Vomiting + Diarrhea

Although the most common cause of vomiting and diarrhea in companion animals is dietary indiscretion (eating anything that is not dog food), there are many possible causes. A veterinarian will use the signalment, the history and physical exam to help rule out many possible causes. This will often times lead to the recommendation of further diagnostics which may help determine a cause and guide the correct route of treatment for your pet.

Some causes of vomiting and/or diarrhea:


  • Developmental, i.e., pyloric hypertrophy
  • Neoplastic, i.e., adenocarcinoma,
  • Infectious–Helicobacter-associated
  • Inflammatory, i.e., all forms of gastritis
  • Iatrogenic–gastric ulceration
  • Foreign body ingestion


Small intestinal

  • Macroparasites
  • Microparasites–viruses, bacteria
  • Neoplastic–lymphoma
  • Immune-mediated–IBD
  • Ileus
  • Foreign bodies


Large intestinal

  • Obstipation secondary to megacolon
  • Colitis



  • Metabolic/endocrine
  • Diabetic ketoacidosis
  • Endotoxaemia/septicaemia
  • Hyperthyroidism
  • Hypercalcaemia
  • Hypokalaemia
  • Hypoadrenocorticism



  • Pancreatitis
  • Peritonitis, including FIP
  • Hepatobiliary disease
  • Renal failure
  • Pyelonephritis
  • Pain



  • Heartworm disease
  • Cystitis
  • Toxins/Drugs
  • NSAIDs, digoxin, chemotherapeutics etc.


If your pet vomits more than once in two hours, has been vomiting for more than six hours, you notice blood or the appearance of “coffee grounds,” is lethargic or disoriented, he should be seen by a veterinarian immediately.

If your pet has diarrhea for over 24 hours (without vomiting) or you notice it is very dark or may have blood in it, these are also indications to see a veterinarian immediately.

If your pet is vomiting or has diarrhea off and on for more than three days a veterinary consult is indicated.

If you are ever uncertain a call is advised and encouraged.