Parasites

• Parasites can cause hematemesis a number of different ways. Extensive fecal testing must be performed to detect the presence of parasites, determine the type of parasite and the necessary treatment requires. Parasites are more commonly the cause of hematemesis in puppies than adult dogs.
  
  

Infection Or Inflammation

• Blood in your puppy's vomit could be caused by the esophagus becoming inflamed or infected. Your veterinarian will perform a complete blood count (CBC) test to determine the presence of inflammation or infection. Once diagnosed, your puppy might require antibiotics or surgery to remedy the situation.
  
  

Kidneys

• Hematemesis can be caused by severe metabolic problems with the kidneys. Testing of the kidneys will also help the veterinarian determine how dehydrated your puppy has become from vomiting. Testing the kidneys can involve biochemical profiling and a urinalysis.
  
  

Foreign Body

• The presence of a foreign body in your puppy's abdominal organs such as a tumor or lead chips can cause hematemesis. An abdominal radiograph, or X-ray, will determine if there is such a presence and will reveal the severity of the problem.
  
  

Other Causes

• Less common causes of blood in your puppy's vomit can be determined by testing usually done on a case-by-case basis. Liver failure, lead in the blood, cancer, blood in the lungs and esophageal diseases are all potential causes of hematemesis.