if the appearance of the area changes.
  • If there is minimal oozing of blood, gently keep the area clean and dry.
  • In case of significant bleeding, seek emergency veterinary care.
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Ear hematomas in dogs: Causes, symptoms, and treatment

A hematoma occurs when blood leaks from blood vessels into the surrounding area. It can either be visible on the body’s surface or occur internally, where it remains unseen. Common causes of hematomas include injuries or underlying blood clotting disorders.

Common locations of hematomas:

  • Ears: Hematomas in the ears result from dogs shaking their heads violently, causing fragile blood vessels in the ear flap to break.
  • Neck or limbs: Hematomas may occur in these areas if a dog has trouble staying still during a blood draw.
  • Scrotum: After a neuter surgery, hematomas can form in the scrotum due to excessive movement during tissue healing.
  • Internally: Hematomas can occur in organs with high blood flow, such as the spleen.


Hematomas can vary in size and appear as swollen lumps beneath the skin. Ear hematomas can cause the entire ear to swell, feel firm, warm, and painful. Smaller hematomas may look like small bulges or raised areas on the inside of the ear flap.

Photo of dog ear hematoma from the side

Smaller ear hematomas

Ear hematomas are a common problem in dogs, often resulting from trauma or excessive head shaking due to ear infections, foreign objects, or allergies. Certain breeds, such as Labradors, Golden Retrievers, and Pit Bulls, are more prone to ear hematomas.

Veterinary diagnosis, treatment, and prevention

To diagnose an ear hematoma, your vet will examine the swollen ear and check for possible ear infections. Treatment involves addressing the underlying cause, such as ear infections or allergies. In severe cases, drainage and medication injection may be necessary, or surgery to prevent recurrence. For home care, specialized bandages or oral sedatives can aid in your dog’s recovery.

Prevention of ear hematomas involves addressing underlying problems that cause excessive head shaking, such as ear infections or allergies. If you notice your dog frequently scratching their ears, shaking their head, or exhibiting a foul odor, schedule an appointment with your vet to address the issue promptly.

Remember, if your dog displays any abnormal symptoms or behavior, consulting a veterinarian is always the best course of action.

For more information about blood blisters and other common skin problems in dogs, visit Katten TrimSalon.