How to Diagnose Feline Intestinal Lymphoma

Last Updated: July 9, 2022 References

Lymphoma is a cancer of lymphocytes, which are white blood cells that are part of the immune system.^{[1]
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Research source} It is the most common type of cancer in cats. Lymphoma can spread to many parts of a cat's body, with the gastrointestinal tract being the most common location. Intestinal lymphoma requires veterinary treatment,^{[2]
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Research source} so it will be important for you to recognize the signs of this cancer and take your cat to your vet for a diagnosis.

Part 1

Part 1 of 2:

Observing Symptoms at Home

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Write down when you first notice symptoms. Feline intestinal lymphoma progresses slowly, with symptoms gradually getting worse over one to three months.^{[3]
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Research source} Knowing how long the symptoms have been going on will help your vet accurately diagnose your cat.
- The symptoms of feline intestinal lymphoma are vague and occur with many other illnesses in cats.^{[4]
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- Don’t worry if lymphoma doesn’t immediately come to mind when you notice the symptoms. Your vet will be able to make the diagnosis.
2
Detect a decreased appetite. Interestingly, a large part of your cat’s immune system is in the digestive tract. When the lymphocytes in your cat’s digestive tract become cancerous, your cat will experience digestive upset. With intestinal lymphoma, your cat will lose its appetite.^{[5]
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Research source} Monitor your cat’s appetite by paying close attention to how much (or how little) your cat eats at meal time.
- In addition to eating less, your cat will start to lose weight. Decreased appetite and weight loss are two of the most common signs of feline intestinal lymphoma.^{[6]
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3
Watch for vomiting. In a cat with intestinal lymphoma, vomiting usually comes after the initial loss of appetite and weight loss.^{[7]
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Research source} It is another common sign of this cancer, occurring in about 50% of cats with feline intestinal lymphoma.^{[8]
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4
Look for changes in your cat’s defecation. Observing your cat’s feces doesn’t sound very pleasant, but it can help with diagnosing intestinal lymphoma. Your cat’s defecation could change in different ways, including diarrhea or constipation. You may also see tinges of blood in the feces. Changes in defecation are less common than appetite loss, weight loss, and vomiting.^{[9]
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- If your cat is constipated, you’ll see fewer feces in the litter box.
- Diarrhea occurs in about 30% of feline intestinal lymphoma cases.^{[10]
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Observe other symptoms of intestinal lymphoma. Sometimes, cats with feline intestinal lymphoma will start drinking and urinating more. They might also develop a swollen abdomen. Other cats with intestinal lymphoma might start eating inedible objects, like paper or cardboard.^{[11]
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- Eating inedible objects is called pica.

Part 2

Part 2 of 2:

Getting a Veterinary Diagnosis

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Have your vet perform a physical exam. Feline intestinal lymphoma requires a veterinary diagnosis. First, your vet will perform a physical exam, paying special attention to your cat’s abdomen. Your vet may feel enlarged abdominal lymph nodes. They may also feel thickened loops of intestine and/or masses within the intestinal walls.^{[12]
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- The abdomen may feel completely normal, even if the lymphoma is advanced.^{[13]
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  Research source} Your vet will need to perform other tests to diagnose intestinal lymphoma in your cat.
- Your vet will also listen to your cat’s heart and lungs.
- During the physical exam, give your vet a history of your cat’s symptoms. Explain when you noticed them, how long you’ve noticed them, and if they’ve gotten worse over time.
2
Allow your vet to take blood samples. After the physical exam, your vet will recommend other diagnostic tests. Blood work can be useful for diagnosing feline intestinal lymphoma. For example, your vet will use a blood sample to test your cat for feline leukemia (FeLV) and feline immunodeficiency virus (FIV). Cats that are positive for either of these viruses are at risk for developing lymphoma.^{[14]
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- Your vet will also analyze your cat’s blood work for anemia, which is the most common blood work abnormality in cats with intestinal lymphoma.^{[15]
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  Beatty J and Barrs V. J Feline Med Surg. 2012;14(3):182‒190.} Anemia is a decrease in red blood cells.
- Your vet will also check your cat’s blood for levels of Vitamin B12 and folate. Blood levels of these two nutrients are commonly reduced in cats with intestinal lymphoma.
- Thyroid testing is also useful to rule out hyperthyroidism (overactive thyroid gland) as a cause for your cat’s symptoms.^{[16]
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  Geiger T. Vet Clin Small Anim. 2011;41(2): 419–432.} Hyperthyroidism can cause vomiting, diarrhea, and weight loss.
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Agree to diagnostic imaging tests. Imaging techniques, such as ultrasounds and x-rays, are also useful in diagnosing feline intestinal lymphoma. Abdominal x-rays will help your vet identify intestinal problems, such as intestinal wall thickening and obstructions. Chest x-rays will show whether the lymphoma has spread to the lungs.^{[17]
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Geiger T. Vet Clin Small Anim. 2011;41(2): 419–432.}
- An abdominal ultrasound will show intestinal wall thickening and enlarged abdominal lymph nodes.
- Your vet can use ultrasound to take a sample of affected tissue to confirm the diagnosis. This is called an ultrasound-guided fine needle aspiration (FNA). An FNA is a collection of cells taken with a thin needle.
4
Discuss options for taking a tissue sample. The most definitive way to diagnose feline intestinal lymphoma is with a sample of affected tissue. This sample can either be a biopsy (large piece of tissue) or ultrasound-guided FNA.^{[18]
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Research source} Your vet can take a biopsy using endoscopy or surgery. Each procedure, which require anesthesia, has its advantages and disadvantages:^{[19]
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Geiger T. Vet Clin Small Anim. 2011;41(2): 419–432.}
- Endoscopy is less invasive and faster than surgery, making it a good option for very sick cats. However, the endoscopy tube can reach only limited sections of the intestines. Also, the sample taken via endoscopy will not be as thick as that taken during surgery.
- Surgery allows for a thicker tissue sample that can be analyzed more thoroughly. However, surgery is invasive.
- Discuss the pros and cons of each procedure with your vet to decide which procedure would be best for your cat.