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Cats are very stoic animals and they are masters of hiding disease and illness. For this reason, vomiting in cats is often brushed off as normal behaviour. Some cats may appear completely healthy and vomit every now and then. If your cat vomits more than twice a month, or if the frequency of their vomiting has increased, or if they have lost weight, it is probably time for a visit to the vet! 

There are many causes of vomiting in cats. Some cats enjoy eating grass and other plants and may frequently vomit. Sometimes, restricting their access to grass and plants may solve the problem. However, vomiting is often due to a more serious underlying disease which needs to be diagnosed in order to treat it specifically. Some commonly diagnosed conditions include: 

• Dietary intolerance/hypersensitivity 
• Inflammatory bowel disease (IBD) 
• Renal disease (chronic kidney disease, CKD) 
• Hyperthyroidism 
• Chronic gastritis 
• Gastric and intestinal obstructions
• Gastric and intestinal cancer (lymphoma, adenocarcinoma, mast cell tumours) 
• Furballs (though this can be due to other underlying intestinal disorders that affect gut motility, such as IBD) 
• Parasites 

Some long haired cats do indeed swallow a lot of hair while grooming and hairballs can develop in their stomachs, so this can be considered to be normal. However, this is not the case in all cats, and especially not in short haired cats. A significant number of cats that bring up hairballs have underlying stomach and/or intestinal disease such as IBD and lymphoma. Both of these diseases often cause reduced motility of the gastrointestinal tract and as a result, hair is unable to move through the digestive tract at a normal speed. This causes the hair to build up into large balls that we end up finding around the house and very inconveniently, on our carpets! Sometimes, hairball diets that are high in fibre or medications can help to manage this if there is no underlying cause to their hairballs other than lots of long hair. We will explain both of these disease processes further below. 

In order to investigate the root cause of vomiting, a thorough physical examination needs to be performed first. Depending on the physical examination, your vet will then be able to recommend which tests to start with. In most cases, we start with comprehensive blood tests and urine tests to check organ function. In older cats, we will recommend checking their thyroid hormone levels as well to rule out hyperthyroidism. In younger cats, we may also recommend examining their faeces. 

Most cats will also require abdominal imaging to look for structural disease. Usually, this involves abdominal ultrasounds and/or abdominal x-rays. An abdominal ultrasound is non-invasive and is very useful for assessing diseases that affect the stomach, small intestines and other abdominal organs such as the kidneys, pancreas, and many more. Our high frequency, high resolution ultrasound machine is capable of measuring increases in the thickness of the intestinal layer down to the tenth of a millimetre. If intestinal thickening is found, there are 2 primary possible diagnoses: inflammatory bowel disease (IBD) and lymphoma, although about 5% of the time, another disease will be identified. The only way to differentiate between IBD and lymphoma is by performing full thickness biopsy samples of the small intestinal wall via abdominal surgery. Endoscopic biopsies are rarely recommended because these types of samples only samples the internal surface layer of the intestines, however most pathology in feline intestines is found in the deeper layers. The biopsy samples are sent to a pathologist who will examine the samples and determine if IBD or lymphoma is present and will also be able to classify the type of each disease. Once a diagnosis is made, a specific treatment plan can then be made and we can determine the prognosis. 

INFLAMMATORY BOWEL DISEASE: 

IBD affects about 50% of cats that have significant intestinal thickening. It occurs due to chronic inflammation of the gastrointestinal tract and can be caused by many diseases such as bacterial and parasitic infections, and food allergies. However, in many cases, the cause of IBD remains unknown or is classified as “idiopathic”. Studies suggest that idiopathic IBD can be due to a breakdown in the relationship between bacterial populations in the gut and the immune system of the gastrointestinal wall. It is important to note that IBD in cats is an entirely different disease process to IBS (irritable bowel syndrome) in humans. Inflammation in the gut interferes with the digestion and absorption of nutrients and as a result, cats with advanced IBD very typically have a history of weight loss despite an increased appetite as they attempt to make up for their nutrient deficiencies. Often, cats with this disease will also vomit (commonly hairballs) and this is due to the poor motility of the thickened intestines. 

Depending on the severity of the disease, a change in diet to hypoallergenic or anallergenic foods (also known as an elimination diet) combined with the use of immunosuppressive drugs (such as prednisolone) is usually the first step in managing this disease. However, in more severe cases, more potent drugs such as chlorambucil are used. Chlorambucil is a type of chemotherapy drug that is used to effectively manage severe IBD. As mentioned above, the inflammation in the intestines results in poor absorption of some nutrients; very commonly, cats with IBD will have lower levels of vitamin B12. Therefore, it is also important to regularly assess their vitamin B12 levels. If your cat is deficient in vitamin B12, injectable supplements are available. 

Unfortunately, IBD is not curable. However proper management and regular monitoring can control the disease and stop or slow the vomiting and weight loss. 

LYMPHOMA: 

Lymphoma is a type of cancer that affects lymphoid tissue. Lymphoid tissue is found in many tissues in the body such as the intestines, stomach, spleen and tonsils. The greatest concentration of lymphoid tissue is found in the intestines and this is why lymphoma commonly occurs in the gut. Lymphoma accounts for about 45% of the cases of intestinal wall thickening and it occurs in two forms: small cell lymphoma and lymphoblastic or large cell lymphoma. A biopsy is required to diagnose lymphoma and to distinguish between its different forms. 

Lymphoma is a very responsive type of cancer in cats and up to 90% of cases undergoing treatment will experience complete remission with minimal side effects. Most treatments will involve the use of a combination of chemotherapy drugs called a “protocol”. Thankfully, cats do not tend to experience the many side effects that humans do, and only very rarely will experience nausea or vomiting. Many owners are surprised and relieved to find that almost all cats undergoing chemotherapy treatment go through their protocol with minimal to no side effects! 

One side effect of chemotherapeutic agents is suppression of the bone marrow. Although this is uncommon, we carefully monitor every cat’s bone marrow function by taking regular blood samples to assess their white blood cell count. If their blood cell count drops too low, chemotherapy treatment is ceased until their blood cell count returns to normal. 

Your cat will not go bald from its chemotherapy treatment. This is because chemotherapy only affects hair that grows continually. Body hair in cats does not grow continually (this is why short haired cats remain short haired and never grow long coats). However, some cats may lose their whiskers with some treatments. Hair re-growth in shaved areas tends to be sparse whilst on chemotherapy treatment. 

Treatment for the two types of lymphoma carries different prognoses. Cats with lymphoblastic lymphoma have lower success rates. Fortunately, only about 15% of the lymphoma cases are of this type. Although many cats respond well to treatment, the prognosis is always guarded. Cats with small cell lymphoma have a much higher success rate. About 70% to 75% of cats will go into remission. The average time of remission is about two years, although we have seen cats live more than four years in remission. It is important that we have realistic goals when treating cancer. Thus, you will often hear the term “remission” used more than “cure”. Remission is when the cat’s vomiting or diarrhoea stops, their appetite returns to normal, lost weight is regained, and the small intestinal wall returns to its normal thickness. 

How do we stop the conversion to cancer?

If your cat is vomiting hairballs, it is important not to ignore this. Evidence shows that IBD may transform into intestinal lymphoma if left unmanaged. Many cats that have been vomiting for months to years are found to have lymphoma. In many cases, their vomiting worsens or their weight loss becomes substantial and only then will an abdominal ultrasound be performed, triggering the investigation process. Therefore, early diagnosis and treatment of IBD is strongly recommended as it is likely to dramatically reduce the risk of possible progression into lymphoma. 

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