Many conditions of pediatric patients require fluid therapy. Depending on the veterinarian’s assessment of hydration and perfusion status, fluids can be administered orally, subcutaneously, intraperitoneally, intravenously, or by the intraosseous route. Pediatric patients are prone to hypothermia, hypovolemia, hypoglycemia, and hypokalemia, which must be addressed during fluid therapy in pediatric patients. Typical parameters used to assess hydration status in adult animals do not always apply to pediatric patients. Veterinarians should be aware of differences between pediatric patients and adult animals in terms of physical assessment, common presentations, and fluid requirements for resuscitation and maintenance needs.