How to tell if a cat is vomiting bile?
The best way to determine if your cat is vomiting bile is to take a look at its color. Bile vomit is usually light green or yellow, and it might have foamy appearance. The cat might only vomit once, or the vomiting might become frequent if there is an underlying condition causing it. The vomit could contain food or it can be just fluid .
Bile is a yellow-green fluid that is produced by the liver. From liver, bile travels to a system of bile ducts to the gallbladder, where it gets stored. When food is ingested, bile is released in the small intestine. It helps to emulsify fat, so that it could be further processed in the intestines. Bile also helps to clear waste products out of the body with feces and urine.
If a cat is vomiting bile, it means that the bile travels from small intestine to the stomach, which is abnormal. Bile irritates the mucosa of the stomach, which leads to vomiting. Vomiting of bile usually occurs in older cats, especially if the cat is only fed once a day .
Cat Vomiting Bile Causes
Most cats vomit from time to time. Most often, vomiting is not a health concern and is caused by overeating or consuming meal too quickly. Cats can also vomit if they have eaten something unsuitable, or have played straight after eating. Still, there are also diseases that can cause the cat to vomit:
- Lack of food, if cat doesn’t receive frequent meals
- Bacterial infection
- Food intolerance
- Foreign bodies in the digestive tract- toys or hairballs
- Kidney failure
- Liver failure
- Gallbladder inflammation
- Toxins or chemicals
- Post-operative nausea
- Viral infections
- Irritable bowel disease
- Thyroid disease [2,3]
The cat might vomit bile only once, or it can be a chronic occurrence. If the vomiting of bile is caused by an underlying condition, there are usually other accompanying symptoms:
- Typically occurs late at night or early in the morning before eating
- Weight loss
- Blood in vomit
- Changes in appetite and water intake, usually avoids eating and drinking
- Stomach tenderness
- Unusual behavior- the cat doesn’t move, or is hiding 
If the previously mentioned signs are present, medical help should be sought.
To make the right diagnosis, proper examination and different tests should be performed.
Before examining the cat the doctor might ask you about previous medial history, vaccinations, the weight of the cat and medications that are used. The doctor might also ask about when the symptoms started, about recent changes in the daily routine and possible causes.
Physical examination includes weighing the cat, measuring the body temperature, checking heart and respiration. The doctor will also look in the cat’s mouth, palpate the abdomen and check for signs of dehydration .
Diagnostic tests include:
- Testing feces for parasites and bacteria
- Blood analyses- complete blood count, chemistry panel
- Special blood tests in case specific diseases are suspected
- X-ray imaging can detect a foreign body, tumor or other anatomical problems
- Barium study can show problems of motility
- Ultrasound imaging is also often used
- In some cases, endoscopic examination is used
- Surgery can be used as a treatment and diagnostic option.
- Biopsy, if a specific organ involvement is suspected 
Treatment of Cat Vomiting Bile
The treatment mostly depends on the cause of cat vomiting bile. In some cases, the exact cause remains unknown and different remedies can be used. also, the duration of treatment mostly depends on how the cat responds to it. Most commonly used treatments are:
- Medications to lower stomach acid secretions. This can reduce the acidity in stomach from acid and bile, preventing vomiting
- Medications to improve gastric motility, which prevents the bile to travel to the stomach
- Dietary changes
- Smaller meals, given more frequently
- Avoiding foods that the cat might not tolerate, for example, if something has been recently added to the cat’s diet
- Liquefying food- solid foods need longer time to be digested
- Diet lower in fat and rich in fiber
- Giving the cat strong peppermint tea- this home remedy can be helpful if the vomiting of bile occurs occasionally, as an isolated event
- Rehydration- in cases where cat is dehydrated, has a fever and is not drinking on its own
- Antibiotics- if a bacterial cause is detected
- Antiparasitic drugs
- Viral infections are usually treated with fluids. Antibiotics are sometimes given to prevent secondary bacterial infection
- Surgery- if an anatomical problem is causing the vomiting
- Chemotherapy- used in case of cancer .
- General information on Cat vomiting bile: http://www.petmd.com/cat/conditions/digestive/c_ct_bilious_vomiting_syndrome