Vascular access is the first and most basic requirement for successful extracorporeal renal replacement therapy (ERRT). Dual-lumen catheters are the most commonly used method of vascular access for ERRT in veterinary patients. An adequately functioning dialysis catheter allows for smooth and efficient patient management, whereas a poorly functioning catheter frustrates the technician, doctor, and patient. These catheters are fairly quick to place but require meticulous care for optimal function. The most common complications are thrombosis and infection. Monitoring catheter performance should be a routine part of dialysis patient care.