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Why Did My Cat Throw Up Yellow Liquid? 5 Possible Reasons

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Reviewed & Fact-Checked By

Dr. Nia Perkins

Vet, DVM

The information is current and up-to-date in accordance with the latest veterinarian research.

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Your cat vomiting can be concerning, but it may alarm you when they throw up yellow liquid. This colorful concoction surely could not be good, right? While yellow vomit looks incredibly unnatural, all it means is that it is mostly bile.

Bile is a digestive fluid secreted into the stomach to break down food for digestion. It’s produced by the liver and stored in the liver and is naturally yellow due to a pigment called bilirubin. Bilirubin and green biliverdin are what gives feces its characteristic brown color. Yellow vomit is just composed of bile, and a few key things can cause this.

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Reasons Why Cats Throw Up Yellow Liquid

1. Empty Stomach

Cat vomiting
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If your cat vomits on an empty stomach, bile is all that will be ejected. Without any solids, the vomit will be yellow liquid. This can happen if the vomiting occurs first thing in the morning after a long period without eating.

The cause of vomiting can be hard to pinpoint; it may indicate a health issue or just a passing gastrointestinal irritation. Look for any other signs to see if your cat needs to see a veterinarian.

Other signs/symptoms:
  • They haven’t eaten in a while
  • No other signs are present
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2. Hairball

Excess loose hair in the digestive tract can accumulate with digestive troubles, causing a blockage. Usually, hairballs can be brought up with vomit, but they can impact the intestines in rare cases and require surgical removal.

Often when hairballs are brought up, they are accompanied by yellow foamy bile. If your cat is vomiting yellow liquid, they may be attempting to bring a hairball up but are unsuccessful. Monitor your cat closely to see if they continue to struggle; they may need urgent veterinary care.

Other signs/symptoms:
  • Vomiting after eating or drinking
  • Wheezing and gagging
  • Bowel difficulties
  • Enlarged abdomen
  • Weakness
  • Physical hairball regurgitated
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3. Hyperthyroidism

Sick cat medicines
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Hyperthyroidism is common in cats, and it’s defined by an overproduction of thyroid hormones from an enlarged thyroid. Some of those hormones are involved in the bile synthesis in the liver and increasing the liver’s enzymes.

Excess bile build-up can cause digestive upset, with subsequent vomit having a large amount of yellow bile.

Other signs/symptoms:
  • Weight loss
  • Excessive hunger
  • Increased thirst
  • Hyperactivity
  • Poor coat condition
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4. Acid Reflux

Cats have a similar digestive tract to us humans, and they can suffer from similar digestive alignments. Many of us are familiar with acid reflux, commonly known as heartburn. Acid reflux is the backflow of bile acids into the esophagus instead of progressing to the intestines for processing. The stomach has a large amount of bile, and most of this is reabsorbed back into the bloodstream.

Acidic or fatty foods, large meals, or genetic predisposition can all contribute to a cat having issues with acid reflux. If your cat vomits, they may bring up some excess bile, causing the yellow color. The best way to clean up bile is with an enzymatic cleaning spray to ensure all stains and odors are removed.

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Other signs/symptoms:
  • Reluctance to eat
  • Discomfort after eating
  • Weight loss
  • Regurgitation
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5. Hiatal Hernia

tired sick cat lying on bed
Image Credit: Natata, Shutterstock

Hernias occur when an organ or fat squeezes through a weak point in muscles or connective tissue. A hiatal hernia is when the stomach is pushed through a gap in the diaphragm. This pressure around the stomach and near the esophagus can cause increased acid reflux rates and nausea, which may be seen as bile in the vomit.

Some hiatal hernias are very mild and don’t require treatment beyond managing reflux. In more severe cases, surgery is required. Hernias can occur in various regions of the body and cause various health concerns. Hernias in areas near the stomach can also produce irritation that causes bile to be expelled.

Other signs/symptoms:
  • Bloating
  • Gas (burping)
  • Difficulty swallowing
  • Loss of appetite

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Final Thoughts

Yellow vomit is a standard occurrence when the vomit is mostly constituted of bile. But vomiting bile is unusual unless they are vomiting on an empty stomach. This can occur when they haven’t eaten in a while or after a period of normal vomiting. Pinpointing the exact issue is impossible for the ordinary owner. Be aware of the potential causes and their symptoms so you can monitor your cat for any signs.

Ultimately, any cause for concern should be immediately directed to your veterinary professional.

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Featured Image Credit: ANASTASIIAKU, Shutterstock

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