Sebaceous Cysts in Dogs: Causes, Treatment, and When to Remove

By Emiel Maddens  ·  Reviewed in consultation with licensed veterinary professionals  ·  Updated June 2026  ·  10 min read

Photo by Mikhail Nilov on Pexels

Sebaceous cysts are one of the most common reasons dog owners visit the veterinarian with concerns about a skin lump. The term "sebaceous cyst" is widely used by pet owners and even some veterinarians, though it is technically a misnomer in most cases. The majority of what are called sebaceous cysts in dogs are actually epidermal inclusion cysts, also known as infundibular cysts or follicular cysts, which are lined by stratified squamous epithelium and filled with laminated keratin rather than true sebaceous (oily) secretions.

Regardless of their precise classification, these cysts are benign, non-cancerous growths that develop when a hair follicle becomes blocked, damaged, or malformed, trapping keratin beneath the skin surface. Over time, the trapped material accumulates and the cyst slowly enlarges. While most cysts remain small and cause no problems, complications can arise when they rupture, become infected, or grow large enough to interfere with movement or daily activities.

This comprehensive guide explains why dogs develop cysts, how to recognize them, when they need veterinary attention, and what treatment options are available, including the definitive surgical approach for cysts that cause recurring problems.

Types of Cysts in Dog Skin

Epidermal Inclusion Cysts (Infundibular Cysts)

Epidermal inclusion cysts are the most common cyst type in dogs and what most people mean when they say "sebaceous cyst." These cysts are lined by keratinizing stratified squamous epithelium that mirrors the structure of the hair follicle infundibulum (the upper portion of the follicle). They produce and accumulate layers of laminated keratin, a cheese-like, whitish-gray material that fills the cyst cavity. On the skin surface, infundibular cysts typically present as firm, round, well-circumscribed nodules ranging from a few millimeters to several centimeters in diameter. Many have a visible central pore, which represents the remnant of the follicular opening. They can occur anywhere on the body but are most common on the head, trunk, and proximal limbs.

True Sebaceous Cysts and Ductal Cysts

True sebaceous cysts, also called steatocystomas, are much rarer than epidermal inclusion cysts. They are lined by sebaceous epithelium and filled with oily, yellowish sebaceous material rather than solid keratin. Sebaceous duct cysts form when the duct draining a sebaceous gland into the hair follicle becomes obstructed, trapping sebum within the expanding duct. On clinical examination, true sebaceous cysts may feel softer or more fluctuant than the typically firm epidermal inclusion cyst. Differentiation between cyst types requires histopathological examination of the excised cyst wall, though from a practical standpoint, management is similar regardless of the specific cyst type.

Dermoid Cysts and Other Variants

Dermoid cysts are congenital developmental cysts present from birth, containing a complex mix of tissue types including hair follicles, sebaceous glands, and sweat glands within their walls. They are rare in dogs and tend to occur along the dorsal midline, particularly in Rhodesian Ridgebacks, where they are associated with the breed's characteristic dorsal ridge and the dermoid sinus, a related congenital abnormality. Hybrid cysts (also called composite cysts) contain elements of more than one cyst type and are an occasional finding on histopathology. Apocrine cysts, arising from sweat glands, represent another variant that can occur in the skin of dogs. While the clinical approach to all these cyst types is similar, accurate identification through histopathology after removal provides useful information, particularly for congenital types that may have deeper tissue connections.

Why Dogs Develop Cysts

Follicular Obstruction and Trauma

The most common mechanism of cyst formation is blockage of a hair follicle opening, which traps keratin-producing cells beneath the skin surface. Follicular obstruction can result from chronic friction (such as from collars or harnesses), previous trauma or scarring, chronic skin inflammation, or accumulation of dead skin cells and sebum at the follicular opening. Once the follicle is sealed, the living epithelial cells lining the cyst wall continue producing keratin, which has no way to exit the skin surface. The keratin accumulates in concentric layers, gradually expanding the cyst. In some cases, a single traumatic event, such as a puncture wound or surgical incision, implants a small fragment of epidermis into the dermis, which can then form an implantation cyst.

Age and Breed Predispositions

Cysts become more common as dogs age, with most presenting in middle-aged to older dogs. Certain breeds are predisposed to cyst development, likely due to inherited differences in follicular structure or sebaceous gland activity. Breeds commonly affected include Boxers, Shih Tzus, Schnauzers (all sizes), Basset Hounds, and Cocker Spaniels. Kerry Blue Terriers are notably predisposed to multiple follicular cysts, sometimes developing dozens over their lifetime. Hairless and sparsely haired breeds, including Chinese Cresteds and Xoloitzcuintli, can develop comedones and cysts in areas of rudimentary follicle formation. Dogs with a history of recurrent skin infections or chronic seborrheic conditions may also have a higher incidence of cyst formation.

Underlying Skin Conditions

In some cases, cyst development is secondary to or exacerbated by underlying skin conditions. Chronic allergic dermatitis, which causes persistent inflammation and disrupts normal follicular cycling, can predispose to follicular plugging and cyst formation. Seborrhea, characterized by abnormal keratinization and excessive sebum production, provides an environment conducive to follicular blockage. Demodicosis, which destroys hair follicles, can leave behind obstructed remnants that form cysts. Identifying and treating underlying skin disease can help reduce the frequency of new cyst development in predisposed dogs, though it may not prevent all occurrences.

Can Diet or Environment Cause Cysts?

There is limited scientific evidence directly linking dietary factors or environmental exposures to cyst formation in dogs. However, general skin health is influenced by nutrition, and dogs fed diets deficient in essential fatty acids, zinc, or vitamin A may have impaired keratinization and skin barrier function that could theoretically increase susceptibility to follicular problems. Obesity has been anecdotally associated with increased skin fold friction and potentially higher cyst rates in predisposed breeds, though controlled studies are lacking. Environmental factors such as exposure to irritants, frequent swimming in chlorinated pools, or chronic dampness in skin folds may contribute to follicular inflammation and secondary cyst formation in some individuals.

Veterinary evaluation of any lump helps confirm whether it is a benign cyst or something that requires more aggressive treatment.

Photo by Anya Prygunova on Unsplash

When Cysts Become a Problem: Rupture and Infection

What Happens When a Cyst Ruptures

The most common complication of epidermal inclusion cysts is rupture, either spontaneously or from external trauma such as being bumped, squeezed, or scratched. When a cyst ruptures, its keratin contents are released into the surrounding dermis and subcutaneous tissue. The body's immune system recognizes this keratin as foreign material and mounts an intense inflammatory response, even though the keratin is chemically the same material produced by the dog's own cells. The result is a sudden, painful, red, swollen mass that may be two to three times the size of the original cyst. The area may feel warm to the touch, and the dog may be reluctant to be touched in that area. This sterile inflammation is called a foreign body reaction and can be just as dramatic as a bacterial infection.

Secondary Bacterial Infection

Ruptured cysts are highly susceptible to secondary bacterial infection. The inflammatory tissue and protein-rich cyst contents create an ideal environment for bacterial colonization, and bacteria from the skin surface can easily enter through the disrupted cyst wall or any draining tract that forms. Infected cysts produce purulent (pus-like) discharge that may be thick, yellowish-green, and malodorous. The surrounding skin becomes increasingly reddened and painful, and the dog may develop fever and lethargy if the infection is significant. Staphylococcus pseudintermedius is the most commonly isolated bacterium from infected cysts, though other organisms can be involved. Treatment typically requires a combination of systemic antibiotics, warm compresses, and sometimes surgical drainage.

Home Care for a Ruptured Cyst

If your dog's cyst has ruptured and is draining clear or slightly bloody fluid without signs of significant infection, gentle home care may be appropriate while you arrange a veterinary visit. Apply warm, moist compresses to the area for five to ten minutes several times daily to promote drainage and comfort. Keep the area clean by gently wiping with a chlorhexidine-based antiseptic solution after each compress session. Prevent your dog from licking or chewing at the site using an Elizabethan collar if necessary. Do not attempt to squeeze or express the cyst, as this can drive contents deeper into the tissue and worsen inflammation. If you notice increasing swelling, heat, pain, or purulent discharge, seek veterinary care promptly, as these signs indicate infection that requires professional treatment.

Why Squeezing Cysts Is a Bad Idea

Many pet owners are tempted to squeeze or pop a cyst, similar to popping a pimple. This is strongly discouraged for several reasons. First, the cyst wall remains intact beneath the skin even if contents are expressed through a surface opening, meaning the cyst will refill over time. Second, squeezing forces cyst contents into the surrounding tissue under pressure, dramatically increasing the inflammatory foreign body reaction and the risk of secondary infection. Third, attempting to express a cyst at home without proper sterile technique can introduce bacteria into the wound. Fourth, not all lumps that look like cysts are actually cysts, and manipulating a mast cell tumor or other neoplasm can have serious consequences. If a cyst is bothering your dog or you, have it evaluated and treated properly by your veterinarian.

Veterinary Treatment Options

Complete Surgical Excision

The gold standard treatment for problematic cysts is complete surgical excision, which involves removing the entire cyst, including its wall (capsule), in one piece. This is important because any epithelial lining left behind retains the ability to produce keratin and will eventually reform the cyst. The surgery is typically performed under general anesthesia or heavy sedation with local nerve blocks. The surgeon makes an elliptical skin incision around the cyst, carefully dissects the cyst away from surrounding tissue while keeping the cyst wall intact, and closes the wound with sutures. When performed properly, the recurrence rate after complete excision is very low. The excised cyst should be submitted for histopathology to confirm the diagnosis and rule out more concerning growths.

Drainage and Marsupialization

For cysts that are actively infected and too inflamed for immediate complete excision, your veterinarian may recommend a staged approach. First, the infected cyst is lanced and drained to relieve pressure and allow pus to exit. The cavity is flushed with antiseptic solution, and the dog is placed on systemic antibiotics to control the infection. In some cases, the cyst wall may be partially opened and sutured to the skin edges (marsupialization), creating a permanent opening that allows ongoing drainage while the inflammation resolves. Once the infection has cleared and the tissue has healed, typically in two to four weeks, the remaining cyst wall can be excised electively with a much lower risk of surgical complications.

Medical Management

Some cysts, particularly small, stable, non-inflamed ones in low-risk locations, may not require surgical treatment. In these cases, your veterinarian may recommend monitoring with periodic re-evaluation. If the cyst shows early signs of inflammation, warm compresses and topical antiseptics can help reduce swelling and prevent infection. For dogs that develop recurrent cysts, addressing underlying conditions such as allergic dermatitis or seborrhea may help slow new cyst formation. Retinoid therapy (synthetic vitamin A derivatives) has been used in some dogs with severe, recurrent cystic conditions to normalize keratinization, though this requires careful veterinary supervision due to potential side effects.

Post-Surgical Care

After cyst excision, your dog will need standard post-surgical wound care. Keep the incision site clean and dry, monitor for signs of infection (redness, swelling, discharge, or wound dehiscence), and prevent your dog from licking the area using an Elizabethan collar. Activity restriction is usually recommended for ten to fourteen days to allow the wound to heal. Sutures are typically removed at a follow-up appointment ten to fourteen days after surgery. Most dogs recover quickly from cyst excision with minimal complications. If multiple cysts were removed or the surgery was more extensive due to infection or large cyst size, your veterinarian may prescribe pain medication and a short course of antibiotics.

Monitoring Cysts and Preventing Complications

How to Monitor Cysts at Home

If your veterinarian has confirmed that a lump is a benign cyst and recommends monitoring, regular at-home assessment is important. Check the cyst weekly, noting its size, firmness, and any changes in the overlying skin. Photography with a size reference (such as a coin placed next to the cyst) provides objective documentation of any changes over time. A stable cyst that remains the same size, shape, and consistency over months is reassuring. Any change in growth rate, development of redness or warmth, onset of tenderness, surface ulceration, or discharge should prompt a veterinary re-evaluation. Keeping a simple log of observations helps you detect gradual changes that might be difficult to notice from day to day.

Reducing Friction and Irritation

For cysts in areas prone to friction, reducing mechanical irritation can help prevent rupture and inflammation. If a cyst is located where a collar sits, switch to a harness for walks and consider removing the collar at home. For cysts in the axillary or inguinal regions, keeping the surrounding area clean and dry minimizes irritation. Avoid tight-fitting clothing or wraps that press against cysts. If your dog has a tendency to scratch at or rub the cyst against furniture, an Elizabethan collar may be needed temporarily to prevent self-trauma during flare-ups.

When Multiple Cysts Are a Concern

Some dogs, particularly those of predisposed breeds, develop multiple cysts over their lifetime. While individual cysts are benign, the pattern of multiple or recurrent cysts may sometimes warrant broader evaluation. Your veterinarian may recommend bloodwork to screen for hypothyroidism or Cushing's disease, both of which can affect skin health and keratinization. Skin biopsy may be performed to confirm that the growths are truly cysts and not a different type of nodular skin disease. For dogs with dozens of cysts, practical decisions must be made about which ones to remove surgically and which to monitor, balancing the benefits of definitive treatment against the cumulative risks and costs of multiple surgical procedures.

Sebaceous Cysts in Dogs FAQ

Q: Are sebaceous cysts in dogs dangerous?

Sebaceous cysts (more accurately called epidermal inclusion cysts) are benign growths that are not cancerous and do not have malignant potential. They are generally harmless when small and stable. The main risk is when they rupture, which triggers intense local inflammation and creates an opportunity for secondary bacterial infection. In rare cases, large cysts in sensitive locations can interfere with movement or comfort. Veterinary evaluation is recommended for any lump to confirm its identity, as some more serious growths can resemble cysts on external examination.

Q: Can I pop my dog's cyst at home?

No, you should never attempt to squeeze, pop, or lance your dog's cyst at home. Squeezing a cyst forces its contents into surrounding tissue under pressure, dramatically worsening inflammation and infection risk. The cyst wall remains intact even after contents are expressed, meaning the cyst will refill. Additionally, what looks like a simple cyst might be a different type of growth entirely, and manipulating it could cause serious complications. If a cyst is causing problems, your veterinarian can safely manage it with proper technique, sterile conditions, and appropriate follow-up care.

Q: Will a cyst come back after surgery?

If the entire cyst, including its complete wall (capsule), is removed during surgery, the recurrence rate at that specific site is very low. Incomplete removal, where fragments of the cyst lining are left behind, can lead to recurrence because the remaining epithelial cells continue producing keratin and rebuilding the cyst. This is why complete excision by an experienced veterinarian is preferred over drainage alone, which always leaves the cyst wall in place. Keep in mind that dogs prone to cysts may develop new cysts at other body locations even after successful removal.

Q: When should I take my dog to the vet for a cyst?

Seek veterinary evaluation if the cyst is growing rapidly, becomes red, warm, or painful, starts draining pus or foul-smelling material, or if your dog seems uncomfortable or is repeatedly bothering the area. Any new lump should be evaluated at least once, ideally with fine needle aspiration, to confirm that it is indeed a benign cyst and not a more concerning growth. Even stable, confirmed cysts should be re-evaluated if any change in size, consistency, or overlying skin appearance occurs.

Q: Do certain breeds get more cysts than others?

Yes, certain breeds have a genetic predisposition to developing cysts. Boxers, Shih Tzus, Schnauzers, Basset Hounds, Cocker Spaniels, and Kerry Blue Terriers are among the most commonly affected. Hairless breeds like Chinese Cresteds may develop cysts in areas of rudimentary follicle formation. The predisposition is likely related to inherited differences in hair follicle structure, sebaceous gland activity, and keratinization patterns. Dogs of predisposed breeds benefit from regular skin examinations to catch new growths early.

Sources

Gross, T.L., Ihrke, P.J., Walder, E.J., & Affolter, V.K. (2005). Skin Diseases of the Dog and Cat: Clinical and Histopathologic Diagnosis, 2nd Edition. Blackwell.

Goldschmidt, M.H. & Hendrick, M.J. (2002). Tumors of the Skin and Soft Tissues. In Tumors in Domestic Animals, 4th Edition. Iowa State Press.

Miller, W.H., Griffin, C.E., & Campbell, K.L. (2013). Muller and Kirk's Small Animal Dermatology, 7th Edition. Elsevier.

Hnilica, K.A. & Patterson, A.P. (2016). Small Animal Dermatology: A Color Atlas and Therapeutic Guide, 4th Edition. Elsevier.

Gross, T.L. et al. (1992). Follicular cysts and dermoid cysts. Veterinary Dermatology, 3(4-5), 209-214.

Related Reading

• Skin Tags and Warts on Dogs, Understanding other common benign growths and when they need attention
• Mast Cell Tumors in Dogs, Why every lump deserves evaluation to rule out this common skin cancer
• Chlorhexidine for Dogs, How antiseptic sprays help manage infected or draining skin lesions
• Pyoderma in Dogs, Understanding bacterial skin infections that can complicate ruptured cysts

Emiel Maddens

Founder of Vetified. Develops topical antifungal and antimicrobial formulations for companion animals. Vetified products are listed on DailyMed and manufactured through FDA-registered facilities in the United States.