What’s That Lump? Exploring the Mystery Mass in Your Cat’s Belly


Feeling a ball or mass in your cat’s abdomen can be concerning for any pet owner. There are several potential causes for abdominal masses in cats that range from mild to serious. This article provides an overview of the common causes of abdominal masses in cats, the diagnostic process, treatment options, and tips for prevention.

The contents of this article include exploring the different types of masses or growths that may be felt in a cat’s belly. We’ll cover benign masses like cysts, hernias, and hairballs, as well as more serious cancers and tumors. Diagnostic tests like bloodwork, imaging, and biopsy will be explained. Available treatments such as surgery, chemotherapy, radiation therapy, and medications will be detailed. Finally, we’ll provide guidance on preventing issues whenever possible through regular vet visits, a healthy diet, and limiting exposure to risk factors.

By the end of this article, cat owners will have a thorough understanding of potential causes, diagnosis, and treatment for an abdominal mass found in their pet. Most importantly, readers will learn that while some causes are harmless, others can be very serious, so consulting a vet right away is imperative.

Possible Causes

There are several possible causes for feeling a lump or ball in a cat’s stomach:

Some common tumors that can form abdominal masses in cats include lymphoma, mast cell tumors, lipomas, adenocarcinoma, and leiomyomas (Walkerville Vet). Tumors can grow rapidly and vary in texture from soft to firm. They may be localized or affect multiple areas.

Cysts can also develop in a cat’s abdomen. Cysts are fluid-filled sacs that form abnormally in the body. They are often slow-growing and benign, though some may impact organ function if they compress other structures. Cysts can sometimes become quite large before being detected (Chewy).

Intestinal hernias occur when part of the intestine protrudes through a weak spot or tear in the abdominal wall muscle. This can create a noticeable lump as the intestinal loop fills with fluid and expands. Hernias require surgical intervention to prevent potentially serious complications.

Ingested foreign bodies like string, cloth, bones, or balls can become lodged in the gastrointestinal tract. This may present as a firm mass in the abdomen as the intestines work to move the object through. Foreign bodies often require emergency surgery for removal.


Feline abdominal tumors may occur in the gastrointestinal tract, spleen, liver, pancreas, bladder or kidneys. Common tumors include mast cell tumors, lymphoma and adenocarcinoma.

Symptoms of an abdominal tumor can include:

  • A palpable mass in the abdomen
  • Vomiting
  • Diarrhea
  • Weight loss
  • Poor appetite

Diagnosis typically involves bloodwork, urinalysis, abdominal ultrasound and biopsy of the mass. Treatment depends on the type of tumor, location and spread. It may include surgery, chemotherapy, radiation therapy or a combination of these.

Unfortunately, the prognosis for abdominal tumors is generally poor long-term due to the difficulty in completely removing or treating them. However, treatments can help extend and improve quality of life if caught early.


Cysts are fluid-filled sacs that can develop in various organs and tissues in cats. Some common types of cysts that may cause an abdominal mass include:

Pancreatic Cysts: These form in the pancreas and are often incidental findings during examinations for other conditions. They may become large enough to feel like a mass in the abdomen. Symptoms depend on the size and location but can include vomiting, diarrhea, and abdominal pain [1].

Intestinal Cysts: Cysts can develop in the intestinal wall, such as epidermoid cysts originating from trapped skin cells. These may cause nonspecific signs like vomiting, diarrhea, constipation, or abdominal discomfort. They are often detected during exploratory surgery for an abdominal mass [2].

Cysts are typically diagnosed via imaging tests like ultrasound, CT scan, or MRI. Needle aspiration of the cyst may be done to confirm the diagnosis. Treatment depends on the type and location of the cyst. Some may be surgically removed while others can be managed conservatively with monitoring.


A hernia occurs when an organ or tissue pushes through a weak spot or tear in the muscle or connective tissue surrounding it.1 There are several types of hernias that can occur in cats:

Types of Hernias

Common types of hernias in cats include:

  • Inguinal hernia – This occurs in the groin area when abdominal contents protrude through the inguinal ring into the inguinal canal.
  • Umbilical hernia – This is a protrusion of abdominal contents through an incompletely closed umbilical ring.
  • Diaphragmatic hernia – This involves a tear in the diaphragm that allows abdominal organs to enter the chest cavity.


Symptoms of a hernia in cats may include:2

  • A visible or palpable bulge underneath the skin in the groin, belly, or chest
  • Vomiting
  • Loss of appetite
  • Blood in the urine
  • Behavioral changes

Diagnosis and Treatment

Hernias are typically diagnosed through a physical exam and imaging tests like x-rays or ultrasound. Small hernias may be managed conservatively with rest and pain medication, but most require surgical repair to push the tissue back into place and stitch the muscle or connective tissue closed.

Foreign Bodies

Cats are known to swallow a variety of foreign objects that can become lodged in their gastrointestinal tract (VCA Animal Hospitals). Some of the most common items include string, thread, wool, rubber bands, fabric, small toys, rocks, bones, and plant material. Linear foreign bodies, like string, are particularly dangerous as they can cause a sawing motion through the intestines (VCA Animal Hospitals).

Common symptoms of a gastrointestinal foreign body include vomiting, loss of appetite, lethargy, and dehydration. The cat may cry out in pain when picking them up or palpating their abdomen. Diagnosis involves imaging tests like X-rays or ultrasound to identify the foreign object. Endoscopy or surgery is often required to remove the foreign body and treat any damage to the gastrointestinal tract. Swift treatment is crucial to prevent intestinal perforation, peritonitis, sepsis, and death.

To prevent foreign body ingestion, keep harmful items out of reach and monitor play with string toys. Cats may eat foreign objects when stressed or bored, so providing environmental enrichment is also beneficial.

Other Causes

Besides tumors, cysts, hernias, and foreign bodies, there are some other potential causes for feeling a mass or lump in a cat’s abdomen:

Abscesses – An abscess is a pocket of pus caused by bacterial infection. Abscesses can develop anywhere in the body, including the abdomen. They may feel like soft, fluid-filled lumps under the skin or deeper inside the body. Abscesses require antibiotic treatment and often drainage.1

Hematomas – Hematomas are pockets of blood that leak from damaged blood vessels and pool up in surrounding tissues. Trauma is the most common cause of hematomas. They can form masses of varying sizes depending on the amount of bleeding.2

Seromas – Seromas are pockets of clear serum that accumulates at a surgical site or from trauma. They feel like soft fluid-filled sacs under the skin. Small seromas often resolve on their own, while larger ones may need drainage and treatment.

Lipomas – Lipomas are benign fatty tumors that can form lumps under the skin. They are soft, movable, and often painless.

Granulomas – Granulomas are nodules that form around foreign bodies, inflammation, or infection. They are hard, solid lumps that can develop anywhere in the body.


To diagnose the cause of an abdominal mass in a cat, a veterinarian will first perform a physical exam, feeling the abdomen for any abnormalities. They may be able to feel the location, size, shape and firmness of a mass during the abdominal palpation.

Imaging tests like X-rays, ultrasound or CT scans can also identify masses and determine if they are benign or malignant. As per the Veterinary Information Network, ultrasound is a preferred method for assessing abdominal masses as it allows visual characterization of the mass (VCA Animal Hospitals). Ultrasound can help visualize the exact location, shape, size and internal architecture of masses.

To definitively diagnose the type of mass, the vet may recommend biopsy or fine needle aspiration. This involves inserting a needle into the mass and drawing out cells for examination under a microscope. Cytology can help determine if the mass is benign or malignant. Biopsy provides a sample of the mass for pathological testing (Feline abdominal masses).


Treatment for intestinal tumors in cats often involves surgery to remove the tumor. As noted in an article on WagWalking.com, “Surgery is the most commonly used treatment for intestinal tumors. The veterinarian will make a small incision into the abdomen in order to remove the tumor.” https://wagwalking.com/cat/condition/intestinal-tumor

Chemotherapy may also be used, especially for cancers like lymphoma. According to VCA Hospitals, “Sometimes chemotherapy is the preferred treatment approach with gastric lymphoma in dogs and cats. In some cases, radiation therapy may also be recommended.” https://vcahospitals.com/know-your-pet/stomach-tumors-epithelial

Lifestyle changes like feeding a high-quality diet and limiting stress can also help cats recovering from tumor removal surgery and undergoing other treatments like chemotherapy.


There are some steps cat owners can take to prevent or catch masses early before they become problematic. The two main ways are through monitoring diet and behavior as well as routine veterinary exams.

Keeping an eye on your cat’s eating habits, energy levels, and litter box usage can help identify changes that may indicate an underlying health issue. Any major changes in appetite, lethargy, or abnormal bathroom habits should prompt a vet visit.

Routine wellness exams by a veterinarian every 6-12 months allows the vet to get familiar with your cat while they are healthy. The vet will monitor your cat’s weight, palpate the abdomen feeling for any abnormalities, listen to the heart and lungs, and more. This establishes a baseline so any changes that could indicate a mass or tumor can be caught early.

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