Pregnancy Relaxin (RLN) Test Kit (Colloidal Gold) Cat. No.: HCY-CY-RLN-10 Size: 10 Tests Storage: 4-30°C Assay time: 10-15 minutes Infection type: Relaxin (RLN) Infected Animal: Feline & Canine Sample for test: Whole blood/ serum Relaxin (RLN) is a hormone produced by the developing placenta following the implantation of the embryo in canines and felines. It is produced to relax the pelvis ligaments to prepare the canine or feline for labour. Therefore, Relaxin can be used as an accurate pregnancy test in both canines and felines. The Pregnancy Relaxin test kit can accurately detect if your pet is pregnant as early as 22-27 days post-breeding using a serum or whole blood sample.