CONDITION
Sebaceous Cysts
Why this matters now
Sebaceous cysts can develop at any age but become increasingly common in middle-aged and older dogs. They may appear as single masses or multiple cysts may develop over time. Certain breeds including Cocker Spaniels, Schnauzers, and Yorkshire Terriers appear more frequently affected. These cysts often grow slowly over months to years and may go unnoticed until they reach a certain size.
Most sebaceous cysts remain stable and benign, enlarging gradually if at all. Some may rupture spontaneously or following trauma, releasing their characteristic thick, white or greyish contents. Ruptured cysts can become infected, leading to localised inflammation and discomfort. Cysts in areas subject to friction may be more likely to become problematic. Rarely, cysts may recur after incomplete removal.
Signals & patterns
Early signals
Small, round, firm lump under the skin
Early cysts present as discrete, well-defined swellings that move with the skin when manipulated.
Smooth surface and regular shape
Unlike some other masses, sebaceous cysts typically have uniform, round contours.
Central pore or dark spot visible
Some cysts have a visible connection to the skin surface appearing as a small dark point.
No pain when touched
Uncomplicated cysts are typically non-tender unless they have become infected or inflamed.
Later signals
Gradual increase in size
Cysts may slowly enlarge over time as sebaceous material continues to accumulate.
Discharge of thick, white-grey material
Rupture releases the characteristic cheesy or waxy cyst contents.
Redness and swelling around the cyst
Infected or inflamed cysts become warm, painful, and surrounded by reactive tissue.
Multiple similar lumps appearing
Dogs prone to sebaceous cysts often develop additional masses in various locations over time.
Click to read about the biological mechanisms
How this is usually investigated
Diagnosis is often made based on characteristic appearance and behaviour. Further investigation may be warranted to confirm the benign nature or if the mass has unusual features.
Physical examination
Fine needle aspirate
Expression of contents
Histopathology following removal
Options & trade-offs
Management ranges from monitoring to surgical removal depending on cyst size, location, and whether complications have developed.
Monitoring without intervention
Regular observation of stable, uncomplicated cysts that are not causing problems.
Trade-offs: Appropriate for small, non-problematic cysts. Requires periodic reassessment. Does not prevent eventual enlargement or rupture.
Surgical excision
Complete removal of the cyst including its wall to prevent recurrence.
Trade-offs: Provides definitive treatment and histopathological confirmation. Requires anaesthesia. Larger cysts require larger incisions.
Expression and drainage
Emptying cyst contents through the skin opening.
Trade-offs: May provide temporary reduction in size. Cyst typically refills as the wall remains. Not a permanent solution.
Treatment of infected cysts
Antibiotics and anti-inflammatory medications for infected or ruptured cysts.
Trade-offs: Addresses the acute infection. Surgical removal may still be needed once inflammation resolves. Hot compresses may help localise infection.
Documentation and mapping
Recording cyst locations and sizes for dogs with multiple masses.
Trade-offs: Essential for monitoring multiple cysts. Helps identify new masses or changes in existing ones.
Common misconceptions
"All skin lumps in dogs are harmless cysts"
Many different types of skin masses occur in dogs, some requiring prompt attention. Any new lump warrants veterinary assessment to determine its nature.
"Squeezing out a cyst cures it"
Expression of cyst contents provides only temporary relief. The cyst wall continues to produce material, and the cyst typically refills. Complete removal requires excision of the entire cyst wall.
"Sebaceous cysts are caused by poor diet or hygiene"
Cyst development relates to individual follicular characteristics and breed predisposition rather than care or diet. They are not a reflection of husbandry.
Owners noticing new lumps on their dog might note whether the mass is attached to the skin or deeper tissues, whether it has changed over time, and whether it seems to cause any discomfort. For dogs with multiple cysts, keeping a simple map of lump locations can help track changes. If a cyst appears to rupture or become inflamed, prompt attention may help prevent secondary infection.
Last reviewed: 24 April 2026 · Dr Alastair Greenway MRCVS