Catalyst Progesterone - Simplifying the Canine Reproductive Cycle Using the Concentration of Progesterone

Oct 12, 2026

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Catalyst Progesterone explains how progesterone concentration (PC) testing supports accurate reproductive consultation in bitches when behavioral signs and clinical experience are insufficient. It contrasts slow lab progesterone turnaround with point-of-care (in-house) assays that deliver immediate results during the patient visit. The content outlines estrous-cycle timing challenges, links PC trends to key events, including LH peak and ovulation, and discusses why mating-time optimization improves pregnancy rates, travel planning, assisted breeding scheduling, and reduces unnecessary male exposure.

LanguageEnglish

CategoryGeneral

FormatPDF

Pages6

Reading Time2 min

AccessFree to download

Introduction

Progesterone assays and point-of-care testing

Estrous-cycle timing challenges

Hormonal events during the heat cycle

Other monitoring methods for estrous cycle

Catalyst® Progesterone Simplifying the Canine Reproductive Cycle Using the Concentration of Progesterone Kurt De Cramer, BVSc, MMedVet (Gyn), PhD Rant en Dal Animal Hospital Introduction Many veterinary practitioners have limited access to bitches that are in estrus and they may lack the experience to interpret reproductive examinations such as vaginal speculum examinations and vaginal smears. Progesterone concentrations (PC) can aid both experienced and less experienced practitioners with reproductive consultations. Progesterone assays have been available from commercial laboratories for some years, but the turnaround time impedes their usefulness in cases where immediate clinical decisions need to be made. Point-of-care (in-house) progesterone assays are now available , allowing for immediate results within the patient visit. Experienced dog breeders are aware of the value of progesterone testing. It is recognized that in the dog up to 75% of failures to conceive can be attributed to incorrect timing of breeding. The reason it is so difficult to time ovulation in the absence of hormone testing is that the stages of the canine estrous cycle vary considerably in length. Proestrus is defined asthe period from onset of vulvar bleeding to the first acceptance of copulation ; its duration averages 9 days , but it can range from 1–27 days in extreme cases.1 Proestrus is followed by estrus. Estrus refers to the stage where the bitch shows outward signs of receptivity , and it is the stage during which the bitch allows mating. Estrus averages 9 days , but it can range from 3–21 days in extreme cases.2 These extreme variations have led to the belief that the bitch’s heat cycle is very elastic and variable. It is only in late estrus that the bitch ovulates and that , a couple of days later, eggs become fertilizable. Fertilization typically occurs between 3–4 days before the end of estrus. The problem is that in observing a bitch during her heat cycle, there is no way of knowing when the end of estrus will be. To complicate matters, some bitches may bleed throughout their entire heat period , whereas other may not. Furthermore, some bitches may stand for a stud willingly, even long before there are eggs available for fertilization, whilst others may only be receptive for a day or two. Certain bitches may not be willing to stand for a stud at all because they only stand for a particular stud. There are many other variations and idiosyncratic behaviors that can confuse the breeder, all contributing to a missed opportunity to breed the bitch successfully. It is also a common misconception among breeders that the duration of the different stages within a heat cycle and the point at which a bitch will allow copulation replicates itself in each repeating heat cycle of each individual bitch. The breeder then uses the data from a previous cycle and applies it to the next cycle . For instance, because a bitch was previously successfully bred on day 10 (starting from first signs of heat), the breeder will keep on mating that specific bitch on day 10. While this might work in some cases, it most certainly won’t work in all cases. Similarly, it is not always true that the stud can sniff out exactly when the bitch is at her peak (optimum time for fertilization) . More precise timing of the breeding events is required when there is limited access to the stud, when artificial reproductive techniques are going to be used, or when the quality of the semen is questionable. The ability to accurately time breeding is of practical and economic importance to breeders. Optimal timing helps breeders in the following ways: • Maximizes pregnancy rates and litter size (Semen and stud fees are expensive .) • Allows the breeder to plan travel for matings • Allows optimization of time for assisted breeding techniques (artificial insemination [AI] using fresh, chilled , or frozen sperm) • Allows optimization of time for breeding when access

FAQs

How does progesterone concentration relate to ovulation timing?

Progesterone rises just before ovulation; around 2 ng/mL it coincides with the LH peak, and ovulation occurs about two days later when progesterone levels reach roughly 5–8 ng/mL. Fertilizable eggs appear after additional maturation time.

Oct 12, 2026

Upload by noah