Intestinal Cancer in Cats: Symptoms, Diagnosis & Vet-Approved Natural Remedies

Intestinal cancer is quite rare in cats, and it is most commonly found in the small intestine (e.g., lymphoma). However, in some cases, the cancer can also affect the colon and/or rectum.

The types of cancer that can occur in cats in the intestine include gastrointestinal stromal tumor, mast cell tumor, leiomyosarcoma, adenocarcinoma, carcinoid, plasma cell tumor, and hemangiosarcoma; the latter two being rarely diagnosed.

Intestinal cancer can be primary when the tumor first appears in the intestine, or secondary, when other cancers have spread throughout the body, including in the intestine. This cancer can be both benign (non-cancerous) and malignant (cancerous, which spreads distantly). Benign intestinal cancer, even if it does not spread distantly, can cause mechanical problems, such as obstruction of the intestinal tract.

The most common type of malignant intestinal cancer in cats is lymphoma, which is found primarily in certain breeds such as the Siamese, Oriental Shorthair, Bengal, and Maine Coon.

Clinical signs of intestinal cancer in cats can include vomiting (occasionally bloody), diarrhea (sometimes bloody), constipation, decreased appetite, and weight loss.

In this article, you will learn what types of intestinal cancer affect cats, what the clinical signs are, how it is diagnosed, how it is treated, and much more.

What Is Intestinal Cancer?

Intestinal cancer refers to the abnormal, chaotic growth of the cells in the gastrointestinal system, which leads to the formation of tumors. It is a disease of the small intestine (small intestine cancer), large intestine (colon cancer), and rectum (rectal cancer).

Intestinal cancer can be primary or secondary.

Primary Intestinal Cancer In Cats

Primary intestinal cancer originates in the gastrointestinal tract, and the tumors develop from the cells lining the intestines. It can be benign or malignant. Malignant tumors can be very aggressive and cause severe health problems. In addition, they can spread throughout the body (metastasize), such as in the lungs or other organs. Benign tumors, although they are not aggressive and do not spread in the body, can cause mechanical problems, such as intestinal obstructions, which can only be remedied surgically.

In this article, we will only talk about malignant intestinal cancers in cats.

Examples of primary intestinal cancer in cats are: lymphoma, mast cell tumor, adenocarcinoma, and leiomyosarcoma.

Secondary Intestinal Cancer In Cats

Secondary intestinal cancer refers to cancers that have spread to the intestines and other organs from other sites. In other words, these cancers originate elsewhere in the body and later invade the gastrointestinal tract.
Examples of secondary intestinal cancer in cats are: metastatic lymphoma, hemangiosarcoma, and carcinomas from other organs.  
Early diagnosis of intestinal cancer in cats and adequate treatment can lead to remission. Otherwise, the prognosis is reserved and the condition can become fatal.

What Are The Clinical Signs Of Intestinal Cancer In Cats?

Intestinal cancer affects the digestive system. As a result, clinical signs will be progressive and nonspecific, and may resemble the clinical signs of other gastrointestinal disorders, such as inflammatory bowel disease (IBD), food allergies, or pancreatitis. Here are the clinical signs you may notice:

• Decreased appetite
• Weight loss, although sometimes the appetite remains unchanged or
• may increase
• Vomiting, sometimes with blood
• Diarrhea, sometimes with mucus and/or blood
• Changes in stool color
• Trouble defecating
• Anemia
• Fever (when secondary infections occur)
• Lethargy
• Weakness
• Distended abdomen (due to fluid accumulation in the abdomen -ascites - or tumor growth)
• Bloating
• Abdominal pain and discomfort
• Behavioral changes (increased aggression, irritability, vocalization, etc.)

If you notice these clinical signs, a medical examination by a veterinarian is necessary because, as mentioned earlier, the clinical signs of cancer can be similar to those of other digestive diseases.

Types Of Intestinal Cancer In Cats

Cats can be affected by several types of intestinal cancer. In this species, the most common type of cancer is lymphoma. In addition, it is possible for cancers that have arisen in other parts of the body to spread to the intestines and other organs.

Here are the most common types of intestinal cancer in cats:

Gastrointestinal Stromal Tumor (GIST)

This type of intestinal tumor is a rare type of tumor from the group of sarcomas. GIST is formed from a type of nerve cell – interstitial cells of Cajal. These cells are part of the autonomic nervous system and are responsible for the peristalsis (contractions) of the digestive tract – they are pacemaker cells responsible for generating electrical slow waves in the smooth muscles of the gastrointestinal tract.

A 2017 study shows that this type of intestinal cancer is very rare in cats and can metastasize to the jejunum (the middle section of the small intestine) and liver, as it does in humans. Older cats are more likely to develop this type of intestinal cancer.

The causes are unknown but certain mutations, particularly in the c-KIT gene, might play a role in GIST development. In cats, this mutation is found in 30-50% of GIST cases.

The clinical signs may include the following:

• Loss of appetite
• Weight loss
• Diarrhea or constipation
• Abdominal pain and discomfort
• Vomiting

When this cancer metastasizes to other organs (liver, spleen, jejunum, etc.), other clinical signs may occur.

Take your cat to the vet if you notice clinical signs or changes in their behavior.

The prognosis for GIST in cats can be good if the tumor is completely removed via surgery. If the cancer metastasizes to other organs, the prognosis can be poor, and your cat may require symptomatic treatment.

Mast Cell Tumor (MCT)

This type of cancer develops from mast cells - cells of the immune system that are involved in various processes, such as inflammation and allergies. MCT can occur anywhere in the body (visceral MCT) or on the skin (cutaneous MCT). In cats, the most common forms of MCT are cutaneous, representing the second most common type of skin cancer in this species. However, when it occurs in the body, the spleen and intestine are the most affected, being the most common splenic cancer and third most common intestinal cancer in cats.

The clinical signs may include the following:

• Appetite loss
• Weight loss
• Intermittent vomiting
• Diarrhea
• Depression
• Lethargy
  

If these clinical signs occur, take your cat to the vet for a proper examination, diagnosis, and treatment.

Splenic and intestinal MCT are often diagnosed in advanced stages when they become more aggressive. Intestinal MCT can metastasize to the liver, lymph nodes, and other organs.

Survival is limited without treatment. The prognosis of intestinal MCT is usually poor, even with surgery.

Leiomyosarcoma

Leiomyosarcoma is an aggressive, painful type of intestinal cancer that affects the smooth muscles of the intestinal wall, which can cause intestinal obstruction. It can spread throughout the body to other organs, such as the liver and lymph nodes.

It is a rare cancer in cats, diagnosed in pets of any breed over 6 years of age. Early diagnosis is often difficult because the clinical signs are noticeable in the advanced stages of the disease.

If your cat suffers from leiomyosarcoma, you may notice the following clinical signs:

• Reduced appetite
• Weight loss
• Intermittent vomiting
• Diarrhea
• Lethargy
• Bloating
• Blood in the stool
• Black stool

Take your cat to the vet if you notice any of these clinical signs for a correct diagnosis and appropriate treatment.

The prognosis can be favorable if surgical treatment is elected. However, if metastases occur, the prognosis is poor, and survival may be only a few months.

Adenocarcinoma

Gastrointestinal adenocarcinoma can occur in any part of the gastrointestinal tract, including the stomach. Intestinal adenocarcinoma is the second most common intestinal cancer diagnosed in cats. It is an aggressive cancer that affects the intestinal lining. Adenocarcinoma develops from the glandular cells of the gastrointestinal tract. It can cause local blockages and ulcerations. In addition, being an aggressive cancer, it can metastasize to other organs, such as the liver, lymph nodes, and lungs.

The age of onset is 6-17 years, with the average age being 12 years. Clinical signs of intestinal adenocarcinoma in cats may include:

• Poor appetite
• Weight loss
• Diarrhea (sometimes bloody) or constipation
• Lethargy
• Abdominal pain

Although the clinical signs are similar to other gastrointestinal diseases, it is advisable to go to the veterinarian for a correct diagnosis and appropriate treatment.

This type of intestinal cancer has a longer median survival time compared to other intestinal cancers. As a result, cats with metastatic small intestine adenocarcinoma that had the tumor surgically removed can have a median survival time of about one year. Cats that do not have signs of metastatic disease can have a median survival time of over 2 years (after surgical treatment).

Carcinoid Intestinal Cancer

Gastrointestinal carcinoid tumors in cats is a rare type of primary malignant neuroendocrine cancer, which can affect the stomach, small intestine, colon, or rectum. This type of cancer arises from neuroendocrine cells in the intestinal mucosa, which secrete serotonin. Carcinoid cancer secretes serotonin, histamine, bradykinins, and tachykinins into the blood – the latter two being substances that are responsible for tissue contraction.

Although it is slow-growing, it is an aggressive cancer that can metastasize to other organs, such as the liver and lymph nodes.

It generally occurs in cats over 7 years of age, and the clinical signs of carcinoid cancer in cats may include:

• Progressive weight loss
• Loss of appetite
• Chronic vomiting
• Persistent or intermittent diarrhea
• Blood in the stool (melena or hematochezia)
• Abdominal pain
• Abdominal distension
• Weakness
• Extreme lethargy

See your veterinarian if your cat shows one or more of these clinical signs.

The prognosis for cats diagnosed with this type of cancer is guarded to poor. Life expectancy for pets that have been surgically treated and do not have metastases is 1-2 years, although the cases where metastases do not occur are rare. Cats that have metastases have a life expectancy of a few months, even with surgical treatment.

Plasma Cell Tumor (plasmacytoma)

Plasma cell tumors can occur anywhere in the body, including the skin, bone, bone marrow, multiple organs, and the gastrointestinal tract. However, intestinal plasma cell tumors or intestinal plasmacytoma is rare in cats – it is a less common location for feline plasmacytoma. This type of cancer is characterized by the abnormal proliferation of plasma cells in the gastrointestinal tract. It usually affects the small intestine.

Clinical signs of intestinal plasmacytoma in cats may include:

• Loss of appetite
• Weakness
• Vomiting
• Decreased activity
• Lethargy
• Distended abdomen

Take your cat to the vet for a proper diagnosis and treatment, if you notice these clinical signs.

Metastatic plasmacytoma has a poor prognosis.

Intestinal Hemangiosarcoma

Hemangiosarcoma is an aggressive cancer that can develop in any organ, especially the heart, spleen, liver, and lungs – when it occurs in organs, it is called visceral hemangiosarcoma. It develops in the endothelial cells that line the blood vessels of the gastrointestinal tract.

Intestinal hemangiosarcoma in cats is a rare cancer. The mean age of diagnosis is 13 years old.

This type of cancer can cause intestinal perforation and severe bleeding. It is an aggressive cancer that can metastasize to the spleen, liver, and lungs. It is usually diagnosed after the tumor ruptures and clinical signs of internal bleeding appear (appetite loss, bleeding, pale gums, weakness, collapse, and rapid breathing).

Clinical signs of intestinal hemangiosarcoma in cats may include:

• Lethargy
• Poor appetite
• Weight loss
• Weakness
• Frequent vomiting
• Bloody stool (melena)
• Painful abdomen
• Enlarged abdomen
• Sudden collapse when the tumor ruptures and causes internal bleeding

Hemangiosarcoma has a poor prognosis – the median survival time is several months from diagnosis. Euthanasia is often recommended due to the increased risk of tumor rupture and internal bleeding.

What Are The Causes Of Intestinal Cancer In Cats?

The exact causes of intestinal cancer in cats are not known. However, several factors make cats more prone to this terrible disease, such as:

Environmental factors – cigarette smoke or ingestion of pesticides, harmful preservatives, detergents, etc. increase the risk of intestinal cancer.

Age – Intestinal cancer is usually diagnosed after the age of 12.

Breed – Siamese, Oriental Shorthair, Bengal, and Maine Coon are breeds more prone to intestinal lymphoma. In addition, Siamese are prone to intestinal adenocarcinoma.

FeLV and FIV infections are associated with an increased risk of intestinal lymphoma.

Chronic inflammation and infections of the intestine – IBD, intestinal infections (e.g., Helicobacter spp. infection), and chronic enteritis can increase the risk of intestinal cancer.

Diet – Foods rich in carbs can contribute to intestinal inflammation and imbalances in the intestinal flora, which in turn can promote the development of cancer.

How Do Vets Diagnose Intestinal Cancer In Cats?

Diagnosing intestinal cancer, like any other type of cancer, is complex and involves multiple methods to identify the type of cancer and the stage of the disease. To confirm a diagnosis of cancer, your veterinarian will use a combination of diagnostic methods such as your pet's medical history, physical examination, laboratory tests, and imaging tests.

1. Medical History

Your vet will ask a series of questions that will help them gain a better understanding of your cat's overall health.

2. General Examination

In addition to the physical examination itself, which involves assessing your pet's vital signs (temperature, pulse, respiration, and blood pressure), palpating their body to detect swelling, tenderness, lumps, or abnormalities of internal organs, and evaluating the clinical signs, the veterinarian will also ask a series of questions about your cat's present clinical signs and behavioral changes.

Clinical signs that may be evaluated during the physical examination include bleeding, difficulty breathing, or painful swellings.

3. Laboratory Tests

If the veterinarian suspects that your cat has intestinal cancer, they may recommend the following lab tests:

Complete blood count (CBC)

CBC analyzes blood cells to assess your cat’s overall health and identify abnormalities in red and white blood cells, such as anemia, infections, or inflammation.

Blood Biochemistry

The function of each organ affects one or more specific biochemical markers. Blood biochemistry analyzes the substances in the blood. It is commonly used to diagnose various conditions, including cancer, by assessing organ function and detecting metabolic abnormalities linked to the disease.

Rapid Tests

Rapid tests are designed to detect antigens associated with various conditions in pets. Since lymphoma in cats is often linked to FeLV or FIV, your veterinarian may recommend FeLV/FIV testing if this type of cancer is suspected. These tests utilize a chromatographic method to identify the presence of (FeLV and FIV) antigens.

Fine Needle Aspiration (FNA)

FNA is a fast, noninvasive, and nonsurgical technique that can help diagnose intestinal cancer with high accuracy. This procedure involves using a fine needle to extract cells from a tumor for analysis. In cases of intestinal cancer, FNA is typically performed under ultrasound guidance and general anesthesia. The collected sample is then examined under a microscope (it is called cytological examination). However, if the results are inconclusive, the vet may recommend tumor biopsy for a definitive diagnosis.

Biopsy

A biopsy is the best method for confirming a cancer diagnosis. It is an invasive procedure, and the pet needs general anesthesia. It involves extracting a portion of the tumor (partial biopsy) or the entire tumor (total biopsy). The collected tissue is then prepared and examined under a microscope (it is called histopathological examination).

It can help determine the type of cancer, the tumor's aggressiveness, and the malignancy grade, including its potential to spread to other parts of the body.

4. Imaging Tests

Imaging tests can reveal intestinal cancer in cats. There are several methods that can be used, such as:

X-rays

X-rays can provide valuable information about obstructions, tumors, and other conditions, especially when combined with the administration of barium and air contrast into the intestine. This non-invasive method usually does not need general anesthesia or sedation.

Abdominal Ultrasound (AUS)

AUS can identify tumors in the cat’s intestine. It is a non-invasive method that usually does not need general anesthesia or sedation.

Computed Tomography (CT)

CT can be recommended to identify masses in the intestine. Although it is a non-invasive method of investigation, it does require general anesthesia because cats need to remain still.

Magnetic Resonance Imaging (MRI)

MRI can also be used to identify intestinal cancer. This method is more detailed than CT, giving more precise information about the location, size, and extent of the tumor. As with CT, it does require general anesthesia because cats need to remain still. MRI is a non-invasive method of investigation.

How Do Veterinarians Treat Intestinal Cancer In Cats?

The treatment for intestinal cancer in cats depends on several factors, such as the type of cancer, the stage of the disease, and the cat’s overall health. The treatment options your vet may recommend can include:

1. Surgery – It is the preferred treatment for localized, well-defined tumors (e.g., intestinal adenocarcinoma). The surgical procedure involves removing the tumor and a portion of the intestine (sometimes) to prevent the cancer from spreading throughout the body.

2. Chemotherapy – Chemotherapy drugs are used to kill cancer cells, especially in aggressive or metastatic cancers. It may be recommended alone or in combination with surgery, depending on the severity of the cancer.

3. Supportive Care – To maintain your cat’s comfort and improve their quality of life, your veterinarian may recommend pain medication, anti-inflammatories, nutritional supplements, and fluids.

4. Diet – If your cat is still able to eat, your veterinarian may recommend a special diet that can help maintain their weight and overall health.

As with any type of cancer, the success of treatment for intestinal cancer in cats depends on the type of cancer and the time of diagnosis. The sooner intestinal cancer is diagnosed, the more effective the treatment can be and the better the prognosis.

How Can You Support Your Cat With Natural Products In Their Fight Against Intestinal Cancer?

Zumalka offers a range of natural products designed to assist your cat in their battle against intestinal cancer. These products help strengthen your pet’s immune system, support the health of their internal organs, and create an improper environment for cancer cells that thrive in acidic environments and inflamed tissues.

One product that can help your cat with intestinal cancer is PIPTOPET, a mother tincture that can strengthen your cat’s immune system and help them fight intestinal cancer better.

PIPTOPET’s key ingredient is Fomitopsis betulina, a medicinal mushroom used for centuries by people for various diseases and ailments. Studies performed on dogs, mice, and monkeys, showed the multiple health benefits Fomitopsis betulina has, such as: anti-inflammatory, antitumoral, antiviral, antibacterial, and antioxidant.

Other natural products that go very well in combination with PIPTOPET for intestinal cancer in cats are:

TONICPET #4: Enhances the body's natural immune defense and supports proper oxygen circulation throughout your cat’s body.

TONICPET #5: Helps maintain healthy blood circulation and an optimal functioning of all your cat’s body systems.

TONICPET #7: Enhances your cat's natural immune response and facilitates healthy oxygen flow to the deeper skin layers.

Additionally, TONICPET #4, 5, and 7 help maintain a healthy inflammatory response, as cancer cells tend to thrive in inflamed environments.

TONICPET #10: Helps maintain optimal acidity balance in your pet’s body while supporting a healthy digestive system. Since cancer cells thrive in acidic environments, TONICPET #10 encourages a more balanced environment to help prevent tumor growth.

By combining these products, you are giving your cat a powerful and natural way to improve their immune system and overall health, while also promoting environmental conditions that prevent the growth of cancer cells.

Frequently Asked Questions (FAQs)

How Long Do Cats With Intestinal Cancer Live?

The average survival time depends on several factors, such as the type of intestinal cancer, its stage, and the cat's general health. In very aggressive types of intestinal cancer, cats can survive for several months, even with surgical treatment if the cancer has metastasized. In cases where the cancer has not spread throughout the body, cats can survive for over a year after surgical treatment (although these cases are rare).

Is Intestinal Cancer In Cats Treatable?

Yes, sometimes treatments can put intestinal cancer into remission. However, the success of treatment depends on several factors, such as the type of intestinal cancer, its stage, and the cat's general health.

When To Euthanize A Cat With Cancer?

The decision to euthanize your pet is heartbreaking. However, this decision must be made to end their suffering. As a result, if your cat with cancer is rapidly losing weight, is weak, is in pain, starts to eat less, has vomiting or diarrhea, is lethargic, and depressed, then it may be time to let them go.

Is It Worth Treating A Cat With Cancer?

It is always worth trying to prolong your cat's life and well-being. Although most cancers in cats are treatable, treatment is rarely curative. As a result, you should focus on prolonging their life while maintaining a good quality of life.

How Do You Know If Your Cat Has Stomach Cancer?

A cat with stomach cancer may show various clinical signs such as chronic vomiting (sometimes bloody with coffee grounds appearance), decreased appetite, weight loss, and lethargy. Clinical signs are progressive, being difficult to notice in the early stages of the disease. Keep in mind that the clinical signs of gastrointestinal cancer are similar to those of other conditions at this level.

How Do I Know If My Cat Has Bowel Cancer?

If your cat has bowel cancer, you may notice the following clinical signs: decreased appetite, weight loss, intermittent vomiting, lethargy, and diarrhea (sometimes bloody) or constipation. As with stomach cancer, the clinical signs of bowel cancer are progressive, making it difficult to identify them in the early stages of the disease. In addition, they are similar to those of other intestinal diseases (e.g., inflammatory bowel disease IBD).

What Is The Prognosis For A Cat With Abdominal Mass?

A cat with an abdominal mass can live from a month or less to over a year, depending on its nature (benign or malignant) and size. Intestinal masses carry a risk of bleeding - they can rupture and lead to internal bleeding, which can be fatal.

How Do You Know When It's Time To Euthanize A Cat With Cancer?

This heartbreaking decision must be taken when your pet is suffering, is in pain, loses weight rapidly, doesn’t eat anymore, is weak, has vomiting or diarrhea, and is depressed. Euthanasia is a humane option to end a pet's suffering when their quality of life is severely compromised.  

What Are The Symptoms Of End Stage Intestinal Lymphoma In Cats?

If your cat has end stage intestinal lymphoma you may notice the following clinical signs: chronic vomiting, diarrhea, severe lethargy, muscle wasting, abdominal pain, and rapid weight loss. In the late stages, the lymphoma can spread to the spleen, liver, and bone marrow.

Is Intestinal Cancer In Cats Painful?

Yes, most types of intestinal cancer in cats are painful, especially as the disease progresses. The tumors can cause blockages, inflammation, or ulceration, which can lead to pain. In addition, as the cancer spreads throughout the cat's body and affects the surrounding tissues, it can lead to abdominal distension, pain, and discomfort. Cats can also feel pain if the tissues become damaged or infected.

How To Tell If A Cat Has Cancer?

Cancer does not have specific clinical signs. As a result, cats with cancer may present clinical signs similar to other conditions, such as vomiting, diarrhea, weight loss, lack of appetite, lethargy, lumps on or under the skin, difficulty eating, difficulty breathing, etc. Clinical signs depend on the type and location of the cancer. For example, in osteosarcoma of the jaw, cats may present with pain when chewing, difficulty eating, refusal of food, facial deformity, etc.; these clinical signs will not occur in mammary cancer.

How To Tell If Your Cat Has A Stomach Tumor?

A cat with gastric cancer may exhibit clinical signs such as chronic vomiting (sometimes bloody, with a coffee-ground appearance), loss of appetite, weight loss, and lethargy. These signs become more obvious as the disease progresses, and are more difficult to notice in the early stages of the disease.

It is important to note that the clinical signs of stomach cancer can resemble those of other digestive tract conditions (e.g., gastric ulcer).

What Is The Prognosis For Intestinal Cancer In Cats?

The prognosis of intestinal cancer varies depending on the type of cancer, its stage, treatment, and the general health of the cat. As a result, the average survival time for intestinal cancer in cats is between a few months and over a year. Cats treated surgically, without metastases, have a longer survival time. Those with metastases or untreated have a survival time of a few months from diagnosis. The earlier the diagnosis and treatment are made, the greater the chances of increasing their survival time.

What Are The Signs And Symptoms Of Intestinal Cancer In Cats?

The clinical signs of intestinal cancer in cats are nonspecific and can easily be confused with those of other diseases of the gastrointestinal tract (e.g., pancreatitis, IBD). Therefore, it is important for your veterinarian to recommend additional tests for a correct diagnosis. Clinical signs of intestinal cancer in cats may include decreased appetite, progressive or rapid weight loss, vomiting and diarrhea (sometimes bloody), lethargy, a distended abdomen, and abdominal pain.

How To Tell If A Cat Has Colon Cancer?

It is very difficult to tell if a cat has colon cancer without additional tests even for a vet because the clinical signs are similar to those of other gastrointestinal conditions. Therefore, clinical signs of colon cancer in cats may include diarrhea (sometimes bloody), constipation, abdominal pain and discomfort, bloating, gas, and lethargy.

How Common Is Stomach Cancer In Cats?

Stomach cancer is rare in cats. However, it is a serious health problem for our little felines. Early diagnosis and appropriate treatment can prolong your cat's life and improve their quality of life. 

About the author

Dr. Iuliana Mihai, DVM, MSc, PhD

Iuliana Mihai, DVM, MSc, PhD, is a Bucharest-based veterinary expert specializing in internal medicine and oncology.

Her work has been published in reputable publications such as Veterinary Medicine Journal, Catster.com, Dogster.com, Hepper.com, Meowiz.com, Springnaturals.com, Petkeen.com, and Wilderharrier.com.

She is a malpractice and negligence veterinary consultant and a graduate of The University of Agronomic Sciences and Veterinary Medicine and The Romanian Academy.

Read the complete profile of Dr. Iuliana Mihai, DVM, MSc, PhD (Veterinarian) here.