When timing your bitch’s breeding, progesterone and LH are important to know when to breed. Progesterone timing is most commonly used, but we do have an LH test available. LH is day 0 of the cycle. It is used to time the date of parturition. All Pets Vet Hospital has an in-house kit for LH testing from Zoetis. For this test, blood must be drawn daily and at approximately the same time each consecutive day. This test is only measurable for a short period of time and can be easily missed.