All cat parents are likely to encounter vomiting in their feline friends on some occasions.
It’s important to understand that vomiting isn’t normal in cats. It always occurs for a good reason, and it requires you to observe your cat carefully.
You should pay attention to how many times your cat has vomited and inform your veterinarian about it. Also, it’s essential to report any other clinical signs, if you have noticed any.
The color of your cat’s vomit is also important here. A cat’s vomit is usually clear, whitish, or slightly yellow.
However, other colors such as green are also possible to notice. This unusual vomit color can make you even more worried about your cat’s health.
Why is my cat throwing up green liquid? There are five common reasons for this. Let’s look at them and discover the best ways to help your pet.
1. An Empty Stomach
Green liquid vomiting in your cat can signify that it’s hungry. This means that your cat is either not getting enough food or not eating often enough.
Lack of sufficient nutrients leads to your cat feeling nauseous and vomiting up stomach bile, resulting in green liquid vomiting.
This does not indicate any severe health issues in your cat, however, this isn’t a good sign, either.
For your cat to be healthy, it needs to have an adequate amount of food daily. Quality food is essential for its physical activities, normal bowel movements, good mood, and its health in general.
How To Help?
To prevent vomiting green liquid due to hunger, it’s essential you provide your cat with an adequate amount of food every day.
There isn’t a single definition here that’s the same for all cats. This depends on a cat’s age, size, and activity level.
If you have two cats, you can notice that their food requirements may be different.
For instance, young kittens typically require around 300 to 500 calories per day, but these requirements change as the kitten grows.
The Preventive Vet suggests that an adult cat needs about 20 calories per pound of body weight a day.
Larger cats like Maine Coons, for example, will, of course, demand a lot more food than a smaller breed like a Siamese.
Furthermore, a cat that prefers to lay around all day will need fewer calories than one that spends most of its time jumping and climbing around.
Here it’s also essential to be sure that your cat is entirely healthy. Perhaps it isn’t hungry because you’re not giving it enough food, but because it can’t eat due to a certain medical condition.
To resolve your doubts, the best thing to do here is consult a veterinarian. You can also ask for advice on a desirable amount of food and daily meals for your furry friend.
2. Green Plants Or Green Food Ingestion
Another possibility for your cat to throw up green liquid is the ingestion of food with a green dye. Or, your cat could have eaten too much of a certain green plant.
This reason isn’t something to be worried about. Most likely, this will be a one-time thing.
However, you should still be careful about your cat eating anything other than meat. In the long run, this could harm its digestive system and disturb its overall health.
How To Help?
Not all plants are dangerous or potentially poisonous for your cat.
Spinach, for instance, can even be beneficial for its health. It’s low in calories, and rich in vitamins, minerals, and fiber.
Still, cats are obligate carnivores and don’t actually need plants in their diet. The best type of diet for them is one based on animal protein.
Plants are something your cat shouldn’t eat often, especially not regularly.
Nothing can substitute meat and its benefits for a cat’s gastrointestinal health and its well-being in general.
3. Inflammatory Bowel Disease (IBD)
If you have noticed chronic vomiting of green liquid in your cat, this can be a sign of a medical condition called Inflammatory Bowel Disease.
According to Albert Jergens  clinical signs like vomiting, weight loss, and diarrhea are predominant with this health problem. Mucosal inflammation may also occur in any part of a cat’s GI tract, especially in the small intestine.
Affected cats can also experience inflammation in other organs, such as the liver and the pancreas.
IBD in general can be described as a disorder in a cat’s gastrointestinal tract.
There are a couple of potential causes of this condition:
• Parasite infection
• Bacterial infection
• An intolerance to a specific protein in a cat’s diet
How To Help?
The veterinarian will need to perform an ultrasound of your cat’s stomach to confirm the IBD diagnosis.
The treatment for IBD includes dietary changes, deworming, or the use of immunosuppressive medications.
Many cats respond well to treatment and maintain a good quality of life. However, some aren’t as fortunate, and will even need to be euthanized because their health will be too disrupted.
4. Ingestion Of A Toxic Substance
Excess green liquid vomiting could point to another severe cause – ingestion of a toxic substance.
Cats are extremely curious and love to investigate their surroundings. While doing this, they enjoy sniffing and licking things, potentially causing them to ingest a certain toxic substance.
According to Dunnellon Animal Hospital, the following are the common signs of cat poisoning:
• Vomiting and diarrhea
• Excessive drooling
• Breathing difficulties
• Skin inflammation
• Shock or collapse
There are many ingredients in your kitchen that are poisonous to your cat, such as chocolate, alcohol, grapes, and onions.
Of course, there are also chemical substances like medications, bleach, disinfectants, and pest control chemicals.
How To Help?
As soon as you notice any of the previously mentioned signs, you need to take your cat to an emergency vet.
You’ll also need to provide a veterinarian with information on how long your cat has been vomiting, and what could potentially cause poisoning in it.
The recovery will depend on how much the poisonous substances your cat has ingested. Also, the moment you notice the first symptoms is crucial, as well as how quickly you have taken it to the vet.
5. Gastrointestinal Obstruction
Finally, vomiting green liquid in cats can be a sign of gastrointestinal obstruction.
This is a very serious condition that can even be life-threatening for felines. According to PetMD, a gastrointestinal obstruction occurs when nothing can pass through the cat’s intestines.
This means that all the content from its intestines will go back up to its stomach, causing it to vomit green liquid.
Additional clinical signs to watch out for include lethargy, hiding behavior, diarrhea, and abdominal pain.
This obstruction is a surgical emergency that, if left untreated, can result in a cat’s death.
How To Help?
Veterinarians typically induce vomiting to treat gastrointestinal obstruction. This should help if a cat has swollen a foreign object that’s blocking its intestines.
Also, they may use an endoscopy or even decide on a laparotomy, which is surgery under general anesthesia.
A cat will also get IV fluids and medications for pain and nausea.
Why is your cat throwing up green liquid?
This could indicate that your cat hasn’t eaten for too long. It needs to get food more frequently, or a larger portion of meals to prevent this type of vomiting.
Another possibility is that your cat has eaten some green-colored food, or even plants. It’s necessary to make sure that the animal protein makes up the majority of your cat’s diet.
There is also a chance for certain underlying health issues causing your cat to vomit green liquid.
The most common ones are IBD, poisoning, and gastrointestinal obstruction.
If you notice any additional clinical signs you should take your cat to a veterinarian as soon as possible.
Bear in mind that vomiting isn’t normal in cats and always shows some kind of change in their gastrointestinal system.
 Jergens AE. Feline idiopathic inflammatory bowel disease: what we know and what remains to be unraveled. J Feline Med Surg. 2012 Jul;14(7):445-58. DOI, Retrieved November 9, 2023.