A dog throwing up yellow bile is likely to have gastrointestinal problems, or stomach reflex, according to PetMD. Stomach and intestinal reflux occurs when a dog's stomach is empty for a long period of time.
PetMD also states that vomiting bile is known as bilious vomiting, and it occurs when bile enters the stomach, causing intestinal and stomach issues. Bile itself serves the role of digesting food and ridding the body of waste. It usually has a yellow-greenish appearance and a watery texture. If bile remains in a dog's stomach without vomiting, it can lead to gastric reflux.
Vet Info highlights that vomiting bile can be symptomatic of a larger problem, such as intestinal parasites or stomach ulcers. However, Vet Info adds that throwing up is common in dogs if they ingested a harmful substance or object. Pet owners should be worried if the dog is frequently vomiting.
Bilious vomiting normally occurs during the morning or late evening since the stomach tends to be empty during those hours. Weight loss and lack of appetite are also prominent factors. A veterinarian may place the dog on a special diet of canned or liquid food during the recovery phase.
Vet Info also notes that a dog's normal diet may be a primary cause of bilious vomiting.