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Cysts on Dogs: Sebaceous and Follicular Cysts

By the Dog Health Handbook team · Updated · Fact-checked against current veterinary references (see sources)

Key takeaways

  • Most "sebaceous cysts" are follicular cysts filled with cheesy keratin. They're benign.
  • Don't squeeze them: it can cause painful inflammation or infection.
  • If one bursts, rinse it gently, stop licking and watch for infection.
  • Have new lumps sampled, because some tumors look like cysts.
  • Removing the whole cyst usually cures it. Draining it doesn't.

Table of Contents

Research Types Burst cysts Treatment Prevention FAQ Sources

Skin and Coat Quicklinks

Overview Infections Irritation Parasites Yeast Infection Ringworm Lumps and Bumps Lipomas Cysts Histiocytomas Warts and Skin Tags Skin Cancer

Cysts are common, usually harmless lumps in or under a dog's skin. Most are filled with keratin, a thick, cheesy, grey, yellow or brown material that can ooze out like toothpaste or cottage cheese if the cyst opens.1,2,3 Owners often call them "sebaceous cysts," but true sebaceous cysts are actually rare in dogs. Most are follicular cysts, which start in a hair follicle.4,5 The most important rule: don't squeeze them. Squeezing can push the contents into the surrounding skin and cause a painful, inflamed lump.5,1,4

Have a cyst checked by your vet if:

  • It's a new lump that hasn't been sampled. Some tumors look like cysts.2,6
  • It's red, hot, swollen, painful or smelly, or leaking pus. Cysts can get infected.2,3
  • It has burst and won't heal, or keeps refilling.2,4
  • It's on or near the eyelid.3

What the Research and References Say

  • Most "sebaceous cysts" aren't sebaceous. A veterinary school professor's review says most are infundibular (follicular) cysts, and genuine sebaceous cysts are extremely rare in dogs.4
  • Follicular cysts are the most common type, ranging from 2 mm to over 5 cm.5,4
  • Squeezing makes them worse. Released keratin often triggers a severe foreign-body reaction in the skin.5
  • Removal cures most cysts, but a cyst can come back if any of its lining is left behind.2,5

Types of Cysts and Cyst Look-Alikes

  • Follicular (infundibular or epidermoid) cysts: single, round, firm lumps, sometimes bluish, filled with cheesy keratin. Common on the head, neck, trunk and legs. Boxers, Shih Tzus, Schnauzers and Basset Hounds are prone.2,5,4
  • Other hair-follicle cysts, including matrix cysts, which can become hard and some of which develop into benign hair-follicle tumors.5
  • Apocrine (sweat gland) cysts: thin, blister-like lumps filled with clear fluid, mostly on the head and neck of middle-aged and older dogs.5,4,2
  • Dermoid cysts: rare cysts present from birth, along the middle of the back or head, that contain hair. Rhodesian Ridgebacks, Kerry Blue Terriers and Boxers are most affected.5,2
  • Sebaceous adenomas and hyperplasia: not cysts but small, warty or cauliflower-like oil-gland growths, very common in older dogs, especially on the head. They're often called "old dog warts" and can be mistaken for cysts.5,3,1

An aspirate (needle sample) can suggest which type of cyst it is, but only a biopsy gives a definite diagnosis and rules out cancer.2

What to Do If a Cyst Bursts

  • Gently rinse the area with lukewarm water or a saline wound wash and pat it dry.2
  • Don't squeeze out the rest of the contents.1,4
  • Stop licking, scratching and rubbing with a cone, soft collar or a T-shirt. A light protective dressing may help until it heals.2
  • See your vet if it becomes red, swollen, painful or smelly, keeps draining, or your dog seems unwell. These can be signs of infection.2,3

Treatment: Leave It or Remove It?

A small cyst that isn't bothering your dog can often just be watched.4 Your vet may suggest removing it if it keeps bursting or refilling, gets infected, grows, or your dog keeps licking or chewing it.2,3 Surgical removal is the treatment of choice and usually cures the cyst, as long as the whole lining comes out.5,2 Draining a cyst with a needle doesn't remove the lining, so it often refills.2,5

Some dogs, particularly certain breeds, tend to keep forming new cysts.2 Antibiotics may be used if a cyst is infected, but they don't make the cyst itself go away.2,3

Can Cysts Be Prevented?

There's no proven way to prevent most cysts. Checking your dog's skin monthly, keeping track of each lump with a photo and measurement, and having new or changing lumps sampled are the best ways to stay ahead of problems.6,7 For other lumps, see lumps and bumps on dogs, lipomas and warts and skin tags.

Frequently Asked Questions

Should I pop my dog's cyst?

No. Squeezing a cyst can force its contents into the skin and cause painful inflammation or infection.

What comes out of a dog's cyst?

Usually thick grey, yellow or brownish material like toothpaste or cottage cheese. Apocrine cysts contain clear fluid.

Can a cyst on a dog be cancerous?

True cysts are benign, but some tumors look like cysts. A needle sample or biopsy tells them apart.

Will my dog's cyst go away on its own?

Usually not. It may burst and shrink for a while, but it often refills unless the lining is removed.

How do I clean a burst cyst?

Rinse gently with lukewarm water or saline, pat dry, stop licking, and call your vet if it looks infected.

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Sources and further reading

This article was written and fact-checked on October 20, 2026 against current veterinary references and specialist guidelines:

  1. Villalobos AE. Tumors of the Skin in Dogs. Merck Veterinary Manual, Pet Owner Version, reviewed June 2018, updated April 2026.
  2. Barnes C, Williams K, Hunter T, Stoewen D. Cysts. VCA Animal Hospitals, updated April 17, 2026.
  3. Eldredge DM. What Is a Sebaceous Cyst or Adenoma on a Dog? Whole Dog Journal, November 19, 2025.
  4. Cortadellas O. Sebaceous cysts in dogs. Are they really sebaceous? Vets and Clinics (Affinity Petcare), accessed October 2026.
  5. Villalobos AE. Epidermal and Hair Follicle Tumors in Animals. Merck Veterinary Manual, Professional Version, reviewed August 2021, updated June 2026.
  6. Ettinger SN. Tumor Detection in Dogs and Cats: See Something, Do Something. Today's Veterinary Practice, July/August 2017.
  7. Berman-Thacker E. Skin Tags on Dogs. PetMD, May 9, 2023.

About this article

Last updated : new page, written using the Merck Veterinary Manual, VCA, a veterinary professor's review of so-called sebaceous cysts, Whole Dog Journal and published research on skin lumps in young dogs.

This page is for general information and is not a substitute for an exam by your veterinarian.