A dog throwing up yellow foam or bile might simply be hungry; when the stomach is empty, gastric acids irritate the stomach lining, causing nausea. However, yellow vomit can also be caused by an illness or something your dog has ingested, so it's important to not dismiss yellow vomit as a sign of hunger.

If your dog just throws up once and otherwise appears fine, it's usually nothing to worry about. However, if your dog shows other signs of illness, it's a good idea to contact your veterinarian. Here are some of the common reasons why dogs throw up yellow foam, bile, or liquid, as well as treatment and prevention of vomiting.

Why Do Dogs Vomit Yellow Bile?

When dogs vomit yellow liquid, it may simply be that the stomach is empty of food. However, yellow vomit may also be related to an illness. Yellow-colored vomit generally consists of stomach acids and bile. It may be thin and watery, foamy, or thick and slimy.

Stomach acids are produced in the stomach lining to aid in digestion, and bile is a fluid produced in the liver and stored in the gallbladder. The bile enters the duodenum (a section of the small intestine located just past the stomach) to further assist with digestion. These gastric acids can irritate the stomach lining when not buffered by food, causing the dog to vomit.

This explains why some dogs will throw up when they are especially hungry. However, there are other problems that can make dogs vomit, so don't overlook your dog's yellow vomit just yet.

Note that yellow liquid may not just be stomach acid and bile; it may be that your dog ate something yellow in color and cannot digest it. There are numerous reasons why your dog is vomiting yellow foam or liquid. In some cases, the vomiting will resolve on its own. However, vomiting of any kind can indicate a more serious illness, especially if it occurs frequently.

Some possible reasons for yellow vomit include bilious vomiting syndrome, indigestion, liver disease, and more.

Bilious Vomiting Syndrome

Also called reflux gastritis, bilious vomiting syndrome is a fairly common cause of vomiting, particularly in older dogs. Dogs with this condition typically vomit yellow bile in the morning before they have a chance to eat breakfast, but act normally after eating. The condition is caused by stomach irritation due to bile. It can often be prevented by feeding the dog a small meal before bedtime, and providing breakfast right away in the morning so the dog doesn't have an empty stomach for long. If that doesn't help, your vet might prescribe an antacid.

Indigestion

Dogs are prone to eating things that really shouldn't qualify as food. If your dog ate something spoiled or overly rich from the trash, grazed on grass, devoured something unpleasant off the ground, or managed to eat from the cat's litter box, the result can be a bout of vomiting. Occasionally, that vomit will contain foamy yellow bile. This is generally a self-limiting event unless your dog continues to eat things they shouldn't.

Pancreatitis

Pancreatitis is an inflammation of the pancreas, a part of the digestive system. It usually occurs after a dog eats an especially rich, fatty meal. Along with vomiting yellow bile, your dog will usually have diarrhea and appear to be in severe pain. Pancreatitis requires a visit to the veterinarian for advice and treatment.

Intestinal Blockage

A dog can get an intestinal blockage by eating a foreign object, such as a toy, bone, or scrap of fabric. Initially, the dog will vomit up food, but once the stomach is empty, the dog may vomit yellow bile. Your dog may also appear to be in pain, seem weak or lethargic, stop eating, and may be unable to pass stool. Intestinal blockages often require surgery, although occasionally the veterinarian can remove the blockage with an endoscope passed through the throat into the animal's stomach.

Toxin Exposure

Sometimes a dog will throw up yellow bile after eating a toxin, such as chocolate, medications, or toxic plants. There will usually be other symptoms, including shivering or trembling, weakness, diarrhea, loss of appetite, or intestinal pain. Should your dog show these symptoms, and especially if you suspect they ate something toxic, call your veterinarian immediately.

Systemic Illness

A dog with a systemic illness, such as kidney disease, liver disease, Addison's disease, or other chronic conditions, might vomit yellow liquid due to digestive disturbance or nausea brought on by the condition. Your veterinarian can advise on the best ways to handle these types of health conditions.

What to Do If Your Dog is Vomiting Yellow Bile

If your dog vomits yellow foam or liquid just once, there is no need for alarm. However, there are some steps to take:

• Watch your dog for lethargy, diarrhea, loss of appetite, weakness, and other signs of illness.
• If your dog seems otherwise normal, feed the next meal as scheduled and watch for more vomiting.
• If the vomiting continues, skip your dog’s next meal and continue to observe.
• Offer the next scheduled meal after skipping one and continue to watch for vomiting and other signs of illness.
• If the vomiting continues or your dog has other symptoms, you should contact your veterinarian for advice.

Treatment for Vomiting in Dogs

Your veterinarian will first perform a thorough examination of your dog and discuss their medical history. Include information about current medications and diet and remember to share information regarding anything you think your dog might have eaten, such as plants, chemicals, or dangerous foods.

Your vet may recommend diagnostic tests to look for the source of the vomiting. This usually means may include blood and urine testing, radiographs (X-rays), and possibly ultrasounds.

If your vet suspects bilious vomiting syndrome, they may recommend feeding a small meal before bed and offering breakfast first thing in the morning.

For ongoing vomiting, treatment usually starts with the administration of anti-nausea medications, antacids, or GI-protectant drugs. Where possible, the first doses may be given via injection to avoid further vomiting. Continuous vomiting frequently results in dehydration, and fluid therapy is often recommended. Subcutaneous fluids or intravenous fluids are recommended based on the severity of dehydration. 

Severe dehydration and other concerns like pancreatitis, systemic illness, and infectious diseases may require hospitalization. Dogs generally get intravenous fluids and frequent medication dosing while being observed in the hospital.

If the vomiting is a result of poisoning, your vet will follow recommended treatments for the specific toxin. This may also call for hospitalization.

If your vet suspects a GI obstruction, then the next step may be surgery or endoscopy to explore the GI tract and remove the obstruction. A hospital stay will be needed for post-operative care.

How to Prevent Vomiting in Dogs

The best way to prevent vomiting is to keep your dog away from items he should not eat, lick, or chew.  Of course, sometimes there is no way to prevent vomiting in your dog since many illnesses occur with no known cause.

The good news is that there are a few things you can do to minimize the risks of vomiting in dogs.

• Bring your dog to the vet for routine wellness check-ups every year (or more if recommended by your vet).
• Feed a proper diet and keep treats to a minimum.
• Keep plants, chemicals, human food, and any other toxins out of reach.
• Monitor your dog while they are playing with chew toys, especially if they like to destroy toys.
• Prevent your dog from licking, chewing, and eating dangerous things.

Remember to contact your veterinarian in the early signs of illness; delaying can only make things worse. When in doubt, head to the nearest open vet office.