Can Dogs Get Cysts? Types, Causes and Where They Appear

Start here: any new lump on a dog should be checked by a veterinarian, and only a needle sample of the cells examined under a microscope can tell you what it actually is. Book a prompt appointment for any lump you have not had examined before, and call the same day if a lump is growing quickly, bleeding, ulcerated or not healing, hot and painful to touch, fixed to the tissue underneath, or if your dog is licking at it, limping, off food, losing weight or unusually tired. Go to emergency care without waiting if a swelling appears suddenly alongside facial puffiness, hives, vomiting, collapse or any difficulty breathing, if a lump sits near the throat and is affecting breathing or swallowing, or if a lump is bleeding heavily and will not stop.

Yes. Dogs get cysts, and skin lumps are one of the most common reasons owners book a veterinary appointment, particularly for middle-aged and senior dogs. A cyst is a closed sac sitting in or under the skin, lined by its own wall of cells and filled with fluid, oil, keratin or cellular debris. In dogs, most of them start in a hair follicle or an oil gland. The majority are benign. The complication is that a harmless cyst and a serious skin tumor can look and feel almost identical from the outside, which is why the lump on your dog's back deserves an exam rather than a month of watching it from the sofa. Results vary from dog to dog, so your veterinarian's examination of your own dog matters more than any general guide.

What a cyst actually is, and what it isn't

Think of a cyst as a pocket that formed where there shouldn't be one. Something blocks the normal exit route of a follicle or a gland, the material that would have drained to the surface keeps accumulating, and the body walls it off with a lining. The sac grows slowly as it fills.

That makes a cyst structurally different from the other things that raise the skin. It is not an infection, though a cyst can become infected if it ruptures. It is not a tumor, because the cells in the wall are not multiplying abnormally, they are just trapped in the wrong arrangement. And it is not an abscess, which is a pocket of pus created by bacteria rather than by blockage.

The practical consequence of that structure matters: because a true cyst has a lining that keeps producing material, the lump does not simply dissolve once it has formed. Squeezing it empties the contents but leaves the sac behind, and the sac refills.

The types of cysts dogs get

Several distinct things get called "cysts" in dogs, and they behave differently.

Type	What it is	Usual location	What owners notice
Follicular / epidermoid cyst	A hair follicle blocked by a keratin plug; the most common skin cyst in dogs	Back, neck, chest, head, limbs	Firm, round lump under hairless skin; thick grey or tan paste if it ruptures
Sebaceous cyst	An oil gland whose duct has blocked, filling with sebum	Trunk, head, tail base	Soft to firm dome, sometimes with a dark central pore
Apocrine (sweat gland) cyst	A fluid-filled sweat gland cyst	Head, neck, limbs	Smooth, soft, sometimes bluish and translucent
Dermoid cyst or sinus	A developmental defect present from birth, well recognised in Rhodesian Ridgebacks	Midline of the back or neck	A dimple, tract or firm cord along the spine
Interdigital furuncles ("paw cysts")	Not true cysts: deep inflammatory, often infected nodules	Between the toes, usually front feet	Red, shiny swellings; licking, limping, discharge
False cysts (hematoma, seroma, salivary mucocele)	Fluid pockets with no true lining, usually after trauma	Ear flaps, surgical sites, under the jaw or tongue	Soft, squashy swelling that appeared quickly

Worth flagging the paw entry, because it drives so many searches: the lumps between a dog's toes are almost never true cysts. Veterinary dermatologists call them interdigital furuncles or interdigital furunculosis, and they are inflamed, frequently infected lesions rather than blocked sacs. That distinction changes everything about how a vet approaches them.

What cysts look like, and the spots they favor

A typical skin cyst in a dog is round or dome-shaped, raised, smooth, and movable within the skin rather than anchored to the muscle beneath. Size ranges from a pea to a grape, occasionally larger. The hair over the top often thins or disappears. Some have a visible dark pore at the centre; some take on a bluish cast when the contents sit close to the surface. They tend to grow slowly over months, then plateau.

If a cyst ruptures, the contents are distinctive: thick, grey-white, tan or brownish, often described as looking like cottage cheese, oily porridge or toothpaste, with a strong smell. The skin around a ruptured cyst usually reddens and becomes sore, because keratin spilling into living tissue sets off a brisk inflammatory response.

Common sites are the back, neck, chest, head, tail base and limbs. Eyelid margins develop their own version from the meibomian glands. Ear canals, especially in cocker spaniels and other breeds with chronic ear disease, can fill with ceruminous gland cysts that look like small dark beads.

Paws deserve separate description. Interdigital swellings sit in the webbing between the toes, usually on the front feet, and present as firm red nodules that may rupture and drain blood-tinged fluid. Unlike a quiet cyst on the back, these are genuinely uncomfortable: dogs lick the foot relentlessly, stain the fur with saliva, and often shift their weight or limp.

What causes cysts on a dog's skin

The common thread is blockage or trapping. Specific contributors include:

• Keratin plugs. The follicle's normal shedding of dead cells jams, and the follicle balloons.
• Trauma and scarring. A bite, a cut, a healed surgical site or a clipper irritation can seal a follicle shut or push skin cells into the deeper dermis, where they continue to produce keratin inside a sac.
• Foreign material. A grass awn, splinter or embedded hair shaft provokes a walled-off reaction.
• Pressure points. Elbows, hocks and hips in large or heavy dogs develop calluses, and follicles under a callus block readily.
• Breed and genetics. Cocker spaniels, schnauzers, poodles, boxers and shih tzus are among the breeds frequently noted for follicular and sebaceous cysts. Dermoid sinus is strongly associated with Rhodesian Ridgebacks.
• Underlying skin disease. Allergies, demodicosis and bacterial folliculitis inflame follicles and set up the deep lesions seen between the toes.
• Conformation and weight. Dogs carrying extra weight on splayed, short-coated feet drive hair shafts into the webbing with every step, a recognised contributor to interdigital furunculosis in breeds like English bulldogs, Labradors and mastiffs.

Age plays a part too. Older dogs accumulate more of these lumps simply because they have had more years of follicle blockages, minor trauma and skin changes.

Cyst or tumor? What the lump can and can't tell you

This is the question that actually matters, and the honest answer is uncomfortable: you cannot reliably tell by looking.

	Points toward a cyst	Points toward something needing urgent attention
Growth	Slow over months, then stable	Rapid growth over days or weeks
Feel	Smooth, round, movable in the skin	Fixed to deeper tissue, irregular, firm
Surface	Intact or with a central pore	Ulcerated, bleeding, crusted, non-healing
Contents	Thick keratin or oily paste if it ruptures	Bloody, watery, or no drainage at all
Dog's response	Usually ignores it	Licking, chewing, pain, lameness
Other signs	None	Weight loss, lethargy, swollen local lymph nodes

Treat the left column as reassuring but not conclusive. Mast cell tumors in particular are notorious for mimicking benign lumps, soft, round and unremarkable, and they can fluctuate in size. The only reliable way to tell a harmless cyst from something that needs removing is cells under a microscope, not a photograph, not a feel, and not a guess. A fine-needle aspirate is quick and usually done in the consult room.

So: are cysts on dogs dangerous? True cysts themselves generally are not. The danger lies in assuming a lump is a cyst when it isn't, and in secondary problems such as rupture, infection, or a cyst in an awkward spot that a collar or harness keeps traumatising. Do they hurt? An intact cyst is usually painless. A ruptured or infected one hurts, and interdigital lesions on the paws hurt a great deal.

Do they go away on their own? Rarely. Small ones occasionally rupture, drain and flatten, but because the lining remains, sebaceous and follicular cysts typically refill and persist. Complete resolution generally means surgical removal of the sac, which is a conversation for your veterinarian rather than a home project: squeezing a cyst at home drives material into surrounding tissue and reliably makes things worse.

What to watch at home

While you wait for an appointment, or while a vet is monitoring a lump that has already been sampled, observation is the most useful thing you can do. Keep it simple and consistent:

• Record the date you first noticed it. Memory blurs quickly, and the timeline is one of the most informative details a vet can have.
• Note the location precisely. Left shoulder, right hock, third webbing of the front left foot. Dogs often have more than one lump, and a vet needs to know which one you are describing.
• Photograph it against something for scale, such as a coin or a ruler, in good light, from the same angle each time.
• Describe the feel. Soft or firm, smooth or knobbly, mobile under your fingers or anchored to the tissue beneath.
• Watch the surface. Hair loss, redness, crusting, a dark central pore, ulceration or any discharge.
• Watch your dog, not just the lump. Licking, chewing, flinching when touched, limping, reluctance to be groomed, changes in appetite, energy, drinking or weight.
• Count. If one lump appears, check the whole dog with your hands and note anything else you find.

Do not squeeze, lance, drain, hot-pack or apply home remedies to a lump. Rupturing a sac pushes irritating material into living tissue, can introduce infection, and can make the eventual surgical site larger.

What to tell your vet

A few minutes of preparation makes the consult far more productive. Bring:

• When the lump appeared and how it has changed since, including whether the change has been gradual or sudden.
• Whether it has ever ruptured, bled or drained, and what came out.
• Whether your dog pays attention to it.
• Any history of previous lumps, what they turned out to be, and whether any were removed and sampled.
• Known skin disease, allergies, ear problems or recurrent paw infections.
• Any recent trauma, grooming, injection sites, insect stings, or walks through long dry grass where a grass seed could have embedded.
• Your dog's full medical history and anything they are currently taking, including anything given over the counter.
• Your photographs, which show change over time better than description does.

Ask the vet directly what the plan is: aspirate now, measure and recheck, or remove and send for laboratory analysis. Ask what signs should bring you back sooner than the scheduled recheck.

When a lump becomes an emergency

Most cysts are not urgent. These situations are:

• Sudden swelling with facial puffiness, hives, vomiting, weakness, collapse or any difficulty breathing. This can be an allergic reaction and needs emergency care immediately.
• A lump in the throat, mouth or neck region that is interfering with breathing, swallowing or eating.
• Bleeding that does not stop with gentle pressure.
• A rapidly enlarging, hot, very painful swelling, especially with fever, lethargy or refusal to eat.
• Severe lameness, a paw your dog will not put weight on, or a swollen foot with an open draining wound.
• A lump near the eye that is rubbing the eye surface, or any lump accompanied by squinting or discharge from the eye.

Recovery, skin and soft tissue after a lump comes off

When a cyst is removed, or when a chronically inflamed paw finally settles, what follows is ordinary soft tissue repair: inflammation, new blood vessel formation, fibroblasts laying down collagen, then weeks of remodelling. Dogs that have been limping or favouring a foot often have secondary stiffness elsewhere by the time the lesion is addressed. How quickly a dog gets back to normal varies from dog to dog, depending on age, size, the site of the lump and the dog's other health conditions.

Surgical removal is often the standard of care for a lump that needs to come off, and whether and when to operate is a decision for your vet or the surgeon handling the case, based on the aspirate findings, the location of the lump and your dog's overall health. If a lump is removed, your vet will usually discuss sending the tissue to a laboratory so the diagnosis is confirmed rather than assumed.

Aftercare is mostly about protecting the site and watching it. Follow your vet's instructions on activity restriction, keep the area clean and dry, and use the collar or recovery suit provided so your dog cannot lick or chew the wound. Check the incision at least twice daily in good light for redness spreading outwards, swelling, gaping, heat, bleeding or discharge, and attend the recheck even if everything looks fine. If your vet prescribes medication, give it exactly as directed and tell the practice if your dog vomits it, refuses it or seems unwell on it. Call the clinic if the wound opens, if swelling increases, if your dog becomes painful, dull or off food, or if anything simply looks worse than it did the day before.

Key Takeaways

• Dogs absolutely get cysts; follicular and sebaceous cysts are the most common skin varieties, and lumps are a leading reason for vet visits in older dogs.
• A cyst is a lined sac filled with keratin, sebum or fluid, not an infection, not a cancer, not an abscess.
• The lumps between the toes are usually interdigital furuncles, not true cysts, and they are painful.
• True cysts rarely resolve permanently on their own, because the lining stays behind and refills.
• Appearance cannot distinguish a cyst from a tumor; a fine-needle aspirate can.
• Fast growth, ulceration, pain, fixation to deeper tissue or any systemic sign means a same-week appointment, and sudden swelling with breathing trouble or collapse means emergency care now.
• Never squeeze, lance or drain a lump at home.

Your veterinarian owns the diagnosis and the treatment plan here: identifying what the lump is, deciding whether it comes off, handling the anaesthetic, the margins and the histopathology. That is not a step to work around. What you can do is notice lumps early, record them carefully, protect the area, and get your dog in front of someone who can put cells under a microscope.

Related guides: Why Is My Older Dog Getting Lumps? (What's Normal) and What Does It Mean If Your Dog Has Skin Tags? (Explained).