SurgiVet Central Venous Seldinger Catheter Sets. Used for venous pressure monitoring, blood sampling and administration of drugs and fluids. Intended to be introduced using the Seldinger Introduction Technique. Use of the “J” wire guide that is included allows you to pass the catheter into specific vessels which cannot be achieved with a catheter alone. Sterile. Each set contains a polyurethane catheter, vessel dilator, “J” wire guide and needle. Feline sizes: CVS301J 3Fr or CVS401J 4Fr. Canine sizes: CVS501J 5Fr.