The classic dramatic heaving sound of a vomiting cat is enough to make most cat owners spring into action to find the source of the tale-tell gagging. If you find that your cat has merely brought up a small amount of yellow or green frothy fluid, rather than the huge avalanche of vomitus that their theatrical performance was implying would happen, is this cause for relief – or concern? In this blog, we look into the reasons why your cat may be vomiting bile, and when to be concerned. 

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What is bile?

If your cat is vomiting small amounts of yellow or green, frothy liquid, this is usually bile and stomach juices. Bile is a digestive fluid produced in the liver and stored in the gall bladder. The gall bladder is stimulated by food, and releases bile into the small intestine to aid digestion. Bile contains bile salts and bilirubin, which help break down fats in food, and carries various nutrients along the digestive process. 

If there is no food entering the stomach to stimulate the gall bladder to contract and expel bile, this fluid can then overflow and back up into the stomach and small intestine. It is very irritating to the stomach lining and causes vomiting. The vomit is usually seen as small amounts of frothy fluid, and is yellow to green in colour. 

Why do cats vomit bile?

Vomiting bile usually occurs because the stomach is empty for too long; leading to bile and stomach juices building up in the stomach and causing irritation. If your cat vomits very infrequently, this may not be too much of a concern. But regular instances will need some investigation. 

There are a few reasons why vomiting bile can occur in cats. 

Feeding schedule

If your cat is only eating once daily, the interval between meals may be too long, allowing bile fluid to build up and overflow back into the stomach. If you notice your cat vomiting yellow fluid, perhaps try and adjust their feeding schedule for more regular mealtimes. Cats who are prone to bilious vomiting often do well on a schedule of multiple small meals, rather than one large one.  

If you own multiple cats, make sure that none of the cats are having their access to the food bowls restricted by another cat, and that there are plenty of resources for each cat. If you have been restricting your cat’s food due to weight management reasons, perhaps try a puzzle feeder or food ball. This allows regular food intake without excess, plus a little exercise and enrichment on the side!

Gastrointestinal disorders

There are various disorders of the gut that can lead to vomiting. Anything which disrupts the normal transit of food through the digestive system, or irritates the stomach and small intestinal lining, may lead to nausea and vomiting. 

Here are some candidates:

  • Dietary indiscretion – your cat has eaten something which has upset the stomach.
  • Gastritis – inflammation of the stomach.
  • Food hypersensitivities or allergies
  • Gastrointestinal obstruction – if the gut is blocked, cats may vomit up food which cannot pass, but then continue vomiting bile after the stomach is empty.
  • Gastrointestinal cancers

Other illness

Health conditions which cause a reduced appetite may also lead to cats vomiting bile, as the stomach is empty for long periods. Some illnesses also cause chronic nausea, which can lead to bilious vomiting when the stomach is empty. 

When to be concerned

It is always worrying to think that your pet may be unwell. If your cat vomits bile just once, and there are no other signs of illness, then it is likely safe just to monitor your cat carefully. They should be eating a complete and balanced diet for their age and lifestyle. And they should be eating and drinking regularly but not excessively. Check that your pet’s parasite prevention plan is up to date. 

If your cat is vomiting bile and seems unwell in other ways, seek veterinary attention. Other symptoms may include diarrhoea or constipation, a change to appetite or thirst, weight loss, hiding away and lethargy. 

If your cat is vomiting regularly, despite no other symptoms, it is also recommended to take your cat for a veterinary check-up. There is a fairly common belief that cats are generally ‘sicky’. But cats should not be vomiting regularly, and investigations should be made into an underlying cause.

Vomiting bile: final thoughts

Bile is a digestive juice, which is produced in the liver and then released by the gall bladder after a meal to aid digestion. However, if there is no food ingested to stimulate this, bile can build up in the gall bladder and then overflow into the stomach, causing irritation and then vomiting. Vomiting bile (small amounts of yellow liquid) is therefore caused by an empty stomach, either due to irregular feeding or due to illness causing problems with food intake or transit. If your cat is regularly being sick, or has other symptoms, make an appointment with a veterinary surgeon. 

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