Cat Cyst: How to Treat It and What to Do Next

Name: Cat Cyst: How to Treat It and What to Do Next
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Cysts in cats how to treat depends on what kind of cyst your cat has. Most skin cysts are benign and can be watched at home, while others need veterinary drainage, antibiotics, or surgery. The right choice comes down to the type, location, and whether the lump is changing.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

Do not squeeze or lance a cyst yourself. Rupturing a keratin-filled cyst spills protein into nearby tissue and triggers severe inflammation [1].
Most benign skin cysts only need monitoring unless they grow, bleed, or bother your cat.
Antibiotics help only when a cyst is infected or has ruptured and become secondarily infected. They do not shrink the cyst itself.
Surgical removal is the usual treatment for cysts that keep coming back, grow quickly, or sit in a spot that interferes with walking, eating, or grooming [1].
Any new lump should be checked by a veterinarian, because cysts and tumors can look alike on the outside [1].

What a Cat Cyst Actually Is

A cyst is a closed pocket of tissue that holds fluid, keratin, hair, or other material. It is not a tumor in the cancerous sense, though some tumors can contain cyst-like spaces. In cats, several distinct types exist, and they behave very differently.

Keratinized skin cysts are filled with keratin, a skin protein. They have a hard or solid core, and most are malformations of hair follicles. They can be the same color as your cat's hair and may appear alone or in groups. These cysts are only occasionally found in cats [1].

Dermoid cysts are developmental abnormalities, meaning a cat is born with them. They usually sit along the dorsal midline, the top line of the body. Under the microscope they look like duplicated skin, complete with collagen bundles, adnexal structures, and a filling of keratin and hairs. In a review of 220 feline cases, the average age at diagnosis was 5.5 years, and 59.5% were male. Domestic shorthairs made up 56.4% of cases. The average cyst diameter was 1.4 cm, and 99.5% were cutaneous or subcutaneous, with the neck being the most common site at 55.9% [2].

Cysts can also form inside the body. Biliary tract cysts involve abnormal dilation of the hepatobiliary system, and diagnosis usually relies on imaging with histopathology for confirmation [3]. Hepatobiliary cystadenoma is an uncommon benign biliary tumor that can mimic a more aggressive cancer, and it also requires histopathology to confirm [4]. Perirenal cyst-like lesions around the kidneys have been reported in a cat with feline infectious peritonitis [5]. These internal cysts are not something you can manage at home.

Signs Owners Notice

External cysts are usually found by touch. You may feel a firm, round lump under the skin while petting your cat. Some sit on a stalk and stick out from the surface. They range from less than 0.4 inches (1 centimeter) to more than 4 inches (10 centimeters) across, and in cats they are often dark in color [1].

Other signs include:

A lump that is hairless over the top
An open sore or ulcerated area on the lump
Redness, warmth, or discharge
A cyst that changes size from week to week
Multiple lumps appearing over time
Limping or reluctance to move if a cyst sits near a joint or paw

Internal cysts cause vague signs. A cat with a biliary cyst may vomit and stop eating [3]. A cat with a large liver cyst may show weeks of vomiting, poor appetite, and a swollen belly [4]. These signs overlap with many other conditions, so imaging is needed to sort them out.

Causes and Risk Factors

The cause depends on the cyst type.

Keratinized cysts come from malformed hair follicles [1]. Dermoid cysts are developmental, present from birth, and most often found on the neck and along the back [2]. Basal cell tumors, which are common in older cats and can form cysts, are seen most in domestic longhairs, Himalayans, and Persians [1].

Age matters. Basal cell tumors tend to appear in older cats [1]. Dermoid cysts are diagnosed at an average age of 5.5 years [2]. Internal biliary cysts have been reported in an elderly cat and in a middle-aged cat, so age alone does not rule them in or out [3][4].

Breed and sex play a smaller role. Dermoid cysts were more common in male cats and in domestic shorthairs in one case series [2]. Longhaired breeds carry higher risk for basal cell tumors [1].

Inflammation is not always part of the picture. In the dermoid cyst review, 66.4% of cases had no associated inflammatory lesions reported [2]. That matters because a quiet lump is not automatically a harmless one, and an inflamed lump is not automatically a serious one.

How Cysts Are Diagnosed

Your veterinarian starts with a physical exam and a history. They will ask when you first felt the lump, whether it has changed, and whether your cat seems uncomfortable.

For lumps on or under the skin, a fine needle aspirate is often the first step. A small needle collects cells, which are examined under a microscope. This helps tell a cyst from a tumor, though it does not always give a final answer.

Imaging helps with deeper or internal cysts. Ultrasound can show a cyst's shape, wall, and contents. In one case, ultrasonography found a multiloculated cyst with thin septa and no mural nodules, and contrast-enhanced computed tomography confirmed a large cystic liver mass with homogeneous fluid attenuation and no solid components [4]. In another case, ultrasound revealed dilation next to the gallbladder [3].

Histopathology, the microscopic study of removed tissue, is the only way to confirm certain diagnoses. Biliary tract cysts and hepatobiliary cystadenoma both require it [3][4]. If your cat has a lump removed, ask that the tissue be sent for analysis. It is the difference between a guess and an answer.

Cysts in Cats: How to Treat Them

Treatment falls into three paths: watch, drain and treat infection, or remove.

Home Monitoring

Small, soft, stable lumps that do not bother your cat can often be watched. Take a photo with a ruler next to the lump every month. Note the size, color, and whether the skin over it is intact. Keep a written log.

Do not squeeze, poke, or try to pop the cyst. Keratinized cysts release keratin into surrounding tissues when squeezed, and that causes severe inflammation [1]. Home lancing kits are not appropriate for cats. You cannot sterilize the field, you cannot control bleeding, and you may turn a harmless cyst into an infected wound.

If the lump is on the neck or back and has been there since your cat was young, a dermoid cyst is possible [2]. These still deserve a veterinary look, because the same location can host other lumps.

When Antibiotics Are Needed

Antibiotics treat bacterial infection, not the cyst. A cyst that has ruptured, been scratched open, or become red and painful may need antibiotics. Your veterinarian calculates the dose from your cat's weight and health, and the choice of drug depends on the exam and sometimes on culture results.

Never give your cat antibiotics left over from another pet or an old prescription. Some antibiotics that are safe for dogs are toxic to cats.

When Lancing or Drainage Helps

Some cysts fill with fluid and become tense and painful. A veterinarian may drain these in the clinic under sterile conditions. Drainage relieves pressure, but the cyst wall usually remains, so the cyst can refill. Drainage is a temporary fix, not a cure.

For internal cysts, drainage may be part of a larger procedure. In one reported case, the content of a cyst-like mass around a kidney was aspirated and the thick wall was fenestrated and partly resected [6]. That is a surgical decision made with imaging and lab work in hand.

When Surgery Is the Answer

Surgical removal is the usual treatment for keratinized skin cysts [1]. It is also effective for basal cell tumors, which are benign but can grow quickly and cause extensive ulceration and secondary inflammation [1].

Removal makes sense when:

The cyst keeps refilling after drainage
It grows quickly or changes character
It is ulcerated, bleeding, or infected
It sits where it interferes with movement, eating, or grooming
Your veterinarian cannot rule out a tumor with less invasive tests

Internal cysts may need major surgery. A biliary tract cyst in one cat was completely excised, and the cat remained stable afterward [3]. A very large liver cyst in another cat required complete excision with preservation of hepatic tissue and partial resection [4]. These are advanced procedures performed by experienced surgeons.

A Simple Comparison

Situation	Typical approach	Why
Small, stable skin cyst, no signs	Monitor at home with monthly photos	Many benign cysts never cause trouble [1]
Cyst that was squeezed or scratched open	Veterinary exam, possible antibiotics	Infection risk after rupture [1]
Tense, fluid-filled cyst	In-clinic drainage	Relieves pressure, may refill
Cyst that keeps returning or grows fast	Surgical removal	Removes the cyst wall, allows histopathology [1]
Internal cyst found on imaging	Advanced imaging, possible surgery	Confirmation needs histopathology [3][4]

Recovery, Outlook, and Long-Term Management

After skin surgery, most cats go home the same day. Your veterinarian will give you wound care instructions and may send home pain medication. Keep your cat from licking or chewing the incision. A cone or recovery suit often helps. Check the site daily for swelling, discharge, or opening of the incision.

After internal surgery, expect a longer recovery. A cat that had a biliary cyst removed stayed stable after complete excision [3]. A cat that had a large liver cyst removed needed biliary reconstruction as part of the procedure [4]. Follow-up imaging and blood work are common after these operations.

Long-term outlook is good for benign skin cysts that are fully removed. Some cats form new cysts elsewhere, so keep checking your cat's skin during regular petting. If your cat has a condition that causes cyst-like lesions, such as feline infectious peritonitis, the outlook depends on that underlying disease [5]. FIP is a serious diagnosis, and treatment decisions are made with your veterinarian.

If your cat also deals with skin or ear problems, these guides may help: How To Treat Cat Ear Infection, How To Treat Flea Dermatitis In Cats, and How Do You Treat Ringworm In Cats At Home. If your cat has been diagnosed with FIP, see FIP in Cats: Symptoms, Diagnosis, and How It Is Treated Today. For urinary signs that can be confused with other illnesses, read What To Do For A Urinary Tract Infection In A Cat.

Prevention

You cannot prevent a developmental cyst, because a cat is born with it [2]. You also cannot prevent hair follicle malformations that lead to keratinized cysts [1].

What you can do is catch problems early. Run your hands over your cat's whole body once a week. Feel the neck, back, legs, belly, and tail base. Note any new lump and measure it. Bring your log to veterinary visits.

Keep your cat's skin healthy. Control fleas and other parasites, treat skin infections promptly, and keep up with routine exams. Older cats and longhaired breeds deserve extra attention because of their higher risk for certain skin tumors [1].

Do not try home remedies on lumps. No cream, compress, or over-the-counter product will remove a cyst, and some can irritate the skin and make diagnosis harder.

Limitations and When to Contact a Veterinarian

No article can tell you what your cat's lump is. A veterinarian needs to see and often sample it. Individual cases need a veterinarian's hands-on exam and testing.

Contact your veterinarian the same day if:

A lump appeared suddenly and is growing fast
A cyst ruptured and is draining pus or blood
Your cat is licking, biting, or scratching at the lump
The skin over the lump is red, hot, or open
Your cat has a lump near the eye, mouth, or paw that affects function

Go to an emergency clinic now if:

Your cat is having trouble breathing
Your cat is vomiting repeatedly and cannot keep water down
Your cat's belly is swollen and painful to touch
Your cat is weak, collapsed, or unresponsive
A lump is bleeding heavily and will not stop

Schedule a routine visit if:

You found a new lump that is small and stable
An existing cyst has changed size or color
Your cat has multiple lumps
You want a baseline measurement and a professional opinion

Frequently Asked Questions

Can I pop a cyst on my cat at home?

No. Squeezing a keratinized cyst pushes keratin into the surrounding tissue and causes severe inflammation [1]. You also risk introducing bacteria and creating an infection that would not have happened otherwise. Let a veterinarian decide whether drainage or removal is appropriate.

Will a cat cyst go away on its own?

Some cysts stay the same size for years and never cause a problem. Others refill after drainage or slowly enlarge. A cyst that disappears on its own is uncommon, and a lump that shrinks without treatment should still be checked, because the change may signal something else.

Are cysts on cats cancerous?

Most cysts are benign. Keratinized skin cysts are benign [1], and dermoid cysts are developmental abnormalities [2]. Some tumors, including basal cell tumors, can contain cyst-like areas and are also benign, though they may grow quickly and ulcerate [1]. A few internal cystic masses can mimic cancer and need histopathology to tell them apart [4].

Does my cat need surgery for every cyst?

No. Small, stable cysts that do not bother your cat can be monitored. Surgery is usually reserved for cysts that grow, rupture, become infected, or interfere with daily life [1]. Internal cysts often need surgery because they cannot be managed from the outside [3][4].

How fast should a cyst be removed?

There is no single timeline that fits every cat. Fast-growing, ulcerated, or painful cysts should be evaluated promptly, often within days. Stable lumps can be checked at a routine visit. Your veterinarian will set the schedule based on the exam, the location, and whether your cat has other health conditions.

References

Tumors of the Skin in Cats - Cat Owners. Merck Veterinary Manual.
Feline dermoid cyst: Retrospective case series and literature review. Veterinary pathology, 2025.
Surgical approach to a biliary tract cyst in an elderly cat. Veterinary research communications, 2025.
Giant Hepatobiliary Cystadenoma Requiring Biliary Reconstruction in a Cat: A Case Report. Veterinary medicine and science, 2026.
Perirenal cyst-like lesions associated with feline infectious peritonitis in a Maine Coon cat. JFMS open reports, 2025.
Suspected unusual digital metastases of a primary renal cell carcinoma in a cat. The Canadian veterinary journal = La revue veterinaire canadienne, 2026.