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Stomach and Intestinal Cancer in Cats
Written By hannah hollinger
Published: 10/27/2016Updated: 01/13/2022
Veterinary reviewed by Michele K.
What is Stomach and Intestinal Cancer?
Types of gastrointestinal cancers include adenocarcinoma, leiomyosarcoma, lymphoma, and mast cell tumors. Older cats have a predisposition for developing gastrointestinal cancers. Feline leukemia virus and immunodeficiency virus may also play a role in the development of gastrointestinal cancer.
Stomach and intestinal cancer is a rare type of feline cancer, accounting for less than one percent of all reported cancers in cats. Gastrointestinal cancers are most commonly found in the small intestine. Stomach and intestinal tumors can be benign, but are typically malignant and aggressive. 
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Symptoms of Stomach and Intestinal Cancer in Cats
Cats suffering from stomach or intestinal cancer will almost always show changes in eating habits due to tumors in the gastrointestinal tract. Stomach and intestinal cancers are serious conditions that require early detection for the best prognosis. If your cat is exhibiting any of the following symptoms, seek immediate veterinary attention:
  • Changes in behavior
  • Lethargy
  • Loss of appetite
  • Vomiting
  • Diarrhea
  • Blood present in vomit or feces
  • Weight loss
  • Depression
  • Difficulty defecating
  • Abdominal pain or swelling
  • Signs of abdominal infection
  • Masses in the abdomen
  • Pale gums or other signs of anemia
Types
Adenocarcinoma
Adenocarcinomas located in the digestive system usually affect the large and small intestines. This type of gastric cancer is extremely rare in cats and doesn’t usually affect the stomach. Adenocarcinomas grow rapidly, tend to be aggressive during metastasis, and may cause blockages in part of the intestines.
Leiomyosarcoma
This type of tumor can be benign or malignant and originates within the smooth muscle. Leiomyosarcoma can occur in any part of the body, but most commonly affects the gastrointestinal tract. Malignant leiomyosarcomas have a high metastatic rate and typically spread to the lymph nodes and liver.
Lymphoma
Lymphoma is a type of aggressive malignant cancer that originates from an uncontrolled growth of lymphocytes. Lymphocytes are a type of white blood cell that protects the cat from foreign bodies or substances that may cause disease. Lymphoma can affect any part of the body, but is most commonly found in the gastrointestinal tract. Lymphoma is the most common type of gastric cancer in cats.
Mast Cell Tumors
Mast cells, like lymphocytes, are a type of white blood cell. While mast cell tumors typically form on the skin, they may also affect the gastrointestinal tract. Bleeding ulcers may be symptomatic of mast cell tumors, and Siamese cats in particular have a predisposition to developing mast cell tumors.
Causes of Stomach and Intestinal Cancer in Cats
The cause of stomach and intestinal cancer in cats will depend on the type of cancer and where it originated. As with most types of cancer anywhere in the body, gastrointestinal cancers are caused when cells begin to grow at an uncontrolled rate. Lymphoma, in particular, may be caused by a previous bout of feline leukemia virus (FeLV) or the immunodeficiency virus. The link, however, is not fully understood by researchers.
Diagnosis of Stomach and Intestinal Cancer in Cats
The vet can make a tentative diagnosis based on presentation of symptoms and a physical examination. Be sure to inform the vet of the duration and extent of your cat’s symptoms, as well as any previous stomach or intestinal problems. An x-ray and a biopsy of the abdominal tissue will be required for a definitive diagnosis. The vet may also conduct other forms of standard testing to assess whether the cancer has spread. In some cases, the vet may perform a gastroscopy, which will require anesthetic.
Treatment of Stomach and Intestinal Cancer in Cats
Treatment will depend on the type and stage of the cancer. Surgery is required for most types of gastrointestinal cancers, apart from lymphoma. Gastrointestinal lymphoma may be partially treated through surgery, but will typically require chemotherapy to ensure the best prognosis possible. 
Before surgery, your vet will run some standard tests, including a blood chemistry profile, blood count, and urinalysis. They may also perform additional x-rays to ensure the cancer hasn’t spread to other organs. The surgery itself will usually involve the partial removal of the stomach and/or affected intestine. The veterinary surgeon will then reconnect the stomach to the intestine. Since radiation therapy can harm nearby organs, this is not usually recommended for most cases of gastrointestinal cancer.

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Recovery of Stomach and Intestinal Cancer in Cats
Your cat will typically be hospitalized for two days following surgery, and will receive intravenous fluid therapy during this recovery period. Your vet may prescribe anti-vomiting and pain management medication, as well as antacids to prevent stomach ulcers. 
On the return home, ensure that your cat has a warm, secure place to rest. You’ll need to limit activity for up to three weeks to allow for adequate recovery, and don’t allow the cat to irritate the surgery site. If you notice any bleeding, swelling, or irritation of the surgery site, contact your vet immediately.
If your cat requires chemotherapy – which will be recommended for most malignant tumors – the vet will schedule follow-up appointments to administer chemotherapeutic drugs via injection. These treatments will begin two weeks after surgery and will occur once every two to three weeks for up to five sessions.
Prognosis will depend on the aggressiveness and stage of the cancer at the time of operation, as well as the success of the operation itself. Surgery may be completely curative for benign tumors. Malignant gastrointestinal cancers tend to have a poorer prognosis and a higher recurrence rate.
Stomach and Intestinal Cancer Average Cost
From 352 quotes ranging from $3,000 - $10,000
Average Cost
$7,000
Top
Stomach and Intestinal Cancer Questions and Advice from Veterinary Professionals
cat
Eleven Years

11 found this helpful

11 found this helpful

My pet has the following symptoms:
Rapid Weight Loss, Vomiting, Stinky Stool
So this one is strange. Lost family cat to what they said was stomach cancer (no scan though so not confirmed). When diagnosed they said she would only last 2 months but she miraculously got better and lived 1.5 more years bit quickly fell ill again with symptoms described plus crazy high appetite and had a seizure she did not wake from. A few months later the other family cat is showing same symptoms (but no crazy appetite only symptoms listed above) and they think it is stomach cancer as well!!!?? Another idea they had was IBD. This seems too coincidental could this be a parasite or something.
Nov. 9, 2020
Answered by Dr. Michele K. DVM
11 Recommendations
Thank you for your question, I am very sorry that this is happening. Those signs are not common, and causes of ascites include heart failure, liver disease, or a protein losing disease. If your veterinarian thinks that there is a cancerous process in the stomach, that may be contributing to a protein loss. Perhaps an abdominal ultrasound would be a good idea, to further explore what might be causing this problem.
Nov. 9, 2020
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Cat
Sophie
10 Years

14 found this helpful

14 found this helpful

My pet has the following symptoms:
Lethargy Loss Of Appetite Weight Loss
Lethargy Loss Of Appetite Weight
Hello I have a 10 year old female cat veterinarian did blood work and said it was lymphoma. Her abdomen is distended. She is only drinking a little beef broth.She is not responding to furosemide. What options do I really have for her ?
Aug. 20, 2018
Answered by Dr. Michele K. DVM
14 Recommendations
From your description, the only real option that is kind for her would be to let her go, humanely, in my opinion. She does not sound like she is having any quality of life, and it is important to make sure that she isn't suffering. I'm very sorry that is happening to your Sophie.
Aug. 20, 2018
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Siemese
Tucker
5 Years

5 found this helpful

5 found this helpful

My pet has the following symptoms:
Weight Gain
Mass In Abdomen
Hello, my cat is 5 years old next month. He is a male. Lately he’s put on a lot of weight (we got a new kitten and he gets into the kitten food). Then today I noticed he has these mass type things in his fat pouch. He doesn’t like his belly touch so it was hard to tell if they hurt him or if he was just annoyed with me but when I was trying to feel them he was not having it.
Aug. 12, 2018
5 Recommendations
Any new lump or bump should be checked by your Veterinarian, I cannot say whether or not this is something to be concerned about or not without examining Tucker myself; keep an eye on the size and pop into your Veterinarian for a check to be on the safe side. Regards Dr Callum Turner DVM
Aug. 12, 2018
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tabby
Sparky
14 Years

8 found this helpful

8 found this helpful

My pet has the following symptoms:
Diarrhea
We have a 14 yr. old male neutered cat. 7 months ago he was perfectly healthy, at 13 lbs. now he weights 6 lbs. We have run test on him and all blood work came back normal, except a couple spots in his feces sample. Was put on antibiotics and probiotics. Severe case of diarrhea, horrible smell. We have changed his diet to prescription hill I/d. Is this a sign of cancer?
Aug. 5, 2018
8 Recommendations
Foul smelling diarrhoea is normally associated with parasites like Giardia, however other conditions may also cause severe diarrhoea too including dietary intolerance among other causes; foul smelling diarrhoea isn’t an indicator for gastrointestinal cancer but together with other symptoms may be suggestive, however you should return to your Veterinarian for a follow up examination if there is no improvement. Regards Dr Callum Turner DVM
Aug. 5, 2018
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Ginger domestic
Peaches
5 Years

4 found this helpful

4 found this helpful

My pet has the following symptoms:
Loss Of Appetite
Fatigue
Not Drinking
Mass swelling in pets abdominal area and loss of appetite.. she isn't drinking and very fetigued. . She went out for 12 hours in the garden and never came in for food or water and just stayed asleep in her spot in the garden
July 22, 2018
4 Recommendations
Without examining Peaches I cannot say what the specific cause is, but if you’re feeling an abdominal mass you should visit your Veterinarian for an examination to be on the safe side. There are many different types and origins for abdominal masses, so it is impossible to narrow down the cause and many of them may lead to lethargy, loss of appetite and other symptoms. Visit your Veterinarian as soon as possible for an examination. Regards Dr Callum Turner DVM
July 22, 2018
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Persian
Baby Zog
13 Years

0 found this helpful

0 found this helpful

My pet has the following symptoms:
Lethargy
Loss Of Appetite
Won'T Drink
Loss Of Mass
13 year old Persian stopped eating and drinking, lost so much weight I took her to the vet. He said she has a mass in her stomach. Bloodwork came back clean. ER vet did an ultrasound, found thickening in 4 inches of intestine. Says it is GI Cancer, 6 months to live, tops. Given her advanced age surgery / chemo was ruled out. I am coaxing her to eat and syringe feeding her food and fluids but do not know what else I can do. Can you tell me if she is in pain? I cannot bear to see her slowly starve to death but I don't want to be remembered as the hated cruel human who force fed her.
Cali
Ms Millie
10 Years

0 found this helpful

0 found this helpful

My pet has the following symptoms:
Loss Of Appetite,
We just lost our Ms Millie,she started pooping in the house on n off,from time to time,we found a rash on her neck,like a ring worm,she was loosing her hair and her appetite,the Vet,did a couple of blood samples,didn’t inform us the results,in the mean time our poor ms Millie started loosing weight rapidly,her hair refused to grow back,she became very Very skinny,she was about 18 lbs,before she got 🤒 ,Reduced to barely a few lbs,her fur had a very funny porcupine like shape with this sickness her pooping became difficult for poor thing,she stopped using her litter box,she stopped eating drinking water,finally she seemed she couldn’t fight anymore,she passed on in her sleep last Thursday morning.
Cat
Fluffer Nutter
12 Years

0 found this helpful

0 found this helpful

My pet has the following symptoms:
Anemia
My 13 year old Fluffer Nutter, has blood present in his free fluids, weight loss, and low red blood cell count. Our vet did a CBC and xray. Told us it was most likely a tumor. We were sent home with nothing, and told he is terminally ill I have been giving him Lasix, a slurry of food and water, tinic ,hydralate and am waiting for a delivery from a Canadian company with an herbal treatment for anemia. He has responded to the lasix, and his breathing is no longer labored. He is weak, has urinated and his feces is just a nugget, brownie like consistency. I am feeding baby food (meat only) in the slurry. He is drinking water 4 o and sometimes food moist or wet on his own. Hoping the meds for anemia arrive today, don't know what else to try. His condition developed over several months. Last year he was treated for fatty liver by the vet. Advice please.
Short hair domestic
Salem
8 Years

0 found this helpful

0 found this helpful

My pet has the following symptoms:
Diahea
Diahea , Vomiting , Bood In Poop ,
I think that my cat was coming in contact with poisons around the apt. complex . Roach poison , rat poison herbicides ( R.U. ) ect. That gave my cat stomach cancer .
Cat
Kelsey
15 Years

0 found this helpful

0 found this helpful

My pet has the following symptoms:
Vomiting
Lethargic
Lymphoma
15 year old female neutered cat. She’s been vomiting pinkish brown liquid and following ultrasound vet says she has thickening /enlargement of her stomach and it’s walls. They’re saying it’s lymphoma but don’t want to do any more invasive tests. She doesn’t move very much during the day apart from to use her litter tray - she eats and purrs though. Always been v food oriented!! They won’t give her any pain relief and have said it’s up to us but given no real guidance!
Stomach and Intestinal Cancer Average Cost
From 352 quotes ranging from $3,000 - $10,000
Average Cost
$7,000

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