Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors

The essentials 

  • A hematoma is a blood-filled sac or blood collection under the skin —  They are sometimes called blood blisters.
  • They most commonly affect the ears and scrotal area They’re known as aural and scrotal hematomas.
  • Head shaking, injury, or surgery can cause hematomas Note that hematomas are also a common side effect of injuries and post-surgery healing in dogs.
  • Healing a hematoma usually requires the help of a veterinarian Awareness, good hygiene, and regular pet care can help prevent them.

What is a hematoma in dogs?

A hematoma is a blood-filled sac or collection of blood under the skin or within tissues that can occur in many different areas of the body. There are many different types of hematomas, and they’re generally named according to their location in the body. They have the ability to form anywhere there’s blood supply in the body, with the most common being aural and scrotal hematomas.

Causes of hematomas

Hematomas in dogs happen when blood vessels burst and cause blood-filled blisters. The blisters are painful and often form due to injury, scratching, or other responses to irritation. See more below on the common causes of two of the main types of hematomas.

Most common types of hematomas


Also known as ear hematomas, aural hematomas occur when a blood vessel in the ear bursts and bleeds into the space between the ear cartilage and skin. This is most commonly associated with trauma such as scratching, shaking the ears, or bite wounds. Dogs with ear infections may violently shake their head or scratch their ears causing an aural hematoma.

👉 Dogs with long, floppy ears are at greater risk for developing ear hematomas.


These refer to hematomas in the scrotal area of dogs. This most likely occurs in male dogs after neutering. Scrotal hematomas are more likely to occur in older adult male large breed dogs with a large amount of scrotal tissue. They’re often a result of blood leakage into a cavity or space left behind after removal of the testicles. If the dog is too active after surgery, this may be more likely to happen. Another cause is a dog who has had a prior clotting issue, leading to possible hematomas after surgery.

Common symptoms of hematomas

The signs of hematomas in dogs depend on where the hematomas are located. When the blister is under the skin, it’s fairly easy to spot from the swelling. Here are some common symptoms you might see with hematomas under the skin in dogs:

  • Swelling of the area
  • Discoloration of the skin
  • Deformity when located on the ear (sometimes called “cauliflower ear”)
  • Pain and aversion to touch
  • Whining, scratching, head shaking, or other signs of discomfort
  • Firmness where the hematoma is located
  • Skin that is warm to the touch

Treatment for hematomas

The treatment options for dogs with hematomas depend on the type of hematoma and the cause of it.

Some hematomas can heal on their own, but this can take several weeks and can leave your dog in pain and discomfort. There is a risk of forming new blisters if your dog further damages the affected area with scratching, chewing, or head shaking. There’s also a chance for permanent disfiguration and scar tissue.

Sometimes, smaller hematomas will be amenable to icing and reduced activity, but not always. Depending on the size and location, your veterinarian may drain the hematoma of blood. However, simply using a needle to drain the sac has a high risk of recurrence and is not generally recommended.

Surgery under anesthesia may be the next option, especially with scrotal hematomas or internal hematomas that aren’t near the skin. With surgery, the blood is drained, the clotting is removed, and the area is sutured so that blood cannot re-enter. If it’s an aural hematoma, the ear(s) may be supported by a bandage or other material applied directly to the ear flap, or by bandaging the ear against your dog’s head. Your pup will likely need to wear an Elizabethan collar to prevent scratching at the surgical site. A follow up check will also be needed to remove sutures and assure there aren’t any additional blood clots forming.

For some dogs, an underlying cause can be the reason for a hematoma to appear especially for aural hematomas. Ear infections, a foreign body lodged in the ear, ear mites, and other ear problems can lead a dog to scratch incessantly, possibly causing a hematoma to form. For other types of hematomas, bloodwork may be necessary to determine if there is a clotting issue or another underlying cause.

🚨 With most hematomas, some form of veterinary care is required.

How to prevent hematomas

Every dog has the capability of hematoma formation. Keeping your dog hematoma-free takes awareness, good hygiene, and regular veterinary visits including physical examinations.

Aural. While you may not be able to prevent your dog from scratching both their external ears and internal ears, be sure to inform your veterinarian if you notice your dog itching more than normal. Your vet can test your dog for allergies, skin issues, or ear issues before a hematoma develops. If your dog’s ear canal smells bad or has discharge, it is definitely time to see your vet. In addition, keep your dog’s ears clean, dry, and well groomed to prevent bacterial or parasitic infections.

Scrotal. To prevent scrotal hematomas in dogs, neutering your dog at a young age (between 6-12 months) and restricting activity following the procedure will reduce the risk of your dog developing a hematoma. Follow all of your veterinarian’s post-surgical instructions including giving pain medications or anti-inflammatories, icing, or other specific practices.

Additionally, trauma-induced hematomas on other parts of a dog’s body can be avoided with proper care and a watchful eye to prevent accidents and injuries.

Frequently asked questions

If it’s a blood blister, won’t it disappear with time, just like a bruise?

This depends on the type of hematoma. If left untreated, an aural hematoma may be slowly reabsorbed, but the associated inflammation will have caused damage to the surrounding ear tissues resulting in a distorted, cauliflower-shaped ear. Other hematomas elsewhere on the body could be an indication of an active bleed and should be evaluated by your veterinarian to rule out anything more serious.

Can you just drain the swelling?

Drainage may result in a temporary correction, but in the vast majority of cases, the hematoma returns within one to two days. The longer the hematoma is left untreated the greater the likelihood of permanent damage and disfigurement. Drainage may be used if the hematoma is very small, or if the dog cannot undergo surgery for some reason.

Can hematomas develop internally, too?

While most develop under the skin, it’s possible to have a hematoma develop internally. Symptoms of internal hematomas depend on which organ(s) are involved. For example, hematomas of the lungs may cause bloody spit, coughing, and difficulty breathing while hematomas of the spleen may cause swelling of the abdomen or collapse. Other serious symptoms include seizures, comas, neurological damage, pain, and incontinence. These types of hematomas are very serious and require immediate medical attention.