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Have you found a little lump on your dog while cuddling with them on the couch? The first thing is, don’t panic. It’s not unusual for masses to develop on a dog’s body throughout their lifetime; more often than not, they aren’t malignant. However, that doesn’t mean it’s something to ignore. Having your veterinarian evaluate the growth promptly means they can establish what it is and if it needs treatment.

One common kind of lump is a cyst. While typically benign, these cysts can grow, which may sometimes lead to complications. So, it’s worth understanding the different types of cysts on dogs and when they can be a cause for concern.

What Are Cysts on Dogs?

Dr. Jerry Klein, Chief Veterinary Officer for the AKC, explains that, in its simplest form, “a cyst is a hollow space, formed around a membrane that’s usually filled with either fluid, semi-fluid, or solid material.” These sacs develop within the tissue on or in any part of the body. But “most of the cysts we think of are usually located on or slightly under the skin,” he says. Typically, cysts contain secretions that occur in the body naturally, but sometimes they can contain atypical breakdown products, such as keratin (a skin protein) or dead cells.

What Causes Cysts on Dogs?

Certain breeds have a genetic predisposition to developing cysts. Dr. Klein explains some terriers are prone to follicular cysts, as are hairless breeds. Breeds like the Chinese Crested “have comedones like blackheads, because the melanin is not activated very much, and they easily get blocked ducts,” he says. Other breeds susceptible to cysts include Basset Hounds, Boxers, English Springer Spaniels, Schnauzers, and Golden Retrievers.

Golden Retriever rolling on its back in the grass.

Some other cyst triggers are injuries, pressure points, infection, certain diseases or medications, and idiosyncratic injection reactions.

Common Types of Cysts on Dogs

Like with humans, there are many types of cysts dogs can develop, with the vast majority being benign, non-cancerous varieties. Below are some of the most common kinds found externally on your dog.

True and False Cysts

“True cysts have a lining that produces secretions. They usually form in the areas of the sweat glands, often related to blocked ducts,” Dr. Klein says. He explains that vets typically recommend surgical excision to prevent a recurrence. False cysts don’t have secretory linings and often occur because of trauma or injury. As the dead tissue liquifies, a fluid-filled mass develops.

Sebaceous Cysts

Dr. Klein explains that sebaceous cysts, one of the easiest types to become infected, are prevalent in dogs. “They’re filled with what’s called sebum or wet wax,” he says. “They can get quite large and ornery and cause inflammation.”

While sebaceous cysts develop in the oil-producing sebaceous glands (which are associated with the hair follicles), don’t confuse these with follicular cysts. You’ll regularly spot sebaceous cysts around the head, neck, and tops of the legs.

Follicular Cysts

“Follicular cysts are cell cysts that are associated with the base of the hair follicle, which often becomes irritated or inflamed,” Dr. Klein says. “You may have comedones, which are like little blackheads, and they have material that can be easily expressed or pushed out.”

He explains the material inside these hard cysts can vary. Sometimes it manifests with black, white, or even some kind of cheesy, foul-smelling discharge. They’re very common in dogs, especially around the mouth and the legs, and, like with sebaceous cysts, they are prone to infection.

Dermoid Cysts

Dermoid cysts aren’t so common, but Dr. Klein explains he has seen these congenital masses on the neck area of Rhodesian Ridgebacks and Kerry Blue Terriers. “They are formed where there is a separation of the epidermis and other underlying tissue,” he says.

How to Recognize Cysts on Your Dog

Cysts can look and feel different, depending on the type. They are typically slow-growing, smooth, raised bumps on or under the skin. Sometimes they ooze a discharge, and over time they can ulcerate and change shade. They are usually colored white, blue, or a dark hue.

poodle skin grooming

You won’t be able to spot internal growths, like ovarian cysts, but symptoms such as behavioral changes, pain, swelling, sickness, or discharge may accompany their growth.

Why a Vet Should Check For Cysts

Whatever type of lump you find on your dog, it’s always a good idea to have a vet check it out as soon as possible. Cysts might not be life-threatening, but they can cause problems as they grow or if they become infected. Plus, what you think might be a cyst could be something more serious or require different treatment. Dr. Klein recommends that if you have a wellness check scheduled within the next couple of weeks, you could wait until then if the cyst isn’t bothering the dog.

During this time, he suggests keeping a little journal. “You’re trying to look at: Is it growing? If so, is it growing evenly? And how fast is it growing? Does it change color when it’s growing or become more red or inflamed? Is it causing the dog more problems? Is the dog biting or scratching at it? Does it erupt out of the surface? Or does it ulcerate?” Of course, if your dog is in pain or discomfort, or you suspect an infection, bring your scheduled appointment forward.

How Vets Diagnose Cysts

Dr. Klein explains many factors go into diagnosing cysts in dogs. “If the growth can be separated from the body structure, the dog breed and age, and the location of the growth all play a factor in a veterinarian’s decision of how to proceed,” he says. However, even if your veterinarian suspects a cyst, “the only way to prove it is through diagnostic means by having all or part of the growth removed and having it assessed in a laboratory,” Dr. Klein says.

This will either be by biopsy or, more commonly, your vet will clean the area antiseptically and do a fine needle aspirate. Dr. Klein explains your vet will take a tiny needle and stick it in the center of the growth to suction out some discharge and then squeeze that onto a slide. Often, the vet will evaluate the tissues in their clinic under a microscope (called histopathology) But they sometimes need to send the material to a laboratory. This can determine the type of cyst and rule out more serious diseases.

Yellow Labrador Retriever getting a shot at the vet.
Cris Kelly via Getty Images

When Should a Vet Treat or Remove Cysts?

If your vet diagnoses the lump on your dog as a cyst, the treatment plan will depend on the type, its location, and the growth stage. If the growth isn’t too large, infected, or causing any pain or discomfort, your vet might suggest leaving it and monitoring it for any changes. Some cysts, like those caused by trauma, can naturally recede.

For ulcerated or infected cysts, non-invasive treatments, including administering medication and cleaning the area, might be the best course of action. If the cyst is causing a lot of pain or growing large, surgical removal might be necessary.

While some owners express follicular cysts themselves following diagnosis, Dr. Klein recommends that a veterinarian always looks at them first. Owners can sometimes cause inflammation and infection or try to express a mass that isn’t a cyst.

What Other Growths Can Be Confused With Cysts?

It’s easy to confuse various lumps with cysts. According to Dr. Klein, growths called lipomas are the ones seen most often. “Lipomas are fat cells that aggregate together and form a growth. They can start out small and get large but, thankfully, they’re usually not cancers,” he says. “Some dogs can live with many lipomas, actually quite large, until it becomes an area that can cause mechanical problems or obstruction.”

“What’s noted about them is that they’re firm, not fluid-filled, unlike cysts,” Dr. Klein says. “Usually when you try to palpate a dog, you can put your fingers around the entire perimeter of it, and you can oftentimes get your finger underneath.” While cancer is the biggest concern, get to the vet as soon as possible for whatever lump you find on your dog. They can do the diagnostics to put your mind at ease or formulate a treatment plan.

Related article: Dog Skin Cancer: Types, Symptoms, and Treatment
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