There are a number of reasons why a cat vomits, and many of these reasons are harmless. Cats may vomit because of hairballs or overeating, and this may be an occasional occurrence. When there is yellow liquid in the vomit, usually bile from the stomach, this may a condition that requires more concern.
Yellow vomit can be from a number of causes, but if the yellow liquid is bile, gastritis is the likely cause, and this is an inflammation of the stomach lining. Inflammatory bowel disease may cause vomiting, and may be the result of an allergic reaction to food. f your cat started a new medication and the vomiting began shortly after, then he may have an allergic reaction to the drug. There are some possible causes that may not be associated with the stomach, for example kidney disease, liver failure, pancreatitis and heartworm.
Vomiting may be your cat's only symptom, but it's important to keep watch for any changes in behaviour or health. Watch for signs of blood in vomit and monitor him for weight loss, painful areas, diarrhoea and lethargy. If any other symptoms appear, or the vomiting does not improve, contact your veterinarian for a thorough evaluation of your cat.
Your veterinarian will ask you questions about your cat, including the way in which he brings up the liquid. "Vomiting is an active process," says University of Washington's College of Veterinary Medicine, and regurgitation takes little effort. This is valuable information for your veterinarian since it will help her determine the cause. Your veterinarian will examine your cat for signs that your cat ingested a foreign object, such as string or plastic. If no signs are evident, she will likely run blood, urine, and faeces tests to determine any abnormalities, and possibly check for heart worm. Other testing may include X-rays or ultrasounds if necessary.
Treatment will vary and depend entirely on the diagnosis. If gastritis, the most common cause of vomiting, is determined to be the cause, your veterinarian may give your cat mediation to help control the vomiting, and may also recommend that your cat not eat or drink anything for a specified amount of time. Reintroduce water and bland food slowly to your cat.
To help with diagnosing your cat's condition, you may want to bring in a sample of your cat's vomit for your veterinarian to examine. If your cat has unusual behaviour before, after, or during an episode of vomiting, you may want to record this on a video to show your veterinarian.