If you are noticing a swelling on the underside of your dog’s elbow, or on his ankle or his hip, then a hygroma could be to blame. 

Learn what a hygroma is, how to treat a hygroma, and how to prevent one from happening in your dog. 

What is a Dog Hygroma?

A hygroma is a swelling filled with fluid that develops under a dog’s skin. Imagine a water balloon under a dog’s skin—that is what a hygroma often looks and feels like. 

Hygromas can show up anywhere there is repeated trauma to the skin from lying on hard surfaces. The most common body parts affected are:

• The underside of the elbow
• Ankle or hock
• Hip (also called ischial hygromas) 

Even though they look like a tumor, hygromas are not cancerous and will not spread to other parts of the body. However, if one elbow has a hygroma, then the other elbow often develops one as well. 

Small hygromas may not be painful, but if a hygroma grows large enough or becomes infected or inflamed, then it can definitely cause pain for your dog.

What Causes a Dog Hygroma?

Hygromas in dogs form in response to repeated pressure trauma to the skin, fascia (connective tissue beneath the skin), and muscle overlying a bony prominence. When body parts are repeatedly under pressure, the body responds by creating a protective inflammatory response that makes a ‘pillow’ of sorts to cushion the body. 

Hygromas usually occur in large or overweight dogs that are constantly lying down on hard surfaces such as concrete or tile. If the dog continues to lie down on hard surfaces, the hygroma will grow larger and potentially develop secondary complications.

Dog Hygroma Symptoms

When they first show up, hygromas look and feel like squishy, fluid-filled lumps located under the skin on bony parts of the body, most commonly the ankle (hock), hip, or elbow. 

In the early stages, a hygroma may be small enough that it’s not noticeable until your veterinarian points it out on a physical exam. 

Late-stage hygromas, on the other hand, are hard to miss. They are often hard, and if they are big or hard enough, they may cause your dog to stop lying on the affected side. 

Hygromas can become infected and cause your dog pain and discomfort. Signs of an infected hygroma may include:

• Weeping fluid
• Deep bacterial skin infection
• Black heads around the hygroma
• Inflamed hair follicles at the site 

Calluses often develop in the same area as hygromas and can be confused with a hygroma. The difference between the two is that hygromas develop swellings under the skin and may not cause hair loss, but calluses develop on the skin, and are characterized by thickened, grey skin and hair loss. 

If you see a callus, however, that is a sign that your dog needs to stop lying down on hard surfaces.

Diagnosing Your Dog With a Hygroma

Any skin swellings should always be checked out by a veterinarian. If you notice something that might be a hygroma, make an appointment with your veterinarian at your earliest convenience. 

Hygromas are diagnosed by having a history of lying down on hard surfaces and physical exam findings. A veterinarian may also recommend laboratory testing, such as a fine needle aspirate of the skin swelling to rule out other conditions, such as skin tumors or infections. 

If your dog has developed a hygroma from lying down too much, it is important to know why. Is he too heavy? Too hot? Does he have arthritis, heart disease, or hormonal conditions that make him tired? If your veterinarian suspects any of these things, she may recommend additional testing or treatment.

How to Get Rid of Hygromas on Dogs

In order to resolve a hygroma, the part of the dog’s body that is affected must be cushioned against hard surfaces. Providing a well-padded and supportive surface for your dog to rest on—like a cushioned pet bed—is the most important part of treatment to prevent a hygroma from growing larger. 

If your dog won’t lie on a bed, you can utilize protective elbow hygroma sleeves or pads that are specifically designed to provide more cushion to dogs with elbow hygromas. If you elect to utilize a dog hygroma sleeve, put a long-sleeve t-shirt on your dog to avoid him from removing the sleeve while you aren’t watching him.  

With adequate cushioning and protection, a small to medium sized hygroma that is not infected may resolve on its own. 

Your veterinarian may recommend draining the hygroma with a needle or treating your dog with cold laser therapy (also called photobiomodulation) to speed healing.

Infected hygromas must be treated with antibiotics to resolve the infection. If your dog is diagnosed with an infected hygroma and prescribed antibiotics, it is important to finish all antibiotics, even if the hygroma appears to have healed before you finish medication. This is necessary to prevent reinfection or development of antibiotic resistant bacteria.  

Hygroma Surgery for Dogs

If a hygroma is very large, painful, or doesn’t resolve with conservative treatment, then surgical intervention is sometimes necessary. 

Large, painful, or infected hygromas can be treated with surgical drainage or by removal of the hygroma entirely. These procedures are done as outpatient surgery or may require one night hospital stay.

Surgical drainage of a hygroma requires heavy sedation or general anesthesia, depending on the dog and the veterinarian. During surgery, Penrose drains (soft, flexible rubber tubes) are placed in the hygroma, and left in place for several weeks to allow the hygroma to drain and heal. 

Aftercare requires changing and monitoring bandages, keeping the dog from removing bandages by utilizing a cone or long sleeve t shirt, preventing the dog from being active during the healing period, and giving medication as prescribed. 

If your dog needs to undergo hygroma surgery, it is important to keep the surgical site well cushioned and protected. You should check daily for signs of infection (redness, odor, discharge) and keep your dog from being active after surgery. 

If the surgical site is not properly cared for, it can swell, become irritated, or open up, requiring additional expensive and painful surgical repairs. If you have an active dog, let your veterinarian know, and she can prescribe a sedative to help limit activity.

Medication for Dog Hygroma

Medications for hygromas include antibiotics, anti-inflammatory medication, and pain medication. 

Some of the more common medications prescribed for dog hygromas include:

• Amoxicillin (oral antibiotic)
• Clavamox (oral antibiotic)
• Cephalosporins (oral antibiotic)
• Carprofen (oral anti-inflammatory)
• Tramadol (oral anti-inflammatory)
• Fentanyl patch (injectable pain medication)
• Morphine (injectable pain medication)
• Hydromorphone (injectable pain medication)

Cost to Treat a Dog Hygroma

The cost of an office visit, physical exam, and fine needle aspirate range from $100-$150 in most areas. If the hygroma is infected, then your veterinarian may recommend culturing any fluid removed from the hygroma to determine what bacteria are involved, and what antibiotic to use. Culture and antibiotic sensitivity testing can cost an additional $75-$150.

The cost of medications depend on the size of your dog and the type of medications prescribed. Antibiotics can range in cost from $30-$125, depending on the size of your dog, length of treatment, type of antibiotic prescribed, and geographic location. In general, brand name medications cost more than generics. 

Surgical removal of a hygroma on your dog could cause the costs of treatment to escalate. Cost of surgery can range from $750-$2,000, depending on the size of the hygroma and how difficult it is to remove. Cost can also depend on the size of your dog and your geographic location.

Hygroma sleeves can range in cost from $35 (on Amazon) to $150 for more custom built items.

How to Prevent Dog Hygromas

To prevent hygromas, there are three main considerations: 

• What your dog sleeps on
• The weight of your dog
• The overall health of your dog

The most important way to prevent hygromas in your dog is to provide a cushioned, supportive surface for your dog to sleep on and rest upon. Bedding needs to be thick enough to cushion bony parts away from the hard floor. 

If you’re unsure whether your dog’s bed is cushioned enough, test it by lying down on it yourself. If you feel the floor, it is likely your dog does as well. 

Orthopedic mattresses and thick memory foam mattresses are much better than polyfill beds. If your dog won’t lie on a bed, then you can utilize interlocking foam tiles to cover larger areas in your home.

The second factor is your dog’s weight. Overweight dogs are more likely to develop hygromas because the added weight increases pressure trauma to body parts that are lying on hard surfaces. Overweight dogs also tend to lie down more, making obesity and hygromas a vicious cycle. If you are unsure if your dog is overweight, talk with your veterinarian. 

Lastly, you need to address why your dog is lying down more. If the cause isn’t your dog’s weight, then there may be another condition, such as painful arthritis or heart disease making your dog less active. Your dog may be too hot in summer, so consider shaving your dog, using a fan to circulate air, or providing a kiddie pool for him to splash around in or lie in when it is hot outside. 

By addressing these factors you not only lower your dog’s chances of developing a hygroma, you also improve your dog’s overall wellbeing and quality of life.

Main photo courtesy of @incredibull_ellie on Instagram.