Hematomas under the skin are a common side effect of injuries and post-surgery healing in dogs. It sounds scary, but this type of hematoma in dogs is essentially just a blood blister. The good news is, it is easy to treat. 

Although a hematoma under your dog’s skin is nothing to lose sleep over, healing one does usually require the help of a veterinarian.  

Here’s everything you need to know about hematomas in dogs, including what causes them and the different types of treatment available to help your dog feel better. 

What is a Hematoma in Dogs?

“A hematoma is basically a blood-filled sac or blood collection under the skin or within tissues that can occur in many different areas of the body,” says Dr. Alisa Hutchison, a veterinarian and clinical instructor at the College of Veterinary Medicine at the University of Missouri.

Types of Dog Hematomas

“There can be many different types of hematomas, and they are generally named according to their location in the body,” says Hutchison. “Hematomas have the ability to form anywhere there is blood supply in the body.”

There are two common types of hematoma in dogs.

Aural hematomas: These are hematomas in the ear. An aural hematoma is usually the result of a self-inflicted injury from your dog’s scratching and head shaking like when they have an ear infection (1). 

Aural hematomas are more common in dogs with longer ears, says Hutchison. They can also be the result of skin allergies, ear infections, Cushing’s disease, parasitic infections in the ear, and low thyroid levels.

Scrotal hematomas: These refer to hematomas in the scrotal area on dogs. This most likely occurs in male dogs after neutering (2). 

“Scrotal hematomas are more likely to occur in older adult male large breed dogs with a large amount of scrotal tissue,” says Hutchison.

Other types of hematomas in dogs are rare. There are instances where hematomas can form inside the body, such as in the spleen and lungs. Internal hematomas are much less common than hematomas of the skin, and can lead to serious complications.

What Causes Hematomas in Dogs?

Ultimately, there could be many causes of hematomas in dogs. 

“Hematomas form when there is self-inflicted trauma to the ear, as a result of trauma that causes bleeding, and/or due to removal of organs where there is a large space left behind after surgery, paired with the potential for bleeding,” says Hutchison. 

Aural hematomas, she adds, form between the cartilage and skin of a dog’s ear. They often result from a dog shaking his head or scratching at his ears. These activities can actually cause small fractures to the ear cartilage, resulting in inflammation. 

The blood vessels in a dog’s ear are also quite fragile, so they can rupture and cause blood leakage, which gets trapped under the skin of the inner ear or ear flap, resulting in an aural hematoma. 

“Scrotal hematomas can form after castration surgery, especially if the scrotum is large, and is often a result of blood leakage into a cavity or space left behind after removal of the testicles,” says Hutchison. “If the dog is too active after surgery, this may be more likely to happen.” 

Other hematomas can form as a result of traumatic injuries.

Symptoms of Dog Hematomas

Hematomas are usually visible, and dogs often display symptoms.

In general, symptoms of hematomas, according to Hutchison, include:

• Swelling of the area
• Firmness where the hematoma is located
• Discoloration of the skin
• Skin that is warm to the touch
• Whining or other signs of discomfort

In aural hematomas, pet owners may see additional signs and symptoms in and around a dog’s ear area. “The ear may hang down if it were once a standing ear,” says Hutchison, “and the canal of the ear may have debris and swelling as well.” 

When dogs have scrotal hematomas, pet owners generally see swelling in a dog’s scrotal area that continues to grow. The area may also be hot and painful to the touch, adds Hutchison. 

While internal hematomas are rare, they require prompt medical attention. Hematomas of the lungs may cause bloody spit, coughing, and difficulty breathing in dogs. Hematomas of the spleen may cause swelling of the abdomen or collapse. However, some dogs may show no outward symptoms.

Diagnosing Hematomas in Dogs

If your dog is experiencing any hematoma symptoms, it’s time to get in touch with your vet.

“Hematomas are often diagnosed by taking the animal to a veterinarian,” says Hutchison. “At that time, a thorough history and physical examination is often what is required for diagnosis.”

If an aural hematoma is suspected, your vet will likely look for signs of an ear infection or examine the ear thoroughly to see if a foreign object is the culprit. 

Your vet may also do some additional testing to find out if there is an underlying cause of the hematoma.

“It is also very important that the veterinarian look for underlying causes for the hematoma by using blood testing and urine testing to look for low thyroid hormone levels, signs of Cushing’s disease, and/or advanced imaging (CT) to look for inner ear disease,” says Hutchison. “It may be important to address allergic skin disease through food allergy or environmental allergy testing.”

Dog Hematoma Treatment

Treatment of dog hematomas depends on the type of hematoma and the cause of it. 

“With most hematomas, some form of veterinary intervention is required, and dependent on the underlying cause,” says Hutchison. “Additional follow up appointments may be needed.

Aural hematoma treatment

Hutchison says that the best method for treating an ear hematoma in dogs is with surgical intervention. 

“An incision(s) is made in the skin of the ear to allow for continued drainage,” she says. “Simply using a needle to drain the sac has a high risk of recurrence and is not generally recommended. Other repairs in the ear include placing a drain in the area to allow for continued drainage.”

If an aural hematoma is left untreated in dogs, it may clear up on it’s own if the dog’s body is able to stop the bleeding and resorb the blood. But the dog’s ear may look permanently disfigured.

“An example of this is what’s called ‘cauliflower ear,’ where the scar tissue in the ear deforms the original shape giving it the look of cauliflower,” says Hutchison. If the hematoma is initially treated surgically, it can look normal. Once the scar tissue forms, surgery will not return the ear to its original shape.

Scrotal hematoma treatment 

If a scrotal hematoma occurs in a dog following neutering, additional surgery may be required to identify and stop the source of the bleeding and to remove excess skin from the area, says Hutchison. 

“Sometimes, smaller hematomas in this area will be amenable to icing and reduced activity,” she says.

Cost to Treat Hematomas in Dogs 

When it comes to treatment cost for dog hematomas, it’s hard to get an estimate.

“There are incredible amounts of variation in approaches to treatment,” says Hutchison. 

In general, though, repairing an aural hematoma is often less expensive than surgically repairing a scrotal hematoma. This is due to the nature of the surgery. Repair of the ear is less invasive while repair of a scrotal hematoma takes longer than the initial neuter surgery.

“A repair of a hematoma in deeper tissues of the body would be the most costly of the types listed,” adds Hutchison.

How to Prevent Your Dog from Getting a Hematoma 

While you may not be able to prevent your dog from scratching his ears, be sure to inform your veterinarian if you notice your dog itching more than normal. Your veterinarian can test your dog for allergies, skin issues, or ear issues before a hematoma develops. If your dog’s ear 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. 

To prevent scrotal hematomas in dogs, Hutchison says that 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, 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.

Hutchison says that keeping your dog hematoma-free takes awareness, good hygiene, and regular veterinary visits. 

“Any dog—despite breed or size—has the capability of hematoma formation,” she says. “Overall, excellent routine and preventative veterinary care is our best chance at identifying and preventing diseases in animals.”